Abstract:
Plants have been one of the important sources of medicines since the beginning of human civilization. There is a growing demand in the present world for plant based medicines, health products, pharmaceuticals, food supplements, cosmetics etc. The antimicrobial activity of extracts of different plants has been recognized for many years for screening purpose. In the present study, crude ethanol extracts of leaves of three medicinal plants of Bangladesh namely, Anonna squamosa Linn. (Fam: Anonnaceae ), Calotropis procera R. Br. (Fam: Asclepiadaceae ), and Piper betel Linn (Fam: Piperaceae ) were prepared and investigated for their in vitro antimicrobial properties and for determining their phytochemical constituents. All the crude extracts were tested against four different gram positive and gram negative bacteria by the disc diffusion technique, where kannamycin (30 μg/disc) disc was used as a standard. Among all, the ethanol extracts of Piper betel Linn. showed the maximum antibacterial activity against Escherichia coli with the maximum zone of inhibition, whereas the Anonna squamosa Linn. and Calotropis procera R. Br.showed significant zone of inhibition against the bacteria used in the study. In phytochemical screening, various tests were performed for the determination of the presence or absence of alkaloids, phenols, steroids, tannins, flavonoids, saponins, glycoside and volatile oils. From the tested results, it was evident that steroids, tannins, saponins, glycosides and volatile oils were present in the Anonna squamosa Linn. leaf extract whereas all the constituents for which the tests were carried out were present in the leaf extract of Calotropis procera R. Br. Piper betel Linn. leaf extract was found to contain alkaloids, phenols, steroids, tannins and volatile oils.
