Colorimetric Micro Research Articles

Antimycobacterial activity of total extracts from Solanum torvum Swartz. (Solanaceae)

Aims and objectives: Tuberculosis (TB) caused by Mycobacterium tuberculosis complex remains a leading cause of morbidity and mortality worldwide. The zoonotic infectious condition represents a never-ending challenge towards which drug discovery efforts are needed. The current study was designed to evaluate the in vitro antimycobacterial activity of ethanolic extracts from roots, stem bark, leaves and unripe fruits derived from Solanum torvum, a shrub traditionally used against respiratory tract illnesses, including tuberculosis. Methods: The phenotypic colorimetric micro plate alamar blue assay (MABA) was used to study the antimycobacterial activity of the ethanolic extracts against six mycobacterial strains. Each experiment was run in triplicate. Data generated was analyzed using descriptive statistics to obtain mean minimum inhibitory concentration values. Results: The roots, stem bark, leaves and unripe fruits exhibited minimum inhibitory concentration values of 1.250 mg/mL, 0.078 mg/mL, 1.250 mg/mL and 0.625 mg/mL against the pathogenic mycobacterial strain, M. tuberculosis H37Rv (ATCC 27294) respectively. Conclusions: In conclusion, Solanum torvum stem bark has demonstrated moderate activity against the pathogenic Mycobacterium tuberculosis strain. This observation validates the ethno pharmacological use of the plant species against tuberculosis. Further studies are required to isolate, elucidate the structure and characterize the antimycobacterial compounds responsible for the observed activity. These will potentially contribute towards bioprospecting for a new class of ligands with activity against sensitive and drug resistant strains of M. tuberculosis.

Epidemiological data and antifungal susceptibility in invasive fungal infections - a Romanian infectious diseases tertiary hospital’s experience. Preliminary report

Abstract Introduction: Invasive fungal infections have stood as an important research subject for the past 20 years, being considered as a crucial effect of advancing healthcare services. Low identification rates of invasive fungal infections in blood cultures and low sensibility of biomarkers determine empiric treatments which lead to a change in epidemiological data and antifungal susceptibility. The aim: The epidemiological evaluation of invasive fungal infections and the assessment of antifungal resistance related to this condition. Methods and material: An “antifungal stewardship” retrospective study was developed between January 2010 and April 2016. An epidemiological analysis was performed on 79 cases with proven invasive fungal infections in bloodstream, catheter, and cerebrospinal fluid. We considered: age, gender, HIV status, place of residence, and first option in medical practice of antifungal treatment. The laboratory analysis was performed by the Microbiology Laboratory at “Prof. Dr. Matei Bals” National Institute for Infectious Diseases, Bucharest. Minimum inhibitory concentrations (MIC’s) of 15 isolates were identified using colorimetric micro broth dilution panel YEASTONE ®YO10 and compared with susceptibilities obtained by VITEK2®C system. Candida parapsilosis ATCC 22019 was used as reference. Results: The incidence of invasive fungal infections was 3.7 on 1000 hospitalized patients. The age of the study population ranged between 12 and 83 years, and most were male (59%). The majority of subjects were from an urban area (84%), and 27% of them were HIV positive. The results obtained in VITEK2C® were similar with those from YEASTONE® YO10 for fluconazole, voriconazole, amphotericin B (100%), without any minor, major or very major errors. The fluconazole was the first option of treatment, followed by voriconazole, caspofungin, anidulafungin. In 37% of cases the first treatment option was replaced with a secondary antifungal therapy accordingly with antifungal breakpoints obtained by Vitek ®. Conclusions: No rates of resistance to fluconazole, amphotericin B, voriconazole were obtained. Fluconazole was the major first line antifungal therapy. Conclusions: No rates of resistance to fluconazole, amphotericin B, voriconazole were obtained. Fluconazole was the major first line antifungal therapy.

The effect of sedation on D(+)‐xylose absorption tests in 6 normal horses

D(+)-xylose absorption tests are commonly performed when investigating suspected small intestinal malabsorption in the horse. The test involves the administration of a D(+)-xylose solution via a nasogastric tube followed by serial blood sampling to determine its rate of absorption. In some horses, nasogastric intubation cannot be safely performed without prior administration of a sedative. Due to its short duration of action, the α(2) agonist xylazine is commonly used for this purpose. However, α(2) agonists have also been reported to influence the rate of gastric emptying as well as small intestinal motility patterns. To evaluate if prior sedation with xylazine would influence the rate of absorption of D(+)-xylose in 6 normal Standardbred horses in a randomised cross-over study. D(+)-xylose was administered by nasogastric intubation at a dose rate of 0.5 g/kg bwt given as a 10% solution with water while xylazine was administered iv at a dose rate of 0.5 mg/kg bwt. A heparinised blood sample was collected prior to administration of D(+)-xylose (and xylazine when used) and then at 30, 45, 60, 75, 90, 120, 150, 180 and 240 min following administration. Samples were immediately analysed using a modified colorimetric micro method. The cumulative amount of D(+)-xylose absorbed at each time point with and without prior sedation were. The significance rate was set at P<0.05. The study failed to demonstrate a statistically significant difference in the amount of D(+)-xylose absorbed between sedated and unsedated animals, although there was a tendency for a less rapid initial uptake with prior sedation. This study suggests that prior sedation with xylazine will not significantly affect the result of a D(+)-xylose absorption test in the normal horse.

