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

Comparative Effects of Silver Nanoparticles, Sucrose and Sodium Chloride as Osmotic Solutions for Tomato Slices: Antioxidant Activity, Microbial Quality and Modelling with Polynomial Regression Model

This study has reported comparative effects of silver nanoparticles  (AgNPs),  sucrose and sodium chloride as osmotic solutions on antioxidant activity and microbial quality of 10 mm tomato slices. 40 g of tomato slices were dehydrated osmotically (OD) at different temperatures (60, 70 and 80 °C) and time (30, 60, 90, 120 150 and 180 min).Water loss, solid  impregnation, water and solid diffusivities of tomato slices were found to increase with increase in solution temperatures and concentrations with AgNPs having the greatest influence. Antioxidant activities using 2,2-diphenyl-1-picrylhydrazyl increased with increase in solution concentrations but decreased with increase in temperature. Three-wayANOVA(R2=0.998) revealed additive statistically significant effects of osmotic agents,  concentrations and temperatures on antioxidant activity;   F(8,54)=67.854,P=0.00. Polynomial regression analysis with response surface methodology validated experiments such that for each unit increase in concentration and temperature, antioxidant activity increased with good coefficients of determination; sucrose (R2 = 0.87), NaCl, (R2 = 0.89) andAgNPs (R2 = 0.91). Potato dextrose and nutrient agars were used for isolating and identifying microorganisms in OD tomato slices. Tomato slices dehydrated with AgNPs had the highest microbial inhibition of fungi with growth occurring after 7 days, unlike in treatments with sucrose and NaCl where fungal growth appeared after 2 and 5 days, respectively. Aspergillus niger was the most prevalent fungus. It can be concluded that AgNPs may serve as a viable means to dehydrate and preserve tomatoes without loss of antioxidant activity.Keywords: Osmotic dehydration, polynomial regression, response surface, antioxidant activity, three-way ANOVA, silver nanoparticles

An overview of biogenic metallic nanoparticles for water treatment and purification: the state of the art

The environment is fundamental to human existence, and protecting it from dangerous contaminants should be a top priority for all stakeholders. Reducing garbage output has helped, but as the world's population grows, more waste will be generated. Tons of waste inadvertently and advertently received by environmental matrixes adversely affect the sustainable environment. The pollution caused by these activities affects the environment and human health. Conventional remediation processes ranging from chemical, physical, and biological procedures use macroaggregated materials and microorganisms to degrade or remove pollutants. Undesirable limitations of expensiveness, disposal challenges, maintenance, and formation of secondary contaminants abound. Additionally, multiple stages of treatments to remove different contaminants are time-consuming. The need to avoid these limitations and shift towards sustainable approaches brought up nanotechnology options. Currently, nanomaterials are being used for environmental rejuvenation that involves the total degradation of pollutants without secondary pollution. As nanoparticles are primed with vast and modifiable reactive sites for adsorption, photocatalysis, and disinfection, they are more useful in remediating pollutants. Review articles on metallic nanoparticles usually focus on chemically synthesized ones, with a particular focus on their adsorption capacity and toxicities. Therefore, this review evaluates the current status of biogenic metallic nanoparticles for water treatment and purification. HIGHLIGHTS Water challenges, pollution and remediation.; Roles of conventional and nanotechnological technologies.; Metallic nanoparticles as adsorbents, photocatalysts, and water disinfectants.; Mechanisms of photocatalysis and water disinfection of metallic nanoparticles.; Possible challenges of metallic nanoparticles in water remediation.

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)

Elemental pollution status of different components of Ologe Lagoon, Lagos, Nigeria

This study evaluated the concentrations and distributions of nutrient and non-nutrient elements in water, sediment, mud, and vegetation of Ologe Lagoon, Lagos, Nigeria. Nutrient elements including Na, Ca, K, and Mg were found in high concentration values in the different components of the freshwater ecosystem. While the water had the least concentration of the elements, Trapa natans had the highest. Aluminium showed similar distribution patterns in the different components, except for T. natans. All the samples correlated significantly with water (p <0.05). Both the sediment and mud showed low potential ecological risk indexes of 5.3 and 5.92, respectively. Copper had the highest ecological risk with respect to single regulator indexes in the mud and sediment, notwithstanding its low concentration in the two components. Pollution indices suggested the low severity of non-nutrient elemental contamination of water, sediment, mud, and vegetation of Ologe Lagoon, and therefore, it is safe for human consumption, but not for agricultural irrigation. Pistia stratiotes and T. natans showed potentiality for use as photo-stabilisers and phytoremediators for some of the elements. The presence of radionuclides and rare earth elements in the components of Ologe Lagoon are instructive for specific policy initiatives to mitigate their effects on the population. HIGHLIGHTS Radionuclides were reported in the components of Ologe Lagoon, a freshwater ecosystem.; High nutrient-element concentration associated with increased salinisation were found in the different components of Ologe Lagoon.; There is a low contamination of the components of the Lagoon with respect to non-nutrient elements.; Water from Ologe is unsuitable for agricultural irrigation owing to high concentration of nutrient metal elements.; Pistia stratiotes and T. natans showed potential for the remediation of Zn, Cr, Cu, Th, and U.

