The research of nicotinamide and β-arbutin on reducing melanin content in the skin of leopard coral grouper (Plectropomus leopardus)

Abstract

Body color is an important economic characteristic of leopard coral grouper (Plectropomus leopardus). In this study, we tried to make the red color more visible on the skin by reducing the melanin level, and aimed to investigate the possible mechanism of nicotinamide and β-arbutin on reducing melanin content in the skin of P. leopardus. 0.5 % nicotinamide or 0.5 % β-arbutin was added to the basal feed formulation to feed P. leopardus for 60 days. After nicotinamide or β-arbutin added feeding, the time for P. leopardus to maintain uniform body color was significantly longer. The melanin content in the skin of P. leopardus was significantly reduced, and the number of melanin particles was reduced. In skin, the enzyme activities of superoxide dismutase (SOD) and catalase (CAT) decreased, and the content of malondialdehyde (MDA) increased. The mRNA expression of TYR, Sox10 and Mitf related to melanin synthesis and proliferation and differentiation decreased. The apoptosis-related gene Bax was upregulated, the Bcl-2 gene was down-regulated, and Bax/Bcl-2 > 1. The content of tyrosinase decreased and the content of melanin metabolizing enzyme increased, and the effect of nicotinamide was more obvious than that of β-arbutin. In summary, nicotinamide or β-arbutin added feeding increased the oxidative stress and the apoptosis level of the skin, increased the metabolism of melanin, decreased the synthesis and differentiation of melanin, thus reduced the content of melanin and the number of melanin particles in the skin. This study provided a new basis for the body color regulation of cultured P. leopardus.