In vitro Study on Anti-salmonella Activities of Boerhaavia diffusa (L. syn) Leaf Extract

Abstract

Various strategies have been employed in the treatment and management of Salmonella infection however, Salmonella strains have gained resistance to antibiotics. This study was to determine in vitro anti-Salmonella activity of Boerhaavia diffusa leaf extract against clinical isolate of Salmonella typhi and Salmonella typhi ATCC 14028. The aqueous and ethanol extracts of B. diffusa were studied for their antibacterial activity against pathogenic Salmonella typhi. This study was carried out between April and September 2018. The in vitro antibacterial activity was performed by agar well diffusion method and broth dilution using spectrophotometric method and the results were expressed as the average diameter of zone of inhibition of bacterial growth around the well and optical density respectively. It was observed that aqueous extract exerted slightly higher activity than ethanolic extract as revealed by the mean diameter of zone of inhibitions at a concentration of 200 mg/ml, the aqueous extract had 35.21±0.47 mm (Salmonella typhi ATCC 14028) compared with ethanol extract 26.41±0.32 mm (clinical). However, in the broth dilution method, ethanol extract significantly (p=0.05) reduced the cell, at 48 hours, the optical density of clinical isolate of S. typhi treated at concentration of 200 mg/ml of extract was 0.47±0.02 nm while at the same concentration of extract, aqueous extract had an optical density of 0.52±0.11 nm respectively. The phytochemical assay revealed that tannin (5.18±0.02 mg/g) and quinone (8.45±0.13 mg/g) in ethanol extract was significantly (p=0.05) higher than aqueous extract while saponin (14.18±0.06 mg/g) was higher in the aqueous extract. The ethanol and aqueous extracts of leaves of B. diffusa whole plant exhibited significant antibacterial activity against both clinical and typed Salmonella typhi. Therefore, the plant extract could be used for the treatment of Salmonellosis, however, the in vivo studies is needed to ascertain the safety of the extract.