Quinochalcones and flavonoids from fresh florets in different cultivars ofCarthamus tinctorius L.

The flavonoid constituents in fresh florets of the three distinctive cultiv ars of Carthamus tinctorius L. were purified and identified to investigate flavonoid biosynthesis in the petals. From the orange flower of cv. Kenba ( K.), four new compounds, anhydrosafflor yellow B (1), two kaempferols, 9 an d 13, and a quercetin, 17, were isolated, as well as the twelve known compo unds, and their structures were determined by spectral data, chemical react ions, and molecular mechanics calculations. From the yellow flower of cv. O gon-hanagasa (O.), two favonols and two quinochalcones, and from the white flower of cv. Shiro-bana (S.), three flavonols were isolated. These compoun ds were the same as those contained in cv. K. To compare the flavonoid cons tituents among the three cultivars, crude extracts were analyzed by a LC/PD A/MS system. In cv. K., six quinochalcones and eleven flavonols were identi fied. In cv. O., three quinochalcones and nine flavonols were identified, b ut the red pigment, carthamin (4), and its precursor, precarthamin (3), wer e not detected. In cv. S., four flavonols without a 6-hydroxyl group were i dentified. On the basis of a comparative study on the constituents among th ese three cultivars, a possible biosynthetic pathway to form quinochalcones via the intermediate, pentahydroxychalcone (19), is proposed.