Where Beauty Meets Business
Citrus fruits such as
lemons and limes are
loaded with vitamin C.
in their order of discovery: Vitamin A
(retinyl/retinal), vitamin C (ascorbic
acid), vitamin D, vitamin E (
tocopherols) and vitamin F (essential fatty
acids). In addition, a number of ingredients are important antioxidants including: Lycopene, ferulic acid, niacinamide
(nicotinamide), coenzyme Q (
ubiqui-none), idebenone, silymarin, quercitin,
genisten, phloretin, oryzanol, curcumin,
turmeric, oleuropein and resveratrol.
Finally, a number of natural extracts
have substantial antioxidant activity including pomegranate, coffeberry,
grapeseed, rosemary, St. Johns Wort, feverfew, artichoke, jojoba, argan, pumpkin seed, kelp, papaya, watercress, pine
bark, açai berry and green tea extracts.
A Review of Vitamin C
For illustrative purposes, and to demonstrate the effectiveness and drawbacks
of antioxidants in sun care formulations,
I will briefly review vitamin C, the gold
standard of antioxidants.
Vitamin C is a weak sugar acid structurally similar to glucose. The body cannot
synthesize it, and therefore it is an essential nutrient. In biological systems, vitamin
C is found as the L-ascorbate enantiomer
(the de-protonated form) as protonation
to form the acid requires a pH of 4 or less.
Vitamin C is a requisite cofactor in several
enzyme reactions, especially those related
to wound-healing and preventing easy
bruising due to fragile capillary walls in
animals and its role in many collagen synthesis reactions.
Vitamin C deficiency results in scurvy
due to collagen synthesis dysfunction.
Ascorbic acid is widely used as a food preservative because of its antioxidant properties. It acts as an antioxidant, keeping
iron and copper atoms in their reduced
states. Ascorbate acts as an antioxidant by
initially donating a single electron to neutralize a free radical and itself becoming an
ascorbyl radical (semidehydroascorbate)
in the process.
Most studies have shown that a min-
imum amount of vitamin C is required
to be effective in quenching free radicals.
Vitamin C must penetrate the skin and
remain stable. Several derivatives have
been employed, but the ascorbic acid
itself remains the most important form
for exerting maximum mitrochondrial
activity so long as certain conditions are
met. These conditions include a mini-
mum of 10% (preferably 15%), a pH en-
vironment of 2. 5-3. 5 and stabilization by
other components. Pinnel and his group
have published studies elucidating the
effect of ferulic acid in stabilizing ascor-
bic acid and vitamin E formulations.
Some cosmetic and sun care manu-
facturers use their topical applications, a
plethora of antioxidants, at ineffectively
low concentrations. Only targeted an-
tioxidants that are effective, stabilized,