Hyaluronic acid in cosmetics
Hyaluronic acid is considered one of the most "pleasant" cosmetic ingredients.
It is a white powder, which dissolves in water slowly but completely, forming
viscous, colourless, slightly opalescent gel even at con-centration of 1%. This
gel can be preserved for subsequent use in cosmetic compositions. Emulsions on
the base of hyaluronic acid have a soft and gentle consistence, and besides,
this acid is perfectly com-patible with the skin and never causes irritations
and allergic reactions.
Sodium salt and potassium salt of hyaluronic acid, which also are used in
cosmetics, have similar proper-ties. If it were possible using of cosmetics to
fill deficiency of hyaluronic acid immediately in the dermis, it would enable to
keep normal hydration of the skin even on the background of the reduced blood
supply. However, hyaluronic acid of cosmetic creams is not capable to penetrate
even into epidermis and further-more to reach the dermis. And still, in spite of
the fact, that the area of influence of the cosmetics contain-ing hyaluronic
acid (also as any other cosmetics), is limited by the cornual layer, it is
capable to wet sub-stantially the skin and apparently to improve its appearance.
The solution of hyaluronic acid is well distributed over the whole surface of
the skin, forming a mild film that takes an active part in moisture absorption
from the air. It promotes to increase the contents of free water in the cornual
layer, and also creates effect of "additional humidity" which helps to lower
evaporation of water from the skin surface.
Hyaluronic acid has series of advantages in comparison with other wide-spread
moisteners . Hyaluronic acid has the highest hygroscopicity (ability to bind
water) in comparison with other wide-spread moistening agents, such, as glycerin
and sorbitol. Thus, in contrast to glycerin, it keeps its activity in a dry
atmos-phere. Such property can be named "effect of pampers"—absorbed water is
kept inside as a gel and not evaporated even at dropping of air relative
humidity. This valuable quality found application in medicine at treatment of
wounds. It appears, that the wound healed without a cicatrix, it should be kept,
contrary to a popular belief, in a condition of constant humidity. A wet sterile
medium enables cells to move freely and carry out necessary repair work. Gel
moistening film from hyaluronic acid or from hyaluronic acid with chi-tosan
enables to create such conditions.
But, according to the results of scientific researches, the role of hyaluronic
acid is not limited to only to moistening of wound surfaces. It is noticed that
the fetus wounds always heal up without formation of cica-trix. At that, in the
wound field is discovered a big quantity of hyaluronic acid. It is supposed,
that it stimu-lates migration of epidermal cells and reduces production of
collagen. Thus, the film of hyaluronic acid on the wound surface has double
influence: creates conditions for movement of cells and activates regenera-tion
processes. In a result, the wound heals, not leaving scars and it is especially
important if the wound is located on the face and other open spots of the body.
After application of cosmetics with hyaluronic acid, the skin looks softer,
smooth and gentle. And it not simply external effect, which is typical for the
majority of emollients. The matter is that the damp medium, which is created by
hyaluronic acid at the skin surface, reduces evaporation of water through the
cornual layer as intensity of evaporation depends on air relative humidity. It
is rather essential, as permeability of the cornual layer for water can be
enlarged sharply under influence of ultra-violet radiation, destructive action
of surfactants and pollution surrounding us every-where.
Also, being the natural UV-filter, hyaluronic acid prevents from infiltration of
hard rays of the range of 280-320 nanometers. Hyaluronic acid in composition of
sun-protection agents, creams for use in day-time and decorative cosmetics
prevents infiltration of free radicals, also can "cover" for a while the damaged
cor-nual layer, not allowing the skin to be dehydrated, while reduction
processes proceed in the epidermis. Besides, the polymeric network, which
hyaluronic acid forms on the skin surface, enables biologically ac-tive
substances included in cosmetics, to stay a longer period on the skin, that
increases probability that they will penetrate into the epidermis. In contrast
to many biologically active substances, hyaluronic acid reveals all valuable
properties at rather low concentration (0.01-0.1%) that allows to create
efficient cos-metics which price will be suit for both manufacturers and
consumers. Basically, it concerns hyaluronic acid of the big molecular weight.
Now hyaluronic acid and its salts are part of moistening creams, lipstick and
balms for lips, anticellulitis creams, gels for eyelid, lotions after tan,
antiphlogistic lotions, wound-healing and sun-protection means. Quality of
hyaluronic acid as cosmetic ingredient is determined by its molecular weight.
Depending on a source and technology of production of hyaluronic acid, its
molecular weight can vary from 70 up to 4000 кDa. The longer molecular chain and
less scattering in molecular weight, the better for creation of the polymeric
network, the greater viscosity at low concentration and the bigger par of the
skin surface can be covered by continuous moistening film. More often hyaluronic
acid is obtained from rooster crests, but in some cases the human umbilical cord
and the vitreous humor of eyes of the cattle are used. Our products are obtained
exclusively from placenta, and it composes originality of our products.
Hyaluronic acid is a natural component of the human skin and it plays the
important role in maintenance of normal aqueous balance of the skin. Various
unfavourable factors of the environment, such as the UV-radiation and chemical
pollution, can cause destruction of hyaluronic acid. Besides, syn-thesis of
hyaluronic acid decreases with the increase of years. Hyaluronic acid of
cosmetics, being on the skin surface, shapes a continuous thin film which keeps
natural humidity of the skin, not breaking gas-exchange. It is perfectly
compatible with the skin and does not cause allergic reactions and irritation.
The cosmetics containing hyaluronic acid, softens, wets and protects the skin,
apparently improving its ap-pearance. In medicine hyaluronic acid is applied to
acceleration of wound healing (especially in burn treatment) and in
ophthalmology. Moistening properties of hyaluronic acid depend on its molecular
weight. The greater molecular weight, the better for shaping of continuous
moistening film. Using technology AMI, hyaluronic acid with molecular weight
1000 кDa is obtained, which enables to achieve excellent moisten-ing effect at
concentration from 0.01% (for a dry powder) up to 1-5% for 1% solution.
Hyaluronic acid is recommended for high-quality moistening gels and creams,
however, it can be applied in any cosmetic products, including decorative
cosmetics.
