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Anthocyanins are naturally occurring compounds that impart color to fruits, vegetables, and plants. They are probably the most important group of visible plant pigments besides chlorophyll. Apart from imparting color to plants, anthocyanins also have an array of health-promoting benefits, as they can protect against a variety of oxidants through a various number of mechanisms. However, anthocyanins have received less attention than other flavonoids, despite this. This article reviews their biological functions and pre-clinical studies, as well as the most recent analytical techniques concerning anthocyanin isolation and identification.

The experimental results showed that ozone (O3) oxidation is an effective means to destroy phenolic organic pollutants present in water. High removal efficiencies can be readily achieved for most of the model compounds fortified in aqueous matrices within a reasonable time frame. This study also included the oxidation of phenolic compounds using ozone in combination with ultraviolet (UV) irradiation. The extent of mineralization measured in terms of the losses in total organic carbon is promoted by the joint action of ozone and UV in comparison with using ozone alone.

Ten flavonoid compounds were isolated from the dried leaves of Polygonum hydropiper L. (Laksa leaves), and identified as 3-O-alpha-L-rhamnopyranosyloxy-3',4',5,7-tetrahydroxyflavone; 3-O-beta-D-glucopyranosyloxy-4',5,7-trihydroxyflavone; 6-hydroxyapigenin; 6"-O-(3,4,5-trihydroxybenzoyl) 3-O-beta-D-glucopyranosyloxy-3', 4', 5, 7-tetrahydroxyflavone; scutillarein; 6-hydroxyluteolin; 3',4',5,6,7-pentahydroxyflavone; 6-hydroxyluteolin-7-O-beta-D-glucopyranoside; quercetin 3-O-beta-D-glucuronide; 2"-O-(3,4,5-trihydroxybenzoyl) quercitrin; quercetin. Evaluation of the antioxidative activity, conducted in vitro, by using electron spin resonance (ESR) and ultraviolet visible (UV-vis) spectrophotometric assays, showed that these isolated flavonoids possess strong antioxidative capabilities. Measurement of the Trolox equivalent antioxidant capacity (TEAC) values, against ABTS (2,2'-azinobis(3-ethyl-benzo-thiazoline-6-sulphonic acid) radicals and phenyl-tert-butyl nitrone (PBN) azo initiator (AI) also showed strong anti-oxidative activity. The most powerful of the antioxidants was 2"-O-(3,4,5-trihydroxybenzoyl) quercitrin (galloyl quercitrin). A combination of two flavonoid compounds was tested for synergistic anti-oxidative capacity, but no significant improvement was observed.

An amperometric enzyme electrode for phenolic compounds was developed via an easy and effective immobilization method using the sol–gel technique. The enzyme electrode comprises tyrosinase immobilized by the thin silica sol–gel layer on a carbon-paste electrode. The tyrosinase retains its bioactivity when being immobilized by the sol–gel film. Phenolic compounds were determined by the direct reduction of biocatalytically liberated quinone species at 0 mV vs. Ag/AgCl (sat. KCl). The process parameters for the fabrication of the enzyme electrode were optimised. The influence of various experimental variables was explored for optimum analytical performance of the enzyme electrode. The effect of oxygen on the response of the enzyme electrode was evaluated. The sensitivities of the enzyme electrode for catechol, phenol, p-cresol, m-cresol, o-cresol and 2-chlorophenol were 1.53, 1.28, 1.05, 0.687, 0 and 0 A M−1, respectively. The enzyme electrode retained ca. 50% of its activity after 15 days of storage in a phosphate buffer solution at 4°C.

An amperometric mediated glucose sensor has been developed via the sol-gel technique in a new ‘sandwich’ configuration: sol-gel-ferrocene:glucose oxidase (GOx):sol-gel using a carbon paste electrode as the primary electrode. The process parameters for the fabrication of a glucose sensor based on tetramethoxysilane (TMOS) sol-gel thin films utilizing ferrocene as a mediator have been optimized. In the sol-gel matrix, the results demonstrate that GOx still retains its activity, and ferrocene is efficient at shuttling the electrons between the enzyme redox centre and the electrode. Cyclic voltammetric and amperometric measurements have been used to study the response of the glucose sensor, which has a fast response and good reproducibility. The effect of oxygen on the sensor response has been investigated. The selectivity, lifetime and fabrication reproducibility of the sensor have also been evaluated.

The effects of power ultrasound on four metal-nonmetal powdered systems: copper-sulphur iron-sulphur, zinc-sulphur and magnesium-sulphur in various solvents, such as hexane and carbon disulphide, are briefly examined here. For each system, a sonication time of 30 min was affected. The sonicated products are analysed by X-ray diffraction, X-ray fluorescence and atomic absorption spectrophotometry to determine their qualitative and quantitative compositions and the percentage yields of the products obtained are then compared and discussed.

