Niacinamide or nicotinamide is a biologically active form of niacin (vitamin B3) involved in over 200 enzyme reactions in the form of nicotinamide adenine dinucleotide and nicotinamide adenine dinucleotide phosphate.
Hakozaki et al. (51) suggested that niacinamide has no effect on tyrosinase activity, melanin synthesis, or cell number in melanocyte monoculture system, and no effect on the proliferation of keratinocytes. The research results showed that niacinamide down – regulated the amount of melanosomes transferred from melanocytes to surrounding keratinocytes in a coculture system by approximately 35-68%.
Daily use of a niacinamide moisturizer was effective in reducing hyperpigmentation and in increasing lightness of basal skin color compared with control moisturizer. The efficacy of topical niacinamide for decreasing facial hyperpigmentation and lightening skin color in vehicle-controlled protocols was evaluated (51).