Photo-Oxidation of Tetracycline Adsorbed in Clayand in Aqueous Suspension

2018 ◽  
Vol 930 ◽  
pp. 552-555
Author(s):  
Josy Anteveli Osajima ◽  
Edson Cavalcanti da Silva Filho ◽  
Norel H. Belhouchat ◽  
Esperanza C. Gil ◽  
Cesar A.V. Iborra

The resistance of some compounds to conventional treatments engenders the search for alternative methods, such as photo-oxidation. Antibiotics and photo-producers are found in the environment, indicating that these compounds are persistent. This work had as its goal to investigate the photo-oxidation of the antibiotic named tetracycline hydrochloride adsorbed in montmorilloniteclay (VHS) and into aqueous suspension. In order to irradiate the interaction products 0,03g were weighed and put in a petri dish to be collected on pre-determined times. The extraction of the drug was made by adding 10 mL of distilled water and put on the ultrasound for 2 hours. The suspensions were prepared by using 200 mL of the concentration from 25mgL-1of tetracycline in 1gL-1g of clay in a borosilicate reactor. This system was stirred in the dark during 1 hour in order to achieve its balance. The samples were radiated by using an Ultra-Vitalux UV lamp, with 300 W for 2 hours. The kinetics were followed through UV-Vis spectroscopy, monitored in 359 nm, in the maximum wavelength of the drug. The suspensions showed a degradation twice as fast when compared to the interaction product, for the rate of degradation of this system was 24%. This decrease on the concentration may have been caused by the hydroxyl radicals generated by the photolysis of the iron hydroxide II. Hence, one concludes that in the case of the system in suspension it was more effective to the photo-oxidation of this antibiotic. Although, there is the need for increasing the exposure time of the interaction product in order to verify possible structural changes of this system by DRX.

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Truong Khanh Linh Dang ◽  
Thach Nguyen ◽  
Michael Habeck ◽  
Mehmet Gültas ◽  
Stephan Waack

Abstract Background Conformational transitions are implicated in the biological function of many proteins. Structural changes in proteins can be described approximately as the relative movement of rigid domains against each other. Despite previous efforts, there is a need to develop new domain segmentation algorithms that are capable of analysing the entire structure database efficiently and do not require the choice of protein-dependent tuning parameters such as the number of rigid domains. Results We develop a graph-based method for detecting rigid domains in proteins. Structural information from multiple conformational states is represented by a graph whose nodes correspond to amino acids. Graph clustering algorithms allow us to reduce the graph and run the Viterbi algorithm on the associated line graph to obtain a segmentation of the input structures into rigid domains. In contrast to many alternative methods, our approach does not require knowledge about the number of rigid domains. Moreover, we identified default values for the algorithmic parameters that are suitable for a large number of conformational ensembles. We test our algorithm on examples from the DynDom database and illustrate our method on various challenging systems whose structural transitions have been studied extensively. Conclusions The results strongly suggest that our graph-based algorithm forms a novel framework to characterize structural transitions in proteins via detecting their rigid domains. The web server is available at http://azifi.tz.agrar.uni-goettingen.de/webservice/.


1997 ◽  
Vol 93 (2) ◽  
pp. 221-229 ◽  
Author(s):  
Takayuki Kitamura ◽  
Hiroyuki Fudemoto ◽  
Yuji Wada ◽  
Kei Murakoshi ◽  
Mitsuhiro Kusaba ◽  
...  

2019 ◽  
Vol 141 (6) ◽  
Author(s):  
P. Mythravaruni ◽  
Parag Ravindran

Oxidation of aorta by hydroxyl radicals produces structural changes in arterial proteins like elastin and collagen. This in turn results in change in the mechanical response of aorta. In this paper, a thermodynamically consistent constitutive model is developed within the framework of mixture theory, to describe the changes in aorta and isolated elastin with oxidation. The model is then studied under uniaxial extension using experimental data from literature.


2007 ◽  
Vol 21 (2) ◽  
pp. 91-103 ◽  
Author(s):  
Helan Xiao ◽  
Guoping Cai ◽  
Mingyao Liu

Extracellular matrix (ECM) plays an important role in cell differentiation, growth, migration and apoptosis. Collagen is the most abundant protein familyin vivo, but its function has still not been clearly defined yet. Reactive oxygen species (ROS) have a central role in oxidative cell stress. Electron spin resonance (ESR) spectroscopy indicates that type I collagen could uniquely scavenge hydroxyl radicals in dose- and time-dependent manner; whereas BSA and gelatin (a denatured collagen) have no such an effect. However, the mechanism by which type I collagen scavenges hydroxyl radicals is different from that of GSH, a well-known free radical scavenger. Using a new method, two-dimensional FTIR correlation analysis, for the first time, we show that the order of functional group changes of type I collagen in this process is amide I earlier than amide II than amide III than –CH– thanν(C=O). The results indicates that the structure of the main chain of collagen changed first, followed by more residue groupν(C=O) exposed to hydroxyl radicals. The reaction with the carbonyl group in collagen causes the hydroxyl free radicals to be scavenged. Therefore, ECM can effectively scavenge ROS under normal physiological conditions. When the proteins of ECM were denatured in the same way as gelatin, they lost their function as a free radical scavenger. All of these results provide new insight into therapy or prevention of oxidative stress, apoptosis and ageing.


