What does hyaluronic acid mean? Scientific review

Hyaluronic acid (HA), also known as (acid salt) or hyaluronan (a unifying designation for an acid and its salt), is an anionic natural polysaccharide (a non-sulfonated simple glycosaminoglycan), which is an important component of nervous, epithelial, connective tissues and the main ingredient of the extracellular matrix.

Hyaluronic acid is also part of many biological fluids inherent in living organisms (synovial fluid, saliva, etc.). This substance can be produced by certain bacteria (for example, streptococci ) and excreted from animal organs (rooster comb, vitreous body and cartilaginous tissue of cattle).

A human body weighing about 70 kilograms contains on average about 15 grams of this endogenous acid, a third of which is converted (broken down or synthesized) every day.

Structure and structure

The structural diagram of HA is characteristic of a linear polysaccharide, consisting of alternating residual parts N-acetyl-D-glycosamine And D-glucuronic acid, sequentially connected by β-1,3 and β-1,4 glycosidic bonds.

One molecule of this acid can include up to 25 thousand similar disaccharide units. HA of natural origin has a molecular weight varying between 5000-20000000 Da. In humans, the average molecular weight of the polymer found in the synovial fluid is 3,140,000 Da.

The acid molecule is energetically stable, including due to the stereochemistry of the disaccharides included in its composition. In the pyranose ring, bulky substituents are located in sterically favorable positions, while smaller hydrogen atoms are located in less favorable axial positions.

Education: Graduated from Vinnitsa National Medical University named after. N.I. Pirogova, Faculty of Pharmacy, higher pharmaceutical education – specialty “Pharmacist”.

Experience: Work in the pharmacy chains "Konex" and "Bios-Media" with the specialty "Pharmacist". Work as a Pharmacist in the Avicenna pharmacy chain in the city of Vinnitsa.

Comments

By the way, I also take hyaluronic acid in a tablet. By the way, Evalar is good, yes, but the effect is cumulative, you need to drink it for 2 months and don’t forget

There were many problems with the skin: it peeled, cracked, and wrinkles began to appear. Because of this, I decided to try hyaluronic acid in tablets, but I ended up taking it. I have already completed 6 courses, my skin has become much better, even the cold is no longer a problem.

Thanks for the good article. I myself have been taking hyaluronic acid for a long time. I tried both cream and injections, but settled on tablets. I think that this is still the most practical thing that has been created.

Molecular Formula: (C14H21NO11)n
Solubility in water: soluble (sodium salt)
LD50:
2400 mg/kg (mice, oral administration, sodium salt)
4000 mg/kg (mice, subcutaneous administration, sodium salt)
1500 mg/kg (mice, intraperitoneal administration, sodium salt)
Related compounds: D-glucuronic acid and DN-acetylglucosamine (monomers)
Hyaluronic acid (hyaluronate or HA) is an anionic, non-sulfated glycosaminoglycan, widely distributed in connective, epithelial and nervous tissue. It is unique among glycosaminoglycans in that it is a non-sulfated form, is formed in the plasma membrane rather than in the Golgi, and can reach very large sizes, with molecular weights often reaching millions. As one of the main components of the extracellular matrix, hyaluronic acid significantly promotes cell proliferation and migration, and may also be involved in the development of some malignant tumors. On average, a 70 kg (154 lb) person has about 15 grams of hyaluronic acid in their body, one third of which is replenished (degraded and synthesized) every day. Hyaluronic acid is also a constituent of the group A streptococcal extracellular capsule A, and is believed to play an important role in virulence (the degree to which a microorganism is pathogenic).

Medical use

Hyaluronic acid is sometimes used to treat osteoarthritis of the knee as an injection into the joint. The effectiveness of hyaluronic acid in this use, however, has not been proven, and such use may be associated with potentially serious side effects. Symptoms such as dry, scaly skin (xerosis) caused by, for example, atopic dermatitis (eczema) can be treated using a skin lotion containing sodium hyaluronate as an active ingredient. In some cancers, hyaluronan levels correlate with malignancy and poor prognosis. Hyaluronic acid is thus often used as a tumor marker to detect prostate cancer and breast cancer. The substance can also be used to monitor disease progression. Hyaluronic acid can also be used post-operatively to promote tissue healing, especially after cataract surgery. Current models of wound healing suggest using larger hyaluronic acid polymers in the early stages of healing to physically make room for white blood cells to mediate the immune response. Hyaluronic acid is also used in the synthesis of biological scaffolds for wound healing. These scaffolds typically contain proteins such as fibronectin attached to hyaluronic acid to facilitate cell migration into the wound. This is especially important for people with diabetes and chronic wounds. In 2007, the EMA extended its approval of Hylan GF-20 for the treatment of osteoarthritis pain of the ankle and forearm.

Functions

Until the late 1970s, hyaluronic acid was considered a “sticky” molecule, a common carbohydrate polymer and part of the extracellular matrix. Hyaluronic acid is the main component of synovial fluid, which increases the viscosity of the fluid. Along with lubricin, hyaluronic acid is one of the main lubricating components of the liquid. Hyaluronic acid is an important component of articular cartilage, where it serves as a coating around each cell (chondrocyte). When aggrecan monomers bind to hyaluronic acid in the presence of protein, large, highly negatively charged aggregates are formed. These aggregates absorb water and are responsible for the elasticity of the cartilage (its resistance to compression). The molecular weight (size) of hyaluronic acid in cartilage decreases with age, but its amount increases. Hyaluronic acid is also the main component of the skin and is involved in tissue repair processes. When the skin is overexposed to UVB rays, it becomes inflamed (sunburned) and cells in the dermis stop producing large amounts of hyaluronic acid and increase the rate of its degradation. After ultraviolet irradiation, hyaluronic acid degradation products accumulate in the skin. Present in abundance in the extracellular matrix, hyaluronic acid also affects tissue hydrodynamics, cell movement and proliferation, and is involved in a number of cell surface receptor interactions, including essential receptors, CD44 and RHAMM. CD44 stimulation is widely used as a marker of cell activation in lymphocytes. The effects of Hyaluronan on tumor growth may be due to its interaction with CD44. The CD44 receptor is involved in cell adhesion mediated interactions with tumor cells. Although hyaluronic acid binds to the CD44 receptor, there is evidence that HA degradation products transduce their inflammatory impulse through toll-like receptor 2 (TLR2), TLR4, or both TLR2 and TLR4 into macrophages and dendritic cells. Toll-like receptor and hyaluronic acid play an important role in the formation of innate immunity. High concentrations of hyaluronic acid in the brains of baby rats, and lower concentrations in the brains of adult rats, suggest that HA plays an important role in brain development.

