Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 11 de 11
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Molecules ; 26(11)2021 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-34198892

RESUMO

This study investigated the antioxidant activity DPPH, ABTS, and Folin-Ciocalteu methods of betulin (compound 1) and its derivatives (compounds 2-11). Skin permeability and accumulation associated with compounds 1 and 8 were also examined. Identification of the obtained products (compound 2-11) and betulin isolated from plant material was based on the analysis of 1H- NMR and 13C-NMR spectra. The partition coefficient was calculated to determine the lipophilicity of all compounds. In the next stage, the penetration through pig skin and its accumulation in the skin were evaluated of ethanol vehicles containing compound 8 (at a concentration of 0.226 mmol/dm3), which was characterized by the highest antioxidant activity. For comparison, penetration studies of betulin itself were also carried out. Poor solubility and the bioavailability of pure compounds are major constraints in combination therapy. However, we observed that the ethanol vehicle was an enhancer of skin permeation for both the initial betulin and compound 8. The betulin 8 derivative showed increased permeability through biological membranes compared to the parent betulin. The paper presents the transformation of polycyclic compounds to produce novel derivatives with marked antioxidant activities and as valuable intermediates for the pharmaceutical industry. Moreover, the compounds contained in the vehicles, due to their mechanism of action, can have a beneficial effect on the balance between oxidants and antioxidants in the body, minimizing the effects of oxidative stress. The results of this work may contribute to knowledge regarding vehicles with antioxidant potential. The use of vehicles for this type of research is therefore justified.


Assuntos
Antioxidantes/farmacologia , Pele/química , Triterpenos/farmacologia , Animais , Antioxidantes/química , Antioxidantes/farmacocinética , Disponibilidade Biológica , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Estrutura Molecular , Espectroscopia de Prótons por Ressonância Magnética , Absorção Cutânea , Solubilidade , Suínos , Triterpenos/química , Triterpenos/farmacocinética
2.
Front Pharmacol ; 12: 658381, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34248621

RESUMO

The effect of cream and gel vehicles containing clove water on skin permeability was compared for a new eugenol derivative (eugenyl dichloroacetate-EDChA) with antioxidant activity. In vitro permeation experiments were conducted in a Franz cell with porcine skin. The cumulative mass and skin accumulation of EDChA were investigated and compared. The antioxidative capacity of the studied vehicles was determined by using the diphenylpicrylhydrazyl (DPPH) free radical reduction method. The antioxidant activity (evaluated with DPPH, ABTS, and the Folin-Ciocalteu methods) of the fluid that penetrated through the pig skin and of the fluid obtained after the skin extraction, were also determined. For comparison, eugenol was also tested. The results of this work could contribute to the development of vehicles with antioxidant potential estimated after 24 h of conducting the experiment, which indicates long-term protection against reactive oxygen species (ROS) in the deeper layers of the skin. The waste water from the clove buds steam distillation -contains several valuable biologically active compounds, and its use is environmentally friendly. We observed that gel vehicles were the best enhancer of skin permeation for both eugenol and its derivative. In most cases, -similar cumulative masses of eugenol and its ester were found in the acceptor fluid. The accumulation of EDChA was higher for cream vehicles in relation to the parent eugenol when applied onto the skin. The greatest amounts of eugenol were accumulated in the skin when these compounds were used in gel vehicles.

3.
AMB Express ; 10(1): 187, 2020 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-33078274

RESUMO

The aim of the study was to determine the antioxidant activity and assess the lipophilicity and skin penetration of eugenyl chloroacetate (EChA), eugenyl dichloroacetate (EDChA), and eugenyl trichloroacetate (ETChA). Identification of the obtained products was based on gas chromatography (GC), infrared spectroscopy (FTIR/ATR), gas chromatography coupled with mass spectrometry (GC-MS), and the analysis of 13C-NMR and 1H-NMR spectra. The antioxidative capacity of the derivatives obtained was determined by the DPPH free radical reduction method, while the octanol/water partition coefficient (shake-flask method) was tested to determine the lipophilicity of these compounds. In the next stage of testing EDChA and ETChA-(compounds characterized by the highest degree of free radical scavenging), the penetration of DPPH through pig skin and its accumulation in the skin were evaluated. For comparison, penetration studies of eugenol alone as well as dichloroacetic acid (DChAA) and trichloroacetic acid (TChAA) were also carried out. The antioxidant activity (DPPH, ABTS, and Folin-Ciocalteu methods) of the fluid that penetrated through pig skin was also evaluated. The in vitro pig skin penetration study showed that eugenol derivatives are particularly relevant for topical application. The obtained derivatives were characterized by a high level of antioxidant activity estimated after 24 h of conducting the experiment, which indicates long-term protection against reactive oxygen species (ROS) in the deeper layers of the skin.

