The antiradical activities of various antioxidants were determined using the free radical, 2,2-Diphenyl-1-picrylhydrazyl (DPPH*). In its radical form. DPPH* has an absorption band at 515 nm which dissappears upon reduction by an antiradical compound. Twenty compounds were reacted with the DPPH* and shown to follow one of three possible reaction kinetic types. Ascorbic acid, isoascorbic acid and isoeugenol reacted quickly with the DPPH* reaching a steady state immediately. Rosmarinic acid and δ-tocopherol reacted a little slower and reached a steady state within 30 min. The remaining compounds reacted more progressively with the DPPH* reaching a steady state from 1 to 6 h. Caffeic acid, gentisic acid and gallic acid showed the highest antiradical activities with a stoichiometry of 4 to 6 reduced DPPH* molecules per molecule of antioxidant. Vanillin, phenol, γ-resorcylic acid and vanillic acid were found to be poor antiradical compounds. The stoichiometry for the other 13 phenolic compounds varied from one to three reduced DPPH* molecules per molecule of antioxidant. Possible mechanisms are proposed to explain the experimental results.

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Use of a Free Radical Method to Evaluate Antioxidant Activity

Structure-antioxidant activity relationships of flavonoids and phenolic acids

Phenolic compounds in plants and agri-industrial by-products: Antioxidant activity, occurrence, and potential uses

The antioxidant capacities (oxygen radical absorbance capacity, ORAC) and total phenolic contents in extracts of 27 culinary herbs and 12 medicinal herbs were determined. The ORAC values and total phenolic contents for the medicinal herbs ranged from 1.88 to 22.30 μmol of Trolox equivalents (TE)/g of fresh weight and 0.23 to 2.85 mg of gallic acid equivalents (GAE)/g of fresh weight, respectively. Origanum × majoricum, O. vulgare ssp. hirtum, and Poliomintha longiflora have higher ORAC and phenolic contents as compared to other culinary herbs. The ORAC values and total phenolic content for the culinary herbs ranged from 2.35 to 92.18 μmol of TE/g of fresh weight and 0.26 to 17.51 mg of GAE/g of fresh weight, respectively. These also were much higher than values found in the medicinal herbs. The medicinal herbs with the highest ORAC values were Catharanthus roseus, Thymus vulgaris, Hypericum perforatum, and Artemisia annua. A linear relationship existed between ORAC values and total phenolic contents of th...

Antioxidant activity and phenolic compounds in selected herbs

Phenolics and polyphenolics in foods, beverages and spices: Antioxidant activity and health effects – A review

A possible way to valorize citrus peels and seeds, which are byproducts of the juice extraction industry, is to use them as natural antioxidants. The antioxidant activity of several citrus peel and...

Antioxidant activity and phenolic composition of citrus peel and seed extracts

Comparison of the Antioxidative Activity of Some Acid-phenols: Structure-Activity Relationship

Eight sage (Salvia officinalis) and twenty-four rosemary (Rosmarinus officinalis) extracts, originating from pilot-plant or commercial sources, had different antioxidative activities as measured by accelerated autoxidation of methyl linoleate. Twenty-seven compounds were characterized in the Labiatae family extracts by high-performance liquid chromatography (HPLC) coupled with mass spectrometry, equipped with an atmospheric pressure chemical ionization interface, and by HPLC coupled with a photodiode array spectrophotometer. Twenty-two compounds were identified, including phenolic acids, carnosol derivatives, and flavonoids. The extracts showed great variation in their HPLC profiles, and no correlation was apparent between their antioxidative efficiency and their composition, in twenty specific phenols. Data indicated that the most effective compounds were carnosol, rosmarinic acid, and carnosic acid, followed by caffeic acid, rosmanol, rosmadial, genkwanin, and cirsimaritin.

Antioxidative activity and phenolic composition of pilot-plant and commercial extracts of sage and rosemary

The antioxidant compounds of oleoresin of sage (Salvia officinalis) were separated by column chromatography and high-performance liquid chromatography. Sir major compounds were purified and identifred by IR, MS, and 1 H NMR spectrometry as carnosol, carnosic acid, rosmadial, rosmanol, epirosmanol, and methyl carnosate. Their antioridative activity was measured with an accelerated test, and their content was quantified in sage and in four commercial rosemary extracts

Hubert Richard

Papers

Antioxidant activity and phenolic composition of citrus peel and seed extracts

Comparison of the Antioxidative Activity of Some Acid-phenols: Structure-Activity Relationship

Antioxidative activity and phenolic composition of pilot-plant and commercial extracts of sage and rosemary

Antioxidant Constituents in Sage (Salvia officinalis)

Comparison of the antioxidative activity of some acid-phenols