Studies on antibacterial, antioxidant, larvicidal, pesticidal activities and phytochemistry of Leonotis nepetifolia (Linn) R. Br.

Abstract

Antibacterial, anti-oxidant, larvicidal, pesticidal activity and phytochemical constituents of the plant Leonotis nepetifolia is studied. The plant, Leonotis nepetifolia was collected from Villiambakkam Village belonging to Chengalpet District of Tamil Nadu State in India. The acetone, chloroform, ethanol and ethyl acetate extracts of leaves, stem and root of the plant were evaluated for their phytochemical constituents. Antibacterial efficacy was studied through Micro dilution technique on Bacillus subtilis (MTCC 121), Escherichia coli (MTCC 443), Klebsiella pneumoniae (MTCC 1320), Pseudomonas aeruginosa (MTCC 424), Staphylococcus aureus (MTCC 96) and Streptococcus epidermidis (MTCC 435), antioxidant potency through DPPH scavenging activity, larvicidal potency using the nauplii of Artemia salina and pesticidal activity using a rice weevil, Sitophilus oryzae. The phytochemical studies revealed that Phlobatannins are completely absent in leaf, stem and root of the plant. Steroids are absent in stem and root and Saponin in stem of the plant. Ethyl acetate extract of the stem of the plant showed significant anti-bacterial activity comparable to Streptomycin as control. The ethanolic extract of the plant, Leonotis nepetifolia recorded the EC₅₀ value at 14 mg/ml against DPPH. The root of the plant was found to possess significant larvicidal and pesticidal activity against Artemia salina and Sitophilus oryzae respectively. The study amply demonstrates that the plant, Leonotis nepetifolia can be potentially used as an antibacterial, antioxidant, larvicidal and pesticidal agent.