scholarly journals Evaluation of residual antimicrobial activity and acute toxicity during the degradation of gatifloxacin by ozonation

2021 ◽  
Author(s):  
Marlon Caianelo ◽  
Caio Rodrigues-Silva ◽  
Milena Guedes Maniero ◽  
Vinicius Diniz ◽  
Mylena Spina ◽  
...  
Keyword(s):  
Antimicrobial Activity ◽  
Wastewater Treatment Plants ◽  
Degradation Products ◽  
Aqueous Media ◽  
Residual Activity ◽  
Fourth Generation ◽  
Alkaline Condition ◽  
Residual Toxicity ◽  
Test Organisms ◽  
Alkaline Conditions

Abstract The concerns regarding the occurrence of pharmaceuticals in wastewater treatment plants have been increased in the last decades. Gatifloxacin (GAT), the fourth generation of fluoroquinolones, has been widely used to treat both Gram-positive and Gram-negative bacteria and has a limited metabolization. The present study aimed to evaluate the ozonation as a technique to degrade GAT. A UHPLC-MS/MS method was used to quantify the residual of GAT and to assess its degradation products. The removal efficiency was higher at alkaline condition (pH = 10), reaching up to 99% of GAT after 4 min. It was also observed that the first ozone attack on the GAT molecule was through the carboxylic group. In contrast, at acid conditions (pH = 3), the ozone attack was first to the piperazinyl ring. The antimicrobial activity was evaluated using Escherichia coli and Bacillus subtilis as test organisms, and it was observed that the residual activity reduced most at the alkaline conditions. In contrast, the best condition to remove the residual toxicity evaluated for the marine bacteria V. fischeri was the acidic one. Due to this, the ozonation seemed to be an exciting process to remove GAT at aqueous media.

Hydrolysis of polydimethylsiloxane fluids in controlled aqueous solutions

2013 ◽  
Vol 68 (4) ◽  
pp. 813-820 ◽  
Author(s):  
Gaëlle Ducom ◽  
Baptiste Laubie ◽  
Aurélie Ohannessian ◽  
Claire Chottier ◽  
Patrick Germain ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Wastewater Treatment Plants ◽  
Degradation Products ◽  
Kinetic Studies ◽  
Solution Ph ◽  
Degradation Kinetic ◽  
Silicon Compounds ◽  
Alkaline Conditions ◽  
Naoh Solution ◽  
Water Ph

Accelerated degradation tests were performed on polydimethylsiloxane (PDMS) fluids in aqueous solutions and in extreme chemical conditions (pH 2–4 and 9–12). Results confirmed that silicones can be degraded by hydrolysis. Higher degradation levels were achieved in very acidic and alkaline conditions. Degradation products are probably polar siloxanols. In alkaline conditions, the counter-ion was found to have a strong influence on degradation level. Degradation kinetic studies (46 days) were also performed at different pH values. Supposing zeroth-order kinetics, degradation rate constants at 24 °C were estimated to 0.28 mgSi L−1 day−1 in NaOH solution (pH 12), 0.07 mgSi L−1 day−1 in HCl solution (pH 2) and 0.002 mgSi L−1 day−1 in demineralised water (pH 6). From these results, the following hypothesis was drawn: PDMS hydrolysis could occur in wastewater treatment plants and in landfill cells. It may be a first step in the formation of volatile organic silicon compounds (VOSiCs, including siloxanes) in biogas: coupled to biodegradation and (self-) condensation of degradation products, it could finally lead to VOSiCs.

Validation of Analytical Methods for Tacrolimus Determination in Poly(ε-caprolactone) Nanocapsules and Identification of Drug Degradation Products

2021 ◽  
Vol 21 (12) ◽  
pp. 5920-5928
Author(s):  
Guilherme A. Camargo ◽  
Amanda M. Lyra ◽  
Fernanda M. Barboza ◽  
Barbara C. Fiorin ◽  
Flávio L. Beltrame ◽  
...  
Keyword(s):  
Liquid Chromatography ◽  
High Performance ◽  
Degradation Products ◽  
Multiple Reaction Monitoring ◽  
Forced Degradation ◽  
Alkaline Stress ◽  
Drug Degradation ◽  
Relative Standard ◽  
Polymeric Nanocapsules ◽  
Alkaline Conditions

