Antibacterial potential of Elletaria cardamomum, Syzygium aromaticum and Piper nigrum, their synergistic effects and phytochemical determination

Abstract

Background: Spices are considered as rich source of bio-active antimicrobial compounds and are indispensable components of Indian cuisines since ancient times. To provide a scientific basis to traditional uses of Elletaria cardamomum, Syzygium aromaticum and Piper nigrum, their aqueous and organic seed extracts, isolated phytoconstituents and combinations were evaluated for antibacterial potential against gram positive (Staphylococcus aureus, Bacillus subtilis) and gram negative (Escherichia coli, Salmonella typhi) bacteria. Methods: Antibacterial activity of aqueous and organic seed extracts was assessed using agar diffusion assay, minimum inhibitory concentration and the effect was compared with some standard antibiotics. The presence of major phytoconstituents was detected qualitatively and quantitatively. The isolated phytoconstituents and combination of spices were subjected to disc diffusion assay to ascertain their antibacterial effect. Results: Organic extracts of all three spices showed good antibacterial activity against all the test strains, which was found to be comparable with standard antibiotics. Minimum inhibitory concentration for aqueous and organic seed extracts ranged from 25 to >50 mg/ml and 2 to 50 mg/ml respectively. Inhibitory activity of all the extracts was found to be increased when used in combination. This synergistic effect supports the use of these spices in combination. Quantitative phytochemical analysis showed the presence of 2.30 – 7.8% alkaloids, 5.7 – 26.2% flavonoids, 11.0 – 33.0% tannins, 0.60 – 3.8% saponins. Conclusion: Antibacterial efficacy shown by these spices and their combinations provides a scientific basis and thus, validates their traditional uses as homemade remedies. Isolation and characterization of different phytochemicals may further yield significant antibacterial agents.