Ecuadorian stingless bee (Meliponinae) honey: A chemical and functional profile of an ancient health product

Stingless bee honey samples from west Amazonian Ecuador were studied for their physiochemical, chemical and functional properties. Reducing sugars (44.9 ± 5.72 g/100 g), water (34.1 ± 4.34 g/100 g), free acidity (31.8 ± 4.05 meq/100 g), diastase activity (1.60 ± 0.20 u.d./g), hydroxymethylfurfural (15.0 ± 1.91 mg/kg), electrical conductivity (0.48 ± 0.06 mS/cm), ash (0.28 ± 0.04 g/100 g), colour (150 mm Pfund) were determined as physicochemical parameters. Melissopalynological analyses were processed evidencing pollen belonging to 14 plant families. Glucose (25.5 ± 3.41 g/100 g), fructose (25.2 ± 3.37 g/100 g) and sucrose (3.72 ± 0.49 g/100 g) contents were determined by HPLC, evidencing equal concentrations between fructose and glucose. Coumarins and flavonoids were determined by densitometric HPTLC: fraxin and bergamotin (0.065 ± 0.009; 0.035 ± 0.005 μg/g) among coumarins; luteolin (0.045 ± 0.006 μg/g), quercitrin (0.020 ± 0.003 μg/g), isoramnetin (0.015 ± 0.002 μg/g) among flavonoids. Among the vitamin E isomers, evaluated by HPLC, the occurrence of the only β-tocopherol (1.12 ± 0.15 μg/g) was noted. All these results were compared with those acquired for two multifloral Apis mellifera honeys. DPPH and β-carotene bleaching tests were performed, showing interesting values for Ecuadorian honey samples, higher than those shown by multifloral A. mellifera honeys (88.1 ± 11.1 DPPH inhibition%; 70.8 ± 8.90 β-carotene inhibition%). Antibacterial activity, against both Gram positive and Gram negative bacteria, revealed MIC values (10–50 μg/ml) always lower than those of A. mellifera honeys. Ecuadorian Meliponinae honey samples also showed anti-mutagenic activity assayed with Saccharomyces cerevisiae D7 strain, inhibiting back mutation over the entire range of concentrations.