THE FLOWER FLAVONOLS OF NICOTIANA SPECIES

Flowers of Nicotiana species were analysed for their flavonol content. Flavonol glycoside distributions were determined for 63 of the 66 recognized species, two accessions of tentative species rank, and 14 interspecific crosses (allotetraploids). Only quercetin and kaempferol glycosides were found in any appreciable quantity. Quercetin and kaempferol 3-(2G-rhamnosylrutinoside), kaempferol 3-rhamnosylgalactoside, kaempferol 3-rhamnosylgalactoside-7-glucoside, kaempferol 3-(2-glucosylgalactoside)-7-glucoside, and kaempferol 3-sophoroside-7-glucoside were identified in several species. The percentage distribution of these compounds and quercetin and kaempferol 3-rutinosides, 3-sophorosides, and 3-rutinoside-7-glucosides showed that the flavonols of the flowers varied much more than leaf flavonols. The data have allowed a chemotaxonomic evaluation of the genus classification.