Isolation, Antimicrobial Susceptibility Testing and Characterization of Ximenia americana and Olax subscorpioidea Plant Extracts Against Salmonella typhi

Abstract

This study aimed at phytochemicals screening, antimicrobial activity and characterization of Ximenia americana and Olax subscorpioidea against clinical isolates of S. typhi. Methanolic extracts from various plant parts were subjected to phytochemical screening using standard methods. Antimicrobial susceptibility testing was carried out using agar well diffusion method. Separations of the crude extract into fractions was done using column chromatography and the active fraction was characterized using Fourier Transform Infrared (FTIR) spectroscopy and Gas Chromatography–Mass Spectrometry (GC-MS). The Results of phytochemicals screening revealed the presence alkaloids, flavonoids, saponins, terpenoids, tannins, and anthraquinones. Antibacterial assays showed that all extracts exhibited dose-dependent inhibition, with Olax subscorpioidea root extract demonstrating the highest potency (MIC = 6.25 mg/mL), followed by the leaf extracts of both plants (MIC = 12.5 mg/mL). Column chromatography and Thin Layer Chromatography (TLC) identified bioactive fraction F4 in both plants as the most effective against S. typhi. FTIR analysis revealed functional groups associated with phenols, flavonoids, and fatty acids, while GC-MS identified palmitic acid, oleic acid methyl ester, and squalene. The superior antimicrobial activity of Olax subscorpioidea root is attributed to its more diverse and complex phytochemical composition. These findings validate the traditional use of both plants in typhoid fever treatment and suggest their potential for developing novel phytotherapeutic agents against MDR S. typhi.