Objective: Aim of this study is to analyze the antibacterial and antioxidant potential of crude saponin extract (CSE) from Abutilon indicum leaves.Methods: CSE was subjected for gas chromatography-mass spectrometry (GC-MS) analysis to identify its components. Antibacterial potentialwas analyzed using agar well diffusion method and minimum inhibitory concentration (MIC) was detected using 96-well plate method, againstStaphylococcus aureus (MTCC: 3160) and Escherichia coli (MTCC: 443). DNA damage study was performed using comet assay. Antioxidant capabilitywas studied using 2,2-diphenyl-1-picrylhydrazyl scavenging assay.Results: GC-MS analysis suggested a library match to benzene-1-4-bis(phenylmethyl), with a molecular weight of 258 g/mol to be the majorcomponent in the CSE at 21.25 RT. CSE demonstrated 96.16% free radical scavenging activity at 2.5 mg/ml concentration. CSE demonstrateda significant antibacterial activity in the well diffusion assay, S. aureus 17 mm and E. coli 15 mm, with a MIC value of 1.11 mg/ml. Comet assaydemonstrated no DNA damage.Conclusion: These results conclude that CSE of A. indicum leaves possesses promising antibacterial and antioxidant potential.Keywords: Abutilon indicum, Saponin, Escherichia coli, Staphylococcus aureus, 2,2-diphenyl-1-picrylhydrazyl, Antibacterial assay.

This study aims at investigation of antibacterial property of Parthenium hysterophorous against aquatic bacterial pathogens and to identify the key bioactive compound of the same. Antibacterial activity of the crude extracts confirmed that chloroform extract PHC has strong antibacterial activity against aquatic pathogens V.anguillarum and V.harveyi with 16mm and 15mm ZOI at 1mg/well concentration. The crude extracts were subjected for GC-MS analysis to identify the secondary metabolites. PHC was subjected to silica-gel column chromatography to separate the individual phytochemicals. PHC was separated into 9 fractions, among which Fraction No.2 demonstrated significant antibacterial activity against V.anguillarum and V.harveyi with 19mm and 17mm ZOI at 10µg/well concentration. Fraction No.2 was identified to be β-sitosterol based on mass spectrometry analysis and fragmentation analysis. In-silico protein ligand docking demonstrated that β-sitosterol has highest affinity to inhibit dihydrofolate reductase (DHFR) enzyme with -10.10Kcal/mol binding energy. This prediction was further validated using molecular dynamic simulation for 20ns. Based on these computational analyses, it was proposed that β-sitosterol exhibits antibacterial activity via inhibition of DHFR enzyme. β-sitosterol is a well known nutritionally valuable compound that reduces cholesterol levels in humans. It is also been used as supplement feed to increase the nutritional value of cultured fishes. β-sitosterol has also been proven to have positive effect in growth and reproduction of cultivated fishes. Findings of this study strongly suggest the usage of β-sitosterol in aquaculture, as nutritional supplement and also as disease control agent to prevent and control fish diseases caused by Vibrio species.