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Further NMR Investigation and Conformational Analysis of an Acylated Flavonol Glucorhamnoside
Author(s) -
Gao Jinhai,
Shi Genbin,
Song Guoqiang,
Shao Yu,
Zhou Bingnan
Publication year - 1996
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/(sici)1097-458x(199604)34:4<249::aid-omr877>3.0.co;2-o
Subject(s) - chemistry , aglycone , hydrogen bond , intramolecular force , nuclear magnetic resonance spectroscopy of nucleic acids , nuclear magnetic resonance spectroscopy , stacking , stereochemistry , rhamnose , proton nmr , crystallography , two dimensional nuclear magnetic resonance spectroscopy , molecular dynamics , carbon 13 nmr , computational chemistry , glycoside , molecule , organic chemistry , fluorine 19 nmr , transverse relaxation optimized spectroscopy , galactose
With the combination of various 2D NMR techniques, the structure of an acylated glycoside (1) was unambiguously determined to be kaempferol 3‐O‐α‐(6‴‐ p ‐coumaroylglucosyl‐β‐1,2‐rhamnoside). The complete 1 H and 13 C resonance assignments were obtained. Based on NMR data and molecular dynamics simulations in DMSO solvent using periodic boundary conditions, a folded conformation was elucidated for 1 in solution, implying a hydrophobic interaction between the aromatic nuclei of aglycone and the acyl group. Such hydrophobic stacking is further assisted by a weak intramolecular hydrogen bond between OH3″ on glucose and O2‴ on rhamnose, as indicated directly by the NMR behaviour (temperature coefficients dδ/d T , NOEs and coupling constants J HOCH ) of the hydroxyl protons on the sugar rings.