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Spectrophotometric estimation

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https://www.readbyqxmd.com/read/28341986/enhancing-effectiveness-of-capillary-electrophoresis-as-an-analytical-tool-in-the-supramolecular-acidity-modification
#1
Paweł Mateusz Nowak, Michał Woźniakiewicz, Magdalena Janus, Paweł Kościelniak
A strategic modification of acidity (pK a values) by the non-covalent host-guest interactions is one of the most promising concepts in current supramolecular chemistry. This work is aimed at enhancing the effectiveness of capillary electrophoresis (CE) in determination of pK a shifts caused by such interactions and their thermal dependencies crucial in a deep thermodynamic description. We show how to (i) minimize the systematic errors related to Joule heating, (ii) minimize the influence of a voltage ramp time, (iii) speed up pK a shift identification and estimation, (iv) interpret thermal effects related to two overlapped dynamic equilibria, and (v) determine pK a shifts by an alternative spectrophotometric method (CE-DAD)...
March 24, 2017: Analytical and Bioanalytical Chemistry
https://www.readbyqxmd.com/read/28317713/a-validated-fast-difference-spectrophotometric-method-for-5-hydroxymethyl-2-furfural-hmf-determination-in-corn-syrups
#2
Jucimara Kulek de Andrade, Camila Kulek de Andrade, Emy Komatsu, Hélène Perreault, Yohandra Reyes Torres, Marcos Roberto da Rosa, Maria Lurdes Felsner
Corn syrups, important ingredients used in food and beverage industries, often contain high levels of 5-hydroxymethyl-2-furfural (HMF), a toxic contaminant. In this work, an in house validation of a difference spectrophotometric method for HMF analysis in corn syrups was developed using sophisticated statistical tools by the first time. The methodology showed excellent analytical performance with good selectivity, linearity (R(2)=99.9%, r>0.99), accuracy and low limits (LOD=0.10mgL(-1) and LOQ=0.34mgL(-1))...
August 1, 2017: Food Chemistry
https://www.readbyqxmd.com/read/28315620/3-e-acridin-9-ylmethylidene-amino-1-substituted-thioureas-and-their-biological-activity
#3
Michal Bečka, Mária Vilková, Othman Salem, Jana Kašpárková, Viktor Brabec, Mária Kožurková
This paper describes the synthesis of a novel series of acridine thiosemicarbazones through a two-step reaction between various isothiocyanates and hydrazine followed by treatment with acridin-9-carbaldehyde. The properties of this series of seven new derivatives are studied using NMR and biochemical techniques, and the DNA-binding properties of the compounds are determined using spectrophotometric studies (UV-vis absorption, fluorescence, and circular/linear dichroism) and viscometry. The binding constants K are estimated as being in the range of 2...
March 8, 2017: Spectrochimica Acta. Part A, Molecular and Biomolecular Spectroscopy
https://www.readbyqxmd.com/read/28303123/trichoderma-asperellum-t42-and-pseudomonas-fluorescens-okc-enhances-resistance-of-pea-against-erysiphe-pisi-through-enhanced-ros-generation-and-lignifications
#4
Jai S Patel, Ravindra N Kharwar, Harikesh B Singh, Ram S Upadhyay, Birinchi K Sarma
Plant signaling mechanisms are not completely understood in plant-fungal biotrophic pathogen interactions. Further how such interactions are influenced by compatible rhizosphere microbes are also not well-studied. Therefore, we explored the pea-Erysiphe pisi (obligate biotroph) system to understand the interaction and applied compatible rhizospheric bio-agents Trichoderma asperellum (T42) and Pseudomonas fluorescens (OKC) singly or in combination to assess their influence on the host while under the pathogen challenge...
2017: Frontiers in Microbiology
https://www.readbyqxmd.com/read/28290364/estimation-of-kinetic-parameters-of-anthocyanins-and-color-degradation-in-vitamin-c-fortified-cranberry-juice-during-storage
#5
Sunisa Roidoung, Kirk D Dolan, Muhammad Siddiq
Color degradation in cranberry juice during storage is the most common consumer complaint. To enhance nutritional quality, juice is typically fortified with vitamin C. This study determined effect of gallic acid, a natural antioxidant, for the preservation of anthocyanins (ACYs) and color, and estimated kinetics of ACYs and color degradation. Juice, fortified with 40-80mg/100mL vitamin C and 0-320mg/100mL gallic acid, was pasteurized at 85°C for 1min and stored at 23°C for 16days. Total monomeric anthocyanins and red color intensity were evaluated spectrophotometrically and data were used to determine degradation rate constants (k values) and order of reaction (n) of ACYs and color...
