The antimicrobial, antioxidant and anti-inflammatory activities, lipoxygenase, xanthine oxidase (XO), acetylcholinesterase activities and phenolic contents of different solvent extracts (ethanol, ethyl acetate, chloroform, petroleum ether and water) of Crotalaria pallida were evaluated using in vitro standard methods. These solvent extracts were most potent inhibiting all isolates with different zones of inhibition. The maximum inhibition of bacteria and fungi was observed from ethanol extract. The minimum microbial concentration (MMC) of the active extract was observed from ethanol, petroleum ether and ethyl acetate ranged from 0.3 to 3.2 mg/ml for the sensitive bacteria. In case of fungi, the minimum inhibitory concentration (MIC) of the active extracts ranged from 0.6 to 4.0 mg/ml. These data suggest that the C. pallida extracts analyzed are potential antimicrobial candidates with a broad range of activity. Phytochemical analysis was conducted to all the solvent extracts to their constituents. The level of total phenol, alkaloids, terpenoids, saponins, phenols, steroids and tannins from ethanol, ethyl acetate and petroleum ether extracts were higher. The antioxidant activities of different solvent extracts of C. pallida were determined by 2, 2-diphenyl-1-picrylhydrazyl (DPPH) and ferrous reducing antioxidant property (FRAP) methods. Ascorbic acid and butylated hydroxytoluene (BHT) were used as standard for antioxidant activity. The ethanol, ethyl acetate and petroleum ether extracts possessed strong scavenging activity in both DPPH and FRAP methods. The ethanol, ethyl acetate and petroleum ether had showed free radical inhibition of 88, 72 and 73 and 3617.89 ± 0.03, 2189.33 ± 0.03 and 1133.26 ± 0.01, respectively. The in vitro anti-inflammatory activities were evaluated using albumin denaturation, membrane stabilization and proteinase inhibitory activities using all the solvent extracts. The ethanol, ethyl acetate and petroleum ether showed activity by inhibiting the heat induced albumin denaturation and red blood cells membrane stabilization with 83.17, 71.33 and 58.14 and 68.21, 61.44 and 60.72 g/ml, respectively. The proteinase activity was significantly inhibited by the ethanol (82.53), ethyl acetate 74.31) and petroleum ether (62.92) g/ml. Aspirin was used as standard drug for the study of antiinflammatory activity. In addition, the ethanol, ethyl acetate and petroleum ether extracts showed antilipoxygenase activity and they also exhibited a moderate xanthine oxidase and acetylcholinesterase inhibitory activity.
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