Biflavonoids, main constituents from Garcinia bakeriana leaves.

The genus Garcinia is a source of a large variety of organic compounds including biflavonoids, acylphloroglucinols and xanthones mainly, but few data are available about the chemical composition of Cuban species. The aim of this investigation was to identify the main constituents of G. bakeriana Urb., a rare Cuban endemic plant. A new biflavonoid, 4'''-O-methyl-I3,II8-biapigenin (1), together with 9 known compounds, namely, the biflavonoids amentoflavone (2), 4'''-O-methylamentoflavone (3), 4'-O-methylcupressuflavone (4), GB-2a (5), volkensiflavone (6), 6"-(2-hydroxy-3-methyl-3-butenyl)-amentoflavone (7), I3,II8-biapigenin (8), and GB-1a (9), and the xanthone norathyriol (10), were isolated from the leaves of this species. All the structures were elucidated by spectroscopic methods including 1D and 2D NMR experiments, as well as ESIMS analysis. These results showed that the isolated biflavonoids possess a C-C interflavonoid linkage between the apigenin units or its derivatives.