Abstract

The polyphenol quercetin is associated with numerous beneficial health effects in various pathologies such as oxidative stress, neurodegenerative disorders, inflammation, neoplastic processes, age-related diseases, and so on. However, the molecular mechanisms underlying the effects of quercetin and its implication in the pharmaceutical practice require additional clarification. In this study we analyzed the biochemical mechanisms of quercetin effect on membrane lipids of fibroblasts cultured as three-dimensional (3D) cultures, which resemble living tissues more adequately compared to cellular monolayers. Quercetin treatment of 3D fibroblasts induced alterations of the plasma membrane phospholipid and fatty acid composition as well as in the phospholipid metabolizing enzymes sphingomyelinase and phospholipase A₂. The level of sphingomyelin (SM), which acts as endogenous membrane antioxidant, was elevated due to quercetin action. Incubation of 3D fibroblasts with quercetin induced augmentation in the saturated fatty acids and reduction of all polyunsaturated fatty acids in the membrane phospholipid molecules of the plasma membranes, indicating an additional increase of the resistance to oxidative damage. Quercetin treatment reduced cholesterol susceptibility to oxidation, a phenomenon which is probably related to the observed increase in the level of SM. In addition, Western blot analysis showed augmented phosphorylation of Akt and expression of Bcl-2 in quercetin-treated cell, indicating that apoptosis was suppressed by quercetin. In conclusion, the reported results contribute to a better understanding of the beneficial effects of quercetin on the structure and functions of plasma membranes of 3D cell cultures, which are a more adequate model of living tissues.

摘要

多酚槲皮素在氧化应激、神经退行性疾病、炎症、肿瘤过程、年龄相关疾病等各种病理中与许多有益的健康影响有关。然而，槲皮素作用的分子机制及其在制药实践中的意义需要进一步澄清。在这项研究中，我们分析了槲皮素对作为三维 (3D) 培养物培养的成纤维细胞膜脂的生化机制，与细胞单层相比，它更类似于活组织。槲皮素处理 3D 成纤维细胞诱导质膜磷脂和脂肪酸组成以及磷脂代谢酶鞘磷脂酶和磷脂酶 A _{2 的改变}. 由于槲皮素的作用，作为内源性膜抗氧化剂的鞘磷脂 (SM) 的水平升高。用槲皮素孵育 3D 成纤维细胞可诱导饱和脂肪酸的增加和质膜膜磷脂分子中所有多不饱和脂肪酸的减少，表明对氧化损伤的抵抗力进一步增加。槲皮素处理降低了胆固醇对氧化的敏感性，这种现象可能与观察到的 SM 水平增加有关。此外，蛋白质印迹分析显示槲皮素处理的细胞中 Akt 的磷酸化增强和 Bcl-2 的表达，表明槲皮素抑制了细胞凋亡。综上所述，