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

Lead and lead isotopes as tracers of soil contamination in southwestern Nigeria

The association of soil Pb levels has received considerable attention in recent times in developing countries like Nigeria due to its human health and environmental effect. Unfortunately, the sources of the pollutant has not been resolved for environmental health interest. Therefore, the aim of this study is to trace the sources of Pb contamination using the isotopic composition of Pb in the soil. Thirty (30) soil samples were collected at 0-20 cm depth in 3 different land-use zones, industrial area (IDA, n=10), municipal solid waste facility (MSW, n=10), and traffic section (TRS, n=10). In addition, 3 rock (gneisses) and 3 blacksmith dust samples were collected in the study area for comparison. Properties of the soil such as physico-chemical parameters (pH, organic content, and soil texture) and mineralogical composition were determined to understand the distribution of Pb in the soil of the study area. Similarly, the samples were analyzed for their Pb concentrations and Pb isotopic compositions using inductively coupled plasma mass spectrometry. The soil pH, organic matter, and texture were slightly acidic (4.9-6.9), average organic content (7.9-19.1%), and sandy clay loam in nature, respectively. Therefore, the Pb distribution was enhanced by the physico-chemical parameters. However, the mineral constituent of the soil in order of their abundance include quartz, feldspars, illite-muscovite, kaolinite, Biotite, goethite, and hematite. Consequently, there is no Pb-rich primary mineral in the soil. The environmental assessment of Pb in the study area showed that all the zones were contaminated on the basis of the average contamination factor and geoaccumulation index values. Similarly, the ecological risk factor estimation of Pb showed that the three zones had moderate potential ecological risk factors (41-54). The isotopic compositions of 208Pb/207Pb, and 206Pb/207Pb of the contaminated soil were lower than the corresponding component in gneisses, while the composition of 208Pb/206Pb was higher than the gneisses. Furthermore, the standard plot of (208Pb/207Pb) vs (206Pb/207Pb) showed clearly that the source of Pb in the contaminated soil was mainly from anthropogenic sources.Therefore, from the Pb concentration and isotopic composition acquired, the Pb contamination was mainly sourced from anthropogenic activities from the study area. These sources mainly include scrap metal recycling industry, vehicle emission and domestic and industrial waste. So, more effective remediation strategies need to be developed to reduce the contamination

Biogenic synthesis of silver nanoparticles using a pod extract of Cola nitida: Antibacterial and antioxidant activities and application as a paint additive

This work reports the biogenic synthesis of silver nanoparticles (AgNPs) using the pod extract of Cola nitida, the evaluation of their antibacterial and antioxidant activities, and their application as an antimicrobial additive in paint. The AgNPs were characterized with UV–Vis spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). The AgNP solution was dark brown with a maximum absorbance occurring at 431.5 nm. The FTIR spectrum showed strong peaks at 3336.85, 2073.48, and 1639.49 cm−1, indicating that proteins acted as the capping and stabilization agents in the synthesis of the AgNPs. The AgNPs were spherical, with sizes ranging from 12 to 80 nm. Energy dispersive X-ray (EDX) analysis showed that silver was the prominent metal present, while the selected area electron diffraction pattern conformed to the face-centred cubic phase and crystalline nature of AgNPs. At various concentrations between 50 and 150 μg/ml, the AgNPs showed strong inhibition of the growth of multidrug resistant strains of Klebsiella granulomatis, Pseudomonas aeruginosa, and Escherichia coli. In addition, at 5 μg/ml, the AgNPs completely inhibited the growth of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger, A. flavus and A. fumigatus in a paint-AgNP admixture. The AgNPs exhibited a potent antioxidant activity with an IC50 of 43.98 μg/ml against 2,2-diphenyl-1-picrylhydrazyl and a ferric ion reduction of 13.62–49.96% at concentrations of 20–100 μg/ml. This study has demonstrated the biogenic synthesis of AgNPs that have potent antimicrobial and antioxidant activities and potential biomedical and industrial applications. To the best of our knowledge, this work is the first to use the pod extract of C. nitida for the green synthesis of nanoparticles

Phytomodulatory effects of silver nanoparticles on Corchorus olitorius: Its antiphytopathogenic and hepatoprotective potentials

This study has reported the effects of biogenic silver nanoparticles (AgNPs) using cocoa pod extract on physiological tolerance indices, antioxidant activity and hepatoprotective potentials of Corchorus olitorius as well as its efficiency for controlling soil phytopathogens. C. olitorius seeds were grown in soil prepared with water (control), 0.05, 0.1, 0.15 and 0.2 mg AgNPs/g soil. C. olitorus grown with AgNPs had significantly (p < 0.05) higher free radical scavenging ability, ferric reducing ability, percentage germination, vigour indices, longer roots and shoots as well as lower moisture content over control. C. olitorius grown with AgNPs attenuated hydrogen peroxide (H 2 O 2 )-mediated reduction in catalase concentrations and H 2 O 2 -induced malondialdehyde elevations in liver. Efficiency of AgNPs to reduce soil phytopathogens (fungi and nematodes) revealed significant (p < 0.05) reduction in the incidences of soil and shoot Meloidogyne spp., Aspergillus terreus, A. niger, Fusarium spp. and Cladosporium spp. with increase in concentrations of AgNPs. More efficiently, there was complete extermination of A. niger and Fusarium spp. in the leaves of C. olitorius grown with AgNPs. Results in this study have shown the positive influence of AgNPs on C. olitorius by strengthening its resistance against fungi, and nematodes, improvement of its shelf-life, modulation of antioxidant activities and promotion of liver-detoxifying potentials.Fil: Azeez, Luqmon. Osun State University; NigeriaFil: Lateef, Agbaje. Ladoke Akintola University Of Technology; NigeriaFil: Wahab, Abideen A.. Osun State University; NigeriaFil: Rufai, Muhammed A.. Osun State University; NigeriaFil: Salau, Amadu K.. Fountain University; NigeriaFil: Ajayi, Ebenezer Idowu O. Osun State University; Nigeria. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra. Universidad Nacional de Córdoba. Instituto de Investigación Médica Mercedes y Martín Ferreyra; ArgentinaFil: Ajayi, Mercy. Osun State University; NigeriaFil: Adegbite, Maryam K.. Osun State University; NigeriaFil: Adebisi, Basirat. Osun State University; Nigeri