Structure

The properties of HA were first established in 1930 in the laboratory of Karl Meyer. Hyaluronic acid is a polymer of disaccharides that are found in D-glucuronic acid and DN-acetylglucosamine, linked through alternating β-1,4 and β-1,3 glycosidic bonds. Hyaluronic acid can be made up of 25,000 repeating disaccharide units in length. HA polymers can vary in size from 5,000 to 20,000 thousand Da in natural conditions. The average molecular weight of hyaluronic acid in human synovial fluid is 3-4 million Da, and the molecular weight of hyaluronic acid isolated from human umbilical cord is 3,140,000 Da. Hyaluronic acid is an energetically stable substance, in part due to the stereochemistry of its constituent disaccharides. The bulky groups in each sugar molecule are in spatially favored positions, while the smaller hydrogen atoms occupy less favorable axial positions.

Biological synthesis

Hyaluronic acid is synthesized by a class of integral membrane proteins called hyaluronic synthases, three types of which are present in vertebrates: Has1, HAS2, and HAS3. These enzymes gradually lengthen gualuronan by alternately adding N-acetylglucosamine and glucuronic acid as it is expelled through the ABC transporter and through the cell membrane into the extracellular space. The synthesis of hyaluronic acid is inhibited by 4-methylumbelliferone (hymecromone, heparvit), a derivative of 7-hydroxy-4-methylcoumarin. This selective inhibition (without inhibition of other glycosaminoglycans) may be useful in preventing metastasis of malignant tumor cells. Recently, genetically modified (GMO) Bacillus subtilis has been developed to produce HA as a patented product suitable for human consumption.

Cellular receptors for hyaluronic acid

Currently, cellular GC receptors are divided into three main groups: CD44, receptor for HA-mediated motility (RHAMM), and intercellular adhesion molecule-1. CD44 and ICAM-1 were already known cell adhesion molecules with other established ligands before their binding to HA was discovered. The CD44 receptor is widely distributed throughout the body. A formal demonstration of HA-CD44 binding was proposed by Aruffo et al in 1990. Today, CD44 is recognized as the main cell surface receptor for HA. CD44 mediates the interaction of cells with GC and the coupling of the two functions as an important part in various physiological functions such as cell aggregation, migration, proliferation and activation; cell-cell and cell-substrate adhesion; endocytosis of GC, which leads to GC catabolism in macrophages, etc. Two significant roles for CD44 in skin processes have been proposed by Kaya et al. The first is to regulate keratinocyte proliferation in response to extracellular stimuli, and the second is to maintain local GC homeostasis. ICAM-1 (intercellular adhesion factor 1) is known primarily as a cell surface metabolic receptor for HA, this protein may be primarily responsible for the clearance of GC from lymph and blood plasma, and may account for the majority of total GC metabolism in the body. . Thus, ligand binding of a given receptor triggers a highly coordinated cascade of events that includes the formation of an endocytic vesicle, its association with primary lysosomes, enzymatic cleavage to monosaccharides, active transmembrane transport of these sugars in cell sap, phosphorylation of aspartic acid, and enzymatic acetylation. ICAM-1 may also serve as a cell adhesion molecule, and the association of GC with ICAM-1 may contribute to the control of ICAM-1-mediated inflammatory activation.

Split

Hyaluronic acid is broken down by a family of enzymes called hyaluronidases. There are at least seven types of hyaluronidase enzymes present in the human body, some of which are tumor suppressors. The breakdown products of hyaluronic acid, oligosaccharides and HA with very low molecular weight, exhibit proangiogenic properties. In addition, recent studies have shown that hyaluronic acid fragments can induce inflammatory responses in macrophages and dendritic cells at the site of damaged tissue and grafted skin.

Action

Wound healing

The skin provides a mechanical barrier to the external environment and acts to prevent the entry of infectious agents. Damaged tissue is susceptible to infection; therefore, rapid and effective treatment is critical to reconstruct barrier function. Skin wound healing is a complex process and involves many interacting processes mediated by hemostasis and the release of platelet factors. The next stages are: inflammation, formation of granulation tissue, epithelialization and reconstruction. HA likely plays a multifaceted role during these cellular and matrix processes. HA has been suggested to play a role in the healing of skin wounds.

Inflammation

Many biological factors such as growth factors, cytokines, eicosanoids, etc. are generated during inflammation. These factors are essential in subsequent stages of wound healing because they are responsible for the migration of inflammatory cells, fibroblasts and endothelial cells at the wound site. At the beginning of the inflammatory phase of the wound healing process, the damaged tissue is saturated with HA. This is likely a reflection of increased GC synthesis. HA acts as a stimulant in the early stages of inflammation and is critical in the healing process of all damaged tissue. To improve cellular infiltration, GC was observed in a mouse air sac model (preclinical studies; a cavity is created in the dorsal region of mice using subcutaneous injection of sterile air) of carrageenan/IL-1-induced inflammation. Kabashi and colleagues showed a dose-dependent increase in the production of the proinflammatory cytokines TNF-α and IL-8 by human uterine fibroblasts at HA concentrations ranging from 10 μg/ml to 1 mg/ml through a CD44-mediated mechanism. Endothelial cells, in response to inflammatory cytokines such as TNF-α, and bacterial lipopolysaccharides, also synthesize HA, which facilitates the primary adhesion of cytokine-activated lymphocytes expressing the GC-linked species CD44 under laminar and static flow conditions. It is interesting to note that HA has opposing dual functions in the inflammatory process. Not only can it promote inflammatory healing as stated above, but it can also induce a mild inflammatory response that can help stabilize the granulation tissue matrix.

Granulation and organization of granulation tissue matrix

Granulation tissue is a perfused, fibrous connective tissue that replaces the fibrin clot during wound healing. It usually grows from the base of the wound and can fill a wound of almost any size. HA is present in abundance in the granulation tissue matrix. The diversity of cell functions that is essential for tissue repair can be attributed to the GC-rich network. These functions include promoting cell migration in the pre-wound matrix, cell proliferation, and organization of the granulation tissue matrix. Initiation of inflammation is critical for the formation of granulation tissue, so the proinflammatory role of HA, as described above, also contributes to this stage of wound healing.

GC and cell migration

Cell migration is essential for the formation of granulation tissue. The early stage of granulation tissue development is mediated by a HA-rich extracellular matrix, which is considered to provide a favorable environment for cell migration within this temporary wound matrix. The role of HA in cell migration can be explained by its physicochemical properties as discussed above, as well as its direct interaction with cells. In the first scenario, HA provides an open water-containing matrix that facilitates cell migration, while in the latter case, directed migration and control of cell motor mechanisms are mediated through specific cell interactions between HA and cell surface HA receptors. As stated previously, the three major cell surface receptors for GC are CD44, RHAMM, and ICAM-1. RHAMM is more related to cell migration. It forms links with several protein kinases associated with cellular locomotion, such as extracellular regulated protein kinase (ERK), p125fak and pp60c-Src. During embryonic development, the migratory pathway through which neural crest cells migrate is rich in GA. HA is closely associated with the process of cell migration in the granulation tissue matrix, and studies suggest that cell movement can be inhibited, at least in part, by degradation of HA or by blocking HA binding to the receptor. Providing dynamic force in the cell, HA synthesis is also associated with cell migration. As a rule, HA is synthesized in the plasma membrane and released directly into the extracellular environment. This may promote hydration of the microenvironment at sites of synthesis, and is important for cell migration by promoting cell shedding.

