Most fungi occur in nature and utilize simple sources of carbohydrates and nitrogen for growth. Sabouraud's dextrose agar has been an ideal medium for primary isolation of fungi from clinical specimens, but for specimens from nonsterile sites or heavily contaminated ones, it has been necessary to include inhibitory substances such as antibiotics like chloramphenicol (antibacterial) and cycloheximide (antifungal). The problems we have in the our laboratory owing to frequent contamination of cultures and the delays in the procurement of cycloheximide have stimulated a search for alternatives in our local environment to enhance effective laboratory diagnoses of fungal infections. Purified extracts of the leaves and bark of Jatropha curcas and Moringa oleifera (common plants in our locality) were tested against clinical isolates of fungi at various concentrations to determine the minimum inhibitory concentration at which common fungal contaminants are inhibited, without affecting the growth of the pathogenic fungi sought for. At a concentration of 0.75 mg ml(-1) contaminants were totally inhibited by the leaf extracts. The bark extracts did not inhibit any fungus even at higher concentrations. From the results it was evident that the leaf extracts of both plants have potentials for use as inhibitory substances in culture media against contaminant fungi including Aspergillus spp., Penicillium spp., etc. J. curcas and M. oleifera are very common plants in our locality. They can be obtained at almost no cost and at any time needed. The benefits of these findings to mycology laboratories in a developing country are enormous.

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The aim of this study was to investigate the antimicrobial, antioxidant and antiproliferative activities of leaves of Senna siamea. A sequential solvent extraction procedure was used in extracting powdered Senna leaves, starting with hexane, ethylacetate, ethanol and distilled water, respectively. Dry extracts obtained were tested at various concentrations against Pseudomonas aeruginosa, staphylococcus aureus, Salmonella typhi and Candida albicans. Antioxidant (Qualitative and quantitative) and antiproliferative tests were carried out on samples of the dry extracts. Ethylacetate extract of Senna siamea showed the highest antibacterial activity against S. typhi (zone of inhibition 15.0 mm) at concentration of 500mg/ml. The aqueous extract had the highest antioxidant activity, evidenced by a low IC50 value of 12.89µg/ml. Antiproliferative activity was determined by calculating the percentage inhibition of germination of Sorghum bicolor L. seeds under appropriate conditions. Plants that inhibit seed germination may inhibit tumour growth. At 24 hours, the plant showed strong antiproliferative activity as evidenced by the high percentage inhibition. Ethanolic extract had the highest antiproliferative activity (90%) at 5000µg/ml, followed by the aqueous extract (88.5%). However, at 48 hours, all organic extracts showed very weak antiproliferative activity as evidenced by the low % inhibition. Only the aqueous extract showed considerable antiproliferative activity at 5000µg/ml (45%). This implies that the aqueous extract has considerable antiproliferative activity, hence, it may be a promising anticancer drug or has components that have anticancer properties. This shows that Senna leaves could serve as source of bioactive compounds with potential antimicrobial, antioxidant and anticancer properties.

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