Flower Colors and Their Anthocyanins in Saintpaulia Cultivars (Gesneriaceae)

The flower colors and anthocyanin constitution of sixteen cultivars of Saintpaulia were surveyed to determine the relationship between their flower colors and anthocyanin components. Six anthocyanins were isolated from the flowers of these cultivars as major anthocyanins along with three minor ones, and their structures were identified by co-HPLC or chemical and spectroscopic techniques. Among them, a novel anthocyanin, pelargonidin 3-O-[6-O-(4-O-(acetyl)-α-rhamnopyranosyl)-β-glucopyranoside] (pelargonidin 3-acetyl-rutinoside; 8) was found in cultivars of ‘Georgia’ and ‘Jessica’ as a major anthocyanin. Regarding the flower color variation in these cultivars, the hue values (b*/a*) of these flower colors were responsible for the glycosidic positions in the anthocyanidin molecule and also the combination of anthocyanins. These flower colors were classified into six groups, A–F, based on the flower colors and anthocyanin components were arranged as follows. In violet-blue flowers of group A (hue values b*/a* = −2.61–−1.72, VB N89B–VB 94B) and purple-violet flowers of group B (−1.06 and −0.81, PV N82A and PV N80B), malvidin 3-acetyl-rutinoside-5-glucoside was the most effective major anthocyanin for flower colors. In purple-violet flowers (−0.69 and −0.53, PV N80B and PV N81A) of group C, peonidin 3-acetyl-rutinoside-5-glucoside was the most effective major anthocyanin for flower colors. In red-purple flowers (−0.44–−0.27, RP 73A–RP N74B) of groups D, pelargonidin 3-acetyl-rutinoside-5-glucoside, in red-purple flowers (−0.03 and −0.02, RP 60D and RP 71D) of group E, pelargonidin 3-acetyl-rutinoside, and in red-purple flowers (0.04 and 0.13, RP 61A and RP 71A) of group F, peonidin 3-acetyl-rutinoside were the most effective major anthocyanins for flower colors. From these results, the glucosylation of 5-OH in anthocyanidin 3-acetyl-rutinoside and an increase in the methylation of the B-ring in anthocyanidin were considered to have the most important effects on flower color variations in these Saintpaulia cultivars.