The Hull of Ripe Pistachio Nuts (Pistacia vera L.) as a Source of New Promising Melanogenesis Inhibitors.

In the present study an acidified methanol pistachio hull extract was investigated for antioxidant and inhibitory effects on melanin biosynthesis by in vitro and in vivo assays. The chromatographic analysis revealed that cyanidin-3-O-galactoside represents the main compound (98.37%). The pistachio hull extract efficiently inhibits the mono and diphenolase activity of mushroom tyrosinase (IC50= 141.07 and 116.08 μg/mL, respectively) and it was able, thanks to its strong antioxidant and free-radical scavenging activities, to hinder the l-DOPA auto-oxidation in a concentration-dependent manner (125–500 μg/mL). Results of in vivo assay showed that the treatment with pistachio hull extract (10 μg/mL) reduced pigmentation in zebrafish embryos at early stages of development (60.01% of inhibition vs control). In conclusion, these findings suggest that the ripe pistachio hull may be considered as a promising source of antioxidant and skin whitening agents for the development of new products useful in preventing the pigmentation disorders in humans and/or to improve the food quality.