A simple and green analytical method for determination of iron based on micro flow analysis

A simple, inexpensive and reagent-less colorimetric micro flow analysis (μFA) system was implemented in a polymethyl methacrylate (PMMA) micro fluidic manifold. A T-shaped micro channel on a PMMA chip was fabricated by laser ablation and topped with molded polydimethylsiloxane (PDMS). The fabricated μFA system was integrated with the optical components as detector and applied to the determination of iron in water samples. It is based on the measurement of Fe(III)–nitroso-R salt complex at 720 nm formed by the reaction between Fe(III) and nitroso-R salt in an acetate buffer solution pH 5. The proposed μFA consumed very small amount of reagent and sample, it released waste of less than 2.0 mL h −1. The relative standard deviation (R.S.D.) was less than 2% ( n = 11) with the recovery of 98.7 ± 0.12 ( n = 5). The linear range for the determination of iron in water samples was over the range of 0.05–4.0 μg mL −1 with a correlation coefficient ( r 2) of 0.9994. The limit of detection (3 σ) and limit of quantitation (10 σ) were 0.021 μg mL −1 and 0.081 μg mL −1, respectively with a sample throughput of 40 h −1.

A modified colorimetric micro method for long-chain fatty acids and its application for assay of lipolytic enzymes

A modification of the Duncombe method for measurement of free fatty acids is presented. Substitution of diphenylcarbohydrazide for diethyldithiocarbamate color complexing agent increases the sensitivity of the method 4- to 6-fold. The absorbancy of the color produced is measured at 540 mμ. Applications of the method for the assay of pancreatic lipase, and rat liver lysosomal lipase and phospholipase are described.

A colorimetric micro method for the determination of formyl groups

The characteristic purple colour formed by N-formyl-N'-2,4-dinitrophenyl-hydrazine in the presence of piperidine and acetone was made the basis of a new quantitative method for the determination of formyl groups. Samples containing N-formyl groups (up to 0.4mumole) are hydrazinolysed at 97-98 degrees for 1hr. and are dinitrophenylated after the removal of excess of hydrazine. Interference from 2,4-dinitrophenylhydrazine is eliminated by subjecting the dinitrophenylated samples to chromatography on an alumina column. Interference arising from the formation of N-acetyl-N'-2,4-dinitrophenylhydrazine, when determining formyl groups in samples containing acetyl, can be avoided by a paper-chromatographic separation before analysis. A standard procedure is described. The method gives satisfactory results when applied to N-formyl-amino acids. Gramicidin, when analysed by this method, was found to contain 0.89 mole of formyl group/mole for a molecular weight of 1880. The method indicated the absence of formyl groups from lysozyme, a protein known not to contain such groups. Generally, the analytical values obtained by the method are within 100+/-4% of theory.

Colorimetric micro determination of calcium in sugar-house products

Colorimetric micro determination of calcium in sugar-house products

Colorimetric micro determination of calcium in sugar-house products

Colorimetric micro determination of calcium in sugar-house products

A colorimetric method for estimation of microquantities of tartaric acid isomers

1. ( 1) A colorimetric micro method for estimation of the tartaric acid isomers is described. The principle of the method consists in the formation of a tartrate-iron (Fe ++) complex, which on addition of dinitrophenylhydrazine followed by addition of alkali forms a purple color. The intensity of this color is proportional to the amount of the tartaric acid isomers in the range of 0.05 to 0.35 μmole. 2. ( 2) The various stages and the optimal conditions of the color reaction were investigated and are described in detail. 3. ( 3) Certain substances, including malic acid, citric acid, materials which bind ferrous ions, oxidizing agents, ferric ions, and possibly also other metallic ions, interfere with estimation of the tartaric acids by this method. However, in cases in which the relative concentration (with respect to tartrate) of such substances is low, the dilution generally required to bring the concentration of the tartaric acid into the appropriate range is usually sufficient to eliminate interfering effects. Under the assay conditions described keto acids also develop a color, but the tartaric acids can be estimated in their presence by a subtraction method. 4. ( 4) It is possible to use the method described for estimation of the other components of the color reaction, the intensity of the color being proportional to the amounts of ferrous ions in the range of 0.1 to 0.3 μmole, and to the amounts of dinitrophenylhydrazine in the range of 0.1 to 0.6 μmole.

A colorimetric micro method for the determination of cholinesterase

1. 1. A colorimetric micro method for the determination of cholinesterase activity using acetylthiocholine as substrate has been developed. 2. 2. The method is rapid, requires simple laboratory equipment, and is sensitive to small amounts of enzyme; the reaction is followed by measuring the appearance of one of the reaction products (thiocholine). 3. 3. The method has been applied to the determination of the cholinesterase activity in rat brain, in whole blood and blood plasma of dogs, and in the brains of 12-, 15-, 18-, and 21-day-old chick embryos.

Studies on Cycasin, a New Toxic Glycoside, ofCycas revolutaThunb

Quantitative paper chromatography of cycasin is described, where the cycasin and sugars separated on the paper are eluted out and determined, according to the colorimetric micro analysis of sugars by Plumel. The contents of cycasin and free sugars contained in both premature and matured cycad seeds determined by this method are presented.

Studies on Cycasin, a New Toxic Glycoside, of Cycas revoluta Thunb

Quantitative paper chromatography of cycasin is described, where the cycasin and sugars separated on the paper are eluted out and determined, according to the colorimetric micro analysis of sugars by Plumel. The contents of cycasin and free sugars contained in both premature and matured cycad seeds determined by this method are presented.

Microdetermination of pyruvic and α-ketoglutaric acids

A colorimetric micro procedure for simultaneous determination of pyruvic and α-ketoglutaric acids in mixtures is described. The yellow color of the 2,4-dinitrophenylhydrazones of these acids, and the red colors produced on subsequent alkali treatment, are measured. The range is from 0.10 to 0.25 μmole of total keto acid contained in 1 ml. of sample. Each acid is determined within about 0.004 μmole at the lower concentration level, and slightly greater than proportional precision is obtained at other levels.