Abstract

In vitro activities of methanol and water (crude) extracts of leaves, barks and seeds from Cassia fistula were tested against Gram-positive and Gram-negative bacteria by using disc-diffusion method at 6.25-100 μg/μl. Of which water extracts of leaf showed powerful antibacterial action against Proteus vulgaris and Staphylococcus aureus than others. Six (6) purified compounds from the most active leaves displayed higher antibacterial activity than the compound (2) and (4) against P. vulgaris and S. aureus. In vitro toxicological properties were evaluated by MTT assay to test the reduction of viability of human lung (MRC-5), skin (HEPK) fibroblasts and human macrophage (U-937) cells with the C. fistula water-leaf extracts and compounds (6) at 62.5 - 2000 μg/ml doses. The water-leaf extracts -showed less cytotoxic activity on MRC-5 cells than the U-937 and HEPK cells. However, the compound (6) was not toxic to all the human cells up to 1000 μg/ml doses. In conclusion, the significant antibacterial activity may be due to the compound flavonoids and the toxicity results proved the traditional usage of this plant for bacterial therapy.

Keywords: Cassia fistula, Konraikki, Compounds, Antibacterial activity, Cytotoxicity, Human cells