Abstract:

Medicinal plants are rich in phytochemicals with various therapeutic potentials, including antibacterial, antioxidant, and haematinic properties. In this study, the effects of ethanolic extracts of Vernonia amygdalina (bitter leaf) and Psidium guajava (guava) on the intestinal microbiota of albino Wistar rats were investigated. Fresh leaves were collected, authenticated, processed, and extracted using ethanol. One hundred and twenty rats were divided into control groups and treatment groups receiving 200 mg/kg and 400 mg/kg of extract for 28 and 56 days, respectively. Preliminary phytochemical screening revealed the presence of alkaloids, flavonoids, tannins, saponins, phenols, terpenoids, glycosides, and steroids in both plants, while anthraquinones were present only in Vernonia amygdalina. Microbial evaluation of stool samples showed that beneficial bacteria (species of lactic acid bacteria) did not change appreciably, while harmful bacteria and fungi (Salmonella spp., Proteus spp., Candida species) were significantly reduced. Statistical analysis revealed a significant reduction (p < 0.05) in total bacterial and fungal load without affecting beneficial flora. These findings support the ethnomedical applications of Vernonia amygdalina and Psidium guajava leaf extracts and highlight their potential as natural antimicrobial agents that modify gut microbiota by depleting harmful bacteria while retaining beneficial ones.