03543nas a2200241 4500008004100000245018300041210006900224260001900293300001400312490000700326520265800333653003302991653003903024653003003063653003703093653002303130100002303153700002103176700002103197700002503218700002203243856003603265 2021 eng d00aAntimicrobial Efficacy, Cytotoxicity, Acute Oral Toxicity, and Phytochemical Investigation of the Aqueous and Methanolic Stem Bark Extracts of Bridellia micrantha (Hochst.) Baill0 aAntimicrobial Efficacy Cytotoxicity Acute Oral Toxicity and Phyt cSeptember 2021 a1248-12560 v133 a

Introduction: Microbial infections cause high morbidity and mortality in humans globally. Antimicrobial resistance, emergence of new strains, high costs of antibiotics, inaccessibility-especially in remote areas, and adverse effects, impede successful eradications of pathogens, hence the need for novel strategies. Bridellia micrantha is used in traditional medicine to treat microbial infections; however, it has not been empirically validated. Methods: Antimicrobial activity of the aqueous and methanolic stem bark extracts of Bridellia micrantha was investigated using the disk diffusion and broth microdilution techniques, described by the Clinical Laboratory Standards Institute (CLSI) guidelines. The brine shrimp lethality assay technique was used to investigate the cytotoxic effects of the studied plant extracts in exposed nauplii. Acute oral toxicity effects of the studied plant extracts in Winstar rats were investigated following the up-and-down procedure described by the Organisation for Economic Development and Co-operation (OECD). Qualitative phytochemical screening was performed following standard procedures. Results: The aqueous and methanolic extract of B. micrantha indicated varied antimicrobial activities against E. coli, S. typhimurium, S. aureus, and C. albicans, with inhibition zones ranging from 6.00mm to 19.00mm. Furthermore, the studied plant extracts exhibited low MIC values (≤100 μg/ml) on selected microbes. Since the MIC values were much lower than 1000μg/ml (the cutoff for antimicrobial efficacy appraisal), it is anticipated that, the studied plant extracts can be strong antibiotics. The aqueous and methanolic stem bark extracts of B. micrantha were cytotoxic to brine shrimp nauplii, with LC50 values of 486.67±3.15 μg/ml and 458.33±2.87 μg/ml, respectively; however, these extracts did not elicit any observable signs of toxicity in rat models. Pharmacologically active phytochemicals, including flavonoids, alkaloids, saponins, tannins, phenols, and anthraquinones were detected in the two studied extracts. Conclusions: The aqueous and methanolic stem bark extracts of B. micrantha have appreciable antimicrobial activity against E. coli, S. typhimurium, S. aureus and C. albicans. Besides, the studied plant extracts are cytotoxic to brine shrimp nauplii; but they do not cause acute oral toxicity effects in rat models. Additionally, the studied plant extracts contain bioactive phytochemicals, with antimicrobial activity.

10aBrine shrimp lethality Assay10aMedian lethal concentration (LC50)10amedian lethal dose (LD50)10aMinimum inhibitory concentration10aZone of Inhibition1 aKathare, Joseph, M1 aMbaria, James, M1 aNguta, Joseph, M1 aMoriasi, Gervason, A1 aMainga, Alfred, O uhttps://phcogj.com/article/1655