scholarly journals Toxic concentrations of metronidazole to Microcystis protocystis

2014 ◽  
Vol 74 (3 suppl 1) ◽  
pp. S120-S124 ◽  
Author(s):  
SMS Magalhães ◽  
CM Brêtas ◽  
JM Brêtas ◽  
GA Pianetti ◽  
MW Franco ◽  
...  
Keyword(s):  
Antimicrobial Agent ◽  
Growth Inhibition ◽  
Culture Medium ◽  
Degradation Products ◽  
Aquatic Environments ◽  
Test Conditions ◽  
Ecological Importance ◽  
The Stability ◽  
Toxic Concentrations ◽  
Environmental Importance

Antimicrobials are among the most commonly used drugs and have become a class of contaminants with great environmental importance. Metronidazole is an antimicrobial used for the therapeutic management of several human diseases. The toxicity of antimicrobials on aquatic species may affect sensitive microorganisms and reduce metabolic processes. Cyanobacteria is a group of organisms that are of great ecological importance in aquatic environments. Studies indicate that cyanobacteria are very sensitive to some antimicrobials. Therefore, it is necessary to evaluate the effects of metronidazole contamination on phytoplankton. The aim of this study was to investigate the effects of metronidazole on the growth of the cyanobacterium Microcystis protocystis and to evaluate the stability of this antimicrobial agent in the culture medium over a period of 96 hours. M. protocystis was resistant to growth inhibition by metronidazole. The EC50 of this antimicrobial for M. protocystis was 117.3 mg L–1. Under the growth inhibition test conditions, neither a significant change in the MNZ concentration nor the presence of drug metabolites or degradation products was observed. These results indicate low cellular uptake of the antimicrobial agent and its persistence in the culture medium.

A New, Rapid and Simple RP-HPLC Method for Stability Quantification of a Protease Inhibitor in Tablets

2021 ◽  
Author(s):  
Rochele Cassanta Rossi ◽  
Josué Guilherme Lisbôa Moura ◽  
Vanessa Mossmann ◽  
Patrícia Weimer ◽  
Pedro Eduardo Fröehlich
Keyword(s):  
Quality Control ◽  
Protease Inhibitor ◽  
Degradation Products ◽  
Gradient Elution ◽  
Hplc Method ◽  
Array Detector ◽  
Forced Degradation ◽  
Control Analysis ◽  
Quality Control Laboratory ◽  
The Stability

Abstract Fosamprenavir calcium is a protease inhibitor widely used in the treatment and prevention of human immunodeficiency virus and acquired immunodeficiency syndrome. This protease inhibitor serves as a prodrug of amprenavir, offering better oral bioavailability. Although this drug was approved by the FDA in 2003, there are few methods established for quantifying the stability for quality control analysis of fosamprenavir-coated tablets. The purpose of the study was to develop and validate a method for determining the stability of fosamprenavir-coated tablets (Telzir®) that may be applied by any quality control laboratory. Chromatographic separation was performed using a Vertical RP-18 column programmed to run a gradient elution with sodium acetate buffer and acetonitrile. Flow rate was 1.2 mL min−1 for a total run time of 15 min. Ultraviolet detection was set at 264 nm and the use of a photodiode array detector in scan mode allowed selectivity confirmation by peak purity evaluation. The analyte peak was found to be adequately separated from degradation products generated during forced degradation studies. Thus, the proposed method was found to accurately indicate stability and was sufficient for routine quantitative analysis of fosamprenavir in coated tablets without interference from major degradation products and excipients.

In Vitro Removal of Ochratoxin A by Wine Lactic Acid Bacteria

2007 ◽  
Vol 70 (9) ◽  
pp. 2155-2160 ◽  
Author(s):  
VINCENZO DEL PRETE ◽  
HECTOR RODRIGUEZ ◽  
ALFONSO V. CARRASCOSA ◽  
BLANCA de las RIVAS ◽  
EMILIA GARCIA-MORUNO ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Lactic Acid Bacteria ◽  
Ochratoxin A ◽  
High Performance ◽  
Culture Medium ◽  
Degradation Products ◽  
Cell Binding ◽  
A Cell ◽  
In Vitro Interaction

A study was carried out to determine the in vitro interaction between ochratoxin A (OTA) and wine lactic acid bacteria (LAB). Fifteen strains belonging to five relevant oenological LAB species were grown in liquid synthetic culture medium containing OTA. The portion of OTA removed during the bacterial growth was 8 to 28%. The OTA removed from the supernatants was partially recovered (31 to 57%) from the bacterial pellet. Cell-free extracts of three representative strains were produced by disrupting cells in a French pressure cell. The ability of crude cell-free extracts to degrade OTA was studied. OTA was not degraded by cell-free extracts of wine LAB strains, and no degradation products of OTA were detected in the high-performance liquid chromatograms of the methanol extract of the bacterial pellet. On the basis of these results, we conclude that OTA removal by wine LAB is a cell-binding phenomenon. The chemistry and the molecular basis of OTA binding to wine LAB remains unknown.

