Polyphenolic constituents of Callistemon lanceolatus leaves.

Two new flavonol glycosides, kaempferol 3-O-beta-D-galacturonopyranoside and quercetin 3-O-(2"-O-galloyl)-beta-D-glucoronopyranoside, were isolated, from leaves of Callistemon lanceolatus DC, as well as eighteen known polyphenols (phenolic acids, flavonoids and three tannins). All structures were established mainly on the basis of chemical and spectroscopic analysis (UV, 1D NMR and negative ESI-MS) and finally confirmed by 2D NMR experiments (HMQC and HMBC), in the case of flavonoid glycosides and tannins.