Structure−Activity Relationships of Flavonoids in the Cellular Antioxidant Activity Assay

Abstract

Chemical antioxidant activity assays are used extensively to evaluate the potential bioactivity of plant foods and their phytochemical constituents, but they do not mimic the complexity of biological systems. The cellular antioxidant activity (CAA) activity assay was developed to be a more biologically relevant model to measure antioxidant activity. Structure-activity relationships of flavonoids have been determined in many chemistry antioxidant activity assays, and they vary with the protocols. The objective of this study was to determine structure-activity relationships of selected flavonoids in the CAA assay. The structures that conferred flavonoids with the most antioxidant activity in the CAA assay were a 3',4'- o-dihydroxyl group in the B-ring, a 2,3-double bond combined with a 4-keto group in the C-ring, and a 3-hydroxyl group. Isoflavones had no cellular antioxidant activity. Flavanols with a galloyl moiety had higher antioxidant activity than those without, and a B-ring 3',4',5'-trihydroxyl group further improved their efficacy. ORAC values for flavonoids were not related to their CAA values. Knowledge of structure-activity relationships in the CAA assay may be helpful in assessing potential in vivo antioxidant activity of flavonoids.

Induction of caspase-dependent apoptosis in melanoma cells by the synthetic compound (E)-1-(3,4-dihydroxyphenethyl)-3-styrylurea

“…However, it is not excluded that the position of OH groups in phenolic compounds could possibly influence the chemical properties of the molecules. Such an effect would be due to OH groups in the ortho-position of the B ring as well as those associated with a 2,3-double bond combined with a 4-keto group in the C-ring, as they are known to be important structural determinants for the anti-oxidant activity of flavonols (14).…”

Effect of Added Garcinia Fruit on Total Phenolic Compound Content, Antioxidant Properties and Quality Changes of the Southern Sour Curry Paste, Keang-hleung, during Storage

“…Surprising again, initial DPPH radical scavenging activity was highest in the basic paste even low in total phenolic content. This result confirmed that antioxidant activity may not well relate to total phenolic content [28]. DPPH radical scavenging activity of the garcinia paste without added salt kept in both storage temperatures increased in the first 2 mo before decreased and was lowest at end of storage.…”

“…This may be a good explanation of using many assays to evaluate antioxidant activity [29]. However, some researchers mentioned that in vitro antioxidant activity such as DPPH, FRAP, ABTS and metal chelation activity may not responsible for antioxidant activity in vivo or even food system therefore using cellular antioxidant activity assay was more useful and close to body system [28,30].…”

Chemical composition and antioxidant activity of extracts from Erythroxylum suberosum A.St. Hil.leaves

“…Currently, there are papers published on the in vitro antioxidant activity of flavonoids and a correlation between the antioxidant capacity and chemical structure (Wolfe and Liu, 2008). Ahn et al (2009) found that the anti-angiogenic action of various components of propolis, such as caffeic acid phenyl ester, kaempferol, and quercetin, is correlated with antioxidant capacity of the same (Ahn, et al, 2009).…”