The role of GC in regulating the inflammatory response

Although inflammation is an integral part of the formation of granulation tissue, for normal tissue repair, the inflammation process must be contained. Granular tissue is susceptible to inflammation and has a high metabolic rate mediated by the degradation of matrix enzymes and reactive oxygen metabolites, which are products of inflammatory cells. Stabilization of the granulation tissue matrix can be achieved by controlling inflammation. GC functions as an important factor in this moderating process, which is contrary to its role in inflammatory stimulation as described above. HA may protect against the harmful effects of free radicals on cells. In studies by Foshee D. and colleagues in a rat model, HA was shown to scavenge free radicals, thereby reducing the damage caused to granulation tissue. In addition to its free radical scavenging role, HA may also function in the negative feedback loop of inflammatory activation through its specific biological interactions with biological components of inflammation. TNF-α, an important cytokine generated during inflammation, stimulates the expression of TSG-6 (TNF-stimulating gene 6) in fibroblasts and inflammatory cells. TSG-6, a GC-binding protein, also forms a stable complex with serum proteinase inhibitor IαI (Inter-α inhibitor), exerting a synergistic effect on the plasmin-inhibitory activity of the latter. Plasmin is involved in the activation of the proteolytic cascade of matrix metalloproteinases and other proteins leading to inflammatory tissue damage. Thus, the action of TSG-6/IαI complexes, which may be further orchestrated by binding to GC in the extracellular matrix, may serve as a powerful negative feedback loop during mild inflammation and stabilize granulation tissue as healing progresses. In a mouse air sac model of carrageenan/IL-1 (interleukin-1β)-induced inflammation, where HA exhibited anti-inflammatory properties, reduction of inflammation could be achieved by administration of TSG-6. The result is comparable to systemic therapy with dexamethasone.

Reepithelialization

HA plays an important role in normalizing the epidermis. HA has important functions in the process of reepithelialization due to several of its properties. It serves as an integral part of the extracellular matrix of basal keratinocytes, which are the main components of the epidermis; HA serves to “cleanse” the skin of free radicals and plays a role in the proliferation and migration of keratinocytes. In normal skin, HA is found in relatively high concentrations in the basal layer of the epidermis, where proliferating keratinocytes are found. CD44 binds to GC in the basal layer of the epidermis, where it is expressed on the plasma membrane, encountering GC-rich matrix sacs. The main functions of HA in the epidermis are to maintain the extracellular space and provide an open and hydrated structure for the passage of nutrients. Tammy P. and other colleagues found an increase in HA levels in the presence of retinoic acid (vitamin A). The proposed effects of retinoic acid on photodamage and skin aging may be due, at least in part, to an increase in HA content in the skin, causing an increase in tissue hydration. It has been suggested that the free radical scavenging properties of HA contribute to solar protection, supporting the role of CD44 as a HA receptor in the epidermis. Epidermal HA also functions as a manipulator in the process of keratinocyte proliferation, which is very important for the normal functioning of the epidermis, as well as during epithelialization during tissue repair. During wound healing, HA is expressed at the edges of the wound, in the connective tissue matrix. Kaya et al showed that suppression of CD44 expression using a specific transgene results in GC deficiency and various morphological changes in basal keratinocytes and abnormal keratinocyte proliferation in response to mitogen and growth factors in animals. Decreased skin elasticity, impaired local inflammatory response, and impaired tissue repair were also observed. Their observations support an important role for HA and CD44 in skin physiology and tissue repair.

Fetal healing of wounds and scars

The absence of fibrous scars is the main sign of wound healing in the fetus. Even over longer periods, HA content in fetal wounds is higher than in adult wounds, suggesting that HA, at least in part, reduces collagen deposition and therefore leads to reduced scar formation. This suggestion is consistent with studies by West et al., which showed that GC withdrawal in adults and in the fetus during late pregnancy causes fibrotic scars.

Role in metastasis

Hyaluronic acid synthases (HAS) play a role in all stages of cancer metastasis. By producing anti-adhesive HA, GCS can allow tumor cells to free themselves from the primary tumor mass, and if HA binds to receptors such as CD44, GTPase activation can promote epithelial-mesenchymal transition (EMT) of cancer cells. During the processes of intravasation or extravasation, the interaction of GCs producing GC receptors such as CD44 and RHAMM provokes changes in cells that allow cancer cells to enter the circulatory or lymphatic systems. During movement in these systems, HA produced by GCS protects cancer cells from mechanical damage. Finally, in the formation of metastatic lesions, GCS produces GC to allow cancer cells to interact with native cells at the secondary site and produce tumor. Hyaluronidases (HAase or HYAL) also play multiple roles in the formation of cancer metastases. By helping to break down the extracellular matrix surrounding the tumor, hyaluronidases help cancer cells escape from the primary tumor mass and play an important role in invasion, allowing the breakdown of the basal lymphatic membrane or blood vessel. Hyaluronidases are involved in the creation of metastatic lesions by promoting extravasation and clearing the extracellular matrix. Finally, hyaluronidases play a key role in the process of angiogenesis. HA fragments stimulate angiogenesis and the hyaluronidases that produce these fragments. Interestingly, hypoxia also increases GC production and hyuloronidase activity. The hyaluronic acid receptors, CD44 and RHAMM, are the most extensively studied for their role in cancer metastasis. Increased CD44 expression clinically positively correlates with metastasis in a number of tumor types. CD44 affects the adhesion of tumor cells to each other and to endothelial cells, rearranges the cytoskeleton through Rho GTPase, and increases the activity of destructive enzymes of the extracellular matrix. Increased RHAMM expression has also been clinically correlated with cancer metastasis. Mechanistically, RHAMM promotes cancer cell motility through a number of pathways, including focal adhesion kinase (FAK), MAP kinase (MAPK), PP60 (c-SRC), and GTPases. The GC-induced motility receptor may also interact with CD44 to promote angiogenesis toward metastatic disease.

Hyaluronic acid injections

Hyaluronic acid is a common ingredient in skin care products. Until recently, hyaluronic acid fillers were injected using a classic sharp hypodermic needle. The needle passed through nerves and blood vessels, causing pain and bruising. In 2009, a new technique was developed in which the skin is pierced with a sharp needle, and then a microscopic hollow needle slides under the skin without piercing it deeper.

Additives in horse breeding

Hyaluronic acid is used to treat joint problems in horses, especially during competition or heavy work. GK is prescribed for carpal and hock dysfunction, in the absence of suspicion of sepsis or fracture. Often used for synovitis associated with osteoarthritis in horses. The substance can be injected directly into the affected joint, or intravenously for less localized disorders. May cause slight heating of the ligaments when injected directly, but does not affect clinical results. When administered intra-articularly, the drug is completely metabolized in less than a week. Please note that, according to Canadian regulations, hyaluronic acid, HY-50, should not be administered to animals intended for slaughter. In Europe, however, they do not believe that this drug has any effect or affects the taste of horse meat.

