Baeckeins F–I, four novel C-methylated biflavonoids from the roots of Baeckea frutescens and their anti-inflammatory activities

•Baeckeins F–I were isolated from the roots of Baeckea frutescens.•The structures were elucidated by analysis of the 1D/2D-NMR and HR-ESI-MS spectra.•The absolute stereochemistry was assigned by quantum chemical CD calculations.•The anti-inflammatory activities for the isolates were also evaluated....

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Bibliographic Details
Published in:Food chemistry 2014-07, Vol.155, p.31-37
Main Authors: Jia, Bei-Xi, Zeng, Xian-Lei, Ren, Feng-Xiao, Jia, Lu, Chen, Xiao-Qing, Yang, Jie, Liu, Hong-Min, Wang, Qiang
Format: Article
Language:English
Subjects:
Absolute configuration
Animals
Anti-inflammatory activity
Anti-Inflammatory Agents - chemistry
Anti-Inflammatory Agents - isolation & purification
Anti-Inflammatory Agents - pharmacology
Baeckea frutescens
Baeckeins F–I
Biflavonoids - chemistry
Biflavonoids - isolation & purification
Biflavonoids - pharmacology
Biological and medical sciences
C-methylated biflavonoid
Cell Line
Drugs, Chinese Herbal - chemistry
Drugs, Chinese Herbal - isolation & purification
Drugs, Chinese Herbal - pharmacology
Food toxicology
Macrophages - drug effects
Macrophages - immunology
Medical sciences
Mice
Molecular Structure
Myrtaceae - chemistry
Plant Roots - chemistry
Toxicology
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Summary:•Baeckeins F–I were isolated from the roots of Baeckea frutescens.•The structures were elucidated by analysis of the 1D/2D-NMR and HR-ESI-MS spectra.•The absolute stereochemistry was assigned by quantum chemical CD calculations.•The anti-inflammatory activities for the isolates were also evaluated. Baeckea frutescens is an aromatic shrub used in South China as an ornamental and as a spice. Four unusual C-methylated biflavonoids named baeckeins F–I (1–4) were isolated from the roots of B. frutescens. The baeckeins F–I possessed a unique carbon skeleton, a flavonol conjugated with a coumaronochromone molecule via the unusual linkages of C-2–C-8∗ and C-3–O–C-7∗. Their structures were elucidated by analysis of the 1D (1H/13C) and 2D NMR (HSQC/HMBC/NOESY) and HR-ESI-MS spectroscopic data, and the absolute stereochemistry for chiral carbons of C-2 and C-3 was established by CD spectrometry combined with quantum chemical calculations. Baeckeins F–I (1–4) were also evaluated for their anti-inflammatory activities by detecting the NO production of LPS-induced RAW264.7 murine macrophage cell line; baeckein I (4) with the β-d-glucose unit and configuration of (2R,3R) exhibited the highest NO inhibitory activity (IC50=15.2μM), which was similar to that of the positive control indomethacin.
ISSN:0308-8146
1873-7072
DOI:10.1016/j.foodchem.2014.01.022