Temperature Dependence of Degradation of Colored Oxo-Biodegradable Low-Density Polyethylene Films under Accelerated Thermal Aging

2017 ◽  
Vol 890 ◽  
pp. 82-85 ◽  
Author(s):  
Reymark D. Maalihan ◽  
Bryan B. Pajarito
Keyword(s):  
Thermal Aging ◽  
Degradation Products ◽  
Low Density Polyethylene ◽  
Effect Of Temperature ◽  
Low Density ◽  
Polyethylene Films ◽  
Hot Air ◽  
Taguchi Design Of Experiments ◽  
Oxidant Concentration ◽  
The Stability

This work reports the effect of temperature on degradation of colored low-density polyethylene (PE) films during thermal aging. Film samples were formulated according to Taguchi design of experiments where colorant, thickness, and pro-oxidant concentration were varied accordingly. Tensile properties of films were monitored with time during heat aging in a hot air oven at 50, 70, and 90 °C. Likewise, surfaces of aged films were analyzed to evaluate the degree of oxidation of PE during thermal aging. The Arrhenius equation was then used to predict the lifetime of PE at an in-use temperature of 30 °C. Results indicate that increasing the temperature reduces the tensile strength and modulus of films. Formation of carbonyl groups as degradation products is also observed at higher temperatures. Consequently, thermal aging at 90 °C offers the highest extent of degradation of exposed films. Regression analysis reveals that white films degrade at a higher rate than yellow and non-colored films. The presence of TiO2 in white films shortens the lifetime of PE while amine stabilizer in yellow films enhances the stability of PE during thermal aging.

Synthesis and action of nitric oxide in rat glomerular mesangial cells

1991 ◽  
Vol 261 (4) ◽  
pp. F600-F606 ◽  
Author(s):  
P. J. Shultz ◽  
M. A. Tayeh ◽  
M. A. Marletta ◽  
L. Raij
Keyword(s):  
Nitric Oxide ◽  
Culture Medium ◽  
Mesangial Cells ◽  
Culture Media ◽  
Degradation Products ◽  
Specific Inhibitor ◽  
Cgmp Level ◽  
Glomerular Mesangial Cells ◽  
Intracellular Cgmp ◽  
Stimulation Of

Macrophages and certain tumor cell lines can be induced to synthesize nitric oxide (NO) from L-arginine after stimulation with lipopolysaccharide (LPS) or cytokines. In the present study, we have found that culture medium collected after 24 h from unstimulated rat mesangial cells (MC) contains 6.3 +/- 1.2 microM of NO3-/NO2- (the degradation products of NO). These levels were significantly increased when MC were incubated with LPS (10 micrograms/ml) for 24 h (23.9 +/- 4.1, P less than 0.05). The specific inhibitor of NO synthesis, NG-monomethyl-L-arginine (L-NMMA) completely inhibited LPS-stimulated production of NO3-/NO2-, confirming that the NO3-/NO2- was derived from NO within the MC. Recent studies suggest that endothelium-derived relaxing factor (EDRF) produced by vascular endothelium is also NO, and we have previously shown that both EDRF and NO stimulate increases in MC guanosine 3',5'-cyclic monophosphate (cGMP). Thus we sought to determine whether NO synthesized by the MC could affect cGMP levels within the same cells. After 24-h incubation with LPS (10 micrograms/ml), intracellular cGMP level within the MC was 706.3 +/- 197 (SE) compared with 40.5 +/- 7 fmol/micrograms protein in control MC incubated in media alone (P less than 0.01). The changes in cGMP in response to LPS were inhibited by greater than 90% by L-NMMA. Similar to LPS, incubation of MC with the cytokine gamma-interferon also increased NO3-/NO2- in the culture media and increased cGMP levels within MC. The induction of NO synthesis within MC and the concomitant stimulation of MC cGMP may be important in the modulation of the effects of endotoxemia, as well as inflammation, within the glomerulus.

