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Lavandulyl Flavanones from the Stems of Hypericum calycinum L.
Author(s) -
Win Thida,
Htwe Thant Thant,
Shwe Htay Htay,
Heilmann Jörg
Publication year - 2012
Publication title -
chemistry and biodiversity
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.427
H-Index - 70
eISSN - 1612-1880
pISSN - 1612-1872
DOI - 10.1002/cbdv.201100310
Subject(s) - chemistry , flavanone , trolox , stereochemistry , circular dichroism , oxygen radical absorbance capacity , hypericum , hela , flavonols , viability assay , antioxidant , in vitro , dpph , biochemistry , flavonoid , botany , biology
One novel lavandulyl flavanone (=2,3‐dihydro‐2‐phenyl‐4 H ‐1‐benzopyran‐4‐one) with an unusual 5,2′,4′,6′‐tetrahydroxy substitution, calycinigin A ( 1 ), was isolated from the stems of Hypericum calycinum L. (Hypericaceae). The structure was elucidated on the basis of 1D‐ and 2D‐NMR analysis, as well as mass spectrometry (LR‐EI‐ and HR‐EI‐MS) and circular dichroism. Three known lavandulyl flavanones with 5,7,2′,4′,6′‐pentahydroxy substitution, i.e. , 2 – 4 , were also isolated. Chemosystematically, this is the first report on the occurrence of prenylated flavanones in the family Hypericaceae. Reduction of cell viability by all compounds was evaluated in a MTT (=3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl‐2 H ‐tetrazolium bromide) assay using HeLa cells. Compound 1 showed moderate activity with an IC 50 value of 9.7±1.8 μ M , whereas compounds 2 – 4 were less active exhibiting IC 50 values of 11.6±0.9, 19.3±1.5, and 40.7±2.4 μ M , respectively. The antioxidant activity was evaluated by an ORAC (Oxygen Radical Absorbance Capacity) assay, and calycinigin A ( 1 ) was again the most active compound with a Trolox equivalent of 2.3±0.2. None of the compounds was able to reduce the TNF‐ α induced ICAM‐1 expression in vitro using human microvascular endothelial cells (HMEC‐1).