In Vitro Screening of the Antibacterial Activity and Identification of Bioactive Compounds From Plants against Selected Vibrio spp. Pathogens

In vitro investigation of the vibriocidal activity of acetone extracts of Saraca indica Linn (Caesalpinaceae) and Datura stramonium Linn (Solanaceae), and aqueous extracts of Allium sativum Linn (Liliaceae) showed that they have antibacterial activity against multidrug-resistant human pathogens. Disc diffusion assay showed that there was significant concentration-dependent antibacterial activity against standard strains of Vibrio cholerae, Vibrio parahaemolyticus, and 12 multidrug-resistant isolates of Vibrio cholerae non-O1. The crude plant extracts had zones of inhibition in the range of 7-27 mm against 1 or more test bacteria, with MIC ranging from 2.5 to 15 mg/ml. Acetone extracts of S. indica and D. stramonium, in most cases, had more potency (low MIC value) than ethanol and aqueous extracts: however, the aqueous extract of A. sativum was the most effective. Thin layer chromatography (TLC), bioautography. and high performance liquid chromatography (HPLC) analysis of the crude extracts revealed that saponin. tannin, scopolamine, atropine, and allicin were the active constituents.