Etymology

Hyaluronic acid is extracted from hylos (Greek for "vitreous humor") and uronic acid, as it was first isolated from the vitreous humor and has a high uronic acid content. The term "hyaluronate" refers to the conjugate base of hyaluronic acid. Because the molecule typically occurs naturally in a polyanionic form, it is commonly referred to as hyaluronic acid.

Story

Hyaluronic acid is found in many tissues of the body, such as skin, cartilage and vitreous body. Therefore, it is well suited to complement biomedical supplements targeting these tissues. The first biomedical HA product, Healon, was developed in the 1970s and 1980s. Pharmacia, and was intended for use in eye surgery (namely, corneal transplantation, cataract surgery, glaucoma, and retinal detachment surgery). Other biomedical companies also produce brands of HA for use in eye surgery. The original hyaluronan has a relatively short half-life (as shown in experiments on rabbits), so various production technologies have been developed to increase the chain length and stabilize the molecule for medical use. Methods used include the introduction of protein-based cross-links, the introduction of free radical scavenging molecules such as sorbitol, and minimal stabilization of the HA chains using chemical agents such as stabilized non-animal hyaluronic acid. In the late 1970s, intraocular lens implantation was often accompanied by severe corneal edema due to damage to endothelial cells during surgery. It was apparent that a viscous, clear, physiological lubricant was required to prevent such scraping from the endothelial cells.

Research

Due to its high biocompatibility and presence in the extracellular matrix of tissues, hyaluronic acid is becoming popular as a biomaterial in tissue engineering research. In particular, a number of research groups have discovered the special properties of hyaluronic acid in the field of tissue engineering. This additional feature allows researchers to formulate the desired shape as well as reproduce therapeutic molecules. Hyaluronic acid can be created by the addition of thiols (trade name: Extracel, HyStem), methacrylates, hexadisyl amides (trade name: Hymovis), and tyramines (trade name: Corgel). Hyaluronic acid can also be created directly from formaldehyde (trade name: Hylan-A) or from divinyl sulfone (trade name: Hylan-B). Due to its ability to regulate angiogenesis by stimulating endothelial cell proliferation, hyaluronic acid can be used to create hydrogels to study vascular morphogenesis. These hydrogels have properties similar to human soft tissues but are also easily controlled and modified, making HA a very suitable substance for tissue engineering research. For example, HA hydrogels are used to reconstitute vasculature from endothelial progenitor cells using appropriate growth factors such as VEGF and Ang-1 to promote proliferation and vasculature formation. These gels exhibit a vacuole (small cavity) and lumen formation, followed by branching and growth through hydrogel degradation and ultimately forming a complex network construct. The ability to generate vascular networks using HA hydrogels leads to the possibility of clinical application of HA. In an in vivo study, when HA hydrogel with endothelial colony-forming cells was implanted into mice three days after hydrogel formation, the replicated vasculature engrafted within 2 weeks of implantation. This indicates the viability and functionality of the vasculature.

Buy hyaluronic acid

Hyaluronic acid is a fairly important component that is part of connective tissue, and is also found in biological fluids (in particular, synovial fluid) and is produced by hyaluronate synthetases (a class of membrane proteins). Hyaluronic acid is a transdermal delivery system for many other active ingredients necessary for healthy facial skin. There are a lot of drugs on the market containing hyaluronic acid as a component and used in cosmetology and medicine.

The invention relates to the poultry processing and pharmaceutical industries, namely to a biochemical method for producing hyaluronic acid, used in medicine as a wound healing agent and prolonger of the action of various drugs, in perfumery and cosmetics. In the method for producing hyaluronic acid, including grinding cockscombs, extraction, combining extracts, separating the aqueous phase, deposition of the target product, before grinding the raw materials are first bled with ethyl alcohol in a ratio of 1: 2, then the crushed raw materials are additionally subjected to ultrasound treatment with a vibration frequency of 16 - 20 kHz for 5 - 10 min, and extraction is carried out with water at a temperature of 45 - 50 o C for 20 - 25 min, while the separation of the aqueous phase is carried out by vacuum filtration, precipitation - 95% ethyl alcohol in a ratio of 1: 3, followed by filtering and drying the preparation. The method makes it possible to simplify the technological process of producing hyaluronic acid. 4 ill., 2 tables.

