Unusual Flavonoid Glycosides from the Hawaiian Tree Metrosideros polymorpha.

Metrosideros polymorpha is a highly variable and widely-distributed tree native to the Hawaiian islands. We describe here the isolation of two new gossypetin derivatives and three new C-methylated flavonol glycosides, which are highly uncommon and may prove to be useful chemotaxonomic markers for the species. In addition, a wide range of known flavonoid glycosides, chalcones, and terpenoids were isolated alongside the new compounds.