Lavandulyl flavanones from the stems of Hypericum calycinum L.
One novel lavandulyl flavanone (=2,3-dihydro-2-phenyl-4H-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-2H-tetrazolium bromide) assay using HeLa cells. Compound 1 showed moderate activity with an IC₅₀ value of 9.7±1.8 μM, whereas compounds 2-4 were less active exhibiting IC₅₀ values of 11.6±0.9, 19.3±1.5, and 40.7±2.4 μM, 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).
Department of Chemistry, Kyaukse University, Myanmar. thida09@gmail.com
Thida
T
Win
Thant Thant
TT
Htwe
Htay Htay
HH
Shwe
Jörg
J
Heilmann
D000975:Antioxidants / Q000737:chemistry / Q000302:isolation & purification; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D044950:Flavanones / Q000737:chemistry* / Q000302:isolation & purification / Q000494:pharmacology / Q000633:toxicity; D005609:Free Radicals / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D020902:Hypericum / Q000737:chemistry*; D018799:Intercellular Adhesion Molecule-1 / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008968:Molecular Conformation; D018547:Plant Stems / Q000737:chemistry; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
D000975:Antioxidants; D044950:Flavanones; D005609:Free Radicals; D014409:Tumor Necrosis Factor-alpha; C575704:calycinigin A; D018799:Intercellular Adhesion Molecule-1