From the Perricone Prescription:
"One bright, sunny August morning, I had taken a particularly long run. By late afternoon, my face had turned bright red from painful sunburn. It occurred to me that since vitamin C was a powerful antioxidant, perhaps it would also act as an anti-inflammatory to help resolve the burn more rapidly. That night, I made a vitamin C solution by mixing crushed vitamin C tablets in water and patted it on my face. At first it stung, but the discomfort soon subsided and I was able to sleep. In the morning, the burn was definately better. The swelling and redness had greatly diminished, although they had not disappeared entirely. Yet my shoulders, on which I hadn't applied the vitamin C, were still quite red and tender. My vitamin C solution showed potential, but there was still work to be done.
Several years later, I returned to the use of vitamin C with a new approach. I reasoned that the solubility of the vitamin C molecule (L-ascorbic acid) interfered with its anti-inflammatory effects. Ascorbic acid, the natural form of vitamin C, is water soluble. Ascorbic acid cannot penetrate the surface of the skin, which repels water-soluble substances. The acidity of the vitamin C also diminished the anti-inflammatory effects. Ascorbic acid lives up to its name. It is very acidic, which can be irritating to the skin. Then there is the problem of potency. Ascorbic acid is fragile and unstable, and it breaks down rapidly. When formulated into a solution, ascorbic acid loses its strength within twenty-four hours. I set out to find a form of vitamin C that would be nonirritating, fat soluble, and retain its strength in skin care preparations.
My search led me to a compound known as vitamin C ester. It is composed of the basic vitamin C molecule (L-ascorbic acid) joined with palmitic acid, a fatty acid derived from palm oil. Vitamin C ester is completely nonirritating and can even be used on an open cut without stinging. This in itself was a leap from the burning and irritation caused by topical ascorbic acid. More important, vitamin C ester is fat soluble, easing its absorption by the skin and the cell plasma membrane."
Hope that helped!
