P-18 トベラ種子の新規カロテノイドPittosporumxanthins B1,B2,C1,C2のMS/MS法を用いた構造研究(ポスター発表の部)

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In the course of the carotenoids studies, six new minor C_<69> carotenoids, named pittosporumxanthins B1, B2, C1, C2, A3 and A4 were isolated from the seeds of Pittosporum tobira. Pittosporumxanthins A1 and A2, which have unique structures including violaxanthin and α-tocoherol moieties, have been reported in the previous symposium. In the present investigations, the structures of six new pittosporumxanthins were determined by detailed analyses of MS/MS, ^1H-NMR, ROESY, and CD data (Fig. 1). The molecular formulae C_<69>H_<104>O_5 for Bland B2, and C_<69>H_<104>O_6 for C1, C2, A3 and A4 were determined by HR-FAB-MS spectra. The partial structures of C_<40>-carotenoid and tocopherol moiety in six new pittosporumxanthins were elucidated by MS/MS experiments. The CID spectra of the fragment ions of m/z 584 and m/z 430 obtained from EI-MS of B1 and B2 were agreed with those of M^+ ions of antheraxanthin and α-tocopherol, respectively. As a same manner, the MS/MS was applied to the partial structure elucidations of neoxanthin and α-tocopherol in C1 and C2 and violaxanthin and α-tocopherol in A3 and A4. The partial structures of C_<40>-carotenoid and tocopherol in six new pittosporum-xanthins derived from the MS/MS spectra were connected on the basis of ^1H-NMR data (H11', H12', H28") as compared those of A1 and A2. The trans configuration between H11' and H12' of all six new compound was revealed by ^1H-^1H spin-coupling constant (9.3Hz) and NOE data. Furthermore, Δ9Z and Δ9'E configurations for B1, B2, C1 and C2, and Δ9E and Δ9'Z for A3 and A4 were determined by long-range coupling and NOEs between H19 and H10, and H19' and H10'. The absolute configurations of 11'(R), 12'(S) for B1, C1 and A3, and 11'(S), 12'(R) for B2, C2 and A4 have been determined by comparison of ^1H-NMR data with those of A1 and A2. Also, the relationship between chiralities at C11' and C12' and Cotton effects of CD spectra in series of pittosporumxanthins were discussed.
天然有機化合物討論会の論文
1995-09-01

P-18 トベラ種子の新規カロテノイドPittosporumxanthins B1,B2,C1,C2のMS/MS法を用いた構造研究(ポスター発表の部)

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