Phytochemical Analysis and Antibacterial Activity of Stem Bark Extract of Guava (Psidium Guajava)

Abstract

Psidium guajava L. (guava) has a long history of use in traditional medicine, but scientific validation of its medicinal properties is essential for identifying alternative therapeutic agents amid rising antibiotic resistance. This study evaluated the preliminary phytochemical profile and in vitro antibacterial efficacy of the hydro-ethanolic stem bark extract of P. guajava against common bacterial pathogens. Fresh stem bark was collected in Damaturu, Yobe State, Nigeria, and extracted using a hydro-ethanolic solvent. Preliminary phytochemical screening was performed using standard protocols to detect secondary metabolites. The antibacterial activity, minimum inhibitory concentration (MIC), and minimum bactericidal concentration (MBC) against Escherichia coli and Staphylococcus aureus were determined using agar well diffusion and broth dilution methods, with ciprofloxacin serving as the positive control. Phytochemical screening revealed the presence of saponins, terpenoids, phenolic compounds, and tannins, while glycosides were absent. The extract exhibited concentration-dependent antibacterial activity against both bacterial strains. The maximum zones of inhibition were recorded at 100 mg/mL, measuring 24.33 ± 1.15 mm against E. coli and 20.67 ± 0.58 mm against S. aureus. The MIC and MBC values were 12.5 mg/mL for E. coli and 25 mg/mL for S. aureus. Although the extract was less potent overall than the ciprofloxacin control, the findings demonstrated bactericidal activity against both Gram-negative and Gram-positive bacteria. In conclusion, the hydro-ethanolic stem bark extract of P. guajava contains bioactive secondary metabolites and exhibits promising in vitro antibacterial properties. These findings provide preliminary scientific support for its traditional ethnomedicinal use and suggest its potential as a natural source of compounds for further investigation in antibacterial drug discovery