Antibacterial and phytochemical effects of ethanol extracts of Syzygium guineense (Willd.) DC barks and Mangifera indica L seeds

Bacterial infectious diseases account for thousands of deaths worldwide. Despite their side effects, synthetic antibiotics are currently utilized to treat bacterial infections. There has been an effort to identify alternative medicines of plant origin. Thus, the current study determined in vitro antibacterial activities of Syzygium guineense barks and seeds of Mangifera indica ethanol extracts, as well as their phytochemical profile. The tested bacteria included Salmonella typhi, Staphylococcus aureus, Bacillus subtilis, and Escherichia coli. Plant samples were collected from Morogoro region, Tanzania and transferred to Kenyatta University for preparation and extraction. In vitro antibacterial activities were determined by disk diffusion, MIC, and MBC methods. Selected phytochemicals of ethanol extracts were determined qualitatively. The highest antibacterial effects were observed in M. indica extract against B. subtilis, S. aureus, E. coli and S. typhi with zones of inhibition of 20.00 mm, 18.00 mm, 17.67 mm, and 15.67 mm, respectively. Antibacterial effects observed in S. guineense extract against B. subtilis, S. aureus, S. typhi and E. coli produced zones of inhibition of 15.00 mm, 14.33 mm, 10.67 mm, and 9.33 mm, respectively. The extracts showed better antibacterial effects against Gram positive bacteria than Gram negative bacteria. Qualitative phytochemical analysis of the ethanol extracts revealed alkaloids, quinones, flavonoids, phenolics, saponins, steroids, terpenoids, tannins, and glycosides. This study indicates that the ethanol extracts of the plants could be used to develop alternative remedies for treating bacterial infections. The study also suggests that the plant extracts should be subjected to in vivo studies.