April 2017: Food Research International
https://www.readbyqxmd.com/read/28282223/analytical-methods-for-metformin-estimation
#6
Durgawati Patel, Puspendra Kumar, Jaya Dwivedi, Swapnil Sharma
Metformin is a widely prescribed oral anti-hyperglycemic agent used in the management of noninsulin dependent diabetes mellitus (NIDDM) or type II diabetes. This article accentuates various analytical methods viz. HPLC, HPTLC, spectrophotometric, electrochemical, capillary electrophoresis and LC-MS for the estimation of metformin in pharmaceutical formulations and in biological matrices.
March 10, 2017: Critical Reviews in Analytical Chemistry
https://www.readbyqxmd.com/read/28275214/investigation-of-drug-polymer-compatibility-using-chemometric-assisted-uv-spectrophotometry
#7
Amir Ibrahim Mohamed, Amr Mohamed Elsayed Abd-Motagaly, Osama A A Ahmed, Suzan Amin, Alaa Ibrahim Mohamed Ali
A simple chemometric-assisted UV-spectrophotometric method was used to study the compatibility of clindamycin hydrochloride (HC1) with two commonly used natural controlled-release polymers, alginate (Ag) and chitosan (Ch). Standard mixtures containing 1:1, 1:2, and 1:0.5 w/w drug-polymer ratios were prepared and UV scanned. A calibration model was developed with partial least square (PLS) regression analysis for each polymer separately. Then, test mixtures containing 1:1 w/w drug-polymer ratios with different sets of drug concentrations were prepared...
January 16, 2017: Pharmaceutics
https://www.readbyqxmd.com/read/28272800/correlation-between-antimicrobial-antioxidant-activity-and-polyphenols-of-alkalized-nonalkalized-cocoa-powders
#8
Vanja Todorovic, Marina Milenkovic, Bojana Vidovic, Zoran Todorovic, Sladjana Sobajic
Many factors can influence antioxidative and antimicrobial characteristics of plant materials. The quality of cocoa as functional food ingredient is influenced through its processing. The main aim of this study was to test if there is difference in polyphenol content, antioxidant capacity, and antimicrobial activity between nonalkalized and alkalized cocoa powders. To estimate polyphenol and flavonoid content in cocoa samples the spectrophotometric microassays were used. Flavan-3ols were determined with reversed-phase high-performance liquid chromatography (RP-HPLC)...
March 8, 2017: Journal of Food Science
https://www.readbyqxmd.com/read/28243615/dataset-on-absorption-spectra-and-bulb-concentration-of-phenolic-compounds-that-may-interfere-with-onion-pyruvate-determinations
#9
Vanesa H Beretta, Florencia Bannoud, Marina Insani, Claudio R Galmarini, Pablo F Cavagnaro
We present data on absorption spectra (400-540 nm) and concentration of phenolic compounds quercetin, myricetin, kaempferol, rutin, catechin, epicatechin gallate (ECG) and epigallocatechin gallate (EGCG), in yellow, red and white onions. These data are related to the article entitled "Variability in spectrophotometric pyruvate analyses for predicting onion pungency and nutraceutical value" (Beretta et al., 2017) [1]. Given the relevance of pyruvate determinations for estimating onion pungency and functional value, it is important to identify compounds that can interfere with pyruvate determinations when using two previously published analytical procedures, namely Schwimmer and Weston (1961) (SW) [2] and Anthon and Barret (2002) (AB) [3], which are based on spectrophotometry and light-absorbance at 420 nm and 515 nm, respectively...
April 2017: Data in Brief
https://www.readbyqxmd.com/read/28229626/the-role-of-hydrogen-sulfide-in-homocysteine-induced-cardiodynamic-effects-and-oxidative-stress-markers-in-the-isolated-rat-heart
#10
M Stojanovic, V Zivkovic, I Srejovic, V Jakovljevic, N Jeremic, D Djuric
This study aimed to assess the role of H2S in homocysteine-induced cardiodynamic effects in the isolated rat heart. The hearts were retrogradely perfused according to the Langendorff technique. The maximum and minimum rates of pressure in the left ventricle (dp/dt max, dp/dt min), systolic and diastolic left ventricular pressures (SLVP, DLVP), heart rate (HR), and coronary flow (CF) were measured. A spectrophotometrical method was used to measure the following oxidative stress markers: index of lipid peroxidation (thiobarbituric acid reactive substances, TBARS), nitrite level (NO2(-)), superoxide anion radicals (O2(•-)), and hydrogen peroxide (H2O2) concentrations...
