Effects of nicotinic acid derivatives on tyrosinase inhibitory and antioxidant activities

Abstract

The tyrosinase inhibitory and antioxidant activities of four nicotinic acid derivatives, namely, nicotinamide, methyl nicotinate, nicotinic acid hydroxamate (NAH), N-methyl nicotinic acid hydroxamate (NAH-M), and kojic acid, were studied. The tyrosinase inhibitory activity was found to follow the trend: NAH>kojic acid>NAH-M>methyl nicotinate>nicotinamide. The concentrations of half-inhibition (IC50) of NAH against monophenolase and diphenolase activity were 2 and 1μM, respectively; the inhibition mode was a mixed-type in the former and an uncompetitive type in the latter. In the antioxidant activity assays, NAH and NAH-M, but not nicotinamide or methyl nicotinate, showed dose-dependent DPPH radical scavenging activity, and their corresponding IC50 values were 65.81 and 125μM, respectively. NAH and NAH-M also showed hydroxyl radical scavenging activity and anti-low-density-lipoprotein peroxidation. These results indicate that NAH and NAH-M have the potential to be useful in cosmetics or food processing, and therefore, they should be investigated further.