Milena Popova(1), Boryana Trusheva(1), Ralitsa Chimshirova(1), Le Nguyen Thanh(2), Vassya Bankova(1)
1 Institute of Organic Chemistry with Centre of Phytochemistry, Bulgarian Academy of Sciences, Sofia, Bulgaria;
2 Graduate University of Science & Technology and Institute of Marine Biochemistry, Vietnam Academy of Science and Technology (VAST), Hanoi, Vietnam;
The chemical composition of 16 propolis samples from four provinces of Vietnam, produced by six species of local stingless bees was examined. Chemical profiles were obtained by GC/MS after silylation of dry ethanol extracts. Most of the samples contained characteristic compounds for Mangifera indica, a well-known propolis source in tropical regions. Xanthones, some of them markers of Cratoxylum cochinchinense, predominate in two of the samples. In three of the samples a high relative content of triterpenes of oleanane, ursane, lupane and dammarane type was observed, with the most probable source being dipterocarp trees. It can be summarized that although the bees had access to the same plants in the same area, they collected different resins to make propolis. Some similarities in propolis from the same bee species were also observed, but we could not conclude unambiguously that the bee species determines the composition of propolis. The only exception is the bee species Homotrigona apicalis, which, regardless of the region, has a preference for the Dipterocarpus species. Further studies of a larger number of propolis samples from different bee species and different regions are needed in order to reveal and confirm the potentional relationship between bee species and propolis chemistry.
The study was funded by Bulgarian Academy of Sciences and Vietnamese Academy of Science and Technology through a bilateral project, Code Number QTBG01.01/20-21.