Anthocyanins as Food Colors edited by Pericles Markakis (1982) pp. 62-63

Copigmentation of Anthocyanins
Yoshinobu Osawa

Harborne (1961) attributed the color of blue roses to copigmentation of cyanin with gallotannin or leucocyanidin. K. Toki, N. Saito, M. Yokoi, and Y. Osawa (unpublished results) found that there is no difference in the basic flavonoid pattern between red and blue roses, but the concentration ratio of flavonols to cyanin varies considerably between the two types of roses: it is 30 to 50 in blue roses and only 1 to 3 in red roses. Suspecting copigmentation, they prepared mixed solutions containing 5 x 10-4 M cyanin and varying concentrations of quercitrin, a major flavonol of blue roses. The results shown in Table VII leave no doubt that copigmentation is effective in these systems.

In the absorption spectra of the preceding solutions, the authors could not see the 600-nm shoulder, which is characteristic of blue rose spectra. By Sephadex column chromatography, they were able to separate two dull-looking pigments, one reddish-purple and the other bluish-purple (Fig. 12)

The authors tentatively concluded that the blueness of the Blue Moon roses are due to the dull-purplish pigments together with the flavonol-copigmented cyanin.

Fig. 12. Absorption spectra of intact blue rose petals (A), an extract from them (B), and two dull-purplish pigments separated from the extract (C and D). Redrawn from K. Toki, N. Saito, M. Yokoi, and Y. Osawa, unpublished.)

CybeRose note: These two dull-purplish pigments are probably the "rosacyanins" identified by Fukui, et al. (2006) in 'Mme Violet'.

Both 'Mme Violet' and 'Blue Moon' are offspring of 'Sterling Silver'.