Extraction, characterization and pharmacological evaluation of leaves and root bark of Dalbergiella nyasae (Baker f.)

Abstract

Introduction:Dalbergiella nyasae (Baker f.) belongs to the family Papilionaceae, small to medium sized herbal plant well known for its medicinal properties in the treatment of gastrointestinal infections including diarrhoea. This study aimed to determine the in vitro antimicrobial activity of crude extracts and fractions from leaves and root bark of D. nyasae against selected bacteria and yeast of gastrointestinal relevance. Methods: Fourteen extracts from leaves and root bark of D. nyasae have been screened for the antimicrobial activity against three bacteria species including Gram negative E. coli and P. aeruginosa, Gram positive S. aureus and one yeast species C. albicans using agar well diffusion, micro broth dilution and Total Activity (TA) analysis methods. Crude extracts have been qualitatively screened for the presence of phytoconstituents and HPLC fingerprint profiles determined. Results: Excellent antibacterial and antifungal activity against Gram positive S. aureus and one yeast species C. albicans respectively were observed in n-butanol fraction of leaves extract. In root bark, best antibacterial activity against S. aureus was observed in ethanol extract while against P. aeruginosa was observed in acetone extract. For E. coli, best antibacterial activity was recorded in ethanol extract. Phytochemical analysis demonstrated the presence of alkaloids, flavonoids, saponins and terpenoids. The HPLC fingerprint profiles of leaves extract recorded one major peak whereas root bark extract recorded two major peaks. Conclusion: This investigation established a good support for use of D. nyasae plant by traditional healers in Malawi as herbal medicine for gastrointestinal infections and a base for development of novel potent drugs and phytomedicine.