Chemical and microbiological studies on some medicinal plants

Abstract

Antibacterial activity of ten locally available medicinal plants, Terminalia ar}una (Arjun), Rauvo/fia serpentina (Sharpagandha), Holarhena antidysenterica .(Kurchi), Aegle marmelos (Bel), HeIiotropium indicum (Hatisur), Helicteres isora (At mora), Syzygium cumini (Kalojam), Polygonum hydropiper (Biskatali), Spondias pinnata (Amra), Swertia chirata (Chirata) were studied against ten gram negative & one garm positive bacteria. Methanol extract of the seeds of Ho/arhena antidysenterica was found to be active against S.aureus; Methanol extract of the bark of Terminalia arjuna was active against Shigella dysenteriae, Shigella jIexneri, Shigella sonnei, Escherichia coli and S.aureus; and Methanol extract of the roots of Rauvo/fia serpentina was active against s.aureus. Extracts of the other plants showed no antibacterial activity. Fractionation of Methanol extracts were carried out by solvent extraction and lor column chromatographic techniques. Antibacterial activity tests of different fractions were carried out against the same test organisms. Ethyl acetate fraction of methanol extract of H.antidysenterica was found to be active against Saureus; Pet. ether-Ethyl acetate fraction (1 :4) of Tarjuna was found to be active against Shigella dysenteriae, Shigella jIexneri, Shigella sonnei,Escherichia coli and S.aureus; Pet. ether-Ethyl acetate fraction (2: I) of methanol extract of R.serpentina was active against Saureus: Antibacterial compound HAl then separated from the Ethyl acetate fraction of Methanol extract of H.antidysenterica with the help of preparative thin layer chromatography. Methanol extracts of Tarjuna and R.serpentina were then purified with the help of column chromatography followed by PTLC to yield compounds TA" and RS. Compound HAl was found to be active against S. aureus, TA, was found to be active against Shigella dysenteriae, Shigella jIexneri, Shigella sonnei,Escherichia coli and S.aureus; and compound RS showed antibacterial activity against Saureus. Three antibacterial compounds were then characterized by physical, chemical and spectroscopic analysis. Compound HAl was steroidal alkaloid with-C=N group ; viii compound TA3 was flavone with ketone group; and compound RS was alkaloid with phenyl hydroxyl group, aryl ether group and carboxylic acid group. Minimum Inhibitory Concentration (MICs) of compounds TAl for Shigella dysenteriae was 640 !1g/ml, that of compound TAl for Sflexneri was 320!1g/ml, that of compound TAl for Ssonnei was 960!1g/ml, that of compound TAl for E.coli was 640!1g/ml and that of compounds HA"TAl and RS for Saureus were 320!1g/ml,320!1g/m! and 160!1g/ml. respectively. The Minimum Bactericidal Concentration (MBC)of compound TAl Shigella dysenteriae was 790!1g/ml, that of compound TAl for Shigella flexneri was 780!1g/ml and that of compound TAl for Ssonnei was J075!1g/ml, that of compound TAl for E.coli was 775!1g/ml, and that of compounds HA"TAl and Rs for Saureus were 8JO!1g/ml,730!1g/ml and 670!1g/ml respectively.