ISOLATION OF EPICATECHIN AND ANTIMICROBIAL EVALUATION OF INDIGOFERA WELWITSCHII (FABACEAE)

Abstract

Proper phytochemical investigations of medicinal plants derived constituent has become of necessary owing to their
versatile application in medicine. Indigofera welwitschii of the family fabaceae; is also among the species not fully
investigated for its medicinal value. It is use in traditional medicine in managing skin problems. The aim is to isolate
and characterize phenolic compounds from the EAF of the aerial parts of Indigofera welwitschii and evaluate its
antimicrobial potential. The plant material upon collection was prepared and extracted with methanol. The resulting
methanol extract was successively partitioned into hexane (HEF), chloroform (CHF), ethylacetate (EAF), n-Butanol
(NBF) fractions and residual aqueous (AQF) fraction respectively. Silica gel chromatographic separation of EAF
using gradient elution and repeated gel filtration using serphadex LH-20 was employed to isolate pure compound. A
portion of the crude methanol extract (CME) and fractions was subjected to preliminary phytochemical and
antimicrobial assessments. The organisms were clinical isolates of Escherichia coli, Staphylococcus aureus, Bacillus
subtilis, Methicillin Resistant Staphylococcus aureus and Pseudomonas aeruginosa. Agar well diffusion technique
was used to determine the susceptibility of the extract (CME) and the fractions while microbroth dilution method
was used to determine both the MIC, and MBC. The structure was elucidated using physico-chemical test, 1D- &
2D-NMR. (-)-Epicatechin (a flavan-3-ol) was identified. The activity against all bacterial isolates tested reveal the
zones of growth inhibition range of between 12-25 mm at a concentration of 50 and 100 mg/mL. EAF and NBF
have the highest activity with lowest MIC/MBC ranges of between 31.25 -62.50 mg/mL