The Isorhamnetin-Containing Fraction of Philippine Honey Produced by the Stingless Bee Is an Antibiotic against Multidrug-Resistant .

Honey exhibits antibacterial and antioxidant activities that are ascribed to its diverse secondary metabolites. In the Philippines, the antibacterial and antioxidant activities, as well as the bioactive metabolite contents of the honey, have not been thoroughly described. In this report, we investigated the in vitro antibacterial and antioxidant activities of honey from and , identified the compound responsible for the antibacterial activity, and compared the observed bioactivities and metabolite profiles to that of Manuka honey, which is recognized for its antibacterial and antioxidant properties. The secondary metabolite contents of honey were extracted using a nonionic polymeric resin followed by antibacterial and antioxidant assays, and then spectroscopic analyses of the phenolic and flavonoid contents. Results showed that honey extracts produced by exhibits antibiotic activity against pathogens as well as high antioxidant activity, which are correlated to its high flavonoid and phenolic content as compared to honey produced by . The bioassay-guided fractionation paired with Liquid Chromatography Mass Spectrometry (LCMS) and tandem MS analyses found the presence of the flavonoid isorhamnetin (3-methylquercetin) in honey extract, which was demonstrated as one of the compounds with inhibitory activity against multidrug-resistant ATCC BAA-44. Our findings suggest that Philippine honey produced by is a potential nutraceutical that possesses antibiotic and antioxidant activities.