Abstract
The study aimed to assess biophysical changes that take place in the peripheral blood mononuclear cell (PBMC) membranes when exposed in vitro to 10 μM quercetin or epigallocatechin gallate (EGCG) for 24 and 48 h. PBMCs isolated from hypercholesterolemia patients were compared to those from normocholesterolemia subjects. The membrane fluidity and transmembrane potential were evaluated and the results were correlated with biochemical parameters relevant to oxidative stress, assessed in the patients’ plasma. The baseline value of PBMC membrane anisotropy for the hypercholesterolemia patients was lower than that of the control group. These results correlated with the plasma levels of advanced glycation end products, which were significantly higher in the hypercholesterolemia group, and the total plasma antioxidant status, which was significantly higher in normocholesterolemia subjects. In the case of normocholesterolemia cells in vitro, polyphenols induced a decrease in membrane anisotropy (7.25–11.88% at 24 h, 1.82–2.26% at 48 h) and a hyperpolarizing effect (8.30–8.90% at 24 h and 4.58–13.00% at 48 h). The same effect was induced in hypercholesterolemia cells, but only after 48 h exposure to the polyphenols: the decrease in membrane anisotropy was 5.70% for quercetin and 2.33% for EGCG. After 48 h of in vitro incubation with the polyphenols, PBMCs isolated from hypercholesterolemia patients exhibited the effects that had been registered in cells from normocholesterolemia subjects after 24 h exposure. These results outlined the beneficial action of the studied polyphenols, quercetin and EGCG, as dietary supplements in normocholesterolemia and hypercholesterolemia patients.
Highlights
Flavonoids are secondary products that are best known as the yellow, red, blue or purple pigments of various vegetal tissues [1, 2]
This study aimed to assess the effects of prolonged in vitro exposure to quercetin and epigallocatechin gallate (EGCG) on the membrane anisotropy and transmembrane potential of peripheral blood mononuclear cells (PBMCs) isolated from NC subjects and HC patients
The consumption of antioxidant supplements was limited for the selected patients for two weeks prior to the study in order to allow the evaluation of their endogenous antioxidant status and the total hydroperoxide level in the plasma
Summary
Flavonoids are secondary products that are best known as the yellow, red, blue or purple pigments of various vegetal tissues [1, 2] Apart from their physiological roles in plants, flavonoids are important components of the human diet. They reduce the severity and progression of already developed lesions and lead to a reduction in dyslipidemia, endothelial dysfunction and hypertension These benefits occur through several mechanisms, including: inhibition of LDL peroxidation, increase in the HDL level, reduction of platelet activation and thrombosis, inhibition of inflammatory processes, inhibition of MMP-2 expression and activity in vascular tissues, and anti-angiogenic properties [15,16,17,18].
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