The aim of this paper was to use chromatographic tools for validating an analytical method for the tacrolimus (TAC) determination in polymeric nanocapsules and for identifying the drug degradation products after alkaline stress. A rapid Ultra-High-Performance Liquid Chromatography coupled with photo-diode array (UHPLC-PDA) method was successfully performed using the following chromatographic conditions: the Shimadzu Shim-pack XR-ODS III C18 column (100 mm×2.00 mm, 2.2 μm), the mobile phase consisting of methanol and acidified ultrapure water (89:11 v/v), the flow rate of 0.55 mL·min−1, and the ultraviolet (UV) detection at 235 nm. This method was validated as per International Council for Harmonisation (ICH) guidelines. In addition, a TAC forced degradation assay was carried out after alkaline stress and its degradation products were investigated using Liquid Chromatography coupled tandem mass spectroscopy (LC-MS/MS). The calibration curve was linear in the range of 100.0–300.0 μg·mL−1 (r >0.9999). Accuracy was confirmed by the TAC recovery of 96.55 to 98.19%. Precision (intraday and interday) were demonstrated by relative standard deviation lower than 0.89% and 3.25%, respectively. Selectivity and robustness were also proved. The method developed it was successfully applied to quantify TAC from polymeric nanocapsules, showing a high loading efficiency rate (>96.47%). The main drug degradation product observed in a multiple reaction monitoring (MRM) experiment was m/z 844, confirming the susceptibility of TAC under alkaline conditions; this finding was first time described.

scholarly journals A facile and effective method for preparation of 2.5-furandicarboxylic acid via hydrogen peroxide direct oxidation of 5-hydroxymethylfurfural

2017 ◽  
Vol 19 (1) ◽  
pp. 11-16 ◽  
Author(s):  
Shuang Zhang ◽  
Long Zhang
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction Time ◽  
Oxidation Mechanism ◽  
Molar Ratio ◽  
Alkaline Condition ◽  
Optimal Parameters ◽  
Direct Oxidation ◽  
Reaction Parameters ◽  
Alkaline Conditions ◽  
Furandicarboxylic Acid

Abstract In this paper, 2,5-furandicarboxylic acid (FDCA) was efficiently prepared by the direct oxidation of 5-hydroxymethylfurfural (5-HMF) using hydrogen peroxide (H2O2) in alkaline conditions without any catalysts. The effects of reaction parameters on the process were systematically investigated and the optimal parameters were obtained as follows: molar ratio of 5-HMF:KOH:H2O2 was 1:4:8, reaction temperature and reaction time were determined as 70°C and 15 minutes, respectively. Under these conditions, the yield of FDCA was 55.6% and the purity of FDCA could reach 99%. Moreover, we have speculated the detailed oxidation mechanism of 5-HMF assisted by hydrogen peroxide in alkaline condition to synthesize FDCA.

scholarly journals STABILITY INDICATING HPLC METHOD FOR DETERMINATION OF VILAZODONE HYDROCHLORIDE

2017 ◽  
Vol 9 (4) ◽  
pp. 123
Author(s):  
Birva A. Athavia ◽  
Zarna R. Dedania ◽  
Ronak R. Dedania ◽  
S. M. Vijayendra Swamy ◽  
Chetana B. Prajapati
Keyword(s):  
Limit Of Detection ◽  
Degradation Products ◽  
Hplc Method ◽  
Alkaline Condition ◽  
Forced Degradation ◽  
Molecular Formula ◽  
Stability Indicating ◽  
Dry Heat ◽  
Limit Of Quantitation

Objective: The aim and objective of this study was to develop and validate Stability Indicating HPLC method for determination of Vilazodone Hydrochloride.Methods: The method was carried out on a Phenomenex, C18 (250x4.6 mm, 5 µm) Column using a mixture of Acetonitrile: Water (50:50v/v), pH adjusted to 3.3 with Glacial Acetic Acid for separation. The flow rate was adjusted at 1 ml/min and Detection was carried out at 240 nm.Results: The retention time of vilazodone hydrochloride was found to be 2.3 min. The calibration curve was found to be linear in the range 25-75µg/ml with a correlation coefficient (R2=0.996). The limit of detection and limit of quantitation were found to be 4.78µg/ml and 14.48µg/ml respectively. The % recovery of vilazodone hydrochloride was found to be in the range of 98.21±0.08 % to 99.07±0.64%. The proposed method was successfully applied for the estimation of vilazodone hydrochloride in marketed tablet formulation.Vilazodone Hydrochloride was subjected to forced degradation under Acidic, Alkaline, Oxidation, Dry Heat and Photolytic degradation conditions. Vilazodone hydrochloride showed 3.12% degradation under acidic condition, 4.78% under alkaline condition, 7.8% under oxidation condition, 3.53% under dry heat condition and 4.9% under photolytic condition.Acid degradation impurity was identified and characterised by LC-MS/MS was found to be 1-(4-Penten-1-yl) piperazine having molecular weight 154.253 (m/z 155.08) and Molecular Formula C9H18N2.Conclusion: A simple, precise, rapid and accurate Stability Indicating HPLC method has been developed and validated for the determination of Vilazodone Hydrochloride in presence of its degradation products as per the ICH Guidelines. 