The invention relates to the poultry processing and pharmaceutical industries, namely to the rational use of raw materials and the development of non-traditional technologies based on a biochemical method for producing hyaluronic acid (HA), used in medicine as a wound-healing agent and prolonger of the action of various drugs, in perfumery and cosmetics. The closest in technical essence and achieved effect is a method for producing hyaluronic acid, which involves repeated extraction of crushed chicken combs with an aqueous solution of n-propyl, iso-propyl or tert-butyl alcohol, combining the extracts, adding sodium chloride to them, stratifying the system, separating the aqueous phase and precipitation of the target product from it. The degree of extraction of hyaluronic acid is 50%, the protein content is less than 1)%. The disadvantages of this method are the duration of the extraction process, significant consumption of organic solvent, toxicity of production, and limited use. The technical objective of the invention is to simplify the technological process, reduce the duration of extraction, reduce the level of toxicity, limited use of organic solvent, its complete regeneration, increasing the economic efficiency of production, the ability to place this production at poultry processing plants, solving the problem of rational use of raw materials. The objective is achieved by the fact that in the method of producing hyaluronic acid, including grinding cockscombs, extraction, combining extracts, separating the aqueous phase, deposition of the target product, what is new is that before grinding the raw material is first bled with ethyl alcohol in a ratio of 1:2, then crushed the raw materials are additionally subjected to ultrasonic treatment with a vibration frequency of 16-20 kHz for 5-10 minutes, and extraction is carried out with water at a temperature of 45-50 o C for 20-25 minutes, while the separation of the aqueous phase is carried out by vacuum filtration, precipitation - 95% with ethyl alcohol in a ratio of 1:3, followed by filtering and drying the preparation. The technical result is expressed not only in achieving the set task, but also in increasing the degree of extraction of hyaluronic acid, improving the quality of the target product, increasing the environmental friendliness of production, the development and implementation of complex technology that allows the use of the remainder of animal tissue from the release of acid in the production of feed flour. Hyaluronic acid is a typical mucopolysaccharide. An important structural feature of it is the presence of alternating residues of amino sugars and residues of uronic acids. In tissues and liquids, HAA exists in a free state or is associated with proteins, forming viscous solutions. The biopolymer is included up to 5% by weight in the composition of the main substance of many types of connective tissue (cockscombs, vitreous body of the eye, synovial fluid, skin). In the tissues of the cock's comb, HAA is distributed in the mucoid fibers of the subcutaneous layer, which is widest at the base. Hyaluronic acid is a white, solid, amorphous substance, soluble in water and insoluble in organic solvents. Its characteristic property is high viscosity. The molecular weight ranges from 510 4 - 810 6, which depends on the origin of the drug, the method and method of determination. In terms of their conformation, HAA molecules are randomly folded balls. The use of acid hydrolysis, methylation, the use of several types of enzymatic hydrolysis with hyaluronidases of various origins and a number of other methods made it possible to propose a formula for hyaluronic acid in which glucuronic acid and N-acetylglucosamine residues alternate. These disaccharide fragments are linked into hyaluronic acid molecules by 1,4-bonds (Fig. 1). The biological significance of hyaluronic acid lies primarily in the fact that it is a cementing, as if gluing, substance for the connective tissue systems of the body. It is the basis for the functioning of the mucolytic system, which determines, in particular, the permeability of tissues and blood vessels. Due to the high molecular weight, the acid acts as a structure former, a “binder” of water in intermediate cavities, gel-like matrices, which determines tissue turgor and increases their resistance to compressive loads. Promotes the body's resistance to infection. The antifriction and damping properties of tissue fluids, in particular synovial fluid, are determined by the presence of a biopolymer in them. The biological properties of the acid have determined its widespread use in the manufacture of medicines, pharmaceuticals and cosmetic products. For example, the feasibility of using HCA as a vitreous substitute has been substantiated. The use of its solutions as an operating environment that protects the internal tissues of the eye from mechanical influences dramatically increases the efficiency of operations on the human eye. Viscoelastic materials are created based on hyaluronic acid. In addition to ophthalmology, acid is used in rheumatology (to replace synovial fluid), in the treatment of arthrosis, in arthroplasty and osteomy to protect cartilaginous surfaces and the peripheral nerve, in dermatology - to protect skin wounds in eczema and trophic skin disorders; in the production of cosmetics (gels, creams, lotions). When determining the general chemical composition of collagen-containing raw materials, the following methods were used: mass fraction of moisture -; fat - Soxhlet method; squirrel - . The fractional composition of proteins was determined by sequential extraction of water-, salt- and alkali-soluble protein fractions, respectively, with distilled water, a solution of potassium chloride with a mass fraction of 5% and a solution of sodium hydroxide with a mass fraction of 10%, followed by quantitative determination of the protein with biuret reagent. Traditionally, umbilical cords, synovial fluid, and the vitreous body of the eye are used as objects for the production of hyaluronic acid. this raw material is most accessible to specialists working in the field of medicine and pharmacology. Cockscombs are also recommended as a source of HAA. Our comparative analysis of the chemical composition of the comb in relation to other collagen-containing poultry slaughter products (Fig. 2) showed the predominance of the mass fraction of protein in it (19.8% by weight of the raw material) with the mass prevalence of the proteinoid fraction (14.4% by weight of the raw material) . Carrying out specific histo-morphological staining of the tissue using the Van Gieson method made it possible to identify a densely packed system of collagen fibers and bundles that determine the strengthened structure of the ridge. A high proportion of collagen fibers in the structure of tissue with a low mass fraction of fat confirms the feasibility of obtaining the biopolymer of interest. At the same time, it should be emphasized that poultry heads with a comb find very limited use for food purposes, and the comb alone is not used as a raw material at all. Its yield is 3.8% by carcass weight. Thus, the poultry processing industry has real and sufficient reserves in obtaining biopolymer by increasing the share of beneficial use of secondary low-value processed products. A necessary condition for the production of hyaluronic acid is, first of all, the possibility of isolating it in its native highly polymerized state, in the form of highly purified preparations free of protein. The method for obtaining hyaluronic acid is as follows. Fresh cockscombs were subjected to pre-treatment in the form of washing with running tap water and bleeding with ethyl alcohol in a ratio of 1: 2. Washed from blood, in order to avoid oxidative destruction, tissues can be “preserved” for a long time (up to 24 months) at a temperature of 4-22 o C in 95% ethanol. For further processing, the combs were crushed using a homogenizer (disintegrator, ball mill). In order to separate the protein and release the acid from its complexes with proteins and other mucopolysaccharides, the prepared combs were subjected to ultrasonic treatment with a vibration frequency of 16-20 kHz for 5-10 minutes and then aqueous extraction at a temperature of 45-50 o C for 20-25 min. The aqueous solution of HAA was separated from the tissue residue by vacuum filtration. From the filtered solutions, HAA was precipitated with 95% ethyl alcohol in a ratio of 1: 3 and filtered. The precipitate was evaporated over phosphorus pentoxide in vacuum. Further, depending on the purpose, GUK is stored in dried form at a temperature not exceeding -18 o C or dissolved in a physiological buffer solution and packaged in convenient containers, for example, syringes. The biological product obtained in this way is a plexus of very thin threads of great rigidity. It is readily soluble in water, giving completely clear, non-opalescent solutions. The raw materials were washed with running water to remove mechanical impurities from the surface of the ridges. Bleeding was carried out with ethyl alcohol in a ratio of 1:2, which helps to improve the color and degree of purification of the finished biopolymer. Using more than 2 volumes leads to unjustified consumption of alcohol, which is not economically feasible, and less does not give the desired effect. Any procedure for isolating HCAs involves the sequential destruction of structures at each level of localization with the targeted use of certain factors. The destruction of tissue level structures is achieved by grinding and homogenization to ensure, first of all, maximum contact with extractants. This contact is enhanced by the pre-treatment of crushed poultry comb tissue with ultrasound, which was carried out with the aim of not only maximizing the extraction of the biopolymer, but also purifying it from protein and other impurities. It is noted that the rational duration of treatment is 5-10 minutes. With a shorter processing time, the separation effect from the protein is insufficient (insignificant degree of extraction). Processing times longer than 10 minutes lead to deep destruction of collagen fibers and high losses of the collagen fraction, which also lead to the impossibility of complete purification from protein impurities, which affects the quality of the finished product. A study of the effect of vibration frequency of ultrasound pre-treatment on the efficiency of biopolymer cleaning shows that the best effect is achieved in the range of 16-20 kHz. A frequency of less than 16 kHz is insufficient for deep and complete tissue destruction, and, therefore, reduces the yield of the finished product, and above 20 kHz it makes cleaning difficult and reduces the quality of the drug. During the aqueous extraction process, temperature has a significant effect on the yield of hyaluronic acid (Fig. 3). It is noted that when the temperature reaches 50 o C, the maximum yield of the biopolymer is observed, and a further increase in temperature does not lead to significant changes and creates conditions for the development of denaturation and coagulation processes that reduce the purity and quality of the drug. And temperatures below 50 o C reduce the extraction rate, and, therefore, lengthen the entire technological cycle. Hyaluronic acid is extracted from an aqueous medium by precipitation with 95% ethyl alcohol. The results of the studies (Fig. 4) show that the maximum yield of the drug is observed when the ratio of aqueous solution and alcohol is 1:3. Further addition of the volume of alcohol is impractical, and volumes less than those indicated do not result in complete precipitation, and, consequently, the yield of the product. The use of alcohol in the production technology of hyaluronic acid implies its complete regeneration. According to the assessment of the chemical composition, the sediment of undissolved tissues (mass fraction of protein - 14.6%; fat - 5.6%) is advisable to use in the production of feed flour. The method of obtaining hyaluronic acid is illustrated with specific examples. Example 1. Fresh cockscombs are pre-washed with running tap water and bled with ethyl alcohol in a ratio of 1:2. Water is added to 100 g of combs crushed on a homogenizer in a ratio of 1:3 and placed in the container of an ultrasonic vibration generator and processed for 5 minutes at a vibration frequency of 16 kHz. The mixture is then subjected to aqueous extraction at 45°C for 20 minutes. The extract is separated from the ridges by vacuum filtration. Hyaluronic acid is isolated from the aqueous medium by precipitation with 95% ethyl alcohol in a ratio of 1:3. The filtered precipitate is evaporated over phosphorus pentoxide in vacuum. Hyaluronic acid is stored in dried form at a temperature of -18 o C. Data for examples 1-4 are presented in Table 1. As can be seen from the data in Table 1, the method of producing hyaluronic acid according to the regimes given in examples 2, 16-20 leads to the production of a biological product that is inferior to the prototype in terms of quality indicators, and therefore is not feasible from a technological point of view. An increase in alcohol consumption for bleeding raw materials and for acid precipitation (example 15, 24) does not lead to a decrease in quality indicators compared to the prototype, but is not practical from an economic point of view. The method for producing HUA according to examples 11-14, 16-23 leads to insufficient purification of the drug and a decrease in yield. The method for producing hyaluronic acid according to the regimes in examples 1, 3-10 makes it possible to obtain a biopolymer with a high degree of purification and yield. The advantages of the proposed technical solution compared to the prototype are presented in Table 2. The degree of extraction of hyaluronic acid according to the proposed technical solution is higher (55%) than in the prototype. This results in lower costs in raw material sources. The proposed method for producing hyaluronic acid significantly expands the scope of application of the technology due to the non-toxicity of production. Allows you to bring it as close as possible to the source of raw materials and comprehensively process raw materials. The duration of extraction is reduced. Economic efficiency increases as a result of the regeneration of used alcohol. The use of ultrasonic treatment increases the yield of the drug, which eliminates the energy costs in the proposed method. The complete exclusion of toxic solvents ensures the environmental friendliness of the technology and allows for rational use of the solid tissue residue after extracting HAA directly for feed purposes. Sources of information 1. Pat. 2017751 Russian Federation, class. C 08 B 37/08. Method for producing hyaluronic acid / V.Yu. Ryashentsev, S.F. Nikolsky, E.S. Vainerman, V.I. Polyakov, A.N. Gurov, A.N. Ovchinnikov, E.Yu. Ignatova / Russia / - N 4939023/05: Declared 05/22/91; Publ. 08/15/94, Bulletin. N 15. 2. Lauert T.C. // Chemistry and Molecular Biology of the Intercellutar Matrix / Ed. E.A. Balazs. - London, 1970. - P. 730. 3. Stepanenko B. N. Chemistry and biochemistry of carbohydrates /polysaccharides/: Textbook for universities. - M.: Higher School, 1977. - 256 p. 4. GOST 9793-74. Meat products. Methods for determining moisture. - Instead of GOST 9793-61; Enter. 01/01/75. - M.: Standards Publishing House, 1978. - 4 p. 5. Zhuravskaya N.K., Alekhina L.T., Otryashenkova L.M. Research and quality control of meat and meat products. - M.: Agropromizdat, 1985. - 296 p. 6. GOST 25011-81. Meat and meat products. Methods for protein determination. - Enter. 01/01/83. - M.: Standards Publishing House, 1982. - 10 p. 7. Workshop on animal biochemistry / E.S. Savron, V.N. Voronyansky, G.I. Kiselev, Chechetkin, N.L. Doktorovich. - M.: Higher School, 1967. - 239 p. 8. Ryabina B.P., Vasyukov S.E., Panov V.P., Starodubtsev S.G. Preparation, properties and use of hyaluronic acid // Chemical and Pharmaceutical Journal. - 1987. - N 2, p. 142-153. 9. Merkulov G.A. Course of pathohistological techniques. - L.: Medicine, 1969. - 423 p. 10. Ignatova E.Yu., Gurov A.N. Principles of extraction and purification of hyaluronic acid (review) // Chemical and Pharmaceutical Journal. - 1990. - N 3. - P. 42-46.