scholarly journals Copper accumulation by the root and leaf biomass of Salvinia natans (L.) All. (Salviniaceae)

2021 ◽  
Vol 14 (7) ◽  
pp. 59-67
Author(s):  
Larissa Braun de Souza ◽  
Franciele de Freitas ◽  
Sabrine Lunardi ◽  
Janaina Saiz Cassins Von der Osten ◽  
Rafael Arruda ◽  
...  
Keyword(s):  
Culture Medium ◽  
Copper Ions ◽  
Cost Effective ◽  
Copper Accumulation ◽  
Leaf Biomass ◽  
Aquatic Environments ◽  
High Accumulation ◽  
Effective Option ◽  
Salvinia Natans ◽  
Cu Ions

Aquatic plants are often exposed to metal contamination. The study evaluated the bioaccumulation of copper (Cu) ions in aqueous solution by the biomass of leaves and roots of the macrophyte Salvinia natans. Plants of S. natans were submitted to culture solutions with different concentrations of Cu ions, evaluated at intervals of seven days. The leaf and root samples were separately subjected to atomic absorption spectroscopy with flame atomization to assess the concentration of copper accumulated in its biomass. The results demonstrated a pattern of accumulation dependent on the concentration of the metal in the culture medium and the time of exposure of the plants to the contamination. The accumulation was greater in the biomass of the roots when compared to the leaves. Throughout the experiment, toxicity symptoms were observed in the morphology of plants subjected to all copper concentrations, demonstrating the macrophyte's viability for bioindicating the toxicity of this metal in aquatic environments. A high accumulation of copper ions was obtained both in the biomass of the roots and leaves of the plants, confirming their potential bioaccumulator of Cu. The analysis of biomass suggests an important characteristic of metal compartmentalization by the plant, associating the absorption by the roots and the possible transfer to the leaves. In general, our results show that S. natans is an organism with a potential bioindicator and bioaccumulator of Cu and consists of a viable cost-effective option for phytoremediation of aquatic environments contaminated by metals

scholarly journals The Instability of Dimeric Fc-Fusions Expressed in Plants Can Be Solved by Monomeric Fc Technology

2021 ◽  
Vol 12 ◽  
Author(s):  
Pia Gattinger ◽  
Shiva Izadi ◽  
Clemens Grünwald-Gruber ◽  
Somanath Kallolimath ◽  
Alexandra Castilho
Keyword(s):  
Monoclonal Antibodies ◽  
Fusion Proteins ◽  
Degradation Products ◽  
Therapeutic Proteins ◽  
Cost Effective ◽  
Full Length ◽  
Peptide Sequence ◽  
Reporter Protein ◽  
The Stability

The potential therapeutic value of many proteins is ultimately limited by their rapid in vivo clearance. One strategy to limit clearance by metabolism and excretion, and improving the stability of therapeutic proteins, is their fusion to the immunoglobulin fragment crystallizable region (Fc). The Fc region plays multiple roles in (i) dimerization for the formation of “Y”-shaped structure of Ig, (ii) Fc-mediated effector functions, (iii) extension of serum half-life, and (iv) a cost-effective purification tag. Plants and in particular Nicotiana benthamiana have proven to be suitable expression platforms for several recombinant therapeutic proteins. Despite the enormous success of their use for the production of full-length monoclonal antibodies, the expression of Fc-fused therapeutic proteins in plants has shown limitations. Many Fc-fusion proteins expressed in plants show different degrees of instability resulting in high amounts of Fc-derived degradation products. To address this issue, we used erythropoietin (EPO) as a reporter protein and evaluated the efforts to enhance the expression of full-length EPO-Fc targeted to the apoplast of N. benthamiana. Our results show that the instability of the fusion protein is independent from the Fc origin or IgG subclass and from the peptide sequence used to link the two domains. We also show that a similar instability occurs upon the expression of individual heavy chains of monoclonal antibodies and ScFv-Fc that mimic the “Y”-shape of antibodies but lack the light chain. We propose that in this configuration, steric hindrance between the protein domains leads to physical instability. Indeed, mutations of critical residues located on the Fc dimerization interface allowed the expression of fully stable EPO monomeric Fc-fusion proteins. We discuss the limitations of Fc-fusion technology in N. benthamiana transient expression systems and suggest strategies to optimize the Fc-based scaffolds on their folding and aggregation resistance in order to improve the stability.

