Phytochemical and antimicrobial activities of <i>Newbouldia laevis</i>’ leaves on isolates from wound infections

Abstract

The leaves of Newbouldia laevis were subjected to ethanolic, hot, and cold aqueous extraction. Standard methods were used for both extraction and phytochemical screening. The antimicrobial activity of the plant extract was done using the modified agar well diffusion method. The extracts (ethanolic, hot, and cold aqueous) at a concentration of 100 mg/ml, and varying concentrations (100mg/ml, 50mg/ml, 25mg/ml) were used to challenge bacterial isolates in duplicates. The test organisms were Escherichia coli, Klebsiella pneumoniae, Proteus sp, Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus epidermidis, Candida albicans.The ethanolic extract was screened phytochemically and revealed the presence of flavonoids, tannins, terpenes, steroidal and cardiac glycosides.The ethanolic extract showed highest antimicrobial activity of 14.5mm on the enteric gram negative organisms (Proteussp, K. pneumoniae and Escherichia coli), followed by the hot aqueous extract (12.5mm) on the enteric gram negative organisms and Staphylococcus aureus. The cold aqueous extract exerted the least inhibition of 11mm on the enteric bacteria. The zones of inhibition of the ethanolic extract for Staphylococcus aureus and Pseudomonas aeruginosa were 13.85mm and 13.86mm respectively; it was 12.5mm against C.albicans and 12mm against S.epidermidis. The hot aqueous extracts had the same diameter zones of inhibition of 12.5mm on Proteus sp, K. pneumoniae, E.coli and S.aureus, and it exerted the same inhibition zone of 11mm on both S. epidermidis and C. albicans, while it had 11.9mm on P.aeruginosa. The cold aqueous extract exerted the least zones of inhibition of 11mm against the enteric bacteria, 10.83mm and 10.8mm on S.aureus and P. aeruginosa respectively; and same inhibition of 10mm on both S. epidermidis and C. albcans. The extracts were subjected to MIC evaluation and the findings showed that E.coli was the most sensitive; followed by K. pneumoniae and Proteus sp, followed by S. aureus and P. aeruginosa, while S. epidermidis and C. albicans were the least affected by the antimicrobial effects of the leaves’ extracts of N.laevis.There was no value for MBC. This work indicates that N. laevis’ leaves possess phytochemicals with antimicrobial activity and could be used to treat wound infections when purified to the appropriate pharmacological level.

Keywords: Newbouldia laevis, Phytochemical, Antimicrobial, Wound isolates