ツユクサの青色メタロアントシアニンの結晶化と その性質とについて

Abstract

(1) A blue anthocyanin was isolated in crystalline state from the petals of “Awobana”.plant (Commelina communis L, var. hortensis Makino) (cf. Fig. 1), and was shown to be identical in all respects with the blue crystals previously obtained from the petals of wild commelina (Commelina communis L. var. communis). We propose the name “commelinin” for this blue anthocyanin.(2) Commelinin seems to be a high molecular compound, which is non-dialysable through semi-permeable membranes. The estimation of the individual components gave the following results: p-coumaric acid 11.83%, delphinidin (as chloride) 27.33% and glucose 30.78%, Mg 0.42%, K 1.47% and Na 0.29%, respectively. Probably, Na is not inherent to the pigment molecule.(3) On treatment with 1% hydrochloric acid, commelinin loses its alkali metals altogether. The resultant product, which is still bound with Mg as before, is also convertible into brilliant blue crystals (cf. Fig. 4). Therefore, it is concluded that the blue color of commelinin is not due to an alkali phenolate of anthocyanin.(4) Mg remains fixed to the pigment molecule even after treatment either with EDTA or cation exchangers. Of course, no perceptible color change occurs in these cases.(5) Besides, commelinin seems to contain an appreciable amount (25-30%) of an unknown substance, which is pale yellowish in color and is presumed to be a flavonoid.(6) To sum up the analytical results obtained, commelinin is a co-ordination compound, in which one atom of Mg combines four molecules of awobanin (delphinidin-3: 5-dimonoglucoside+p-coumaric acid) around it, and an unknown flavonoid-like substance is further brought into association with it (cf. Table 3 and 4).