Antimicrobial activity of flavonoids

Publisher Summary This chapter discusses ferric reducing/antioxidant power (FRAP) assay. The ferric reducing/antioxidant power (FRAP) assay is a recently developed, direct test of “total antioxidant power.” The FRAP assay is robust, sensitive, simple, and speedy and facilitates experimental and clinical studies investigating the relationship among antioxidant status, dietary habits, and risk of disease. Measurement of the total antioxidant power of fresh biological fluids—such as blood plasma—can be measured directly; the antioxidant content of various dietary agents can be measured objectively and reproducibly and their potential for improving the antioxidant status of the body investigated and compared. The FRAP assay is also sensitive and analytically precise enough to be used in assessing the bioavailability of antioxidants in dietary agents to help monitor longitudinal changes in antioxidant status associated with an increased intake of dietary antioxidants and to investigate the effects of disease on antioxidant status.

Ferric reducing/antioxidant power assay: direct measure of total antioxidant activity of biological fluids and modified version for simultaneous measurement of total antioxidant power and ascorbic acid concentration

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

Both lipophilic and hydrophilic antioxidant capacities were determined using the oxygen radical absorbance capacity (ORACFL) assay with fluorescein as the fluorescent probe and 2,2‘-azobis(2-amidinopropane) dihydrochloride as a peroxyl radical generator on over 100 different kinds of foods, including fruits, vegetables, nuts, dried fruits, spices, cereals, infant, and other foods. Most of the foods were collected from four different regions and during two different seasons in U.S. markets. Total phenolics of each sample were also measured using the Folin−Ciocalteu reagent. Hydrophilic ORACFL values (H-ORACFL) ranged from 0.87 to 2641 μmol of Trolox equivalents (TE)/g among all of the foods, whereas lipophilic ORACFL values (L-ORACFL) ranged from 0.07 to 1611 μmol of TE/g. Generally, L-ORACFL values were <10% of the H-ORACFL values except for a very few samples. Total antioxidant capacity was calculated by combining L-ORACFL and H-ORACFL. Differences of ORACFL values in fruits and vegetables from different...

https://faculty.missouri.edu/~glaserr/3700s14/Antioxidant_WuJAgFoodChem5240262004.pdf

Lipophilic and hydrophilic antioxidant capacities of common foods in the United States

The antioxidative activity of a total of 92 phenolic extracts from edible and nonedible plant materials (berries, fruits, vegetables, herbs, cereals, tree materials, plant sprouts, and seeds) was examined by autoxidation of methyl linoleate. The content of total phenolics in the extracts was determined spectrometrically according to the Folin-Ciocalteu procedure and calculated as gallic acid equivalents (GAE). Among edible plant materials, remarkable high antioxidant activity and high total phenolic content (GAE > 20 mg/g) were found in berries, especially aronia and crowberry. Apple extracts (two varieties) showed also strong antioxidant activity even though the total phenolic contents were low (GAE < 12.1 mg/g). Among nonedible plant materials, high activities were found in tree materials, especially in willow bark, spruce needles, pine bark and cork, and birch phloem, and in some medicinal plants including heather, bog-rosemary, willow herb, and meadowsweet. In addition, potato peel and beetroot peel extracts showed strong antioxidant effects. To utilize these significant sources of natural antioxidants, further characterization of the phenolic composition is needed.

Antioxidant activity of plant extracts containing phenolic compounds

Antimicrobial effects of Finnish plant extracts containing flavonoids and other phenolic compounds

The distribution of total phenolics and main betacyanins in red beetroot (Beta vulgaris) root was determined. Also, the subsequent effects of cold storage on the content of total phenolics, main betacyanins (betanin and isobetanin), and the main known ferulic acid ester (β-d-fructofuranosyl-α-d-(6-O-(E)-feruloylglucopyranoside) were determined in the peel, which is the root part containing the largest amount of total phenolics. The content of total phenolics in the red beetroot water extracts was determined according to a modification of the Folin−Ciocalteu method and expressed as gallic acid equivalents (GAE). The compounds of interest were identified by HPLC−ESI−MS and NMR techniques, and the contents of compounds were determined by HLPC analyses. The total phenolic contents in various root parts were found to decrease in the order peel, crown, flesh. Significant differences in the contents of total phenolics and individual compounds were found when the effect of cold storage (5 °C, 0−196 days) on the c...

Phenolics and betacyanins in red beetroot (Beta vulgaris) root: distribution and effect of cold storage on the content of total phenolics and three individual compounds.

Four cultivars of red beetroot (Beta vulgaris) were evaluated with respect to their betalain and phenolic contents. The compounds were analysed using HPLC and identified by HPLC-DAD, HPLC-ESI-MS and NMR techniques. Betalains (vulgaxanthins I and II, betanin and isobetanin) and phenolics [5,5',6,6'-tetrahydroxy-3,3'-biindolyl, feruloylglucose and β-D-fructofuranosyl-α-D-(6-O-(E)-feruloylglucopyranoside)] were determined in different parts of the root; betalains were analysed separately in the water extract and phenolics in the fractionated 80% aqueous methanol extract (betalain-free water fraction). In each cultivar, both betanin and isobetanin were found in greater amounts in the peel than in the flesh. A similar trend was not observed in the distribution of vulgaxanthins. The three studied phenolics appeared in all root parts of the beetroot cultivars with the flesh generally containing the least content. Additionally, two phenolic amides (N-trans-feruloyltyramine and N-trans-feruloylhomovanillylamine) and four flavonoids (betagarin, betavulgarin, cochliophilin A and dihydroisorhamnetin) were detected in the fractionated 80% aqueous methanol peel extracts (acetonitrile fraction) of beetroot.

Betalain and phenolic compositions of four beetroot ( Beta vulgaris ) cultivars

The extraction of red beetroot (Beta vulgaris) peel betalains and phenolics was compared with two extraction methods and solvents. The content of total phenolics in the extracts was determined according to a modification of the Folin-Ciocalteu method and expressed as gallic acid equivalents (GAE). The profiles of extracts were analysed by high-performance liquid chromatography (HPLC). The compounds of beetroot peel extracted with 80% aqueous methanol were characterised from separated fractions using HPLC- diode array detection (HPLC-DAD) and HPLC-electrospray ionisation-mass spectrometry (HPLC-ESI-MS) techniques. The extraction methods and the choice of solvent affected noticeably the content of individual compounds in the extract. The betalains found in beetroot peel extract were vulgaxanthin I, vulgaxanthin II, indicaxanthin, betanin, prebetanin, isobetanin and neobetanin. Also cyclodopa glucoside, N-formylcyclodopa glucoside, glucoside of dihydroxyindol-carboxylic acid, betalamic acid, L-tryptophan, p-coumaric acid, ferulic acid and traces of unidentified flavonoids were detected.

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Tytti S. Kujala

Papers

Antioxidant activity of plant extracts containing phenolic compounds

Antimicrobial effects of Finnish plant extracts containing flavonoids and other phenolic compounds

Phenolics and betacyanins in red beetroot (Beta vulgaris) root: distribution and effect of cold storage on the content of total phenolics and three individual compounds.

Betalain and phenolic compositions of four beetroot ( Beta vulgaris ) cultivars

Betalains and phenolics in red beetroot (Beta vulgaris) peel extracts: extraction and characterisation.