The colouring matter of the flowers of Tagetes patula: Isolation of a new flavonol, patuletin and its constitution

Abstract

A new flavonol, patuletin has been isolated from the petals of the flowers of Tagetes patula (French Marigold). It contains five hydroxyl groups and yields a pentaacetate and a pentamethyl ether. It is, therefore, isomeric with quercetin and herbacetin. On oxidation in cold alkali, the substance decomposes into protocatechuic acid which could be isolated after methylation as veratric acid. The completely methylated ether also yields veratric acid on boiling with potash. Assuming that a hydroxyl group is present in position 5, as is the case with most of the naturally occurring flavones and flavonols, the remaining hydroxyl group in the compound is concluded to be in position 6 in view of the properties of the flavonol and its resemblance to quercetagetin. Hence patuletin is represented as 3∶5∶6∶3'∶4'-pentahydroxy flavone.