Antibacterial Activity of Glycosylated Flavonoids Isolated from Ocotea notata Leaves

Abstract

Research into natural products has led to the discovery of new drugs. This work shows relevant data on the antibacterial activity of Ocotea notata leaves. Dichloromethane fraction (DF) from leaves of O. notata showed antibacterial activity at the concentration of 512 μg/mL against strains of Staphylococcus. The DF was fractionated to investigate bioactive compounds and yielded six subfractions (DF1-DF6). The DF3, DF5, and DF6 showed bacteriostatic activity, and DF4 showed bactericidal activity at the concentration of 2048 μg/mL and additive effect when combined with the antibiotic oxacillin. The flavonoids miquelianin (1), isoquercitrin (2), reynoutrin (3), guaijaverin (4), and afzelin (5) were isolated from the DF4 and characterized via NMR and HPLC-DAD-MS/MS analyses. Flavonoids 1-5, especially reynoutrin (3), seem to be responsible for the DF4 antibacterial activity. Reynoutrin showed activity against Staphylococcus epidermidis ATCC 12228 and S. aureus methicillin-resistant ATCC 33591. This is the first report regarding the reynoutrin antibacterial activity and the first description of the flavonoid guaijaverin for O. notata.