茶多酚协同荷叶碱的抗氧化活性及其对结肠癌细胞的抑制作用

目的：探讨茶多酚协同荷叶碱的体外抗氧化活性及茶多酚单独对结肠癌细胞Caco-2的毒性作用。方法：采用二苯基-2-三硝基苯肼（1,1-diphenyl-2-picrylhydrazyl，DPPH）法、2,2’-联氮双（3-乙基苯并噻唑啉-6-磺酸）二铵盐（2,2’-azinobis（3-ethylbenzothi azoline-6-sulfonic acid）ammonium salt，ABTS）法检测茶多酚、荷叶碱及二者协同对DPPH自由基、ABTS＋?的清除作用；采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳法检测茶多酚、荷叶碱及二者混合物对Cu2＋/H2O2体系诱导的牛血清白蛋白（bovine serum albumin，BSA）氧化损伤的保护作用；采用噻唑蓝（methyl thiazolyl tetrazolium，MTT）法，AO/EB、DAPI荧光染色法检测茶多酚对Caco-2细胞的毒性。结果：茶多酚、荷叶碱具有清除DPPH自由基、ABTS＋?及保护BSA蛋白氧化损伤的作用且呈剂量依赖性，两者之间存在显著的协同效应；1 mg/mL茶多酚作用24 h能显著降低Caco-2细胞活力，诱导Caco-2细胞发生凋亡。结论：茶多酚能有效地清除DPPH自由基、ABTS＋?，抑制蛋白氧化，且与其他活性成分具有协同效应；茶多酚能抑制Caco-2细胞的活力。

Inhibitory Effect of Tea Polyphenols on Caco-2 Cells and Their Synergistic Antioxidant Activity with Nuciferine

The synergistic antioxidant activity of tea polyphenols with nuciferine in vitro was evaluated by determining their
abilities to scavenge DPPH and ABTS free radicals and protect against Cu2＋/H2O2-induced protein damage. Cytotoxicity of
tea polyphenols on Caco-2 cells was assessed by MTT, AO/EB and DAPI assays. The results showed that tea polyphenols
and nuciferine could significantly scavenge DPPH and ABTS free radicals, and significantly protect against Cu2＋/H2O2-
induced protein damage in a dose-dependent manner with an obvious synergism between both antioxidants. Tea polyphenols,
when used at a concentration of 1 mg/mL, significantly reduced the viability of Caco-2 cells after 24 h incubation. In
conclusion, tea polyphenols and nuciferine scavenge DPPH and ABTS free radicals and protect against oxidative protein
damage in a synergistic way. Tea polyphenols significantly reduce the viability of Caco-2 cells.