Abstract
The study aimed to evaluate phenolic content and antioxidant and antibacterial potentials of the fractions of the hydroethanolic extract of Uvaria chamae leaves, a food plant from Burkina Faso. Thus, the hexane, dichloromethane, ethyl acetate, and butanol fractions of the hydroalcoholic extract after drying were used to determine phenolic compound content, antioxidant activity, and antimicrobial potential on strains of pathogenic bacteria responsible for food contamination. Phytochemical analyses were performed according to standardized methods, while antioxidant activity was evaluated by DPPH and FRAP methods. The antibacterial activity of the fractions was determined by diffusion and microdilution methods on the agar medium with gentamicin as a reference antibiotic. All the six strains, namely, Salmonella typhi ATCC 19430, Escherichia coli ATCC 8739, Staphylococcus aureus ATCC 25923, Pseudomonas aeruginosa ATCC 9027, Bacillus cereus ATCC 13061, and Listeria monocytogenes ATCC 7644, were sensitive to the fractions tested. Minimum inhibitory concentrations ranged from 37 µg·mL(-1) to 1.67 mg·mL(-1), respectively, gentamicin and butanolic fractions, while minimum bactericidal concentrations of the fractions ranged from 0.037 to 2.500 mg·mL(-1) depending on the bacterial strain. Antioxidant activity varied significantly between fractions. For DPPH free radical scavenging activity, the butanol fraction was the most active, with an IC50 of 280 μg/mL, while the lowest activity (705 μg/mL) was recorded by the hexane fraction. Those of trolox and ascorbic acid used as standards were 80 and 100 μg/mL, respectively. Ferric reducing power (FRAP) ranged from 0.34 to 0.40 mmol EAA/g extract for the hexanic and ethyl acetate fractions, respectively. Phenolic compound contents also varied significantly between fractions. Butanoic and ethyl acetate presented the best contents of total phenolics and flavonoids, respectively. Significant and positive correlations were also recorded between phenolics and antioxidant activities. The antibacterial and antioxidant activities of the active fractions would be related to their richness in bioactive compounds, including phenolic, which are powerful natural antioxidants. U. chamae leaf extracts could therefore be used as dietary supplements to boost the immune system and prevent bacterial infections.