By means of variable temperature NMR spectra, conformation of 8-C-glucosyl prunetin, isolated from the leaves of Dalbergia hainanensis (Leguminosae), was studied. The restricted rotation around the C (sp3)-C (sp2) bo...By means of variable temperature NMR spectra, conformation of 8-C-glucosyl prunetin, isolated from the leaves of Dalbergia hainanensis (Leguminosae), was studied. The restricted rotation around the C (sp3)-C (sp2) bond in the C-glucosides isoflavonoid results in two main conformers (syn and anti). With the help of MM calculation, the preferred conformation A has H-1 gauche to the 7-OCH3. The barrier to rotation was 18.1 kcal/mol. This result agrees with the calculated value 16.2 kcal/mol of free energy of activation for the interconversion between the conformers.展开更多
Objective To study the chemical constituents from the roots of Flemingia philippinensis. Methods The chemical constituents were isolated and purified by combination of silica gel column, Sephadex LH-20, polyamide, and...Objective To study the chemical constituents from the roots of Flemingia philippinensis. Methods The chemical constituents were isolated and purified by combination of silica gel column, Sephadex LH-20, polyamide, and ODS column chromatography. The structures of the isolated compounds were identified by means of spectral data. Results Ten compounds were isolated from F. philippinensis and identified as isoderrone (1), dalparvin A (2), prunetin (3), 7,3′-dihydroxy-5,4′,5′-trimethoxyisoflavone (4), pratensein-7-O-β-D-glucoside (5), sissotrin (6), sophororicoside (7), formononetin (8), orobol (9), and biochanin A (10). Conclusion Compounds 1-6 are obtained from this plant for the first time.展开更多
文摘By means of variable temperature NMR spectra, conformation of 8-C-glucosyl prunetin, isolated from the leaves of Dalbergia hainanensis (Leguminosae), was studied. The restricted rotation around the C (sp3)-C (sp2) bond in the C-glucosides isoflavonoid results in two main conformers (syn and anti). With the help of MM calculation, the preferred conformation A has H-1 gauche to the 7-OCH3. The barrier to rotation was 18.1 kcal/mol. This result agrees with the calculated value 16.2 kcal/mol of free energy of activation for the interconversion between the conformers.
基金National Natural Science Foundation of China (30973635)the Knowledge Innovation Program of the Chinese Academy of Sciences (KSCX2-YW-R-217+2 种基金 KSCX2-EW-J-28)the Program of South China Botanical Garden (201037)Guangdong Province Natural Science Foundation (10151065005000026)
文摘Objective To study the chemical constituents from the roots of Flemingia philippinensis. Methods The chemical constituents were isolated and purified by combination of silica gel column, Sephadex LH-20, polyamide, and ODS column chromatography. The structures of the isolated compounds were identified by means of spectral data. Results Ten compounds were isolated from F. philippinensis and identified as isoderrone (1), dalparvin A (2), prunetin (3), 7,3′-dihydroxy-5,4′,5′-trimethoxyisoflavone (4), pratensein-7-O-β-D-glucoside (5), sissotrin (6), sophororicoside (7), formononetin (8), orobol (9), and biochanin A (10). Conclusion Compounds 1-6 are obtained from this plant for the first time.
