THE LEAVES OF THE COMMON BOX, BUXUS SEMPERVIRENS (BUXACEAE), BECOME RED AS THE LEVEL OF A RED CAROTENOID, ANHYDROESCHSCHOLTZXANTHIN, INCREASES

摘要

Carotenoids from the leaves of the common box, Buxus sempervirens (Buxaceae), which turn red in late autumn to winter, were analyzed by reversed-phase HPLC. A novel carotenoid, monoanhydroeschscholtzxanthin (3), was isolated from the red-colored leaves. UV-VIS, MS, H-1-NMR and CD spectral data showed that the structure of 3 was (3S)-2', 3', 4', 5'-tetradehydro-4,5'retro-beta, beta-caroten-3-ol. As well as anhydroeschscholtzxanthin (2), the major red carotenoid in the leaves, eschscholtzxanthin (4) was identified. Very small amounts of yellow carotenoids (neoxanthin, violaxanthin, lutein and beta-carotene), which are major components of green leaves, were present in the red-colored leaves. The amounts of chlorophyll a and b in the leaves decreased markedly during coloration, even at the early stages, whereas those of the yellow carotenoids decreased gradually. In contrast, the content of 2, a red carotenoid, increased steadily during coloration. The biosynthetic pathway of 2 in B. sempervirens was deduced tentatively on the basis of the individual carotenoid contents during autumnal coloration.