Evaluation of antibacterial activity against Burkholderia pseudomallei VTCC 70157 and cytotoxicity ofpomegranate (Punica granatum) aqueous extract

Abstract

Melioidosis is a severe acute infectious disease caused by Burkholderia pseudomallei, especially high epidemiological risk factors in agricultural operations with people frequently exposed to soil or water sources containing this bacterium. In this study, the thermal and gastric stability of antimicrobial activity of aqueous extracts prepared from pomegranate (Punica granatum) against Burkholderia pseudomallei VTCC 70157 (NA23) was evaluated by agar plate diffusion, minimal inhibitory dilution (MID), and minimal bactericidal dilution (MBD) methods. Additionally, the cytotoxicity of aqueous extract to HEK293, HepG2, and HT29 cell lines was also studied. The results showed that aqueous extracts of different pomegranate parts had a high antibacterial activity with an antibacterial zone diameter in the range of 21-28 mm. MID and MBD values were under 1:256 and 1:128, respectively. At the extraction temperature of 100oC, antibacterial activities were significantly higher than those of 25 and 70oC. This study also demonstrated that the antibacterial activity of the extracts highly remained under simulated gastrointestinal conditionsexcept for the MID value of the twig extracts which was increased by two times. In addition, the extracts exhibited low cytotoxicity with the tested human cell lines, with ID50 values consistently being remarkably higher than the corresponding MID values. The study results suggest that aqueous extracts of pomegranate prepared by decoction according to traditional medicine might be effective through oral administration for the treatment of melioidosis.