Claim

A method for producing hyaluronic acid, including grinding cockscombs, extraction, combining extracts, separating the aqueous phase, deposition of the target product, characterized in that before grinding the raw materials are first bled with ethyl alcohol in a ratio of 1: 2, then the crushed raw materials are additionally subjected to ultrasonic treatment at a vibration frequency 16 - 20 kHz for 5 - 10 minutes, and extraction is carried out with water at a temperature of 45 - 50 o C for 20 - 25 minutes, while the separation of the aqueous phase is carried out by vacuum filtration, precipitation - 95% ethyl alcohol in a ratio of 1: 3 followed by filtering and drying.

Hyaluronan is a glycosaminoglycan that forms huge complexes with proteoglycans in the extracellular matrix. These complexes are especially present in large quantities in cartilage tissue, where hyaluronan binds to the proteoglycan aggrecan through a linker protein.

Hyaluronan carries a strong negative charge and therefore binds to cations and water molecules in the extracellular space. This leads to an increase in the rigidity of the extracellular matrix and creates a cushion of water between the cells, which dampens compressive forces

Hyaluronan is composed of repeating disaccharide units linked into long chains

Unlike other glycosaminoglycans, hyaluronan chains are synthesized on the cytosolic surface of the plasma membrane and then exit the cell.

Cells bind to hyaluronans through a family of receptors known as hyaladherins, which initiate signaling processes that control cell migration and cytoskeletal assembly.

Hyaluronan(HA), also known as hyaluronic acid or hyaluronate, is a glycosaminoglycan (GAG). Unlike other glycosaminoglycans (GAGs) associated with the extracellular matrix, hyaluronan is not covalently linked to core protein proteoglycans, but forms very large complexes with secreted proteoglycans.

Among these most important complexes are those present in cartilage tissue, where HA molecules, secreted by chondrocytes (cartilage-forming cells), bind to approximately 100 copies of the proteoglycan aggrecan. The aggrecan core proteins bind through a small linker protein to one HA molecule at 40 nm intervals. Such complexes can reach more than 4 mm in length and have a molecular mass exceeding 2 x 108 daltons. Thus, with the participation of HA, large hydrated spaces are created in the extracellular matrix of cartilage tissue.

These space play a particularly important role in tissues with a low density of blood vessels, since they ensure the diffusion of nutritional components and the removal of waste products from the extracellular space.

Hyaluronic acid(HA) have a very simple structure. Like all GAGs, they are linear polymers of one of the disaccharides, glucuronic acid, linked to N-acetylglucosamine through a (3 (1-3) bond. As shown in the figure below, GA molecules contain on average 10,000 (and up to 50,000 of these disaccharides , linked by b(1-4) bonds. Since disaccharides carry a negative charge, they bind cations and water molecules.

