Chemical profile and antioxidant activity of geopropolis from Melipona subnitida collected inside and outside the nest

Abstract

Melipona subnitida (“jandaíra”) is a species of stingless bee endemic to the Caatinga, a dry forest in the northeastern Brazilian semi-arid. Propolis is a product containing beeswax and plant resin. It contains compounds that can be able to prevent health problems by protecting cells against damage by oxidative agents. M. subnitida produces geopropolis, a mixture of propolis with soil. Samples of geopropolis of M. subnitida, one of inside and another outside of the nest from a hive in the municipality of Mossoró (northeastern Brazil) were analyzed by HPLC-PDA-ESI-MS/MS and their antioxidant activity evaluated by the DPPH and β-carotene/linoleic acid methods. Both samples exhibited similar chemical profile, characterized by 26 phenolic compounds, however, the compounds detected were more abundant in sample collected from inside of the nest. They were tentatively characterized as galloyl hexoses, coumaroyl-O-galloyl-hexoses, cinnamoyl-O-galloyl-hexoses, coumaroyl- and cinnamoyl- galloyl hexoses, phenylpropanoyl-O-benzoyl hexoses, flavanones and ellagitannins. Flavonoids, galloyl hexoses, coumaroyl-O-galloyl-hexosides, cinnamoyl-O-galloyl-hexosides and coumaroyl-cinnamoyl-galloyl hexosides were reported previously in this genus, however ellagitannins and phenylpropanoyl-O-benzoyl hexoses are reported for the first time. Comparing the antioxidant activity of the geopropolis samples from inside and outside of the nest, the latter was higher than the former.

Keywords

• Melipona subnitida
• geopropolis
• resin source
• nest entrance
• phenolic compounds
• hydrolyzable tannins
• antioxidant activity