Julie Woodward, MD is Associate Professor
of Ophthalmology and Associate Professor
in Dermatology Chief; Oculoplastic and
Reconstructive Surgery Service, Duke
University Medical Center.
The research of Sheldon R. Pinnell, MD changed the face of modern cosmeceuticals. Sadly, the father of topical antioxidants, as he has become known, passed away this past July 4, 2013. A brief review of his research will be presented here.
THE ROLE OF ANTIOXIDANTS
Oxidation is a process wherein a molecule is created that is missing a paired electron. This is called a free radical. This occurs not only from UV radiation, but also from visible light, infrared light, poor diet, pollution, and emotional stress. The production of too many free radicals and reactive oxygen species can cause the death of a cell by a chain reaction that damages DNA or destroys the cell wall. This creates far more free radicals that result in a cascade of further destruction.
This is where antioxidants (AOXs) come to the rescue. AOXs carry the gifts of donor electrons that neutralize the free radicals and thus stop the cell reactions that cause cell death.
In general, antioxidants have been shown to slow down the progression of cardiovascular disease, Parkinson's disease, cancer, and macular degeneration. It is important to realize that there are a variety of oral antioxidants, and not all are appropriate in high dosages to treat these diseases. For example, beta-carotene was removed from the AREDS 2 clinical trial for macular degeneration due to increased risk of lung cancer in previous smokers.
Our society has evolved the desire for not only quantity but also quality in our lives. After pounding our joints in the 80s with aerobics, we now are more gentle on them with yoga. Whole Foods has grown from a single small grocery store in Austin, TX to a major force that is gaining momentum around the world. People do not seem to mind paying double for their groceries on the chance that they may be healthier. Part of this mindset of eating healthy is increasing antioxidants through fruits and vegetables. We even want to be more pure with the consideration that incobotulinum may be more pure than onobotulinum toxin.
Zinc-based sunblocks provide a good barrier to reflect UVA and UVB rays. But what about exposure to atmospheric pollution, emotional stress, poor diet? What about visible light, and IRA, IRB, and IRC rays? Fifty four percent of the damage to our skin can come from IR radiation. IRA penetrates the deepest into the dermis and even the subcutaneous layers of skin.
APPLYING ANTIOXIDANT THEORY
What about when an apple a day is not enough? This is where Dr. Pinnell's research on the application of topical antioxidants comes into play. He researched five of the major antioxidants that work in skin and discovered that only L-ascorbic acid and alpha-tocopherol can actually be formulated in a way that will enter the cells.
The formulation for entrance of vitamin C into cells includes a pH of <3.5. A peak level can be reached after three to four days. Interestingly, it will take three to four days for the levels to drop after cessation of the product. This means that the product will protect skin over a long weekend if it is left at home.
It is very important to understand that there is a plethora of attempts to replicate Dr. Pinnell's formula for vitamin C. These are most often not formulated in such a way that they will enter the cells. Many products at department stores and drugstores do not have the proper pH or concentration to enter skin, and therefore, just sit on top of the skin and do not enter the intracellular space where they can act in the aqueous environment of the cell to do their desired antioxidant activity. There is a lipid-based product that boasts it can penetrate deep into the skin, but there is no evidence of its antioxidant protection in the aqueous environment in the intracellular space.
Dr. Pinnell went on to discover that alpha-tocopherol (Vitamin E) exerts its antioxidant effect to protect cell walls. Again, other forms of vitamin E found in drugstore products are nice emollients, but they will not enter the cells. Alpha-tocopherol helps regenerate the vitamin C and both are stabilized by Ferulic acid that protects plants from sunlight. These three molecules therefore work together in concert. His formulations were found to protect cells internally via the following:
- Increasing photoprotection and decreasing sunburn detected on colorimetry;
- Decreasing the number of cells in apoptosis cell death found on biopsy after UV radiation; and
- Decreasing thymine dimer formations which are DNA mutations associated with skin cancers.
Since Dr. Pinnell's research left its important mark on dermatology, topical antioxidants have become a mainstay in healthy and preventative skin care (in addition to the other main categories of exfolients, pigment correctors, and growth factors that are well known to all skin care specialists). We celebrate his accomplishments and thank him for good healthy skin in many of our patients.
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