The fresh Thai local herbs in vitro antibacterial activity against Listeria monocytogenes 10403S

Abstract

Thai local herbs are one important ingredient of Thai food. Six fresh herbs extracted by five different ethanol concentrations (0%, 25%, 50%, 75%, and 95%) were investigated for their individual antibacterial activity; Chilli (Capsicum annuum), kaffir lime (Citrus hystrix), cumin (Cuminum cyminum L.), shallot (Allium ascalonicum L.), garlic (Allium sativum), lemongrass (Cymbopogon citratus), and galangal (Alpinia galanga) against Listeria monocytogenes 10403S by using the agar disk diffusion method on Brain Heart Infusion media (BHI), five different ethanol concentrations (0%, 25%, 50%, 75%, and 95%). The results showed that 95 % ethanolic crude extracts gave the highest antibacterial activity against L. monocytogenes 10403S. Of all herbs, lemongrass extracted by 95% ethanol showed the highest antibacterial activity; 9.79 ± 1.68 mm. The minimum inhibitory concentrations (MICs), using a broth dilution method, were found to be between 16-128 µl/ml. The minimum bactericidal concentrations (MBCs), using a broth dilution method, were greater than 32-128 µl/ml. This indicated that all Thai local herbs showed the promising antibacterial activity against L. monocytogenes 10403S.