Antimicrobial activity of Uvaria rufa (Annonaceae) leaf extracts

Antimicrobial resistance is considered a threat to global health. Given the use and benefits of herbal medicine, the healthcare community has been investigating plant-derived compounds for their potential antimicrobial activity. Susong kalabaw (Uvaria rufa) was studied for its antibacterial activity using fractionated leaf extracts. U. rufa leaves were extracted using 70% ethanol and fractionated using five solvents, including water, methanol/water, sec-butanol, DCM, and hexane. Phytochemical screening was performed on crude extracts. Moreover, the inhibitory activity of crude and fractionated leaf extracts of U. rufa was evaluated using the Kirby-Bauer test and MIC assay. Phytochemical screening confirmed the presence of alkaloids, flavonoids, saponins, tannins, and terpenoids in crude extracts. The Kirby-Bauer test showed that crude extracts inhibited the growth of Escherichia coli (8.3 mm), Bacillus subtilis (10.0 mm), and Staphylococcus aureus (14.5 mm). The fractions, including water (10.3 mm), methanol/water (11.2 mm), and sec-butanol (17.8 mm), also revealed inhibitory activity against S. aureus. Moreover, Pseudomonas aeruginosa was susceptible to the sec-butanol fraction, showing an average zone of inhibition of 9.3 mm. For the MIC assay, the methanol/water fraction inhibited the growth of S. aureus at a substantially lower concentration of 67.35 μg/mL. On the other hand, B. subtilis and S. aureus were susceptible to water and sec-butanol fractions, showing lower concentrations of 68.1 μg/mL and 26.21 μg/mL, respectively. These results emphasized that crude and fractionated leaf extracts of U. rufa demonstrated promising antibacterial activity against bacterial samples in the Kirby-Bauer test and MIC assay.