[Synthesis and vasorelaxation action of flavonoids].

AIM

To search for flavonoids which possess stronger vasorelaxation action.

METHODS

Four quercetin glycosides (1a - d) were synthesized from quercetin in three steps i. e. selective protection of quercetin, condensation with corresponding acetyiglycosyl bromide, and then removal of the protecting group; Six flavone compounds (2a - f) were prepared from phloroglucinol according to the conventional methods; The structures of synthetic compounds were confirmed by IR, 1H NMR, 13C NMR and MS. Vasorelaxation action of ten synthetic quercetin derivatives (or analogues) and four natural flavonoids compounds were examined on the isolated rat thoracic aorta rings; Comparative octanol-water partition coefficients (logP) were measured using a reversed-phase HPLC method.

RESULTS

Most of the tested flavonoids showed concentration dependent relaxation effects against PE-induced contractions of rat aortic rings. These compounds had stronger action with the augment of logP values.

CONCLUSION

Compound 3-bromo-5 ,7-dihydroxyflavone (2d) was identified to have the most potent vasodilating action. These compounds exert vasodilating effects that are related to the logP values. A structure-activity relationship of flavonoids was suggested.