Propolis and geopropolis from stingless bees as sources of natural antioxidant compounds: a systematic review and meta-analysis

Stingless bee products have been studied in various regions worldwide in the search for bioactive compounds. In this work, we aimed to conduct a systematic review and meta-analysis of studies that assessed the antioxidant capacities, chemical compositions, and total contents of phenolic and flavonoid compounds of stingless bee propolis and geopropolis. Results obtained from 50 studies involving 43 species of stingless bees showed that the 2,2-diphenyl-1-picryl-hydrazyl radical capture method and ethanol were the most used method and extraction solvent, respectively, to evaluate antioxidant capacity. Samples from South America and the genus Melipona showed the largest antioxidant capacity. Research on the antioxidant properties of propolis from stingless bees has intensified in recent years (67% of studies in the last five years) and demonstrated the great application potential of this natural bioactive product in various industry sectors.