Design, synthesis, QSAR modelling and molecular dynamic simulations of N-tosyl-indole hybrid thiosemicarbazones as competitive tyrosinase inhibitors

Tyrosinase is an enzyme crucial for the progression of melanogenesis. Immoderate production of melanin may be the cause of hyperpigmentation and darkening leading to skin diseases. Tyrosinase is the most researched target for suppressing melanogenesis since it catalyzes the rate-limiting stage of melanin production. Thiosemicarbazones have been reported to possess strong inhibition capability against tyrosinase. We have designed and synthesized eighteen N-tosyl substituted indole-based thiosemicarbazones as competitive tyrosinase inhibitors in the current work. All the compounds exhibited outstanding to good potency with half maximal inhibitory concentration in the range of 6.40 ± 0.21 µM to 61.84 ± 1.47 µM. The compound 5r displayed the top-tier inhibition amongst the entire series with IC₅₀ = 6.40 ± 0.21 µM. Compounds, 5q and 5r exhibited competitive inhibitions in concentration dependent manner with Ki = 3.42 ± 0.03 and 10.25 ± 0.08 µM respectively. The binding mode of 5r was evaluated through in silico molecular dynamics simulations and molecular docking, while ADME assessment studies predicted the drug-like characteristics of the derivatives. The newly synthesized derivatives may serve as a structural guide for designing and developing novel tyrosinase inhibitors.