C serum is proportional to the concentration, but only up to 20%. At this pH, the ionic charge on the molecule is removed and it is transported well across the stratum corneum.įrom a clinical point of view, it is important to note that the efficacy of the Vit. C is controlled by maintaining a pH of less than 3.5. It is unstable and, on exposure to light, gets oxidized to Dehydro Ascorbic Acid (DHAA), which imparts a yellow color. Of these, only the serum contains active Vit. C is available in the market as a variety of creams, serum and transdermal patches.
It was noted that this triple combination was very useful for the reduction of acute and chronic photodamage, and could be used for prevention of skin cancer in the future. E synergistically limit chronic UV damage by significantly reducing both cell apoptosis and thymine dimer formation.Ī combination of 0.5% ferulic acid (a potent antioxidant of plant origin) with 15% Vit. E together protect the hydrophilic and lipophilic compartments of the cell, respectively.
C alone can provide photoprotection, it works best in conjunction with Vitamin E (Vit. C showed statistical reduction of UVB-induced erythema by 52% and sunburn cell formation by 40-60%.Īlthough Vit. Under laboratory conditions, it has been shown that application of 10% topical Vit.
C does not absorb UV light but exerts an UV-protective effect by neutralizing free radicals, while this effect is not seen with sunscreens. To optimize UV protection, it is important to use sunscreens combined with a topical antioxidant. Photoageing can be prevented by prevention of UV-induced erythema, sunburn cell formation and inducing collagen repair. However, sunscreens block only 55% of the free radicals produced by UV exposure. Sunscreens when properly applied prevent UV-induced erythema and thymine dimer mutations that contribute to cutaneous carcinogenesis. UVB causes sunburn, ROS, epidermal mutations and skin cancer. Thus, UVA causes skin ageing and possibly melanoma formation. UVA mutates and destroys collagen, elastin, proteoglycans and other dermal cellular structures. Repeated small doses of UVA penetrate 30-40-times deeper into the dermis as against UVB, which mostly affects the epidermis. C is equally effective against both UVB (290-320 nm) and UVA (320-400 nm). This may explain the elastotic changes observed in photoaged skin.Īntioxidants are necessary for neutralizing the ROS formed due to UV exposure. ROS also increase the elastin mRNA level in dermal fibroblasts. This produces a number of mediators that contribute to inflammation and skin ageing. Oxidative stress induces nuclear transcription factor kappa B (NFkB).
Oxidative stress also triggers certain cellular events mediated by transcription factors such as ROS upgrade transcription factor activator protien-1 (AP-1) that increases matrix metalloprotienase (MMP) production, leading to collagen breakdown. The harmful effects of ROS occur as direct chemical alterations of the cellular DNA, the cell membrane and the cellular proteins, including collagen. These radicals have a potential to start chain or cascade reactions that damage the cells. C and photoprotectionĪs mentioned above, the exposure of skin to UV light generates ROS. UV light, reactive oxygen species (ROS) and skin damage - Vit. The use of topical ascorbic acid is therefore favored in the practice of dermatology.
C in the skin is inadequate when it is administered orally. C in the gut is limited by an active transport mechanism and hence a finite amount of the drug is absorbed despite high oral dosage. However, only LAA is biologically active and thus useful in medical practice.
These are essentially isomeric molecules and are mutually interchangeable. C is found in equal parts as LAA and D-ascorbic acid. L-ascorbic acid (LAA) is the chemically active form of Vit. C molecule from red peppers and identifying its role in Scurvy. Albert Szent Goyrgi was awarded the Nobel Prize for his work in isolating the Vit.
C-rich foods like lemons were carried by sailors on long journeys to avoid Scurvy, a disease of bleeding gums. C hence, they must acquire it from natural sources such as citrus fruits, green leafy vegetables, strawberries, papaya and broccoli. Humans and certain other vertebrates lack the enzyme L-glucono-gamma lactone oxidase required for in vivo synthesis of Vit. Most plants and animals are able to synthesise Vit. C) is one of the naturally occurring antioxidants in nature.