Physicochemical characterization and antibacterial activity of the leaf oil of Crotalaria pallida Aiton

Antibiotic resistance has led to the search for more effective antimicrobial agents among plant materials that can serve as source and template for the synthesis of new antimicrobial drugs. The current study aims to analyses the oil, extracted from the leaves of Crotalaria pallida for its physicochemical and antimicrobial properties. Leaf oil was extracted by petroleum ether (40–60 °C) and its fatty acid constituents were isolated as a mixture after saponification. Mixture of fatty acid was purified by TLC and characterized by IR, GC and GC–MS analysis by converting them into their FAME. MIC of the oil against the Gram positive and Gram negative bacteria was determined by agar diffusion method. Nineteen fatty acids were identified by gas-liquid chromatography followed by GC–MS. It was found that unsaturated fatty acids were present in greater amounts than saturated fatty acids. Most predominating unsaturated and saturated fatty acids were linolenic acid (34.06 ± 0.23%) and palmitic acid (24.47 ± 0.22%) respectively. The acid value (19.63 ± 0.22) and saponification value (109.08 ± 2.87) were also estimated to evaluate the quality of the oil. The oil showed good antimicrobial activities against Gram-positive bacteria, Bacillus subtilis as well as Gram-negative bacteria, Escherichia coli and Acinetobacter junii.