Investigation of the antioxidative and radical scavenging impact of natural compounds in-vitro and on cell metabolism

  • In an aerobic environment the occurrence of reactive oxygen species (ROS) is a common phenomenon. The diverse roles of ROS in cellular function and in diseases make them a target of interest in many research areas. Substances capable of directly or indirectly reducing the (harmful) effects of ROS are referred to as “antioxidants”. However, the term is applied miscellaneously in the chemical and the biological context to describe different attributes of a substance. In this work the potential of an electrochemical assay to detect different ROS in-vitro was explored. The method was optimized to investigate the radical scavenging activities (antioxidant potential) of trolox and different plant compounds (ascorbic acid, caffeic acid, epigallocatechin gallate, ferulic acid, kaempferol, quercetin, rutin, and Gynostemma pentaphyllum extract) in-vitro. The obtained data was compared to established antioxidant in-vitro assays. Further, the impact of the plant substances on cellular parameters was evaluated with the electrochemical assay and established cell assays. The optimization of the electrochemical assay allowed the reproducible detection of ROS. The sensor electrode proved differently sensitive towards individual ROS species. The highest sensitivity was recorded for hydroxyl radicals while superoxide and hydrogen peroxide had little impact on the sensor. Extracellular ROS concentrations could be detected from cell lines releasing elevated ROS into the extracellular space. The antioxidant activity of the investigated plant substances could be demonstrated with all in-vitro assays applied. However, the absolute as well as the relative activity of the individual substances varied depending on the experimental parameters of the assays (pH, radical species, phase, detection method). The plant compounds modified redox related intracellular parameters in different cell lines. However, a direct correlation between intracellular and extracellular effects of the plant compounds could not be established. The work demonstrates the feasibility to use the electrochemical assay to sense ROS as well as to evaluate the radical scavenging activity of molecules. The in-vitro antioxidant activities demonstrated for the individual plant substances are not reliable to predict the cellular effects of the molecules.
  • In der vorliegenden Arbeit wurde der Einsatz eines elektrochemischen Sensors zur Detektion von reaktiven Sauerstoffspezies (ROS) untersucht und dahingehend optimiert die antioxidative Aktivität verschiedener Pflanzeninhaltsstoffe zu bestimmen. Die Ergebnisse wurden mit etablierten Messmethoden und den Auswirkungen auf intrazelluläre Redox-Parameter in unterschiedlichen Zelllinien verglichen. Die Arbeit verdeutlicht die Abhängigkeit antioxidativer Aktivitäten von den experimentellen Bedingungen.

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Metadaten
Author: Dana Alexandra Thal
URN:urn:nbn:de:gbv:9-opus-23624
Title Additional (German):Untersuchung des Einflusses der antioxidativen und Radikalfänger-Eigenschaften von natürlichen Verbindungen in-vitro und auf den Zellmetabolismus
Referee:PD Dr. rer. nat. Heike Kahlert, Prof. Dr. rer. nat. Uwe Schröder, Prof. Dr. rer. nat. Valentin Mirčeski
Advisor:PD Dr. rer. nat. Heike Kahlert, Prof. Dr. Uwe Lendeckel, Prof. Dr. rer. nat. Michael Lalk
Document Type:Doctoral Thesis
Language:English
Year of Completion:2018
Date of first Publication:2018/10/19
Granting Institution:Universität Greifswald, Mathematisch-Naturwissenschaftliche Fakultät
Date of final exam:2018/08/10
Release Date:2018/10/19
Tag:polycrystalline gold, radical polishing, secondary plantmetabolites, self assembled monolayer
GND Keyword:Antioxidans, Elektrochemischer Sensor, Oxidativer Stress, Polyphenole, Radikalfänger, Reaktive Sauerstoffspezies
Pagenumber:149
Faculties:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Chemie und Biochemie
DDC class:500 Naturwissenschaften und Mathematik / 540 Chemie
500 Naturwissenschaften und Mathematik / 570 Biowissenschaften; Biologie