13C CP/MAS NMR studies of flavonoids

Author(s): Wawer I, Zielinska A


C CP/MAS NMR spectra were recorded to characterize the solid-state conformation of flavonoids: galangin, kaempferol, quercetin, myricetin, chrysin, apigenin, luteolin, acacetin, hesperetin and naringenin. Correct assignment of the signals in solution-state spectra (using APT, HSQC and HMBC) and solid-state spectra (using dipolar dephased and short contact sequences) for the above flavonoids is reported. The locked conformation of OH and OCH3 groups in solids results in an increased shielding of carbon adjacent to C—OH or C—OCH3 hydrogens, enabling conclusions as to the orientations of these groups to be drawn. The C-5—OH hydroxyl (and C-3—OH) points towards the carbonyl group oxygen, forming intramolecular hydrogen bonds. Considerations of C2′ and C6′ carbon shielding suggest that ring B is not coplanar with the benzopyran fragment in kaempferol, acacetin and myricetin. Copyright © 2001 John Wiley & Sons, Ltd.

Similar Articles

Targeting postprandial hyperglycemia: a comparative study of insulinotropic agents in type 2 diabetes

Author(s): Carroll MF, Gutierrez A, Castro M, Tsewang D, Schade DS

Inhibitors of the rate of carbohydrate and lipid absorption by the intestine

Author(s): Puls W, Krause HP, Müller L, Schutt H, Sitt R, et al.

Trans-chalcone: a novel small molecule inhibitor of mammalian alpha-amylase

Author(s): Najafian M, Ebrahim-Habibi A, Hezareh N, Yaghmaei P, Parivar K, et al.

Plant alpha-amylase inhibitors and their interaction with insect alpha-amylases

Author(s): Franco OL, Rigden DJ, Melo FR, Grossi-De-Sá MF

Analgesic and Anti-Inflammatory Activity of PinusroxburghiiSarg

Author(s): Kaushik D, Kumar A, Kaushik P, Rana AC

Anticonvulsant activity of alcoholic extract of bark of PinusroxburghiiSarg

Author(s): Kaushik D, Kumar A, Kaushik P, Rana AC

GC-MS Analysis and Antimicrobial Activity of Essential Oil of PinusroxburghiiSarg

Author(s): Kaushik D, Kaushik P, Kumar A, Rana AC, Sharma C, et al.

Evaluation of Anticancer Activity of PinusroxburghiiSarg

Author(s): Kaushik P, Khokra S, Rana A, Kaushik D

The phenols and prodelphinidins of white clover flowers

Author(s): Foo LY, Lu Y, Molan AL, Woodfield DR, McNabb WC