Novel [1,2,4]triazolo[3,4‐b][1,3,4]thiadiazine derivatives embedded with benzimidazole moiety as potent antioxidants

Abstract

AbstractFourteen novel [1,2,4]triazolo[3,4‐b][1,3,4]thiadiazine derivatives bearing benzimidazole moiety (7a‐n) have been synthesized using the one‐pot nitro reductive cyclization method. All the synthesized compounds were confirmed by 1H nuclear magnetic resonance (1H NMR), 13C NMR, fourier‐transform infrared (FT‐IR), mass spectrum, and elemental analyses. All the title compounds were subjected to in vitro antioxidant activity. The free radical scavenging activity of the compounds was examined using DPPH, nitric oxide, and superoxide radical scavenging methods. The results demonstrated that compound 3‐(2‐(3,4‐dimethoxyphenyl)‐1‐propyl‐1H‐benzo[d]imidazol‐5‐yl)‐6‐4‐tolyl‐7H‐[1,2,4]triazolo[3,4‐b][1,3,4]thiadiazine (7c) was potent in scavenging both DPPH and nitric oxide radical with IC50 values of 13.57 and 18.55 μg/ml when compared to the standard with IC50 values of 23.75 and 23.14 μg/ml, respectively, which was due to the presence of electron‐donating groups. The activity was found to decline when electron‐donating groups were replaced by electron‐withdrawing groups. Moderate scavenging activity was observed for the superoxide radical. Structure activity relationship and physiochemical properties were studied for all the derivatives.