Antimicrobial, Antioxidant and Antiproliferative Properties of the Leaves of Senna siamea

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.