Detection of Fourth Generation Synthetic Halocarbons in the Upper Troposphere

2021 ◽  
Author(s):  
Tanja Schuck ◽  
Katharina Meixner ◽  
Peter van Velthoven ◽  
Simon O’Doherty ◽  
Martin Vollmer ◽  
...  
Keyword(s):  
Degradation Products ◽  
Stratospheric Ozone ◽  
Montreal Protocol ◽  
Gas Chromatography Mass Spectrometry ◽  
Fourth Generation ◽  
Oh Radicals ◽  
Sample Collection ◽  
Upper Troposphere ◽  
Wide Range ◽  
Air Sample

<p>Synthetic halocarbons are used for a wide range of applications, for example air conditioning or foam blowing. Many of them are long-lived greenhouse gases contributing to climate change and, in addition, may contribute to stratospheric ozone depletion if containing chlorine or bromine. Therefore, their production and use are regulated by the Montreal Protocol and its amendments. These long-lived halocarbons are increasingly replaced by a fourth generation of unsaturated short-lived halocarbons, the hydrochlorofluoroolefines (HCFOs) and hydrofluoroolefines (HFOs). The main removal process of these compounds in the atmosphere is reaction with OH radicals, and their average lifetimes are of the order of up to a few tens of days.</p><p>As part of the IAGOS-CARIBIC instrument package we operate an automated air sample collection system during regular flights in the upper troposphere and lowermost stratosphere. At altitudes around 10-12 km, samples are collected in stainless steel and glass flasks at predefined times. Post-flight laboratory analyses include gas chromatography - mass spectrometry measurements of a wide range of halocarbons. The short-lived compounds HFO-1234ze(E) and HCFO-1233zd(E) were detected in a small number of samples, indicating that these compounds are sufficiently long lived for transport into the upper troposphere. There were not found in stratospheric samples.</p><p>At this altitude, low abundance of OH and low temperatures may slow down chemical decay, and tracer lifetimes may increase significantly. Based on average temperatures and OH abundance, we estimate local lifetimes of HFO-1234ze(E) and HCFO-1233zd(E)  in the mid-latitudes of up to 75 days and 200 days, respectively. Short-lived H(C)FOs reaching the upper troposphere could thus be transported over large distances and their degradation products may be deposited  far from their emission sources.</p>

Antimicrobial, antioxidant and quantitative phytochemical evaluation of the dichloromethane and methanolic leaf extracts of Solenostemon monostychus P. Beauv

2021 ◽  
Vol 1 (1) ◽  
pp. 008-013
Author(s):  
Ere Diepreye ◽  
Eboh Abraham Sisein ◽  
Ovuru German Salvation
Keyword(s):  
Antimicrobial Activity ◽  
Methanolic Extract ◽  
Antioxidant Activities ◽  
Diffusion Method ◽  
Bacillus Species ◽  
Leaf Extracts ◽  
Microbial Infections ◽  
Test Organisms ◽  
Dpph Scavenging ◽  
And Staphylococcus Aureus

Solenostemon monostachyus P. Beauv (Lamiaceae family) is an important herb that is widespread in West and Central Africa.The leaves are used in various decoctions traditionally to treat diseases most especially microbial infections associated with the foot. In this study, the phytochemicals (qualitative and quantitative) of the plant were determined. The antimicrobial and antioxidant activities of the plant were also evaluated by standard methods. Results showed alkaloids, tannins, flavonoids, saponins phenolics in the methanolic extract of Solenostemon monostachyus. Cardiac glycosides and steroids absent in the methanolic extract were found present in the dichloromethane extract. The quantitative phytochemicals recorded were alkaloids (18.05 ± 0.87%), saponins (11.3 ± 0.56 %), tannins (3.3 ± 0.19 GAE). The antioxidant activity testing showed that the methanolic extract has higher DPPH scavenging ability over dichloromethane extract and standard ascorbic acid. In the antimicrobial activity testing, the cup-plate diffusion method was used and the result showed that the dichloromethane extract inhibited the growth of Bacillus species at concentrations 100 mg/ml, 50 mg/ml, 20 mg/ml and 10 mg/ml while methanolic extract inhibited the growth of bacillus species only at 100 mg/ml with 5 mm zone of inhibition. However, both methanol and dichloromethane extract showed no antimicrobial activity on the other test organisms such as Psudomonas aeruginosa, Escherichia coli and Staphylococcus aureus. In conclusion both methanolic and dichloromethane extracts of Solenostemon monostachyus are potential sources of antimicrobial and antioxidant.

