# Natural Tyrosinase Inhibitors from Lycopodium japonicum

## TL;DR

This study identifies natural tyrosinase inhibitors from Lycopodium japonicum, a plant with potential cosmetic and medicinal uses.

## Contribution

The discovery of fifteen new secondary metabolites, five of which show strong tyrosinase inhibition.

## Key findings

- Five compounds (4, 12, 13, 14, and 15) showed significant tyrosinase inhibition with IC50 values between 1.46 and 6.82 mM.
- Molecular docking revealed key amino acid residues involved in compound-tyrosinase interactions.
- L. japonicum is confirmed as a rich source of natural tyrosinase inhibitors.

## Abstract

Natural tyrosinase inhibitors are an important group of compounds with cosmetical and medicinal applications. With the aim of finding new types of natural tyrosinase inhibitors from ornamental and medicinal plants, Lycopodium japonicum was selected and studied. As a result, fifteen structurally diverse secondary metabolites 1–15 were isolated and identified. Their chemical structures were identified by analysis of their spectral data and compared with those reported in the literature. In the tyrosinase inhibitory bioassay, five phytochemicals, 4, 12, 13, 14, and 15, exhibited significant inhibitory effects, with half-maximal inhibitory concentration (IC50) values ranging from 1.46 to 6.82 mM. Additionally, molecular docking studies disclosed that Lys376, Lys379, Gln307, and other amino acid residues played key roles in the potential binding interactions between the active compounds and the tyrosinase. These findings suggest that the species L. japonicum is a warehouse of natural tyrosinase inhibitors.