Abstract
The sparing/recycling effect of a highly purified, high molecular weight fraction
of catechin oligomers (procyanidins) from Vitis vinifera seeds on α-tocopherol was studied in both homogeneous solution and in heterogeneous
phase (phosphatidylcholine liposomes and red blood cells). By HPLC and electron spin
resonance (ESR) spectroscopy we evidenced that tocopheroxyl radical, induced by reaction
of α-tocopherol with the stable radical DPPH (2,2-diphenyl-1-picrylhydrazyl) is recycled
by procyanidins. In addition procyanidins significantly and dose-dependently spare
vitamin E from consumption (HPLC monitoring) during the autooxidation phase of the
HO-induced peroxidation of phosphatidylcholine, by 23% at the lowest concentration
(0.5 µM) and by 65.5% at 3 µM. In this membrane model the combination of 0.5 µM procyanidins
and 2 µM α-tocopherol results in a marked delay in the appearance of conjugated dienes
in respect to the single antioxidants (synergistic interaction), while catechin showed
to be active only at 5 µM. In red blood cells oxidatively stressed by UVB exposure,
procyanidins at 0.1-1.0 µM prevent vitamin E loss, markedly decrease membrane lipid
peroxidation, linearly related to the concentration of vitamin E in the membranes,
and significantly delay the onset of hemolysis (catechin protects between 5 and 10
µM)
Key words
Procyanidins -
Vitis vinifera
- Vitaceae - vitamin E - sparing effect - phosphatidylcholine liposomes - red blood
cells
