Characterisation of phenolic compounds by UPLC-QTOF-MS/MS of geopropolis from the stingless bee Melipona subnitida (jandaira)

Introduction: Melipona subnitida Ducke (jandaira) is a stingless bee native to northeastern Brazil, which produces geopropolis, a mixture of beeswax, plant resins, pollens and earth that is used for sealing beehives. Objective: To extend the knowledge on phenolic compounds in fractions obtained by C18-solid phase extraction (SPE) of nine geopropolis samples from Melipona subnitida collected at different times. Methodology: Chromatographic profiles of nine samples of geopropolis from jandaira were analysed by ultra-performance liquid chromatography coupled with a diode array detector and quadrupole time-of-flight mass spectrometry (UPLC-DADQTOF-MS/MS) and combined with the use of data-independent acquisition (MSE) for the profiling and structural characterisation of the phenolic compounds. The isolated compound was identified by nuclear magnetic resonance of hydrogen and carbon (H-1-and C-13-NMR). Results: The present study with geopropolis of jandaira resulted in the characterisation of 51 phenolics by UPLC-DAD-QTOF-MS/ MS: four galloyl glucosides, one ellagic acid, 11 acyl-hexosides, 23 acyl-galloyl-hexosides and 12 flavonoids. The structures of two compounds (1,6-di-O-(E)-coumaroyl-2-O-galloyl-beta-D-glucopyranoside and 1-O-cinnamoyl-6-O-(E)-coumaroyl-2-O-galloyl-beta-D-glucopyranoside) were established by H-1 and the attached proton test (APT) experiments as well as high-resolution electrospray ionisation mass spectroscopy (HR-ESI-MS) analysis. Conclusion: The geopropolis of jandaira showed phenolic compounds galloyl hexosides, ellagic acid, acyl-(cinnamoyl/coumaroyl)-hexosides, acyl-(cinnamoyl/coumaroyl)-galloyl-hexosides and flavonoids (aglycones and acylated-O-glycosides).