Synthesis of Some Novel 2-Substitutedbenzyl-(4)7-phenyl-1H-benzo[d]imidazoles in Mild Conditions as Potent Anti-Tyrosinase and Antioxidant Agents

Abstract

Novel 2-substitutedbenzyl-4(7)-phenyl-1H-benzo[d]imidazole compounds were synthesized and characterized. Although 2a and 2b were reported previously in the literature, 11 compounds were synthesized (nine of them were newly synthesized) and the tyrosinase inhibitory effects and antioxidant activities of these compounds were studied for the first time. All of the synthesized compounds displayed certain inhibitory effects on tyrosinase, with IC₅₀ values ranging from 37.86 ± 0.24 to 75.81 ± 2.49 μM. Among the compounds, 2j exhibited similar tyrosinase inhibitory effect (IC₅₀ = 37.86 ± 0.24 µM) to the positive control, kojic acid (IC₅₀ = 21.93 ± 0.11 µM). Kinetic studies revealed it to act as non-competitive tyrosinase inhibitor with a K_i value of 50.2 µM. The antioxidant activities of the compounds were investigated by using in vitro antioxidant assays, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing antioxidant power (FRAP). All of these results indicated that the compounds might have potential application as tyrosinase inhibitors.

Keywords: Assay; Inhibitors; Substituent effect; Synthesis.