Anti-Salmonella and Radical Scavenging Activities of Sarcocephalus latifolius leaves and Synclisia scabrida roots against Human (Salmonella typhimurium) and Bovine Strains of Salmonella enterica

Abstract

Typhoid fever is caused by Salmonella enterica, it can spread throughout the body affecting many organs. It could be fatal if not treated and can be transmitted through the ingestion of contaminated food or drink. Sarcocephalus latifolius (Sm.) E.A. Bruce (Rubiaceae) and Synclisia scabrida Meirs (Menispermaceae) are traditionally used in the management of typhoid by the people of Esan North East Local Government Area, Edo state. This study is to determine the anti-salmonella and radical scavenging activities of these selected plants. Powdered plant materials were extracted into methanol. The free radical scavenging activity and cytotoxicity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and brine shrimp lethality assay respectively. The antimicrobial activity of the extracts was assessed by the agar diffusion method and their Minimum Inhibitory Concentration (MIC) was determined against six strains of Salmonella typhi, from Cow (Co6b, Co11 and Co41), clinical strains (Salmonella typhimurium (sp), Salmonella typhimurium (SA) and a typed strain (Salmonella typhi ATCC 33458). Gentamycin was the standard drug used. The most active extract was subjected to liquid-liquid partitioning and the antimicrobial activity of the fractions determined. The DPPH results showed Sarcocephalus latifolius leaves extract (SLLE) having inhibitory concentration (IC₅₀) of 25.36 μg/mL while Synclisia scabrida roots extract (SSRE) had 14.04 μg/mL as compared with the standard drug (ascorbic acid) with IC₅₀ of 9.26 μg/mL. The results of the brine shrimp lethality assay showed SLLE with LC₅₀ of 735 μg/mL while SSRE had 158.67 μg/mL as compared to the standard drug cyclophosphamide with LC₅₀ of 98.76 μg/mL. The MIC of the extracts SLL and SSR were 1.56 mg/mL and 0.78 mg/mL respectively. The result of the study justified the traditional claim of both plants in the treatment of typhoid and could provide lead for anti-typhoid fever drug development.

Keywords: Typhoid fever, Sarcocephalus latifolius, Synclisia scabrida