Phenolic composition, enzyme inhibitory, and antioxidant activity of Bituminaria bituminosa

This study aimed to evaluate the in vitro antioxidant and enzyme inhibitory activities of ethyl acetate, methanol, and water extracts of Bituminaria bituminosa. In phosphomolybdenum assay, the methanol extract showed the highest activity (166.78 mu mol TEs/g dry plant). The water extract exhibited the highest scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH center dot) and 2,2-azino-bis (3-ethylbenzothiazloine-6-sulphonic acid) (ABTS(center dot+)). In addition, it exhibited the highest activity in cupric ion reducing (CUPRAC) and ferric reducing antioxidant power (FRAP) assays (41.26 and 46.82 mu mol TEs/g dry plant). The extracts did not show cholinesterase and tyrosinase inhibitory activity. However, alpha-glucosidase inhibition assay resulted in the superiority of water extract (1233.86 mu mol ACEs/g dry plant). In the case of alpha-amylase inhibitory assay, the ethyl acetate extract showed the highest activity (53.65 mu mol ACEs/g dry plant). The water extract exhibited the highest phenolic content (31.70 mu mol GAEs/g dry plant). In contrast, the methanol extract was found rich in flavonoid compounds (5.29 mu mol REs/g dry plant). The water extract contained considerable amounts of rosmarinic acid, luteolin, quercetin, and rutin. Therefore, it can be used as a source of new and alternative antioxidant and enzyme inhibitory agents.