86,200+ expert documents for the skincare aficionado.
Perennial / Wisdoms
Selected Skin CareAvene
La Roche Posay
Ti-Silc / Z-Silc
Browse more brands.
Facial Skin Condition Treatments
Body Skin Condition Treatments
Skin Care IngredientsAlpha Lipoic Acid
Arginine + Serine
Capryloyl Salicylic Acid
Hydrolyzed Hyaluronic Acid
Sodium Laureth Sulfate/Sulphate
Browse more ingredients.
Clinical Procedures and Topics
Sheldon R. Pinnell, M.D., J. Lamar Callaway Professor, Dermatology.
New methods of photoprotection are needed to curb the epidemic of skin cancer — an epidemic worsened by an aging population, ever-increasing outdoor activities and escalating immunosuppression related to medical treatments.
Recent studies point out that in actual usage individuals apply only 20-25% the amount used to determine SPF values.
Since SPF is an exponential function, actual protection is no more than three to fourfold at this level of application for any sunscreen.
Moreover, the best sunscreens available only protect against 55% of free radicals generated in skin by ultraviolet irradiation.
The skin naturally protects itself from the sun with antioxidants.
My research laboratory is interested in developing antioxidant formulations that can be applied to skin to increase the natural reservoir and provide additional photoprotection.
Since antioxidants are naturally unstable compounds, they provide challenges for formulation.
To work, they must be chemically stable, they must get into skin, and they must be used at meaningful concentrations.
Finally, they must be effective at providing photoprotection.
It must be at a pH below 3.5 in order to enter skin. It is maximally effective for increasing skin levels at a concentration of 20%. Skin can be saturated in 3 days, and following saturation, half life of removal is about 4 days. It is effective for protecting the skin against UVB and UVA and can protect against UV-immunosuppression.
Alpha tocopherol (vitamin E) can enter skin when applied topically. Maximal percutaneous absorption occurs at 1% concentration. Alpha tocopherol is effective for protecting skin against photoinjury, photocarcinogenesis and UV-immunosuppression.
Vitamin C derivatives include ascorbyl palmitate and magnesium ascorbyl phosphate. Vitamin E derivatives include tocopherol acetate. These derivatives must then be converted in tissue, back to the vitamin to be effective.
These derivatives are successfully converted in the stomach when used in vitamin pills, but not readily converted when used topically for skin protection.
In the human body, antioxidants function as an interactive network, with chemical reconstitution of antioxidants after they are oxidized during protective functions. As a network they work synergistically. Vitamin C and vitamin E, when formulated together at maximal concentrations for percutaneous absorption, provide synergistic photoprotection for skin when applied topically.
We have recently discovered that ferulic acid provides added chemical stability to a solution of vitamin C and vitamin E.
A solution of 15% L-ascorbic acid, 1% alpha tocopherol and 0.5% ferulic acid provides eight- to ten-fold protection against solar-simulated irradiation of skin. Protection is demonstrated for erythema, sunburn cell formation, caspase-3 and caspase-7 activation and thymine dimer formation. Thymine dimers are critical DNA mutations intimately involved in skin cancer formation.
In summary, topical vitamins C and E stabilized with ferulic acid provide synergistic photoprotection for skin and prevent thymine dimer formation.
Derivatives of vitamins C and E are not readily converted to free vitamins when used topically.
Photoaging — Update and Treatment, Sheldon R. Pinnell Reference List
Related Skin Care Information, Products and Expert Discussions
Instructions for Absolute Rehydration of Dry and Stressed Skin : A Year of Photoprotection — Results from Topical Vitamin C (as Ascorbic Acid) and Dermatological Sunscreen Use : Lin et aI., 2005 — Journal of Investigative Dermatology 125:826-32 (2005). : Photoaging — Update and Treatment, Sheldon R. Pinnell : Placzek et aI., 2005 — Journal of Investigative Dermatology 124:304-7 (2005) : Skinceuticals Antioxidant Storage Notes — Protective/Preservative Refrigeration : Skinceuticals Foaming Cleanser/SPF 20/B5 Gel Special Set : Skinceuticals Light and Easy Extended Skin Resurfacing/Freshening… : Skinceuticals Normal to Dry Skin Reconditioning Massage : Skinceuticals: Poor Health / Poor Results :