Three New Acyclic Diterpene Glycosides from the Aerial Parts of Paprika and Pimiento
Chemical and pharmaceutical bulletin
The isolation and structure elucidation of acyclic diterpene glycosides designated as capsianosides II, IX-X, XIII, and XV-XVI from the fruits of paprika Capsicum annuum L. var. grossum 2) and C-F, 3) and IЈ-III and IV from the fruits of pimiento Capsicum annuum L. var. grossum 1) have been reported. Now our study is focused on the water-soluble constituents of the aerial parts of paprika and pimiento. In this study, we have isolated three new acyclic diterpene glycosides named capsianosides
... I (1), V methyl ester (2) and XIV (3) along with capsianosides I 1) and II. 2) The distribution of these new compounds is summarized in Table 1 . Capsianoside XVII (1) : An amorphous powder, [a] D Ϫ53.6°(MeOH), was found to have a molecular formula C 44 H 74 O 21 Na at m/z 961.4678 by HR-FAB-MS. The 13 C-NMR spectrum of 1 showed signals due to eight double bond carbons at d 115.8, 144.5, 126.0, 135.9, 152.6, 110.5, 131.1, and 132.9; one methylene carbon at d 67.9, one methine carbon at d 75.3 and one quarternary carbon at d 81.5 with an oxygen function; three methyl carbons at d 16.3, 21.9, and 23.3; and six methylene carbons d 42.7, 23.6, 36.9, 35.0, 32.5, and 27.3. Further, the 1 H-NMR spectrum disclosed the presence of terminal vinyl protons at d 5.20 (1H, br d, Jϭ11.0 Hz, H-1b), 5.23 (1H, br d, Jϭ17.7 Hz, H-1a), and 5.93 (1H, dd, Jϭ11.0, 17.7 Hz, H-2), two olefinic protons at d 5.15 (1H, m, H-6) and 5.45 (1H, t, H-14); one secondary hydroxyl group at d 3.99 (1H, m, H-10); seven methylene groups at d 1.61ϫ2 (each 2H, m, H 2 -4, 9), 1.95-2.30 (8H , m, 8, 12, 13), 4.16 (1H, d, Jϭ11.6 Hz, and 4.34 (1H, d, Jϭ11.6 Hz, H-17a); one olefinic methylene group at d 4.89 Paprika and pimiento are used as vegetables and spices. We have obtained three new acyclic diterpene glycosides, called capsianosides XVII (1), V methyl ester (2) and XIV (3) together with capsianosides I 1) and II 2) from the aerial parts of paprika and pimiento. The structures of these compounds have been established by 1 H-and 13 C-NMR spectra and two-dimensional NMR methods.