Abstract:
The main objective of this study was to investigate Phytochemicals, in vitro antibacterial and
antioxidant activity of stem bark extract of stereospermum kunthainum (Botoro). The plant part
was collected from East Wollega Zone Wayu Tuka district around Bonaya kebele and air dried.
The weighted sample size for experimental investigations was powdered and extracted
successively with petroleum ether, ethyl acetate and methanol followed by physical filtration
using Whitman no 1 filter paper. Filtrates were concentrated using rotary evaporator. The
preliminary phytochemical screening test was carried out using appropriate reagents and the
result showed the presence of alkaloid, flavonoids, saponins, tannins and phenols. The crude
extract of petroleum ether, ethyl acetate and methanol was also subjected to determination of
total flavonoid contents which was indicated, petroleum ether (65.05 g), ethyl acetate (174.2g)
and methanol (205.85 g) values. Test solution of the extracts were prepared in DMSO (dimethyl
Sulfoxide) for antibacterial activity which was determined by disk diffusion methods adopting
Gentamycin as standard. The methanol extract of the stem bark of S.kunthainum showed
significant inhibition zone against the selected bacterial strains (S.aureus, S.Pyogens, E.coli, and
K.Pneumonia). While ethyl acetate and petroleum ether extracts does not shown any growth
inhibition on the given test strains. Antioxidant activity of petroleum ether, ethyl acetate and
methanol crude extracts was also evaluated using ascorbic acid as reference by DPPH assay
and FRAP method in which, the results showed that inhibitory concentration (IC50) values of
34.43 ppm 24.68 ppm, 17.49 ppm and 8.66 ppm for P.ether, Ethyl.acetete, methanol crude
extract and reference ascorbic acid respectively. The antibacterial and scavenging power of free
radicals result of this study depict the plant stem was positively associated with phytochemical
contents of the stereospermum kunthainum (Botoro) extract.