December 2016: Physiol Int
https://www.readbyqxmd.com/read/28217539/analysis-of-plasma-lipid-peroxidation-and-antioxidant-enzymes-status-in-patients-of-oral-leukoplakia-a-case-control-study
#11
Kumar Chandan Srivastava, Deepti Shrivastava
AIMS AND OBJECTIVES: Imbalances between the oxidant-antioxidant status have been implicated in the pathogenesis of several diseases, including oral cancer. Mostly, all oral cancer lesions are preceded by a stage of premalignancy. The present study aims to evaluate lipid peroxidation and antioxidant status in the venous blood of patients with different clinicopathologic stages of leukoplakia. MATERIALS AND METHODS: A case control study was designed with the inclusion of 20 new cases of histopathologically proven leukoplakia of various clinical stages along with an equal number of positive and negative control individuals...
December 2016: Journal of International Society of Preventive & Community Dentistry
https://www.readbyqxmd.com/read/28215962/two-colour-fluorescence-fluorimetric-analysis-for-direct-quantification-of-bacteria-and-its-application-in-monitoring-bacterial-growth-in-cellulose-degradation-systems
#12
Kwabena O Duedu, Christopher E French
Monitoring bacterial growth is an important technique required for many applications such as testing bacteria against compounds (e.g. drugs), evaluating bacterial composition in the environment (e.g. sewage and wastewater or food suspensions) and testing engineered bacteria for various functions (e.g. cellulose degradation). T?=1,^FigItem(1) ^ReloadFigure=Yesraditionally, rapid estimation of bacterial growth is performed using spectrophotometric measurement at 600nm (OD600) but this estimation does not differentiate live and dead cells or other debris...
February 17, 2017: Journal of Microbiological Methods
https://www.readbyqxmd.com/read/28159256/variability-in-spectrophotometric-pyruvate-analyses-for-predicting-onion-pungency-and-nutraceutical-value
#13
Vanesa H Beretta, Florencia Bannoud, Marina Insani, Claudio R Galmarini, Pablo F Cavagnaro
Onion pyruvate concentration is used as a predictor of flavor intensity and nutraceutical value. The protocol of Schwimmer and Weston (SW) (1961) is the most widespread methodology for estimating onion pyruvate. Anthon and Barret (AB) (2003) proposed modifications to this procedure. Here, we compared these spectrophotometry-based procedures for pyruvate analysis using a diverse collection of onion cultivars. The SW method always led to over-estimation of pyruvate levels in colored, but not in white onions, by up to 65%...
June 1, 2017: Food Chemistry
https://www.readbyqxmd.com/read/28153358/synthesis-of-new-chromeno-carbamodithioate-derivatives-and-preliminary-evaluation-of-their-antioxidant-activity-and-molecular-docking-studies
#14
Sampath Kumar Bandari, Bal Raju Kammari, Jyothi Madda, Nagaiah Kommu, Arunapriya Lakkadi, Srimai Vuppala, Parthasarathy Tigulla
New chromeno carbamodithioates (7a-i), have been synthesized from 2, 3-dimethyl-7-(oxiran-2-ylmethoxy)-4H-chromen-4-one (5), carbondisulphide and commercially available acyclic and cyclic secondary amines in acetonitrile with good to excellent yields. The free radical scavenging activity of novel chromone-carbamodithioate analogues was quantitatively estimated by spectrophotometric method. Whereas, molecular docking studies were performed with the active site of cyclooxygenase-2 to identify hydrogen bonding, hydrophobic and ionic interactions between protein and ligands...
January 21, 2017: Bioorganic & Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/28138346/effect-of-high-carbohydrate-diet-on-elongase-and-desaturase-activity-and-accompanying-gene-expression-in-rat-s-liver
#15
Jagoda Drąg, Anna Goździalska, Małgorzata Knapik-Czajka, Anna Gawędzka, Katarzyna Gawlik, Jerzy Jaśkiewicz
BACKGROUND: Hepatic fatty acids (FAs) are modified through different metabolic pathways including elongation and desaturation. These processes are catalyzed by elongases and desaturases, respectively. Glucose, by transcription factors, regulates these processes. The aim of the study was to evaluate the influence of high carbohydrate diet (68%) on the expression of elongase (Elovl-2, Elovl-5, and Elovl-6) and desaturase (∆5D, ∆6D, Scd 1, Scd 2) genes and the activity of the enzymes...
