Bioactive Constituents of Melipona quadrifasciata anthidioides Geopropolis with Antifungal Activity against Sporothrix brasiliensis

Sporotrichosis caused by Sporothrix brasiliensis represents an emerging public health challenge in Brazil, with increasing therapeutic limitations and antifungal resistance. This study investigated Brazilian geopropolis produced by Melipona quadrifasciataanthidioides as a potential source of antifungal bioactive compounds. Bioassay-guided fractionation of the ethanolic extract led to the isolation of three constituents, identified by NMR, Fourier transform infrared spectroscopy (FTIR)-ATR, and LC-HRMS analyses as kaurenoic acid, cinnamoylgrandifloric acid, and 3S(+)-vestitol, the latter two being reported for the first time in this matrix. The dichloromethane fraction exhibited the best antioxidant capacity among the tested fractions (EC50 = 200.22 μg mL–1). In vitro assays against clinical isolates of S. brasiliensis revealed minimum inhibitory concentration (MIC) values ranging from 170.18 to 567.11 μg mL–1 for the extract and isolated compounds. Among them, 3S(+)-vestitol showed the strongest antifungal activity (MIC = 170.18 μg mL–1). These findings demonstrate that M. quadrifasciata geopropolis contains bioactive diterpenes and isoflavonoids with significant antifungal activity, highlighting its potential as a source of lead compounds for developing new therapeutic strategies against endemic sporotrichosis.