Antioxidant structures, related

Tocopherols and tocotrienols belong to the vitamin E family of compounds, which are potent antioxidants. The four isomers of tocotrienols (a-T3, P-T3, y-T3, 8-T3) are structurally related to their corresponding homologues of tocopherols (a-T, p-T, y-T, 8-T), but differ in their side-chain in that T3... 

Potent antioxidant analogs of LA, exemplified by structures 362 and 363 <2003EJM1>, containing the W-alkyl-substituted morpholine ring and thioamide or thiocarbamate moiety, respectively, have also been developed and pharmacologically tested. In comparison to the structurally related amide or carbamate linker analogues, compounds 362 and 363 are more promising antioxidants. 

Concentrations Compare antioxidants at the same mole concentration of active compound, and an appropriate reference compound should also be used, which may be a structurally related reference compound. With crude extracts (e.g., natural antioxidants), compositional data are needed to compare samples. 

FLAVONOIDS AS NUTRACEUTICALS STRUCTURAL RELATED ANTIOXIDANT PROPERTIES AND THEIR ROLE ON ASCORBIC ACID PRESERVATION... 

Free radical formation is associated with the normal natural metabolism of aerobic cells. The oxygen consumption inherent to cell growth leads to the generation of a series of free radicals. The interaction of these species with molecules of a lipid nature produces new species such as hydroperoxides and different kinds of peroxides [135, 136], This group of radicals (superoxide, hydroxyl, and lipoid peroxides) may interact with biological systems in a cytotoxic manner. In this respect, it has been shown to posses an important antioxidant activity towards these radicals, which is mainly based on the properties of the hydroxyphenolic groups and the structural relations between the different parts of the chemical structure. Together with an ability to capture electrons, these... 

Natella, R, Nardini, M., Felice, M.D., and Scaccini, C., Benzoic and cinnamic acid derivatives as antioxidants Structure-activity relation. J. Agric. Food Chem., 47, 1453-1459, 1999. 

Chalcones (l,3-diaryl-2-propen-l-ones) are flavonoids lacking a heterocyclic C ring. Also this category of flavonoids displays a broad spectrum of bio activities such as anticancer, antifungal, antibacterial, antiviral, and anti-inflammatory properties (Calliste et al. 2001). Dihydrochalcones, which do not have a P double bond, comprise phloretin [P- (4-hydroxyphenyl) -1 -(2,4,6-trihydroxypropiophenone) and its glucoside, phlo-ridzin (phloretin 2- P-D-glucose). Comparison with structurally related compounds revealed that the antioxidant pharmacophore of phloretin is 2,6-dihydroxyacetophenone (Rezk et al. 2002). The po-... 

Natella F, Nardini M, Di Felice M, Scaccini C (1999) Benzoic and cinnamic acid derivatives as antioxidants structure-activity relation. Free radical research group, national institute of nutrition, Roma, Italy. J Agric Food Chem 47 1453-2323... 

Several studies indicate that catechins and procyanidins are powerful scavengers of ROS. Some findings regarding the antioxidant activity of proanthocyanidins are listed in Ref. [100]. Other antioxidant mechanisms are the chelation of transition metals, as well as the mediation and inhibition of enzymes. The metal-chelating activity of proanthocyanidins is thought to be due to their capacity to reduce the concentration, and thus the oxidative activity, of hydroxyl radicals formed by Fenton reaction catalyzed by iron or copper. Flavanols also influence oxidative stress via enzyme modification and modulation of cell signaling pathways the extent of the effect relies greatly on flavanol structure-related protein reactivity [101]. 

The traditional antioxidant, BHT, was among the best performers. Foams prepared with AO-2 showed a sUghtly higher level of discoloration as compared with BHT. This small difference in performance may be structurally related. AO-2 is similar to BHT, differing only in the substitution of the para methyl group with a nonyl hydrocarbon chain. This substitution results in over a 50% increase in molecular weight with no increase in active substituents. The dilution effect of the alkyl chain may contribute to the observed marginal decrease in performance. 

Raman spectroscopy has been used to study a series of structurally related antioxidant phenolic esters, including PG and OG [86]. Distinct vibrational patterns were observed for these compounds, which evidences the usefulness of this technique to obtain structural information. 

The proposed stopped-flow method can be utilized for testing antioxidant compounds of unknown kinetics toward ABTS + at different pH values, and the results can be used to predict the total antioxidant capacity of structurally related compounds. 

The efficiency of the phenoKc antioxidants is related to their chemical structure, especially steric hindrance by alkyl substituents in the 2- and 6-position and substitution in the 4-position [35] ... 

The antioxidant properties of phytoestrogens have been studied in vitro and it has been suggested that these may be related to the chemical structure... 

The ability of carotenoids to act as antioxidants is closely related to their long-chain conjugated polyene structures (see Section 2.2 in Chapter 2). Two main types of antioxidant actions can be distinguished singlet oxygen quenching and reactions with radicals. The first mechanism occurs in vivo in plants and has been extensively studied in vitro. Reactions with radicals of different types have also been extensively studied in vitro under different conditions but their occurrence in vivo is still a matter of discussion. 

---