Antibacterial and antioxidant activity of leaf organic extracts of local cultivars of Murraya koenigii (L.) Spreng from Tamilnadu

Abstract

The aim of the present study was to evaluate the antibacterial activity against fi ve bacterial pathogens and anti-oxidant activity of three organic extracts prepared from the leaves of local cultivars of Murraya koenigii. Agar well diffusion was utilized to determine the zone of inhibition. Broth microdilution was employed to fi nd out the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC). Anti-oxidant activity was analysed using 2,2-Diphenyl-1-picryl hydrazyl (DPPH) free radical scavenging assay. The organic extracts displayed promising antibacterial activity against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa. Ethyl alcohol extract presented highest inhibitory activity when compared to hexane and chloroform extracts. In relation to agar diffusion method, the ethyl alcohol extract displayed lowest MIC and MBC value of 12.5 and 25 mg ml-1 against Staphylococcus aureus and same MIC and MBC value of 25 and 50 mg ml-1 against Escherichia coli and Pseudomonas aeruginosa. The radical-scavenging activity of ethyl alcohol extract (IC 50 = 30 μg ml-1) is very close to that of the standard compound, gallic acid (IC 50 value of 35 μg ml-1). The results suggested that the local cultivars of M. koenigii carry benefi cial health effects in terms of antimicrobial and anti-oxidant activities and could be used as a promising dietary supplement.