Cosmeceuticals Part 2

Hydroxy acids: Hydroxy acids are likely the second most available cosmeceutical, and in low concentrations, they are found in mass-marketed cosmetic formulation. Hydroxy acids are organic carboxylic acids classified into alpha hydroxy acids (AHAs) and beta hydroxy acids (BHAs) according to their molecular structure.

AHAs range from simple aliphatic compounds to complex molecules. Many are derived from natural sources
and are often referred to as fruit acids. The different AHAs include the following: glycolic acid, lactic acid, citric acid, mandelic acid, malic acid, and tartaric acid.

AHAs have been shown to decrease the signs of aging. The skin appears smoother and more uniform. The
likely cause of these changes is the property of AHAs to enhance epidermal shedding. Some claim that AHAs increase the synthesis of GAGs, improve the quality of elastic fibers, and increase the density of collagen. Scientific evidence to support such claims is still incomplete and controversial.

BHAs are aromatic compounds. Salicylic acid is the reference BHA; it has dermolytic properties and helps in various xerotic and ichthyotic disorders. Other BHAs include 2-hydroxy-5-octanoyl benzoic acid, also known as beta-lipohydroxyacid (B-LHA), and tropic acid.

Despite their popularity, the exact mechanisms of action of hydroxy acids remain unknown and are largely
controversial; however, at least one aspect of its biological activities may be attributed to the inherent acid strength of the compounds. Studies show that AHAs may increase sensitivity to UV radiation and that sunscreen application may be advisable when these products are used.

The skin is frequently exposed to a constant assault of endogenous and exogenous damaging agents. Agents such as UV radiation, drugs, air pollutants, and heat and/or cold are continually challenging the protective character of the skin.
In addition to these external insults, the skin also has to cope with endogenous mitogens, most importantly reactive oxygen species (ROS) and other free radicals. These species are continuously produced during physiological cellular metabolism. To counteract the harmful effects of ROS, the skin is equipped with an antioxidant system to maintain equilibrium between the
pro-oxidants, or damaging agents, and the antioxidants, or protective agents; these antioxidants intervene at different levels in the protective process.