Melissopalynological and chemical analyses of propolis from Scaptotrigona nigrohirta Nogueira & Santos-Silva, 2022 (Apidae - Meliponini) in the Lower Amazon River region

Abstract

The chemical composition of propolis is highly variable and complex and is related to the phytogeography of a region. Therefore, the ecology of the local flora is directly related to its chemical composition. The aim of this study was to identify the pollen types and chemical substances of the hexane extracts present in Scaptotrigona nigrohirta propolis from a meliponary in Santarém, Pará state, in the Lower Amazon River region, in order to obtain data that can be used for the sustainable conservation of the bee species and flora in this Amazonian region. Pollen analyses were performed on 11 propolis samples collected at the meliponary and chemical analyses on only two (wet and dry seasons). For the melissopalynology, the propolis was diluted in acetone and then applied to acetolysis. For a chemical evaluation, hexane extractions of propolis samples from April and August 2018 and gas chromatography-mass spectrometry analyses were performed. A multivariate analysis was performed on pollen and chemical data. Seventy-seven pollen types were found, defining the propolis as heterofloral, with the families Fabaceae, Anacardiaceae and Myrtaceae being the most significant in the pollen spectrum of the samples. The most frequent species were: Copaifera martii, Eugenia brasiliensis, Mitracarpus strigosus, Protium heptaphyllum and Tamarindus indica. The hexane extracts of propolis had a 35.75% yield. Sixteen compounds were found and cycloartenol, lupeol acetate and lupenone were identified as major constituents.