Skin whitening wheat, rye, and barley. It is applied topically in a cream formulation at a 10–20% concentration. Azelaic acid is used to treat acne, but there also is research showing it to be effective for skin discolorations. Other research also indicates azelaic acid may be an option for inhibiting melanin production. Vitamin C and its various forms (ascorbic acid, magnesium ascorbyl phosphate, etc.) are considered an effective antioxidant for the skin and help to lighten skin. One study found it raises glutathione levels in the body. Another study found that brownish guinea pigs given vitamin C, vitamin E and L-cysteine, simultaneously,
Vitamin C -Galactose reacts with the enzyme -galactose dehydrogenase, whereby the lactone ring opens and forms again but with between the carbonyl on C1 and hydroxyl group on the C4, resulting in -galactonolactone. -Galactonolactone then reacts with the mitochondrial flavoenzyme -galactonolactone dehydrogenase. to produce ascorbic acid. -Ascorbic acid has a negative feedback on -galactose dehydrogenase in spinach. Ascorbic acid efflux by embryo of dicots plants is a well-established mechanism of iron reduction, and a step obligatory for iron uptake. All plants synthesize ascorbic acid. Ascorbic acid functions as a cofactor for enzymes involved in photosynthesis, synthesis of plant hormones, as an antioxidant