Evaluation of tyrosinase inhibitory activity and mechanism of Leucrocin I and its modified peptides

This research first reports the tyrosinase inhibition and mechanism of Leucrocin I and its modified peptides (TILI-1 and TILI-2). Docking simulation showed that these peptides were predicted to bind and interact to active site of tyrosinase and exhibited the possibility to promote tyrosinase inhibition. Therefore, these peptides were synthesized, and their inhibitory activity was investigated. The results showed that the highest tyrosinase inhibition was achieved by TILI-2 followed by TILI-1 and Leucrocin I. A Lineweaver–Burk plot indicated that Leucrocin I exhibited mixed type characteristics, while its modified peptides exhibited competitive inhibition. Based on the greatest tyrosinase inhibition, TILI-2 was selected for further study. TILI-2 showed irreversible inhibition with two-step inactivation. Additionally, Leucrocin I and its modified peptides showed no toxicity toward B16F1 and HaCaT cells and decreased melanin and tyrosinase content in B16F1 cells. These results suggest that these peptides are promising peptides for the treatment of hyperpigmentation. •Leucrocin I, TILI-1 and TILI-2 could inhibit tyrosinase activity.•Leucrocin I, TILI-1 and TILI-2 interacted with tyrosinase active site.•The stronger interaction of peptide with copper exhibited the higher inhibition.•TILI-2 is competitive inhibitor with two step of irreversible inactivation.•Leucrocin I, TILI-1 and TILI-2 decrease melanin and tyrosinase activity in cells.