In vitro antioxidant, brine shrimp lethality and antimicrobial activities of methanol and petroleum ether extracts of Cassia renigera fruit

Cassia renigera (C. renigera) is an evergreen tree (family Caesalpiniaceae) is locally known as Minjiri (Bengali). It is locally used as a medicinal plant. In this study we investigated antioxidant, brine shrimp lethality and antimicrobial activities of the fruit extracts of this plant using different in vitro assay models. Methanol extract showed better activities than petroleum ether extract in total phenol, total flavonoid and total antioxidant capacity assays. Besides, methanol extract also showed higher 1,1-diphenyl- 2-picrylhydrazyl (DPPH) and Nitric oxide radical scavenging activities than petroleum ether extract. In cupric reducing and reducing power capacity assays methanol extract exhibited dose dependent reducing capacity. In brine shrimp lethality bioassay petroleum ether extract (LC50 of 89.385 mu g/mL, chi(2) = 215.968, p < 0.05) was found to be more potent than methanol extract (LC50 of 128.042 mu g/mL, chi(2) = 235.274, p < 0.05). In disk diffusion technique, it was observed that Gram positive bacteria are more susceptible than Gram negative bacteria. Both extracts showed broad spectrum antimicrobial activity. Methanol extract showed antibacterial activity against all tested microorganisms. The highest activity (minimum zone of inhibition 11.25 +/- 0.35 mm) was exhibited by methanol extract against Bacillus cerus. No activity was observed against Escherichia coli and Shigella dysenteriae by petroleum ether extract. In a nutshell, it is suggested that the fruit can be used as a potential source for the above mentioned bioactivities. That is why extensive researches may be carried out to investigate the active principles responsible for these activities.