scholarly journals Isolation and Structural Characterization of Degradation Products of Aceclofenac by HPLC, HRMS and 2D NMR

2019 ◽  
Vol 31 (4) ◽  
pp. 851-854
Author(s):  
Santhosh Guduru ◽  
V.V.S.R.N. Anji Karun Mutha ◽  
B. Vijayabhaskar ◽  
Muralidharan Kaliyaperumal ◽  
Raghu Babu Korupolu ◽  
...  
Keyword(s):  
Degradation Product ◽  
Degradation Products ◽  
Acid Stress ◽  
2D Nmr ◽  
Stress Conditions ◽  
Preparative Hplc ◽  
Mass Spectral ◽  
2D Nmr Spectra ◽  
The Stability

The stability of aceclofenac under stress conditions was assessed to identify the degradation products. So, it was subjected to stress conditions like acid, base and oxidation, according to ICH guideline Q1A (R2). One degradation product formed when the drug was subjected to acid stress. Three degradation products were formed during the basic stress condition. The drug substance was found to be stable to oxidative stress. The degradants formed during the stress were separated on a C-18 column using gradient preparative HPLC elution. The only product (DP-2) formed during the acid stress and this one is same as of one of the three degradation products (DP-1, DP-2, DP-3) were formed during base stress. 1D and 2D NMR spectra and mass spectral analysis supported the proposed structures for the products. The products DP-2 and DP-3 have been reported earlier but this is the first report of product DP-1 as a degradation product of aceclofenac.

scholarly journals Development and Validation of a Novel Stability-Indicating Reversed-Phase Ion-Pair Chromatographic Method for the Quantitation of Impurities in Marbofloxacin Tablets

2018 ◽  
Vol 101 (4) ◽  
pp. 1021-1029
Author(s):  
Priyanka Maheshwari ◽  
Neelima Shukla ◽  
Manish Kumar Dare
Keyword(s):  
Mobile Phase ◽  
Chromatographic Method ◽  
Degradation Products ◽  
Reversed Phase ◽  
Ion Pair ◽  
Stress Conditions ◽  
Main Peak ◽  
Stability Indicating ◽  
Photolytic Degradation ◽  
The Stability

Abstract A stability-indicating isocratic reversed-phase ion-pair chromatographic method was designed for the separation of impurities in the presence of degradation products. Marbofloxacin tablets and a placebo were exposed to the stress conditions of oxidative, acid, base, humidity, thermal, and photolytic degradation. Significant and moderate degradation was observed in acidic and oxidative stress conditions, respectively. The degradation products were well resolved from the main peak and its impurities, thus proving the stability-indicating analytical method. The method was developed by using an XTerra RP18 3.5 μm (150 × 4.6 mm) column, with the mobile phase containing a mixture of buffer (pH 2.5)–methanol–glacial acetic acid (77 + 23 + 0.5, v/v). The flow rate of the mobile phase was 1.2 mL/min, with a column oven temperature of 40°C and a detection wavelength of 315 nm. The proposed method met Veterinary International Conference on Harmonization requirements and was successfully used for impurity quantitation in marbofloxacin tablets.

Stability-Indicating Liquid Chromatographic Procedure for Determination of Allantoin in Cosmetic Lotion

1988 ◽  
Vol 71 (2) ◽  
pp. 290-294
Author(s):  
Ramesh J Trivedi
Keyword(s):  
Degradation Products ◽  
Glyoxylic Acid ◽  
Uv Detector ◽  
Stability Indicating ◽  
Assay Procedure ◽  
Relative Standard ◽  
The Stability ◽  
Chromatographic Parameters ◽  
Liquid Chromatographic

Abstract A sensitive, specific liquid chromatographic (LC) procedure was developed for determination of allantoin [(2,5-dioxo-4--imidaazolidinyl) urea or 5-ureidohydantion] in cosmetic lotion. A reverse-phase, ionsuppression mechanism separated allantoin from interfering constituents of the sample matrix, and the compound was determined with a UV detector at 240 nm with a sensitivity limit of ((.20 mg/mL. The chromatographic parameters were optimized for retention time, efficiency, and relative response to the analyte. The assay procedure was validated with spiked laboratory-prepared samples at 100 ± 15% levels. An average recovery of 99.4% with a relative standard deviation of 1.5% (n = 7) was obtained. The stability-indicating characteristics of the method were established by recovery study (99.8%) of samples spiked with known degradation products (urea, allantoic acid, and glyoxylic acid).

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