Phenolic compounds were measured in leaf tissues of apple cvs Jonagold and Golden Delicious, healthy and infected by Venturia inaequalis. Leaves were sampled from May to September 2005 and analyzed by high performance liquid chromatography. Hydroxycinnamic acids detected were chlorogenic, caffeic, ferulic and pcoumaric. In addition, the presence was ascertained of the dihydrochalcone phloridzin...

free radicals involved in a number of diseases due to the oxidative damage to dna, lipids, and proteins and which can result in failure of cellular functions. dried plant bulbs and leaves methanolic and ethanolic extracts were prepared. total antioxidant activities of the methanolic extracts of romulea ramiflora and gagea fibrosa were determined using β-caroten-linoleic acid assay. romulea-bulb...

In the calorimetric methods for the determination of tyrosine and tryptophane, described by Folin and Ciocalteu (1) in 1927, 1 or 2 gm. of protein material are taken for the preliminary hydrolysis. It has seemed desirable to try to adapt these methods to the use of smaller amounts of material (0.1 gm.) in order to broaden the applicability of the methods. While this work was in progress, there ...

Methods available for the measurement of antioxidant capacity are reviewed, presenting the general chemistry underlying the assays, the types of molecules detected, and the most important advantages and shortcomings of each method. This overview provides a basis and rationale for developing standardized antioxidant capacity methods for the food, nutraceutical, and dietary supplement industries....

The aim of this work was to compare determination of quercetin concentration using HPLCUV/VIS method with antioxidant properties of selected red wines. Typical Slovenian wine varieties like “Merlot”, “Refošk”, “Barbera”, “Cabernet Sauvignon”, “Teran”, “Blue Pinot” and “Blue Frankish” were chosen. We applied the conventional Folin-Ciocalteu spectrophotometric method for determination of the tota...

The main objective of this study was the screening of some selected aromatic plants very popular in Greece, with respect to their total phenolic content, antioxidant capacity, reducing activity, and oxidative stability. All plants were extracted with the conventional method, reflux with methanol. The essential oils of the plants were also analyzed for their antioxidant properties. The total phe...

We describe a reversed-phase HPLC method that uses gradient elution and diode array detection to determine four biologically active phenolic constituents of red wines: gallic acid, trans-resveratrol, quercetin and rutin. The method permits direct injection without sample pre-treatment. ODS Hypersil served as the stationary phase; the gradient was formed by acetic acid, methanol, and water. Each...

Methanolic extracts of 13 commercially available citrus spp., peels and tissues growing in Iran were investigated for their antioxidant activity by DPPH method. IC50 for antioxidant activity ranged from 0.6-3.8 mg ml(-1). Total phenolic content of the citrus spp. samples (based on folin Ciocalteu method) varied from 66.5 to 396.8 mg gallic acid equivalent/g of extract and flavonoids content (ba...