著者

眞岡 孝至 秋元 直茂 藤原 靖弘 橋本 圭二

出版者

天然有機化合物討論会

雑誌

天然有機化合物討論会講演要旨集

巻号頁・発行日

no.45, pp.611-616, 2003-09-01

---

The ripe fruits of paprika (Capsicum annuum L.) is a good source of carotenoids and is used widely as a vegetable and food colorant. The red carotenoids are mainly capsanthin and capsorbin, possessing 3-hydroxy-6-oxo-κ-end group. In the course of the carotenoids studies of paprika, two new carotenoids 1 and 2 were isolated as minor components. The MeOH extract of ripe fruits of paprika (4kg) was saponified with 5% KOH/MeOH, and unsaponifiable matter was chromotographed on silica gel using an increasing percentage of acetone in hexane. The fraction eluted with acetone-hexane (1:9) was subjected to a series of HPLC on ODS with CHCl_3-acetonitrile (1:9) and on silica gel with acetone-hexane (2:8) to yield 1 (2mg) and 2 (0.5mg). The molecular formula of 1 was determined to be C_<40>H_<56>O_2 by HR FAB MS. The positive ion FAB MS/MS spectrum of the molecular ion (M^+) of 1 is shown in Fig 1a. Characteristic product ions of M-111 and M-139 which attributed to cleavage between C-5' and C-6' and between C-6' and C-7', respectively suggested the presence of 6-oxo-κ-end group in 1. The structure of 1 was determined to be 3-hydroxy-β,κ-caroten-6'-one by ^1H- and ^<13>C-NMR, COSY, TOCSY, NOESY, HSQC and HMBC data and named 3'-deoxycapsanthin. The structure of 2 was determined to be 3,4-didehydro-β,κ-caroten-6'-one by HR FAB MS, FAB MS/MS, UV-Vis and ^1H-NMR data. From the CD spectral data and biosynthetic consideration 3R, 5'R and 5'R chiralities were proposed for 1 and 2, respectively. They are the first example of carotenoids possessing 6-oxo-κ-end group.