scholarly journals SPS-neutralization in tissue samples for efficacy testing of antimicrobial peptides

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Gabrielle Sherella Dijksteel ◽  
Peter H. Nibbering ◽  
Magda M. W. Ulrich ◽  
Esther Middelkoop ◽  
Bouke K. H. L. Boekema
Keyword(s):  
Antimicrobial Activity ◽  
Antimicrobial Peptides ◽  
Antimicrobial Agents ◽  
Ex Vivo ◽  
Residual Activity ◽  
Gram Negative Bacteria ◽  
Tissue Samples ◽  
Gram Negative ◽  
Viable Bacteria

Abstract Background Accurate determination of the efficacy of antimicrobial agents requires neutralization of residual antimicrobial activity in the samples before microbiological assessment of the number of surviving bacteria. Sodium polyanethol sulfonate (SPS) is a known neutralizer for the antimicrobial activity of aminoglycosides and polymyxins. In this study, we evaluated the ability of SPS to neutralize residual antimicrobial activity of antimicrobial peptides [SAAP-148 and pexiganan; 1% (wt/v) in PBS], antibiotics [mupirocin (Bactroban) and fusidic acid (Fucidin) in ointments; 2% (wt/wt))] and disinfectants [2% (wt/wt) silver sulfadiazine cream (SSD) and 0.5% (v/v) chlorhexidine in 70% alcohol]. Methods Homogenates of human skin models that had been exposed to various antimicrobial agents for 1 h were pipetted on top of Methicillin-resistant Staphylococcus aureus (MRSA) on agar plates to determine whether the antimicrobial agents display residual activity. To determine the optimal concentration of SPS for neutralization, antimicrobial agents were mixed with PBS or increasing doses of SPS in PBS (0.05–1% wt/v) and then 105 colony forming units (CFU)/mL MRSA were added. After 30 min incubation, the number of viable bacteria was assessed. Next, the in vitro efficacy of SAAP-148 against various gram-positive and gram-negative bacteria was determined using PBS or 0.05% (wt/v) SPS immediately after 30 min incubation of the mixture. Additionally, ex vivo excision wound models were inoculated with 105 CFU MRSA for 1 h and exposed to SAAP-148, pexiganan, chlorhexidine or PBS for 1 h. Subsequently, samples were homogenized in PBS or 0.05% (wt/v) SPS and the number of viable bacteria was assessed. Results All tested antimicrobials displayed residual activity in tissue samples, resulting in a lower recovery of surviving bacteria on agar. SPS concentrations at ≥0.05% (wt/v) were able to neutralize the antimicrobial activity of SAAP-148, pexiganan and chlorhexidine, but not of SSD, Bactroban and Fucidin. Finally, SPS-neutralization in in vitro and ex vivo efficacy tests of SAAP-148, pexiganan and chlorhexidine against gram-positive and gram-negative bacteria resulted in significantly higher numbers of CFU compared to control samples without SPS-neutralization. Conclusions SPS was successfully used to neutralize residual activity of SAAP-148, pexiganan and chlorhexidine and this prevented an overestimation of their efficacy.

scholarly journals Steroids from the Leave of Persicaria perfoliata (L.) H. Gross

2019 ◽  
Vol 22 (2) ◽  
pp. 224-227
Author(s):  
Md Sagar Hossain ◽  
NM Mofiz Uddin Khan ◽  
Md Saiful Quddus ◽  
AM Sarwaruddin Chowdhury
Keyword(s):  
Antimicrobial Activity ◽  
Cytotoxic Activity ◽  
Brine Shrimp ◽  
Methanol Extract ◽  
Soluble Fraction ◽  
Pharmaceutical Journal ◽  
Antimicrobial Screening ◽  
Brine Shrimp Lethality ◽  
Persicaria Perfoliata ◽  
Test Organisms

β-sitosterol (1) and β-sitosterol-D-glucoside (2) were isolated from the dichloromethane soluble fraction of a methanol extract of the leave of Persicaria perfoliata. The crude fraction was subjected to antimicrobial screening and brine shrimp lethality bioassay, where moderate antimicrobial activity was observed against most of the test organisms was seen. The hexane soluble fraction also displayed significant cytotoxic activity with LC50 0.64 μg/ml in brine shrimp lethality bioassay. This is the first report of occurrence of these compounds from this plant. Bangladesh Pharmaceutical Journal 22(2): 224-227, 2019

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