N-Substituted acetamide glycosides from the stems of Ephedra sinica. (June 2015)

• Record Type: Journal Article
• Authors: Zhang, Dan; Deng, An-Jun; Ma, Lin; You, Xue-Fu; Zhang, Zhi-Hui; Li, Zhi-Hong; Jiang, Jian-Dong; Qin, Hai-Lin
• Is Part Of: Phytochemistry letters. Volume 12(2015:Jun.)
• Page Start: 320
• Page End: 327
• Publication Date: 2015-06
• Subjects: Ephedra sinica -- Ephedraceae -- N-mono-/bis-substituted acetamide glycosides -- Rotamerism; Botanical chemistry -- Periodicals; Chimie végétale -- Périodiques; 572.205
• DOI: 10.1016/j.phytol.2015.04.014
• Languages: English
• ISSNs: 1874-3900

Abstract

Graphical abstract: Five new N -mono-/ N, N -bis-substituted acetamide glycosides were isolated from the stems of Ephedra sinica . The structures of these new compounds were elucidated on the basis of extensive spectroscopic analyses. Highlights: More information on the chemical constituents of Ephedra sinica are described. Five new acetamide glycosides were characterized. The N, N -bissubstituted acetamides showed obvious rotamerism in solution. Abstract: Five new N -mono-/bis-substituted acetamide glycosides, N -{4- O -[3- O -(4- O -α-l -rhamnopyranosyl-β-d -glucopyranosyl)-α-l -rhamnopyranosyl]-phenethyl}-acetamide (1 ), N -methyl- N -{4- O -[3- O -(4- O -α-l -rhamnopyranosyl-β-d -glucopyranosyl)-α-l -rhamnopyranosyl]-phenethyl}-acetamide (2 ), N -methyl- N -{4- O -[3- O -(6- O -benzoyl-4- O -α-l -rhamnopyranosyl-β-d -glucopyranosyl)-α-l -rhamnopyranosyl]-phenethyl}-acetamide (3 ), N -methyl- N -{4- O -[3- O -(6- O -benzoyl-β-d -glucopyranosyl)-α-l -rhamnopyranosyl]-phenethyl}-acetamide (4 ), and N -methyl -N -{4- O -[3- O -(6- O - trans -cinnamoyl-4- O -α-l -rhamnopyranosyl-β-d -glucopyranosyl)-α-l -rhamnopyranosyl]-phenethyl}-acetamide (5 ), along with one known acetamide derivative, N -methyl- N -(4-hydroxyphenethyl)-acetamide, the shared aglycone of 2 –5, were isolated from the ethanol extract of the stems of Ephedra sinica . The structures of these new compounds were elucidated on the basis of extensive spectroscopic examination, mainly including multiple 1D and 2D NMR and HRESIMS examinations, and qualitative chemical tests. All N, N -bissubstituted acetamide glycosides were found to show the obvious rotamerism, as in the case of the isolated known N -methyl- N -(4-hydroxyphenethyl)-acetamide, under the experimental NMR conditions, with the ratios of integrated intensities between anti - and syn -rotamers always being found to be about 4 to 3.