Exploring the Antimicrobial Properties of Guava leave extract against selected Food Pathogens

Abstract

Guava (Psidium guajava L.), is an important tropical plant with diverse benefits. In this study, the antimicrobial properties of guava leaf extract were explored against some food-borne pathogens (E. coli, Salmonella, and S. aureus). Three different extracts (water, methanol and ethanol) were obtained from the guava leaves by maceration for 3 days. The phytochemical content and antioxidant activity of the extracts were evaluated. The antimicrobial susceptibility and minimum inhibitory concentration (MIC) of the extracts were also determined. The phytochemical screening revealed constituents such as phenols and tannins, flavonoids, terpenoids, saponins, and glycosides. Phenolic content was highest in the methanolic extract (0.261 mg/ml) while flavonoid content was highest in the ethanolic extract (16.41mg/ml). The aqueous and methanolic extracts recorded the highest zone of inhibition (ZOI) against S. aureus while the aqueous was ineffective against E. coli and Salmonella and the methanolic extract recorded no ZOI against Salmonella. However, the ethanolic extract showed the highest ZOI against E. coli. The MIC of the methanolic extracts was 50% against S. aureus, 30% against E. coli, and 10% against S. aureus. For the ethanolic extract, it was 50% against E. coli, 20% against S. aureus, and 70% against Salmonella. The phytochemicals in the extracts contributed to their antioxidant and antibacterial activities. The ethanolic extract of the guava leaves was most effective against the selected foodborne pathogenic microorganisms. Both gram-positive and negative bacteria were susceptible to the extracts, although some gram-negative bacteria were resistant at certain concentrations of the guava leave extracts