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Tannins and catechin gallate mediate the vasorelaxant effect of Arbutus unedo on the rat isolated aorta
Author(s) -
Legssyer Abdelkhaleq,
Ziyyat Abderrahim,
Mekhfi Hassane,
Bnouham Mohamed,
Herrenknecht Christine,
Roumy Vincent,
Fourneau Christophe,
Laurens Alain,
Hoerter Jacqueline,
Fischmeister Rodolphe
Publication year - 2004
Publication title -
phytotherapy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.019
H-Index - 129
eISSN - 1099-1573
pISSN - 0951-418X
DOI - 10.1002/ptr.1513
Subject(s) - chemistry , methyl gallate , catechin , proanthocyanidin , methanol , polyphenol , pyrogallol , gallate , tannin , chromatography , nuclear chemistry , biochemistry , organic chemistry , food science , gallic acid , antioxidant
This study examined the vascular effect of Arbutus leaves (aqueous extract) and described the isolation of several fractions responsible for their vasorelaxant activity. The aqueous extract (AE) of leaves was tested on rat aortic rings precontracted with 0.1 µ m noradrenaline. At 10 −2 g/L, AE produced an endothelium dependent relaxation of 66% ± 5%, ( n = 8). The leaves of Arbutus were then extracted successively with different solvents and the methanol extract was the most active. When tannins (primarily condensed tannins) were precipitated from the methanol extract, they showed a strong vasorelaxant activity (87% ± 4%, n = 5), whereas the elimination of tannins in the methanol extract reduced signicantly its vasorelaxant activity (42% ± 8%, n = 8, p < 0.005). The methanol extract was further separated semi‐preparatively by reversed‐phase HPLC. Four fractions (Fr2, Fr3, Fr4 and Fr6) were the most active and produced 88% ± 2% ( n = 5), 75% ± 6% ( n = 5), 76% ± 3% ( n = 7) and 77% ± 3% ( n = 10) relaxation, respectively. These four fractions mainly correspond to polyphenol compounds. Analysis of Fr6 indicated that this fraction contained catechin gallate. In conclusion, the vasorelaxant activity of Arbutus is likely to be due to polyphenol compounds, primarily condensed tannins and catechin gallate. Copyright © 2004 John Wiley & Sons, Ltd.