Syntheses, characterizations and antioxidant activities of copper complexes of quercetin as influenced by redox states

Copper is an essential element for living but imbalance between Cu+ and Cu2+ produces free radicals. Quercetin is an effective metal chelator and its chelates are often better free radical scavengers than free quercetin. In this study, the syntheses, characterizations, antioxidant activities of quercetin as well as its Cu (I) and Cu (II) complexes using UV-VIS, IR spectrometric methods, and 2,2-diphenyl 1-picrylhydrazyl (DPPH) scavenging assay were investigated. 1:1 and 2:1 stoichiometric ratios were obtained for the dark-brown Cu+ and green Cu2+ quercetin complexes respectively. Bathochromic shifts from 268 nm (band II) and 362 nm (band I) in quercetin were observed at 302 nm and 386 nm for Cu (I) –quercetin complex and at 281 nm and 394 nm for Cu (II) - quercetin complex. FT-IR showed shifts in the positions of carbonyl and hydroxyl groups with presence of bands at 932.01 cm-1 in Cu (I) – quercetin and 928.57 cm-1 in Cu (II) – quercetin confirming complexation. Both complexes were better free radical scavengers than free quercetin with Cu (I)-quercetin complex having the highest antioxidant activity. Higher antioxidant activity and differences in spectra characters of Cu (I) quercetin complex are related to relative stability of fully filled orbital of Cu+ over Cu2+.© 2015 International Formulae Group. All rights reserved.Keywords: Oxidation state, relative stability, DPPH, Stoichiometric ratio, complexatio

Target Analysis of Antibiotic Drugs in Poultry Feedstuff by Solid Phase Extraction and Ultra-High Performance Liquid Chromatography-Tandem Mass Spectrometry

Seventy-five poultry feed samples of two feed types were analysed for antibiotic drugs using a simple generic solid phase extraction procedure with dichloromethaneacetonitrile after delipidation with n-hexane. Analytical separation was performed on a Waters Acquity C18 column with gradient elution consisting of water and acetonitrile. Liquid chromatography–tandem mass spectrometry (LC-MS/MS), with positive and negative electrospray ionization methods in the multiple reaction monitoring modes (MRM), was used for the quantification of 21 compounds from six classes including fluoroquinolones, sulfonamides, lincosamides, anthelmintics, macrolides and the β-lactams in a single chromatographic run of 14 minutes. All the six classes of the drugs were found in the two feed types at concentration ranging between 0.22 – 1505 ng/g. Sulfadimethoxine, sulfaguanidine, sulfamerazine, and sulfamethoxazole were the major sulfonamides in the two feed types with concentration at the part per million levels. Albendazole, penicillin-G, sulfadiazine, sulfaquinoxaline and sulfixosazole were not detected in the layers mash exclusively fed to laying birds; also, sulfamethazine and sulfamozole were the only two drugs not detected in the growers mash meant for birds raised for meat. Ciprofloxacin, sulfadimethoxine, sulfamethoxazole, sulfamerazine, and sulfaguanidine were the most prominent antibiotic drugs in the two feed types. Results from the present study suggest that feed millers surreptitiously fortify their feeds with antibiotics without declaring same, thus exposing poultry chickens to sub-therapeutic dosages of the drugs. It is evident that self-regulation for safety in the poultry industry should be discouraged thus relevant authorities must take steps to reduce and control the use of antibiotics to protect public health

Novel biosynthesized silver nanoparticles from cobweb as adsorbent for Rhodamine B: equilibrium isotherm, kinetic and thermodynamic studies

Abstract This study has investigated the adsorption of Rhodamine B (Rh-B) dye on novel biosynthesized silver nanoparticles (AgNPs) from cobweb. The effects of contact time, initial pH, initial dye concentration, adsorbent dosage and temperature were studied on the removal of Rh-B and they significantly affected its uptake. Adsorption isotherms were evaluated using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm models. The adsorption process was best described by Langmuir isotherm with R 2 of 0.9901, indicating monolayer adsorption. The maximum adsorption capacity (q max) of 59.85 mg/g showed that it has relatively high performance, while adsorption intensity showed a favourable adsorption process. Pseudo-second-order kinetics fitted best the rate of adsorption and intra-particle diffusion revealed both surface adsorption and intra-particle diffusion-controlled adsorption process. Negative values of thermodynamic parameters (∆H°, ∆S° and ∆G°) indicated an exothermic and spontaneous adsorption process. The mean sorption energy (E) and activation energy (E a) suggested the uptake of Rh-B onto AgNPs was chemical in nature (chemosorption)

Bioactive compounds’ contents, drying kinetics and mathematical modelling of tomato slices influenced by drying temperatures and time

This study investigated the influence of drying temperature, and time on antioxidant activity, phenolic, flavonoid, lycopene and β – carotene contents of tomato slices. It also evaluated the influence of drying process on drying kinetics, moisture diffusivity and activation energy. Oven processed tomato slices had temperature-dependent significant increase in antioxidant activity at 30 and 60 min, phenolic from 30 to 120 min and lycopene contents from 120 to 300 min. Significantly decreased contents of flavonoid and β – carotene were obtained for oven processed tomato slices with increasing drying temperature and time. Page model accurately predicted the drying process of tomato slices. Similarity between experimentally determined moisture ratio and Page predicted moisture ratio was obtained with high correlation (R2 = 0.9986). Effective moisture diffusivities indicated that drying process of tomato slices was temperature dependent while Arrhenius equation explained the relationship between activation energy and temperature. Keywords: Page model, Drying temperature, Phytochemicals, Moisture diffusivity, Tomato slice