Flavonoids, Flavonoid Metabolites, and Phenolic Acids Inhibit Oxidative Stress in the Neuronal Cell Line HT-22 Monitored by ECIS and MTT Assay: A Comparative Study

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• 作者：Beata Kling ; Daniel B眉cherl ; Peter Palatzky ; Frank-Michael Matysik ; Michael Decker ; Joachim Wegener ; J枚rg Heilmann
• 刊名：Journal of Natural Products
• 出版年：2014
• 出版时间：March 28, 2014
• 年：2014
• 卷：77
• 期：3
• 页码：446-454
• 全文大小：493K
• 年卷期：v.77,no.3(March 28, 2014)
• ISSN：1520-6025

文摘

A real-time and label-free in vitro assay based on electric cell-substrate impedance sensing (ECIS) was established, validated, and compared to an end-point MTT assay within an experimental trial addressing the cytoprotective effects of 19 different flavonoids, flavonoid metabolites, and phenolic acids and their methyl esters on the HT-22 neuronal cell line, after induction of oxidative stress with tert-butyl hydroperoxide. Among the flavonoids under study, only those with a catechol unit and an additional 4-keto group provided cytoprotection. The presence of a 2,3-double bond was not a structural prerequisite for a neuroprotective effect. In the case of the phenolics, catechol substitution was the only structural requirement for activity. The flavonoids and other phenolics with a ferulic acid substitution or a single hydroxy group showed no activity. Electrochemical characterization of all compounds via square-wave voltammetry provided a rather specific correlation between cytoprotective activity and redox potential for the active flavonoids, but not for the active phenolics with a low molecular weight. Moreover this study was used to compare label-free ECIS recordings with results of the established MTT assay. Whereas the former provides time-resolved and thus entirely unbiased information on changes of cell morphology that are unequivocally associated with cell death, the latter requires predefined exposure times and a strict causality between metabolic activity and cell death. However, MTT assays are based on standard lab equipment and provide a more economic way to higher throughput.