2017: Genes & Nutrition
https://www.readbyqxmd.com/read/28107044/quercetin-attenuates-cell-survival-inflammation-and-angiogenesis-via-modulation-of-akt-signaling-in-murine-t-cell-lymphoma
#16
Akhilendra Kumar Maurya, Manjula Vinayak
AKT signaling is important to maintaining normal physiology. Hyperactivation of AKT signaling is frequent in cancer, which maintains a high oxidative state in a tumor microenvironment that is needed for tumor adaptation. Therefore, antioxidants are proposed to exhibit anticancer properties by interfering with the tumor microenvironment. Quercetin is an ubiquitous bioactive antioxidant rich in vegetables and beverages. The present study aimed to analyze cancer preventive property of quercetin in ascite cells of Dalton's lymphoma-bearing mice...
April 2017: Nutrition and Cancer
https://www.readbyqxmd.com/read/28098944/validation-of-a-smartphone-based-point-of-care-hemoglobin-assay-for-use-in-dogs
#17
Kate S Farrell, Phillip L Chapman, Lauren A Sullivan
OBJECTIVE: To validate a smartphone-based spectrophotometric assay for point-of-care (POC) measurement of hemoglobin (Hgb) concentration against the standard measurement method in dogs without increases in serum lipemia, hemolysis, or bilirubin. DESIGN: Prospective observational study. SETTING: University teaching hospital. ANIMALS: One hundred thirty-nine dogs that had a CBC and corresponding biochemical profile submitted to the clinical pathology laboratory...
March 2017: Journal of Veterinary Emergency and Critical Care
https://www.readbyqxmd.com/read/28074209/cu-i-and-ag-i-complex-formation-with-the-hydrophilic-phosphine-1-3-5-triaza-7-phosphadamantane-in-different-ionic-media-how-to-estimate-the-effect-of-a-complexing-medium
#18
Francesco Endrizzi, Plinio Di Bernardo, Pier Luigi Zanonato, Francesco Tisato, Marina Porchia, Abdirisak Ahmed Isse, Andrea Melchior, Marilena Tolazzi
The complexes of Cu(i) and Ag(i) with 1,3,5-triaza-7-phosphadamantane (PTA) are currently studied for their potential clinical use as anticancer agents, given the cytotoxicity they exhibited in vitro towards a panel of several human tumor cell lines. These metallodrugs are prepared in the form of [M(PTA)4](+) (M = Cu(+), Ag(+)) compounds and dissolved in physiological solution for their administration. However, the nature of the species involved in the cytotoxic activity of the compounds is often unknown. In the present work, the thermodynamics of formation of the complexes of Cu(i) and Ag(i) with PTA in aqueous solution is investigated by means of potentiometric, spectrophotometric and microcalorimetric methods...
January 11, 2017: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/28060334/measuring-nitrite-and-nitrate-metabolites-in-the-nitric-oxide-pathway-in-biological-materials-using-the-chemiluminescence-method
#19
Barbora Piknova, Ji Won Park, Katelyn S Cassel, Cameron N Gilliard, Alan N Schechter
Nitric oxide (NO) is one of the main regulator molecules in vascular homeostasis and also a neurotransmitter. Enzymatically produced NO is oxidized into nitrite and nitrate by interactions with various oxy-heme proteins and other still not well known pathways. The reverse process, reduction of nitrite and nitrate into NO had been discovered in mammals in the last decade and it is gaining attention as one of the possible pathways to either prevent or ease a whole range of cardiovascular, metabolic and muscular disorders that are thought to be associated with decreased levels of NO...
December 25, 2016: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28025107/apigenin-potentiates-the-antitumor-activity-of-5-fu-on-solid-ehrlich-carcinoma-crosstalk-between-apoptotic-and-jnk-mediated-autophagic-cell-death-platforms
#20
Hanaa H Gaballah, Rasha A Gaber, Darin A Mohamed
BACKGROUND: Although 5- Fluorouracil (5-FU) has exhibited effectiveness against cancer, novel therapeutic strategies are needed to enhance its antitumor efficiency and modulate its cytotoxity. Apigenin, a flavonoid present in fruits and vegetables, is a potent dietary phytochemical effective in cancer chemoprevention. AIM: This study was undertaken to investigate the potential synergistic antitumor activity of apigenin and 5-FU on Solid Ehrlich carcinoma (SEC). METHODS: Eighty Swiss albino male mice were divided into four equal groups: vehicle treated control SEC, SEC+5-FU, SEC+apigenin, SEC+ 5-FU+apigenin...
December 23, 2016: Toxicology and Applied Pharmacology
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