Like proteoglycans HAs increase the stiffness of the extracellular matrix and serve as a lubricant in connective tissue structures such as. Hydrated HA molecules also form a cushion of water between cells, which allows tissues to absorb compressive forces.

Molecules hyaluronic acid(GA) are much larger than other GAGs. Because of this, cells must expend large amounts of energy on their formation. It is estimated that to form one average-sized HA chain, 50,000 equivalents of ATP, 20,000 NAD cofactors, and 10,000 acetyl-CoA groups are required. Therefore, in most cells, HA synthesis is tightly controlled.

Synthesis of hyaluronic acid(GK) is catalyzed by transmembrane enzymes, GK synthases, localized in the plasma membrane. These enzymes are somewhat unusual in that they assemble the HA polymer on the cytosolic side of the plasma membrane and then transport it across the membrane into the extracellular space. This is fundamentally different from the synthesis of other GAGs, which are formed in the Golgi apparatus and covalently bind to proteoglycans of core proteins as they pass through the secretory pathway.

The most important way of regulation synthesis of hyaluronic acid(GK) is a change in the expression of enzymes, GK synthases. The expression of these enzymes is induced by cell-specific growth factors. For example, fibroblast growth factor and interleukin-1 are inducers of enzyme expression in fibroblasts, while glucocorticoids suppress expression in these same cells. Epidermal growth factor stimulates expression in keratinocytes but not in fibroblasts. GC secretion is controlled independently of GC synthesis, providing at least two ways to control tissue GC levels.

Along with participation in tissue hydration, hyaluronic acid(HA) binds to specific surface receptors, which leads to stimulation of intracellular signaling pathways that control processes such as cell migration. The main receptor for GC is CD44, which belongs to a family of proteins called giladherins that bind to GC. Other members of this family include proteoglycans (eg, versican, aggrecan, brevican) and a linker protein that links HA to aggrecan in cartilage tissue. Multiple forms of CD44 are generated by alternative splicing of single gene transcripts, although the functional differences between these isoforms remain unclear.

CD44 exists as homodimers that are expressed in many cell types or as heterodimers with ErbB, a tyrosine kinase that is expressed on epithelial cells.

Cytoplasmic region CD44 has several functions. It is required for proper binding to HA and for sorting of receptors on the cell surface. It is also involved in intracellular signal transmission processes. Mapping of functional regions in the cytoplasmic region of CD44 was carried out by studying the expression of mutant forms of CD44 in cell culture, and the activation of signaling pathways after cell attachment to GCs.

From these studies we know that CD44 homodimers and CD44/ErbB heterodimers activate non-receptor tyrosine kinases, such as Src, as well as members of the small G protein family, Ras. These kinases activate signaling proteins such as protein kinase C, MAP kinase, and nuclear transcription factors.

Along with this, as shown in the figure below, the signals transmitted by CD44, can alter the assembly of the actin cytoskeleton at the cell surface. This occurs through the activation of actin-binding proteins such as fodrin and the small G protein, Rac-1. One of the consequences of actin reorganization is the stimulation of cell migration under the influence of CD44 binding to HA. In tumors, increased CD44 expression and GC secretion correlate with increased aggressiveness and are a poor prognostic sign.

It is generally believed that hyaluronic acid (GK) plays a dual role in stimulating cell migration. First, by binding to the extracellular matrix, HA disrupts intercellular interactions and cell-matrix interactions. Mice that do not express HA are characterized by a small amount of intercellular space, as a result of which the animals cannot develop normally. Because HA has a large hydrated volume, increased HA secretion in the tumor disrupts the integrity of the extracellular matrix, resulting in the formation of large gaps through which tumor cells can migrate.

Secondly, when binding of HA to CD44 receptors Intracellular signal transmission processes can be activated, directly leading to cytoskeletal rearrangements and activation of cell migration. This is confirmed by data obtained in experiments on the addition of HA to cells in culture. Cells expressing CD44 begin to migrate immediately upon contact with HA, and compounds that disrupt intracellular signaling molecules and bind to CD44 inhibit this migration.

Hyaluronic acid! There is a lot of talk about it; it is included in the formulations of new skin care products. All cosmetics manufacturers claim to use the best types of hyaluronic acid in their products. But what is hyaluronic acid, what does it do, how does it work, and what type is considered the best?

Hyaluronic acid (HA) is the most important factor in skin hydration. This molecule forms a three-dimensional network that acts like a sponge and literally traps water around and within its folds.

In addition, HA is used by the body as a lubricant in joints, the auricle is mainly composed of it, and it is also one of the structural polymers of the vitreous body of the eye. HA can stimulate or inhibit inflammation, promote wound healing and skin restoration. It is an important component of the intercellular substance of literally all connective tissue of the human body.

In the skin, HA is found primarily in the basement membrane of the epidermis and dermis, maintaining the space between cells, moisturizing and facilitating the passage of nutrients.

The body of a woman weighing 60 kg contains about 13 g of hyaluronic acid, 4.3 g of this amount is processed and renewed every day.

However, before discussing how HA works and what it can do for the skin, it would be a good idea to first present a short dossier on this substance to better understand its mode of action.

Hyaluronic acid 101

Hyaluronan, or hyaluronic acid, is a natural polymer, that is, a large molecule made up of many repeating small molecules called “subunits.”

In the case of hyaluronic acid, this subunit is the disaccharide D-glucuronic acid and N-acetyl-D-glucosamine bound together.

The length of a HA molecule can range from 2 to 25 thousand disaccharides. The molecular weight of this natural polymer ranges from 800 to 2,000,000 Daltons (Da), with an average molecular weight of HA of 3 MDa in joints and about 2 MDa in skin.

The body continually synthesizes and breaks down HA (as mentioned above, the body completely replaces HA approximately every three days). As large HA molecules gradually degrade, fragments of very different molecular weights are formed. A set of these fragments - from 800 Da to 2 MDa - is present at any time in normal tissues.

Based on the size of the HA molecules, they are divided into different fractions.

• Very high molecular weight: 3–20 MDa.
• High molecular weight: ~ 2 MDa.
• Average molecular weight: ~ 1 MDa.
• Low molecular weight: ~300 kDa.
• Very low molecular weight: ~60 kDa.
• Oligomers: from 800 Da to 10 kDa.

Appearance and biological effects

It is clear that molecules, whose molecular mass can vary up to 12,500 times, look and behave completely differently in biological systems, producing different biological effects. This has been shown in more detail in numerous studies conducted in recent years.

It is commonly said that HA can absorb 1000 times its own weight in water. However, this only applies to high molecular weight HA, and those with a lower molecular weight are obviously able to absorb much less water.

Therefore, in practice, if you take 1% high molecular weight HA in water, you can get a rather viscous liquid or liquid gel. Low molecular weight HA at the same concentration will be a much less viscous liquid or a completely watery gel, while the oligomer will be as liquid as water. Needless to say, HA with a molecular weight of 20 MDa will be a very thick gel in this case.

