Evaluation of Potential Antimicrobial Activity of Stem Barks Extract of Persea americana (Mill) and its Solvent Fractions against Randomly Selected Pathogenic Bacteria and Fungi

Persea americana stem barks are used locally in parts of Nigeria in treating bacterial infections. This study aims to determine the antimicrobial potential of the methanol extract and fractions against S. aureus, B. substilis, E. coli, P. aeruginosa, C. albicans and Aspergilus species. The plant material was extracted with 80% methanol and partitioned into chloroform and aqueous phases which were evaluated for antimicrobial activities using agar well diffusion method. The methanol extract inhibited the growth of the test organisms; P. aeruginosa showed the most activity at 100mg/mL. The CHCl3 fraction of the plant extract was ineffective against gram negative bacteria (E. coli and P. aeruginosa) at low concentrations. The CHCl3 fraction was most effective against S. aureus at 50mg/mL but ineffective against gram-negative organisms at lower concentrations. The extract's H2O fraction had the most antimicrobial activity. The H2O fraction inhibited B. substilis at 50mg/mL (8.50±1.08mm).Alkaloids, saponins, tannins, steroids, among others were observed in the extract and fractions. Owing to the higher antimicrobial activity in the H2O fraction, the active antimicrobial compounds could be polar in nature. The higher inhibitory activity recorded by the H2O fraction supports the folkloric use of P. Americana

Euphorbia Graminea Jacq. (Euphorbiaceae): A Comparative Antimicrobial Evaluations of Stem and Root Extracts

Antimicrobial resistance is a global issue. Euphorbia plants are used locally to treat microbial infections. This study examined the antimicrobial potential of Euphorbia graminea stem and root extracts. The stems and roots extracts of E .graminea were extracted using 80% methanol and tested for antimicrobial activity at concentrations between 4.69-300mg/mL against non-clinical isolates (S. aureus, E. coli, P. aeruginosa, C. albican, A. niger). The active roots extract was fractionated using vacuum liquid chromatographic fractionations (VLC) and the resulting fractions bulked and tested against the organisms at 6.25-100mg/mL.  The MIC of extracts and vlc bulked fractions were tested at 0.39-6.25 mg/mL.  The root extract recorded higher antimicrobial activities over the stem extract especially against S. aureus and E.coli, hence was fractionated. Among the vlc sub-fractions of the roots extract, fractions A (2) recorded no activity against the test organisms while fractions C (9-10) recorded 7.50 and 3.50 mm against S. aureus and E. coli only at the maximum concentration of 100mg/mL. However, fractions B (3-8) conspicuously gave zones of inhibitions far higher than the other fractions. This study has shown that the roots extract of E. graminea has higher antimicrobial activities more than the stems, further justifying the ethno-botanical potentials of the plant in treating skin infections