C-Prenylated flavonoids in Philippine propolis from nests of stingless bee (tetragonula biroi friese)

The dichloromethane extract of Philippine propolis from nests of Tetragonula biroi Friese, collected in Sorsogon, afforded two C-prenylated flavonoids: the flavanone Propolin H or Macarangaflavanone A (TB-4), and the dihydroxyflavonol Glyasperin A (TB-1), along with six known triterpenes: a mixture of a-amyrin (TB-2a), b-amyrin (TB-2b), and lupeol (TB-2b), and a mixture of urs-12-ene-3-one (TB-6a), olean-12-ene-3-one (TB-6b), and lupenone (TB-6c). The structures TB-4 and TB-1 were elucidated using 1D and 2D NMR spectroscopy. Stereochemistry of TB-4 was determined using CD spectroscopy. This the first report on the isolation of Glyasperin A from propolis. Furthermore, this is the first report on the isolation of secondary metabolites in Philippine propolis