Alpha lipoic acid is a potent antioxidant that is both lipid and water soluble. Because it is both lipid and water soluble, it can reach all portions of the cell, including both the membrane and the nucleus. Alpha lipoic acid is also involved in energy production on a cellular level, working in the mitochondria, assisting the citric acid cycle. This boosts the metabolism in aging cells, allowing the cell to repair itself and empty metabolic byproducts.
Although alpha lipoic acid is itself an antioxidant, it is its reduced form, dihydrolipoic acid, that is the most active as an antioxidant. Because dihydrolipoic acid is so easily oxidized (it oxidizes within minutes), it makes topical application of dihydrolipoic acid impossible. Fortunately, alpha lipoic acid is readily converted into dihydrolipoic acid within the skin, eliminating the need to reduce alpha lipoic acid to dihydrolipoic acid before topical application.
Alpha lipoic acid is also known for its ability to protect and preserve vitamin C and vitamin E levels in the skin, even with UV radiation exposure. Without alpha lipoic acid present, vitamin C and vitamin E levels steadily decrease, particularly when under UV radiation. The ability of alpha lipoic acid to protect these antioxidants in the skin furthers the level of free radical protection that alpha lipoic acid offers.