Cosmeceuticals Part 3

Antioxidants

Vitamin C: Vitamin C (L-ascorbic acid) is essential for life. Since its discovery in the 1930s, much work has been undertaken to elucidate its mechanisms of action. The roles of vitamin C are numerous. Vitamin C is necessary for the hydroxylation of procollagen, proline, and lysine. Deficiency results in purpura, keratotic follicles, and bleeding gums. Vitamin C is a water-soluble antioxidant that clenches free radicals and regenerates vitamin E. It is an important regulator of collagen expression stimulating its synthesis. Studies have shown that vitamin C levels on the skin are severely depleted after UV irradiation and that, histologically, vitamin C improves and normalizes the changes caused by photodamage. Thus far, however, studies on vitamin C have been few, and information about its effect in vivo is lacking.

Vitamin C has been used effectively to stimulate collagen repair, thus diminishing some of the effects of photoaging on skin. However, vitamin C is easily degraded by heat and light, which along with its high acidity, presents certain challenges for use in a multipurpose skin care formulation. A recently introduced synthetic collagen fraction offers greater stability and compatibility, along with improved efficacy.

Vitamin E: Vitamin E (alpha-tocopherol) is the major lipophilic antioxidant in plasma, membranes, and tissues. The term vitamin E collectively refers to 8 naturally occurring molecules (4 tocopherols and 4 tocotrienols), all of which exhibit vitamin E
activity. Its major role is generally considered to be the arrest of chain propagation in lipid peroxidation by scavenging lipid peroxyl radicals, hence protecting the cell membrane from destruction. Vitamin E topically applied before UV irradiation has been shown to reduce erythema, edema, sunburn cells, immunosuppression caused by sunlight, and DNA adduct formation.

Panthenol: Panthenol, the alcohol analog of vitamin B-5, is a water-soluble humectant commonly found in various commercial skin creams, lipsticks, lotions, and hair preparations. It is stable in the presence of oxygen and light but unstable in the presence of acids, bases, and high temperatures. Panthenol is converted in the skin to pantothenic acid, which is an important component on coenzyme A essential for normal cellular metabolism.

Lipoic acid: Lipoic acid is a unique free radical protector. It is fat and water soluble. Once lipoic acid crosses the cell membrane, it is broken down into dihydrofolic acid, which is also an antioxidant. Alpha lipoic acid also recycles other key
antioxidants, such as vitamin C, vitamin E, and glutathione.

Ubiquinone: Ubiquinone, also known as coenzyme Q, is a lipid-soluble quinone derivative that is present in the mitochondria and is used to generate adenosine triphosphate (ATP), enhancing energy. It has been shown to decrease peroxidation of the low-density lipoproteins better than vitamin E.

Niacinamide: Niacinamide (nicotinamide) is a basic amide that is a member of the vitamin B complex. It is used in the prophylaxis and treatment of pellagra. Niacinamide does not induce the peripheral flush that accompanies therapy with nicotinic acid. It is one of the newest vitamins in the marketplace. In vitro studies have shown anti–tumor activity on keratinocytes and suppression of UV-B photocarcinogenesis. The main reason for its surge in popularity is its stability. Niacinamide is stable in the presence of oxygen, acid, and high temperatures, and it is inexpensive to formulate. Most of its known effects are the result of increased epidermal turnover and exfoliation.

Dimethylaminoethanol:

Topical preparations containing dimethylaminoethanol (DMAE) have been touted for their ability to improve skin firmness and to lift sagging skin. DMAE has been used as a dietary supplement and is associated with improving mental function and enhancing physical performance due in part to its ability to increase the neurotransmitter responsible for stimulating muscles. DMAE is able to diminish the cross-linking of proteins that occurs during aging, probably acting as a free-radical scavenger. It also increases the activity of these enzymes in a dose-dependent manner only in the particulate fractions glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase.