Infectious diarrhea is a gastrointestinal illness that results in around 1.7 billion cases and 525,000 deaths annually, particularly among children under five, according to the World Health Organization. While some Cameroonian medicinal plants show promise for treating diarrhea, many plants are used without established scientific evidence of their efficacy. These plants include Tithonia diversifolia (T. diversifolia) and Solanum torvum (S. torvum), which are traditionally used to treat diarrheal symptoms. This study sought to investigate the anti-Shigella activity of leaf extracts from T. diversifolia and S. torvum.
Methods
Extracts from T. diversifolia and S. torvum were obtained by successive maceration in solvents of increasing polarity, including hexane, dichloromethane, ethyl acetate, methanol, and water. The as-prepared extracts (10) were evaluated for antibacterial activity against selected Shigella species using an in vitro experiment. The mode of action of the bioactive extracts was determined in Shigella through growth kinetic analysis.
Results
Hexane extract from S. torvum (St-HEX-F) and dichloromethane extract from T. diversifolia (Td-DCM-F) inhibited the growth of Shigella flexneri NR-518 and Shigella boydii NR-521 with minimum inhibitory concentration (MIC) values of 500 and 1,000 µg/mL, respectively. Shigella flexneri and Shigella boydii were the most sensitive strains, whereas Shigella sonnei was the most resistant strain. Bacterial growth kinetics revealed that St-HEX-F and Td-DCM-F are bacteriostatic at MIC and bactericidal at 2×MIC and 4×MIC.
Conclusions
The extracts from S. torvum and T. diversifolia, obtained by successive maceration using solvents of increasing polarity, were further screened for antibacterial effect against three Shigella species (S. flexneri NR-518, S. boydii NR-521, and S. sonnei NR-519). As a result, the hexane extract from S. torvum leaves (St-HEX-F) and the dichloromethane extract of T. diversifolia (Td-DCM-F) revealed significant antibacterial activity against S. flexneri NR-518, with MIC values ranging from 500 to 1,000 µg/mL.
Kinetics of bacterial mortality (S. flexneri NR-518) with St-HEX-F and Td-DCM-F revealed a bacteriostatic orientation at MIC and a bactericidal trend at higher extract concentrations (2×MIC and 4×MIC). Overall, extracts from S. torvum and T. diversifolia demonstrated antibacterial effects, thus confirming the traditional use of these plants in treating bacterial infections. However, the mechanistic basis of the antibacterial action, in vitro and in vivo toxicity experiments, and pharmacokinetics are warranted to support the use of these plants in ethnomedicine. Moreover, activity-guided fractionation and isolation of the antibacterial compounds should also be investigated.
Full text
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The study was recently published in the Journal of Exploratory Research in Pharmacology .
Journal of Exploratory Research in Pharmacology (JERP) publishes original innovative exploratory research articles, state-of-the-art reviews, editorials, short communications that focus on novel findings and the most recent advances in basic and clinical pharmacology, covering topics from drug research, drug development, clinical trials and application.
