Inhibitory effect of apocarotenoids on the activity of tyrosinase: Multi-spectroscopic and docking studies

• The effective usage of food colorant apocarotenoids as an alternative to synthetic anti-browning agent.
• Apocarotenoids reversibly inhibited tyrosinase activity through extensive hydrophobic interaction.
• The allosteric binding of apocarotenoids to tyrosinase.
• In vitro studies showed that apocarotenoids inhibited melanin synthesis and tyrosinase activity in B16F0 cell line.

In this present study, the inhibitory mechanism of three selected apocarotenoids (bixin, norbixin and crocin) on the diphenolase activity of tyrosinase has been investigated. The preliminary screening results indicated that apocarotenoids inhibited tyrosinase activity in a dose-dependent manner. Kinetic analysis revealed that apocarotenoids reversibly inhibited tyrosinase activity. Analysis of fluorescence spectra showed that apocarotenoids quenched the intrinsic fluorescence intensity of the tyrosinase. Further, molecular docking results implied that apocarotenoids were allosterically bound to tyrosinase through hydrophobic interactions. The results of the in vitro studies suggested that higher concentrations of bixin and norbixin inhibited tyrosinase activity in B16F0 melanoma cells. Our results suggested that apocarotenoids could form the basis for the design of novel tyrosinase inhibitors.