a b s t r a c tChemical investigation of the dichloromethane extracts of the propolis collected from bee (Tetragonula biroi Friese) hives in San Roque, Sorsogon, Philippines afforded propolin A (1), propolin E (2), propolin H (3), glyasperin A (4), squalene, a mixture of lupeol, ␣-amyrin and -amyrin, and another mixture of urs-12-en-3-one, olean-12-en-3-one and lup-12-en-3-one. The structures of 2-4 were elucidated by extensive 1D and 2D (COSY, HSQC, and HMBC) NMR spectroscopy, while 1 was identified by comparison of its NMR data with 2.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.