A glucose biosensor was fabricated using chitosan film for the immobilization of glucose oxidase (GOX) and mediator in the following “sandwich” configuration:chitosan-ferrocene:GOX:chitosan using a carbon paste electrode as the basic electrode. To prevent loss of immobilized GOX under optimized conditions, the biosensor surface was cross-linked with glutaraldehyde (GA). Despite the multilayer configuration, the biosensor exhibited a relatively fast response (less than 10 s) and a linear response with glucose in the range of 8×10−4 to 1.7×10−2 M. The biosensor retained about 65 % of its original activity after 30 days of storage in a phosphate buffer at 4 °C. Applicability of the biosensor was demonstrated in real samples and the results obtained by this biosensor corroborate well with a classical UV spectrophotometric technique.

Kinetin (free base and riboside), which was assumed by many scientists to be a synthetic cytokinin plant growth hormone, has been detected for the first time in the endosperm liquid of fresh young coconut fruits ("coconut water"). To facilitate the study, we developed a sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the identification and quantification of kinetin and kinetin riboside in purified coconut water extract sample. Following a solid-phase extraction of cytokinins in coconut water using C18 columns, the samples were further purified by Oasis MCX columns and analyzed by LC-MS/MS for kinetin and kinetin riboside. Detection by mass spectrometry was carried out using selected reaction monitoring (SRM) mode, by identifying the putative kinetin and kinetin riboside based on their characteristic fragments. Based on a signal-to-noise ratio of 3, the limits of detection in SRM mode were 0.02 microM and 0.005 microM for kinetin and kinetin riboside, respectively. Furthermore, optimal conditions for a baseline chromatographic separation of 18 cytokinin standards by high performance liquid chromatography (HPLC) were developed. The HPLC method had been employed for the confirmation and further fractionation of kinetin in coconut water extracts. The confirmation and fractionation of kinetin riboside was carried out using a further modified HPLC program due to the presence of other interfering material(s) in the sample matrix. Finally, fractions of putative kinetin and kinetin riboside collected from HPLC eluate of coconut water sample were further authenticated by independent capillary zone electrophoresis (CZE) experiment.

A study of the involvement of free oxygen radicals in trapping and digestion of insects by carnivorous plants was the main goal of the present investigation. We showed that the generation of oxygen free radicals by pitcher fluid of Nepenthes is the first step of the digestion process, as seen by EPR spin trapping assay and gel-electrophoresis. The EPR spectrum of N. gracilis fluid in the presence of DMPO spin trap showed the superposition of the hydroxyl radical spin adduct signal and of the ascorbyl radical signal. Catalase addition decreased the generation of hydroxyl radicals showing that hydroxyl radicals are generated from hydrogen peroxide, which can be derived from superoxide radicals. Gel-electrophoresis data showed that myosin, an abundant protein component of insects, can be rapidly broken down by free radicals and protease inhibitors do not inhibit this process. Addition of myoglobin to the pitcher plant fluid decreased the concentration of detectable radicals. Based on these observations, we conclude that oxygen free radicals produced by the pitcher plant aid in the digestion of the insect prey.

This work studied the destruction of various M–EDTA complexes and trace organic pollutants in treated reusable wastewater under advanced oxidation using UV irradiation and ozonation. Effect of dosage of hydrogen peroxide and acidity of reaction matrices on oxidation efficiencies were investigated. The rate constant of mineralization presents a decreasing trend as Fe(III)–EDTA > Fe(II)–EDTA > Al(III)–EDTA > Pb(II)–EDTA > Na(I)–EDTA > Zn(II)–EDTA > Cu(II)–EDTA. The mineralization efficiencies using ozone alone are 15%, 40% and 15% for the water samples after reverse osmosis (RO), microfiltration (MF) and superfiltration (SF) processes, respectively. The presence of hydrogen peroxide in photochemical reaction matrixes can effectively enhance the mineralization of organic carbon species. When 150 mg l−1 of H2O2 was added in the effluents, the mineralization markedly increased to 80%, 92% and 89%, respectively.

Capillary electrophoresis with wall-jet amperometric detection was used to detect kaempferol and its derivatives kaempferol-3-glucoside, kaempferol-3-glucosylrhamnoside and kaempferol-3-(p-coumaroyl)glucoside. The influence of buffer pH on separation was investigated and optimized. With a phosphate buffer at pH 7.5, nearly complete separation of the four kaempferols was achieved according to their different electrophoretic mobilities. The detection potential was also evaluated and optimized. At detection potential of +0.80 V vs. saturated calomel electrode, an amperometric response with high sensitivity and stability was obtained for these four compounds. Detection limit estimated for all the kaempferols examined was less than 1.4 fmol, based on S/N=3. The use of this method for the separation and detection of these compounds present in balsam flowers (Impatiens balsamina) is reported.

Ultrasonic irradiation of copper and lead, separately, in hydrochloric acid shows that mechanistic effects would depend largely on the structural nature of the solid reactants: if the size of a solid reactant is substantially large, microject formation will be the predominant mechanism.

New polynuclear iron carbonyl complexes having the stoichiometry LFe3(CO)10 have been obtained from the reactions of Fe3(CO)12 with the di(tertiary arsine) ligands (CH3)2AsC(X)(Y)CF2As(CH3)2 (X = Y = H; X = H, Y = F; X = F, Y = CF3). The structures of the new cluster complexes have been investigated using i.r., n.m.r., and Mössbauer spectroscopies. Mössbauer data are also reported for LFe3(CO)10 and LFe3(CO)9 derivatives of the mixed ligand [Formula: see text].