2018 ◽  
Vol 4 (4) ◽  
pp. eaar2547 ◽  
Author(s):  
Yingjun Liu ◽  
Roger Seco ◽  
Saewung Kim ◽  
Alex B. Guenther ◽  
Allen H. Goldstein ◽  
...  

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4236
Author(s):  
Kaethe N. Leonard ◽  
Joshua M. Blose

Osmolytes and macromolecular crowders have the potential to influence the stability of secondary structure motifs and alter preferences for conserved nucleic acid sequences in vivo. To further understand the cellular function of RNA we observed the effects of a model osmolyte, polyethylene glycol (PEG) 200, and a model macromolecular crowding agent, PEG 8000, on the GAAA tetraloop motif. GAAA tetraloops are conserved, stable tetraloops, and are critical participants in RNA tertiary structure. They also have a thermodynamic preference for a CG closing base pair. The thermal denaturation of model hairpins containing GAAA loops was monitored using UV-Vis spectroscopy in the presence and absence of PEG 200 or PEG 8000. Both of the cosolutes tested influenced the thermodynamic preference for a CG base pair by destabilizing the loop with a CG closing base pair relative to the loop with a GC closing base pair. This result also extended to a related DNA triloop, which provides further evidence that the interactions between the loop and closing base pair are identical for the d(GCA) triloop and the GAAA tetraloop. Our results suggest that in the presence of model PEG molecules, loops with a GC closing base pair may retain some preferential interactions with the cosolutes that are lost in the presence of the CG closing base pair. These results reveal that relatively small structural changes could influence how neutral cosolutes tune the stability and function of secondary structure motifs in vivo.


2020 ◽  
Vol 12 (12) ◽  
pp. 144
Author(s):  
M. E. N. Ferreira ◽  
C. F. Pinto ◽  
R. R. de Sena ◽  
J. G. de Mendoça Neto ◽  
C. R. Lobo ◽  
...  

Fungi are among the main agents of plant diseases, being responsible for major losses in agriculture. The control of these microorganisms carried out using chemical compounds and numerous cases of resistance have already been observed, which makes it necessary to search for alternative methods of management of these pathogens. Therefore, the aim of this study, to evaluate the antifungal potential in plants. Twenty-four (24) plant extracts were tested for their antifungal potential against five plant pathogenic fungi: Sclerotinia sclerotiorum (Ss), Stromatinia cepivora (Sc), Fusarium oxysporum (Fox), Colletotrichum gloesporioides (Cg) and Verticillium dahlia (Vd). For the evaluation of the fungicidal potential, plant extracts were prepared by liquefying the plants in distilled water. The extracts were incorporated into PDA (Potato-Dextrose-Agar) culture medium to a final concentration of 35% and autoclaved. Then, PDA discs colonized by the aforementioned fungi were added to the center of each plate with the respective treatments (plant extracts). When all control treatments (PDA medium without plant extract) had colonized the entire Petri dish, the diameters of the fungal colonies were measured to calculate the Mycelial Growth Inhibition Index (MGI). Tests showed that all these plant extracts have some antifungal activity, ranging from 0 to 100% inhibition. In general, extracts of basil, lavender, guaco, rue, toxic cassava and black plum were the ones that stood out, with MGIs above 50%. New studies are being conducted to evaluate the activity of plant extracts without autoclaving, inhibition of sclerotia formation, to determine the minimum inhibitory concentration, as well as other parts of plants like roots and seeds, mixtures of plant extracts and in vivo antagonism tests.


2002 ◽  
Vol 46 (4-5) ◽  
pp. 43-50 ◽  
Author(s):  
A. Kornmüller ◽  
S. Karcher ◽  
M. Jekel

Granulated iron hydroxide (b-FeOOH) is used as a regenerable sorbent and catalyst for reactive dye removal in textile wastewater treatment. In oxidative regeneration the previously sorbed reactive dye is catalytically oxidized after activation of hydrogen peroxide to hydroxyl radicals on the FeOOH surfaces to regain adsorption capacity and reuse the sorbents. A high initial H2O2 concentration is needed for an efficient mass transfer water/solid but its consumption per oxidized dye results only in 7-25 mg mg−1. At room temperature a regeneration time of 3.5 h is necessary for decolorization and 6 h for further decomposition of the formed oxidation products to enable a reloading without any loss in adsorption capacity. Compared to Fenton's reagent, this oxidation process takes advantage of pH-independence between 4 and 8 and additionally no sludge is produced. Salts are commonly used in textile dying processes. While chloride improves the dye sorption, the presence of sulfate results in deteriorating sorption. Carbonate reacts as a scavenger of hydroxyl radicals resulting in a higher hydrogen peroxide consumption, but the efficiency of dye oxidation is only slightly affected. Nearly 20% of DOC of the sorbed dye can be attributed to short chain organic acids (formate, acetate, oxalate) indicating the far-reaching catalytic oxidation and enabling biological post-treatment.


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