Flower Colors and Flavonoids in the Cultivars of Verbena hybrida

Abstract

The flower colors and flavonoids of 16 cultivars of Verbena hybrida Groenl. & Rumpler (Verbenaceae) were examined to evaluate the relationship between flower color and flavonoid components. Fifteen anthocyanins {3-O-glucoside, 3,5-di-O-glucoside, 3-O-[6-O-(acetyl)-glucoside], 3-O-[6-O-(malonyl)-glucoside], and 3,5-di-O-[6-O-(acetyl)-glucoside] of delphinidins, cyanidins, and pelargonidins}, seven flavones {7-O-(glucuronide) of apigenin, luteolin, tricetin, and 4'-O-methyl-luteolin, 7-O-[2-O-(glucuronosyl)-glucuronide]-4'-O-(glucuronide) of apigenin, and 7-O-[2-O-(glucuronosyl)-glucuronide] of apigenin and luteolin}, two flavonols {3-O-glucoside and 3-O-[6-O-(acetyl)-glucoside] of kaempferols}, and chlorogenic acid were isolated from the flowers of these cultivars. Their structures were identified using co-HPLC, nuclear magnetic resonance, and mass spectrometry. For the Red to Purple-Violet cultivars, the corresponding color chart names were responsible for the major anthocyanidin types, and the hue values (b*/a*) of these flower colors reflected the anthocyanins concentration. Based on the relationship between the distribution of flavones, flavonols, and chlorogenic acid among cultivars and flower color, we conclude that flavonoids other than anthocyanins and chlorogenic acid make little contribution to flower color. The yellowish red color is thought to be affected by carotenoids.