Triterpenes and their Biological Activities from Propolis of Stingless Bee Tetrigonilla collina

Propolis from stingless bees has been used in traditional medicine in many countries to treat diseases. Recently, chemical constituents and biological activities of stingless bee propolis have garnered increasing scientific attention. A phytochemical study of propolis of stingless bee Tetrigonilla collina collected in the Kon Ka Kinh forest-Vietnam, was performed using combined chromatographic methods. Six triterpenes including five oleanane-type triterpenes: —uncarinic acid M (1), 3-oxo-6β-hydroxy-12-oleanen-28-oic acid (2), 3β,6β,19α-trihydroxy-12-oleanen-28-oic acid (3), sumaresinolic acid (4), and siaresinolic acid (5),—and one dammarane-type triterpene isofouquirenone (6) were isolated. The chemical structures of the compounds 1-6 were elucidated by NMR and MS spectroscopic analysis. These triterpenes were identified for the first time in stingless bee propolis. The chemical composition suggests that Styrax tonkinensis is a botanical source of stingless bee propolis. The isolated compounds were evaluated for their cytotoxic, antimicrobial and anti-inflammatory effects. Compound 2 displayed antimicrobial activity against Gram-positive strains Bacillus subtilis and Lactobacillus fermentum. Sumaresinolic acid (4) exhibited anti-inflammatory activity with the IC50 values of 21.38±2.0 µg/mL. Compounds 1, 2, 4 and 6 showed weak to moderate cytotoxicity against HepG-2, KB, and A-549 cell lines.