Antibacterial activity of Cassia angustifolia. Vahl (Sinameki) leaf extract against some pathogenic bacteria

Cassia angustifolia. Vahl (Sinameki) is one of the best-known medicinal herbs for the treatment of constipation in Iraq and many Arabic countries and it has long been used as a medicinal agent. In the present study, the antibacterial potential of Sinameki and its synergistic effect with antibiotics including tetracycline and amoxicillin were investigated at various concentrations (50, 100, and 150 mg/mL) against three pathogenic bacterial strains including Pseudomonas aeruginosa (P. aeruginosa), Escherichia coli (E. coli), and Staphylococcus aureus (S. aureus). A dilution method was used to determine the MIC (minimum inhibitory concentration) of the plant leaf extract against E. coli, S. aureus and P. aeruginosa. The synergistic effect between the extract and antibiotics was evaluated using a diffusion method. Sinameki (methanol extract) showed a potent inhibitory activity against all the tested bacteria, while Sinameki (methanol extract) revealed lower inhibitory activity against all tested bacteria compared to the negative control. The highest inhibitory activity of Sinameki (methanol extract) was confirmed against E. coli, S. aureus and P. aeruginosa with an inhibition zone of 8, 5, and 4 mm, respectively. The combination of Sinameki extract with antibiotics including tetracycline and amoxicillin has resulted in increasing the antibacterial activity. The findings are very important for further study of the Sinameki as an alternative herbal medicine leading to cure diseases caused by microbial pathogens.