Antibacterial Potential by Rupture Membrane and Antioxidant Capacity of Purified Phenolic Fractions of Persea americana Leaf Extract

The present research focused on evaluating the antibacterial effect and the mechanism of action of partially purified fractions of an extract of Persea americana. Furthermore, both its antioxidant capacity and composition were evaluated. The extract was fractionated by vacuum liquid chromatography. The antimicrobial effect against Staphylococcus aureus (ATCC 6538), Escherichia coli (ATCC 11229), Pseudomonas aeruginosa (ATCC 15442), and Salmonella choleraesuis (ATCC 1070) was analyzed by microdilution and the mechanism of action by the Sytox green method. The antioxidant capacity was determined by DPPH, FRAP, and ABTS techniques and the composition by Rp-HPLC-MS. All fractions showed a concentration-dependent antibacterial effect. Fractions F3, F4, and F5 (1000 µg/mL) showed a better antibacterial effect than the extract against the bacteria mentioned. The F3 fraction showed inhibition of 95.43 ± 3.04% on S. aureus, F4 showed 93.30 ± 0.52% on E. coli, and F5 showed 88.63 ± 1.15% on S. choleraesuis and 86.46 ± 3.20% on P. aeruginosa. The most susceptible strain to the treatment with the extract was S. aureus. Therefore, in this strain, the bacterial membrane damage induced by the extract and fractions was evidenced by light fluorescence microscopy. Furthermore, the extract had better antioxidant action than each fraction. Finally, sinensitin was detected in F3 and cinnamoyl glucose, caffeoyl tartaric acid, and cyanidin 3-O-(6′′-malonyl-3′′-glucosyl-glucoside) were detected in F4; esculin and kaempferide, detected in F5, could be associated with the antibacterial and antioxidant effect.