You may wonder why there is so much information about the size of the molecules and the appearance of the gel. The answer is quite interesting. HA with a molecular weight of 3–20 MDa, that is, high molecular weight HA, is the type of HA found in cellulite. This is an abnormally large size of HA molecules, due to which water is firmly retained in the subcutaneous fatty tissue, which in turn contributes to the manifestation of visible signs of cellulite.

Therefore, the presence of HA with too high a molecular weight in tissues is undesirable - this is a sign of a pathological process. On the other hand, the presence of too many HA fragments in tissues, that is, too many oligomers or even 20 kDa HA, is also undesirable, since they are known to stimulate inflammation. However, even inflammation has a right to exist in some situations, and sometimes it is necessary (for example, when healing wounds).

All other molecular weights (50 kDa - 2 MDa) appear to be neutral or beneficial, with 2 MDa considered the most "normal" (so to speak) and inhibits inflammation.

So we can say that the only truly “bad” type of HA is the extremely high molecular weight HA, which also promotes fibrosis.

Diet, lifestyle and hyaluronic acid

A diet rich in vegetables (magnesium) and fruits (ascorbic acid) is thought to help increase the body's natural synthesis of GC. Also, some foods are rich in HA or its precursors. Examples include bone broth, organ meats, and joint cartilage.

Hyaluronan can also be taken orally as a dietary supplement and actually reaches the skin and joints to help increase hydration, keep them looking youthful longer, and maintain health. This is similar to taking hydrolyzed collagen orally, which also helps delay skin aging and maintain the firmness and elasticity of ligaments and tendons.

Ultraviolet radiation reduces the HA content of the skin, which leads to dryness and inflammation. By providing the skin with a sufficient amount of HA in the summer, including from the inside, we can be sure that it will be able to remain hydrated and protected from sun rays.

There is no specific food that has a proven ability to increase the body's own HA synthesis, but drinking a certain amount of drinking water daily will promote hydration, since the water molecule is no less important for this than hyaluronic acid, because without water, hyaluronan is absolutely useless. Ideally, you should drink two liters of water per day. Thus, to improve skin hydration and obtain a rejuvenating effect, it is advisable to combine the oral use of HA in the form of dietary supplements and drinking a sufficient amount of water. For maximum results, you can additionally use a high-quality serum, gel or cream containing HA.

Dermal absorption of HA from cosmetic formulations

Since HA stimulates skin repair and hydration, and the skin produces less and less of it as we age, it goes without saying that you want to add some HA to your skin in the form of a beauty serum, cream or gel.

It is clear that HA with a large molecular weight will not even be able to penetrate the epidermis, while everything below 300 kDa penetrates the dermis and even subcutaneous fat. The lower the molecular weight, the deeper HA can penetrate the skin.

However, not all so simple. As we mentioned above, you need to understand why we use lower molecular weight HA in our formulation. By “pushing” HA with a molecular weight of 20 kDa into the skin, we do not solve all skin problems, since this can be both beneficial and irritating for the skin. When using HA with an extremely low molecular weight, things become even more complicated.

However, most research studies have shown that HA molecules with a molecular weight somewhere between 50 and 300 kDa penetrate well into the skin and have beneficial effects on it. My personal experience also suggests that this is the best molecular weight range to use.

HA with a molecular weight of 1 MDa can hydrate the epidermis itself without penetrating further, while a molecule with a molecular weight of 2 MDa simply sits on the surface of the epidermis and does not go anywhere else. On the other hand, I have found that 10 kDa HA is not as beneficial and can be irritating to the skin in high concentrations, as evidenced in the scientific literature.

This different absorption capacity of HA, depending on its molecular weight, is the reason that more and more cosmetic companies are now using HA of different molecular weights in their formulations.

HA molecules can also be linear or cross-linked. The linear molecule is the standard HA found in humans and in nature. Cross-linked HA is a human invention and is a more stable form of HA with a higher hydrating capacity. But unfortunately, cross-linked HA has less ability to penetrate the skin because the molecule is “thicker” and cannot easily cross the epidermis.

Cross-linked HA is used as a filler in mesotherapy, but today it can also be found in some anti-aging creams.

Serums, gels and creams

It is quite easy to make a cosmetic serum or gel using HA and water. However, creams are a different matter. Here, HA can greatly increase the instability of the emulsion system. Therefore, most HA products on the market are gels and serums, which are easier to obtain.

Many HA cosmetics on the market contain about 0.1% of this substance, that is, 1 part HA and 999 parts water and some other ingredients. However, more concentrated products may contain up to 2% HA. Higher concentrations are not practical because the cream or gel becomes too thick and uncomfortable.

Hyaluronic acid is currently one of the most popular and important ingredients for anti-aging skin and facial care. It can also be found in some body care products. Unfortunately, unless the type and concentration of HA is specifically mentioned on the packaging of a cosmetic product, it is very difficult to understand what exactly is used and in what concentrations, but this applies to all ingredients in cosmetic formulations.

On the other hand, some skin care products include active ingredients that increase the skin's own HA synthesis. This gives a slightly delayed result, but bypasses the problem of HA absorption, since the “own” HA is synthesized within the skin. Other active substances used in cosmetics can inhibit the action of HA-degrading enzymes, hyaluronidases, in the human body (most polyphenols have this activity). This prolongs the useful life of HA in the skin and suppresses its early or excessive degradation.

What is the origin of HA for cosmetics?

Once upon a time, HA of animal origin, obtained from pig ears or rooster combs, was used in cosmetics. I remember that the first HA we purchased for use in our products in 2002 was derived from piglets.

Today, HA is produced by bacterial fermentation, which produces a standard molecular size of 2 MDa. It is then “cut” either by enzymes or by hydrolysis to produce smaller molecules. The same thing happens in the human body - HA with a molecular weight of 2 MDa is cut into smaller pieces by enzymes called hyaluronidases.

Hyaluronidase and cellulite

Sometimes, to destroy the HA with an excessively high molecular weight, which we mentioned above, doctors inject hyaluronidase into the tissue.

One such use of hyaluronidase is to temporarily reduce the appearance of cellulite. I use the word “temporary” because the human body can restore the molecular weight of newly synthesized HA to 20 MDa in just a few days.

Therefore, a long-term solution to cellulite cannot be achieved with hyaluronidase injections. These should be measures primarily aimed at reducing water retention in tissues and reducing the synthesis of HA with a molecular weight of 20 MDa. But that's a story for another article...

Conclusion

As we age, the human body synthesizes less and less HA, which is why it is necessary to protect the existing HA and increase its content in the skin.

This can be done by avoiding excessive sun exposure; with a diet rich in vegetables, herbs, and organ meats; drinking enough water; using good HA-based skin care cosmetics with molecules of different molecular weights, ideally from 50 to 300 kDa.

Dietary supplements with hyaluronic acid also help because they actually have a beneficial effect on the skin (and joints), helping to hydrate and nourish the body from the inside out.