Hesperidin, a bioflavonoid, is an abundant and inexpensive by-product of Citrus cultivation. A deficiency of this substance in the diet has been linked with abnormal capillary leakiness as well as pain in the extremities causing aches, weakness and night leg cramps. No signs of toxicity have been observed with the normal intake of hesperidin or related compounds. Both hesperidin and its aglycone hesperetin have been reported to possess a wide range of pharmacological properties. This paper reviews various aspects of hesperidin and its related compounds, including their occurrence, physical and chemical properties, analysis, pharmacokinetics, safety and toxicity and the marketed products available. A special emphasis has been laid on the pharmacological properties and medicinal uses of these compounds.

Chemistry and pharmacology of the citrus bioflavonoid hesperidin

A review is presented dealing with the use of carbon paste as an electrode maaterial for electrochemical sensors (311 references). It covers mainly publications which appeared during the period 1990–1993; numerous applications demonstrate the widespread applicability of carbon paste in the field of electrochemical analysis, such as voltammetry, amperometry, and potentiometry, but also as an electrode for electrochemical detectors in flow systems.

Sensors based on carbon paste in electrochemical analysis: A review with particular emphasis on the period 1990–1993

Endogenous antioxidants are enzymes, like superoxide dismutase, catalase, glutathione peroxidase or nonenzymatic compounds, such as uric acid, bilirubin, albumin, metallothioneins. When endogenous factors cannot ensure a rigurous control and a complete protection of the organism against the reactive oxygen species, the need for exogenous antioxidants arises, as nutritional supplements or pharmaceutical products, which contain as active principle an antioxidant compound. Amongst the most important exogenous antioxidants, vitamin E, vitamin C, β-carotene, vitamin E, flavonoids, mineral Se are well

https://www.longdom.org/open-access/methods-for-total-antioxidant-activity-determination-a-review-2161-1009.1000106.pdf

Methods for Total Antioxidant Activity Determination: A Review

Phenolic antioxidants are ranked by reducing strength and characterized for reversibility using cyclic voltammetry at a glassy carbon electrode. Phenolics with an ortho-diphenol group show a first oxidation peak close to 400 mV (vs. Ag/AgCl) in a model wine solution (12% ethanol, 0.033 M tartaric acid, adjusted to pH 3.6), with a linear concentration dependence below 0.01 mM. Dilution of white wines 10×, and red wines 400×, gave first oxidation peak currents in the 1.5 to 2.2 μA range and 1.9 to 3.4 μC of charge passed by 500 mV, producing values for the concentrations of phenolic antioxidants with low oxidation potentials in the wines. Further peaks in the cyclic voltammograms of the diluted wines correspond to classes of phenolics with higher oxidation potentials, providing a qualitative assessment of wine phenolics based on reducing strength. Keywords: Cyclic voltammetry; wine; phenolics; antioxidants

A cyclic voltammetry method suitable for characterizing antioxidant properties of wine and wine phenolics.

Determination of rutin and quercetin in plants by capillary electrophoresis with electrochemical detection.

Preconcentration at a carbon-paste electrode and determination by adsorptive-stripping voltammetry of rutin and other flavonoids

The pre-concentration of indole and other indolic compounds of biochemical and pharmaceutical interest at a carbon paste electrode (Nujol/graphite) has been studied. All the compounds examined can be determined, by direct voltammetric measurements in their solutions, in the concentration range 1–8 µM. Indole, methylated indoles, harmaline and serotonin were accumulated at the electrode by a combined adsorption/extraction process. By applying the medium-exchange procedure, the accumulated compounds can be determined in the same concentration range, after a 60-s pre-concentration period, enhancing, therefore, the selectivity of the voltammetric determination. A procedure for the indirect determination of L-tryptophan in serum has been developed, which is based on these findings. L-Tryptophan was cleaved to indole by tryptophanase, and indole was subsequently determined voltammetrically after a 2-min pre-concentration period at the carbon paste electrode. From 0.3 to 1.2 µg of L-tryptophan in a total of 75 µl of serum sample (20–80 µM) can be determined with an average error of ca. 0.03 µg, whereas the recovery of added L-tryptophan in serum samples is in the range 105–115%.

Pre-concentration of indolic compounds at a carbon paste electrode and indirect determination of L-tryptophan in serum by adsorptive stripping voltammetry.

Nikolaos E. Zoulis

Papers

Preconcentration at a carbon-paste electrode and determination by adsorptive-stripping voltammetry of rutin and other flavonoids

Pre-concentration of indolic compounds at a carbon paste electrode and indirect determination of L-tryptophan in serum by adsorptive stripping voltammetry.

Voltammetric determination of N-alkylated anilines by adsorption/extraction at a carbon-paste electrode