Scaptotrigona mexicana Propolis from Totonacapan Region: Chemical Composition, Antioxidant and Antibacterial Activities

The propolis produced by stingless bees is a complex mixture of natural sticky components mixed with soil or clay. Global research on propolis has focused on studying the biological and pharmacological properties and chemical composition of stingless bee propolis from Brazil, Indonesia, and other regions. However, studies of stingless bee propolis produced in Mexico are scarce. This study aimed to determine the chemical composition of the geopropolis of Scaptotrigona mexicana collected in the Totonacapan region and to evaluate its antioxidant and antibacterial activities. The phenolic contents of the ethanolic extract of the collected propolis ranged from 2.45 +/- 0.03 mg GAE/g to 3.48 +/- 0.56 mg GAE/g of dry extract. The total flavonoid content ranged from 0.69 +/- 0.03 mg QE/g to 0.84 +/- 0.009 mg QE/g of dry extract. The antioxidant activity of the ethanolic extracts was assessed via DPPH, ABTS, and FRAP assays. The minimum inhibitory concentration values exhibited by the ethanolic extract (>512 g/mL) for Gram-negative bacteria (Pseudomonas aerugunosa and Phorphyromonas gingivalis) were higher than those of Gram-positive bacteria. The stingless bee propolis extract showed the highest antibacterial activity against Streptococcus mutans (256 g/mL). Five known compounds, taraxeryl acetate (1), lupeol (3), cicloart-23-en-3 beta,25-diol (5), mangiferoic acid (6), and 5-(11'Z-heptadecenyl)-resorcinol (7), and two irresoluble mixtures of 3-O-acetyl-alpha-(2a) and 3-O-acetyl-beta-amyrins (2b), and alpha- (4a) and -amyrins (4b), were identified by nuclear magnetic resonance spectroscopy and mass spectrometry. Additionally, 39 volatile compounds were identified via headspace-solid phase microextraction using the hyphenated gas chromatography coupled to mass spectrometry time-of-flight. The main volatile compounds detected include trans-alpha-bergamotene (8.15%), hexanal (7.17%), 2-heptanone (7.60%), and alpha-copaene (7.09%).