Vol. 7, Issue 1, Part A (2025)

Background: Psidium guajava (guava) is a tropical plant extensively used in traditional medicine for its nutritional and pharmacological properties. Its leaves are known to contain a diverse range of bioactive phytochemicals with potential antimicrobial effects. This study investigates the phytochemical profile and antimicrobial activity of P. guajava leaf extracts against three clinically significant bacterial pathogens.
Methods: An experimental study was conducted between May and August 2024 using healthy guava leaves collected from the Western Area Rural District of Sierra Leone. Aqueous, methanol, and petroleum ether extracts were prepared using Soxhlet extraction and maceration. Qualitative phytochemical screening was carried out using standard chemical tests. Antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Streptococcus pyogenes was assessed using the agar well diffusion method. Zones of inhibition were measured after 24-hour incubation at 37°C.
Results: Phytochemical screening revealed the presence of alkaloids, tannins, flavonoids, glycosides, phenols, terpenoids, and saponins, with methanol and aqueous extracts showing the richest profiles. The petroleum ether extract exhibited fewer detectable phytochemicals but demonstrated the highest antimicrobial activity, with inhibition zones of 32 mm, 29 mm, and 17 mm against E. coli, S. pyogenes, and S. aureus, respectively. Methanol and aqueous extracts also exhibited antimicrobial activity, albeit to a lesser extent.
Conclusion: P. guajava leaves contain diverse bioactive compounds, especially in methanolic and aqueous extracts. Despite having fewer detectable constituents, the petroleum ether extract showed superior antibacterial efficacy, indicating that non-polar bioactive compounds may significantly contribute to antimicrobial action. These findings support the traditional use of P. guajava in herbal medicine and its potential for antimicrobial drug development.