PHYTOCHEMICAL SCREENING, ANTIBACTERIAL AND ANTIOXIDANT ACTIVITIES OF AQUEOUS AND ORGANICS STEM EXTRACTS OF STROPHANTHUS HISPIDUS DC.

Antibacterial and antioxidant activities of Strophanthus hispidus stem aqueous and organic (cyclohexane, chloroform, ethyl acetate and ethanol) extracts were investigated in order to assess its use in traditional medicine. In vitro antibacterial activity assessed by Disc diffusion and Microdilution methods, was tested against Gram positive bacteria (sensible Staphylococcus aureus) and gram negative bacteria (Escherichia coli and Pseudomas aeruginosa) at a concentration of 0.5 mg/ml. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) values for all extracts range respectively from 0.05 mg/mL to 7.5 mg/mL and 0.117 mg/mL to 7.5 mg/mL. The activity was higher for cyclohexane and aqueous extracts. Cyclohexane extract had only terpenoids in considerable amount whereas aqueous extract contain alkaloids anthraquinone, tannin, saponine and polyphenols. Antioxidant activity evaluated using 2,2-diphenyl-2-picryl- hydrazyle ( DPPH) revealed that only ethanolic extract had appreciable antioxidant activity with an IC₅₀ value of 37,9 µg/mL. Ethanolic extract contain polyphenol, flavonoids, tannins, alkaloids, terpenoids and saponines. The presence of these secondary metabolites explains the use of this plant in traditional medicine.