Abstract
This study is aimed at determining the relationship of flavonoid structures to their chemical and intracellular antioxidant activities. The antioxidant activities of 60 flavonoids were investigated by three different antioxidant assays, including 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, oxygen radical absorption capacity (ORAC), and cellular antioxidant activity (CAA) assays. The result showed 6 flavonoids as good cellular antioxidants evaluated for the first time. The cellular antioxidant activities of compounds 7-methoxy-quercetin, 3-O-methylquercetin, 8-hydroxy-kaempferol, quercetin-3-O-α-arabinofuranose, kaempferol-7-O-glucopyranoside, and luteolin6-C-glucoside were linked with the upregulation of antioxidant enzyme activities (superoxide dismutase, catalase, and glutathione peroxidase). A structure-activity relationship suggested that 2,3-double bond, 4-keto groups, 3′,4′-catechol structure, and 3-hydroxyl in the flavonoid skeleton played important roles in the antioxidant behavior. Furthermore, the cell proliferative assay revealed a low cytotoxicity for 3-O-methylquercetin. The present results provide valuable information for the dietary application of flavonoids with different structures for high antioxidant.
Highlights
The reactive oxygen species (ROS) are known to damage the tissues of the body, which leads to disturb the established order on the body system
The antioxidant activities of flavonoids were assessed by oxygen radical absorption capacity (ORAC) and DPPH assays
The ORAC assay is based on the oxidation of a fluorescent probe by radicals coming from the spontaneous decomposition of AAPH
Summary
The reactive oxygen species (ROS) are known to damage the tissues of the body, which leads to disturb the established order on the body system. The ROS attacked biomolecules like DNA, lipids, and proteins to free radical damage, which stimulated the development of many diseases, such senility, angiocardiopathy, and cancer [1]. Researchers have found that flavonoid consumption can improve cancer and cardiovascular diseases [2]. Many researchers have discovered a wide range of biological activities of the flavonoids in prevention and relieve various diseases such as obesity, diabetes, cancer, angiocardiopathy, and heart diseases [5,6,7]. To our knowledge, systematic studies on differences in the antioxidant ability of various flavonoids and the structure-activity relationships are still scarce. The influence between different structural flavonoids and the antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSHPx)) has rarely been studied
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