Antioxidant activity maximization

A free 3-OH group is required to get the maximal antioxidant activity out of a flavonoid with a catechol moiety in the B-ring and a C2-C3 double bond, such as quercetin. Blockade of the 3-OH group by introducing a glycoside reduces the antioxidant activity, which was showed by a TEAC value of 2.4 mM for rutin compared to 4.72... 

Documented effects The powdered root has astringent properties (Khalmatov 1964). This species improves the hver s ability to detoxify, helps patients with moderately high blood pressure, has diuretic actions, and is good for treatment of constipation and fevers (Nuraliev 1989). Compounds isolated from plants collected in Uzbekistan exhibited antioxidative activity (Kogure et al. 2004). (+)-rhododendrol and epi-rhododendrin isolated from Acer nikoense Maxim, suppressed nitric oxide (NO) production in mouse peritoneal macrophages in vivo (Fushiya et al. 1998). 

Li, H., Deng, Z., Wu, T., Liu, R., Loewen, S., and Tsao, R. 2012. Microwave-assisted extraction of phenolics with maximal antioxidant activities in tomatoes. Food Chem. 130 928-936. 

Increase in TAC is not always a good prognostic it may simply indicate an initial response to oxidative stress, as with concentrations of individual antioxidants and activities of antioxidant enzymes, or when it is due to disturbances in uric acid metabolism. Because uric acid is the main determinant of TAC of blood plasma, TAC increases in situations when the concentration of urate is increased, for example, in metabolic disorders and kidney failure. TAC is increased in urine from renal transplant recipients with delayed graft function (SI6). Ischemia of small intestine leads to an increase in TAC of rat blood serum, which is maximal (almost twofold) immediately after termination of 45-min ischemia (S22). TAC of blood plasma of rats poisoned with a high dose of carbon tetrachloride (1200 mg/kg, intraperitoneal injection, measurement 16 hr after injection) was significantly (over twofold) increased (Kl). These apparently paradoxical effects can be explained, however, by release of antioxidants from cells undergoing necrosis. Increase in TAC after intensive physical exercise also may be a marker of tissue... 

The antioxidant efficiency of phenolic acids, as determined by the accelerated autooxidation of methyl linoleate and scavenging of the free radical 2,2-diphenyl-1-picrylhydrazyl (141) ° methods, was found to be inversely proportional to the maximal detector response potential in the voltammetric determination of these compounds. No similar correlation was found for the flavonoids . A good correlation was found between the O—H bond dissociation energy of a phenolic compound and its effectiveness as antioxidant, expressed as the rate constant of free radical scavenging . The bond dissociation energy of the phenol O—H bond was estimated by a three-dimensional quantitative structme-activity relationship method incorporating electron densities computed using the Austin Method 1 (AMI) followed by correlation of the... 

---