Phytochemical and Antimicrobial Evaluation of Leaf-extracts of Pterocarpus santalinoides

Aim: This study was undertaken to examine the phytochemical constituents and antimicrobial activity of leaf-extracts of Pterocarpus santalinoides, a plant with wide application in Igede people’s traditional medicine against microbial infections.

Methodology: Successive extraction of leaves of this plant at room temperature using petroleum ether, ethyl acetate, butanol, ethanol and water was carried out. These extracts were phytochemically screened qualitatively for the presence of alkaloids, flavonoids, saponins, tannins and terpenoids using established literature procedures. Agar well diffusion technique was used to screen the extract for antimicrobial activity. MICs, MBCs and MFCs for the various extracts were determined by the tube dilution technique. Graded concentrations of the extract solutions in Mueller Hinton broth were used for the tests. MBCs and MFCs were done to establish the nature of antimicrobial activity of these extracts.

Results: Qualitative phytochemical screening of leaf-extracts of P. santalinoides revealed presence of alkaloids, flavonoids, terpenoids, saponins-glycosides and tannins (except ethanol extract that contained no tannins). These extracts inhibited growth of test organisms, and implies antimicrobial activity on E. coli, P. mirabilis, S. typhi, S. aureus and C. albicans. Zones of inhibition ranged from 17-24 mm. The MICs ranged from 5.0 mg/ml to 10 mg/ml while MBCs and MFCs ranged from 10 mg/ml to 20 mg/ml. Ethanol extracts showed the widest zone of inhibition followed by aqueous extracts (24 mm and 21 mm, respectively).

Conclusion: These results lend support to the ethnomedicinal applications of this plant by the Igede people of North Central Nigeria, in treating infections caused by these test organisms which are human pathogens. The ethanol extract in particular, may be exploited as a possible antimicrobial agent for the management of infectious pathogenic diseases caused by these microorganisms.