Comparative analysis of the antioxidant, antibacterial and plant growth promoting potential of five Indian varieties of Moringa oleifera L

The aqueous and ethanolic leaves and seeds extract of M. oleifera varieties, ‘Jaffna’, ‘PKM-1’ (Periyakulam-1), ‘PKM-2’ (Periyakulam-2), ‘ODC’ and ‘Conventional’ were analyzed for their free radical scavenging effect on DPPH (2, 2-diphenyl-2-picryl hydrazyl) and ABTS (2, 2-azinobis,3-ethyl-benzothiazolin-6-sulfonic acid). The DPPH and ABTS activity (based on IC50 values) trend with leaves extract was: Conventional > ODC > PKM-2 > PKM-1 > Jaffna and Conventional > ODC > PKM-2 > PKM-1 > Jaffna respectively. Similarly, the DPPH and ABTS radical scavenging activities of seeds extract was: Conventional > ODC > PKM-2 > PKM-1 > Jaffna and Conventional > ODC > PKM-2 > PKM-1 > Jaffna respectively. The trend observed with total phenolic content (TPC) and total flavonoid content (TFC) values for both leaves and seeds extracts was: Jaffna > PKM-1 > PKM-2 > ODC > Conventional. The antibacterial activity (disc-diffusion method) of the aqueous and ethanolic leaves and seeds extracts of the five varieties on Pseudomonas aeruginosa, Bacillus subtilis, Escherichia coli, and Staphylococcus aureus showed a similar trend: Jaffna > PKM-1 > PKM-2 > ODC > Conventional. A comparative assessment of the plant growth promoting potential of the leaves extracts on Stevia rebaudiana was also performed. The trend observed was: Jaffna > PKM-1 > PKM-2 > ODC > Conventional. Therefore, the comparative study reveals that ethanolic leaf and seed extracts of Jaffna variety possess strong antioxidant and antibacterial properties with a high TPC and TFC, as compared to the other varieties. It also exhibits a promising plant growth promoting activity. Thus, this variety can be explored further as a reliable source of natural bacteriostatic agent, antioxidants and plant growth enhancer.