The Antimicrobial Activities of the Stem Extract of Strophanthus Gratus, Apocynaceae

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The ethanolic and aqueous extracts of the stem of Strophanthus gratus from the Botanical Gardens, KNUST, were tested for in vitro antimicrobial activities. Traditional herbal practitioners use the decoctions of the stem of this plant to treat gonorrhoea and syphilis. Phytochemical tests on the extracts showed that they contained saponins, flavonoids, steroids, alkaloids, anthraquinone glycosides, cyanogenetic glycosides, cardiac glycosides and tannins. Test organisms used included E. faecalis, Pr. vulgaris, Staph aureus, B. subtilis, B. thuringiensis, S. typhi, Ps aeruginosa and Neisseria gonorrhoeae. The results showed that both the ethanolic and aqueous extracts were active against the test organisms. However, the ethanolic extract recorded lower Minimum Inhibitory Concentrations against the organisms when compared with the aqueous extract. When the activities of the extracts were compared with those of ciprofloxacin under the same experimental conditions, it was realized that the extracts were more active than ciprofloxacin against the test organisms with the exceptions of Neisseria gonorrhoeae, S. typhi and E. coli. Auxiliary tests on the ethanolic extract of the plant showed that the plant has some antioxidant activity in addition to its antimicrobial activity.
A Thesis submitted to the Department of Chemistry, Kwame Nkrumah University of Science and Technology in partial fulfillment of the requirements for the award of the degree of MASTER OF SCIENCE (ORGANIC CHEMISTRY) College of Science. October, 2013