Synthesis and investigation of tyrosinase inhibitory activity of some new benzimidazole derivatives

In this study, 4 new 2-(4-(1Hbenzimidazol-1-yl)phenyl)-3-(substitutedphenylamino)thiazolidin-4-one (2a-d) and 7 new 2-(4-(1H-benzimidazol-1-yl)phenyl)-3-(substitutedphenyl)thiazolidin-4-one (3ag) were synthesized and their tyrosinase inhibitory activity were investigated. The structures of the target compounds were elucidated using 1H/13C-NMR, IR and MS. The structure of 2b was also characterized using HSQC NMR technique. The inhibitory activity of the compounds against tyrosinase was evaluated and kojic acid was used as positive control in the activity studies. Among the target compounds, 3bg demonstrated stronger tyrosinase inhibitory activity (IC50 values for 3b-g ranged from 80.93 to 119.20 μM), compared to the positive control kojic acid (IC50: 125.08 μM). With IC50 value of 80.93 μM, 5-(2-(4-(1H-benzimidazol-1-yl)phenyl)-4- oxothiazolidin-3-yl)-2-methylbenzenesulfonamide 3g was found to be the most active derivative of the series. The MTT assay studies used to determine the cytotoxicity of 3b-g showed that 3c, 3d, 3f and 3g were not cytotoxic in the range of 0-200 µM. Considering its tyrosinase inhibitory activity and cytotoxic effect, 3g exhibits promising potential for further research and development as a novel tyrosinase inhibitor.