The potential of Monascus purpureus pigments of red yeast rice for skin-lightening cosmetics: an in silico pharmacology approach towards human tyrosinase-related protein 1 and Aspergillus oryzae active-tyrosinase and in vivo validation in UVB-exposed Wistar rats.

Monascus purpureus red yeast rice (RYR) was reported to exhibit photoprotective and anti-melanogenic activities in vitro. This study aims to predict the pharmacokinetic properties of Monascus pigments, their binding modes, and complex stability towards tyrosinase enzymes using in silico techniques, validate them in an animal model, and determine the protein and monacolin K in the extract. All the pigments exhibit low absorption, low distribution, low skin permeability, and are unlikely to alter CYP2D6, but may be metabolised by CYP3A4. They interact with tyrosinases, showing a binding mode similar to kojic acid. MD simulation demonstrates the stability of monascorubrin/AoTYR and monascin/hTRP1 complexes. The extract contains 13.28% protein and monacolin K. M. purpureus RYR at 2% and 4% reduced erythema in UVB-exposed skin in rats. These findings suggest that M. purpureus RYR may be developed as a component of skin-lightening dermatocosmetic products; however, further mechanism studies are needed to confirm this effect.