Comparative study of the ethanolic extracts of four Nigerian plants against some pathogenic microorganisms

The ethanolic extracts of Cassia alata (CA.), Walnut-Juglan nigra (JN), Ocimum basilicum (OB) and Aloe vera (AV) were studied for their in vitro antimicrobial activity against tested pathogenic microorganisms using Agar diffusion method. Preliminary phytochemical screening showed the presence of tannin, fats and oil, saponins and glycosides in the ethanolic extracts of all tested plants. Juglan nigra has the highest activity against all tested organisms Escherichia coli, Staphylococcus aureus and Candida albican. While the least activity against tested organism was shown by OB, ethanolic extracts of AV was the most effective against Staphylococcus aureus, while JN was the most effective against Escherichia coli and Candida albican. Also, the combined 600 mg mL-1 (concentration) of the four extracts showed a remarkable inhibitory effect on the organisms, produces over 50% of the activity of a standard antibiotic, Fulcin. Walnut-Juglan nigra (JN) showed the best antibacterial activity out of the four; hence this plant can be further subjected to isolation of the therapeutic antimicrobials and further pharmacological evaluation. © 2009 Academic Journals Inc.