4.
Polymers (Basel) ; 12(2)2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-32028605

RESUMO

In this work the preparation of polyamide 12 (PA12) based composites reinforced with pristine and surface-modified carbon nanotubes is reported. A qualitative and quantitative evaluation of multi-walled carbon nanotube functionalization with oxygen containing reactive groups achieved by different procedures of chemical treatment is presented. Simple strong oxidative acid treatment as well as chlorination with subsequent chloroacetic acid treatment were applied. Carbon nanotubes (CNTs) were also subjected to chlorine and ammonia in gaseous atmosphere with small differences in after-ammonia treatment. Commercial COOH-functionalized carbon nanotubes were compared with nanotubes that were laboratory modified. The effect of CNT functionalization was evaluated basing on the improvement of mechanical and thermal properties of polyamide 12 composites prepared by in situ polymerization. It was found that high concentration of oxygen-containing functional groups on nanotube surface is not sufficient to improve the composite performance if the structure of carbon nanotubes is defective. Indeed, the best effects were achieved for composites containing nanotubes modified under mild conditions, seemingly due to a compromise between morphology and surface chemical structure.

5.
Water Air Soil Pollut ; 220(1-4): 373-385, 2011 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-21949452

RESUMO

The capability of environmental microorganisms to biodegrade simazine-an active substance of 2-chloro-s-triazine herbicides (pesticide waste since 2007)-was assessed. An enormous metabolic potential of microorganisms impels to explore the possibilities of using them as an alternative way for thermal and chemical methods of utilization. First, the biotope rich in microorganisms resistant to simazine was examined. Only the higher dose of simazine (100 mg/l) had an actual influence on quantity of bacteria and environmental fungi incubated on substrate with simazine. Most simazine-resistant bacteria populated activated sludge and biohumus (vermicompost); the biggest strain of resistant fungi was found in floral soil and risosphere soil of maize. Compost and biohumus were the sources of microorganisms which biodegraded simazine, though either of them was the dominant considering the quantity of simazine-resistant microorganisms. In both cases of periodic culture (microorganisms from biohumus and compost), nearly 100% of simazine (50 mg/l) was degraded (within 8 days). After the repeated enrichment culture with simazine, the rate of its degradation highly accelerated, and just after 24 h, the significant decrease of simazine (20% in compost and 80% in biohumus) was noted. Although a dozen attempts of isolating various strains responsible for biodegradation of simazine from compost and biohumus were performed, only the strain identified as Arthrobacter urefaciens (NC) was obtained, and it biodegraded simazine with almost 100% efficiency (within 4 days).

6.
J Hazard Mater ; 137(3): 1479-87, 2006 Oct 11.
Artigo em Inglês | MEDLINE | ID: mdl-16730892

RESUMO

The results and a numerical simulation of studies on dynamics of the adsorption from seven-component aqueous solution of light chlorinated hydrocarbons on activated carbon have been presented. Aqueous solution of 1,2-dichloroethane (12DCE), 1,1,2,2-tetrachloroethane (S-TET), chloroform (CHCl(3)), carbon tetrachloride (CCl(4)), 1,1-dichloroethene (VDC), perchloroethene (PER) and 1,1,2-trichloroethene (TRI) was used. Concentrations of chlorohydrocarbons were similar as in wastewater from vinyl chloride plant. A cell model that incorporates the diffusion through a laminar layer of liquid around a particle was used to describe the experimental results. The applied calculation methods, which take kinetics into account, allows to well describe a phenomenon of dynamic adsorption. Mean relative deviations between the experimental and calculated values amounted 17%. The breakthrough curves become steeper along with an increase of the bed height. A consistency of the experimental results with those calculated indicates for a negligible contribution of the axial diffusion on the dynamic adsorption process of light chlorinated hydrocarbons from aqueous solution under the hydrodynamic conditions corresponding to the Reynolds number equal to 1.3. Determined optimal bed height for waste linear flow rate-15 cm/min is in the range 80-120 cm.


Assuntos
Carbono/química , Cloro/química , Hidrocarbonetos/química , Adsorção , Modelos Químicos , Soluções
7.
J Hazard Mater ; 136(3): 854-8, 2006 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-16513262

RESUMO

Technological parameters of the ammonolysis of (3-chloropropyl)trimethoxysilane to (3-aminopropyl)trimethoxysilane have been determined. Influence of temperature, reaction time and the molar ratio of ammonia to (3-chloropropyl)trimethoxysilane has been examined. Influence of the parameters has been described using the following factors describing the process: the degree of conversion of (3-chloropropyl)trimethoxysilane and the selectivity of transformation to (3-aminopropyl)trimethoxysilane in relation to consumed (3-chloropropyl)trimethoxysilane.


Assuntos
Amônia/química , Propilaminas/química , Silanos/química , Cromatografia Gasosa , Espectrometria de Massas , Temperatura
8.
J Colloid Interface Sci ; 296(2): 458-64, 2006 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-16219316

RESUMO

The results of studies on the adsorption dynamics of light chlorinated hydrocarbons, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chloroform, carbon tetrachloride, 1,1-dichloroethene, perchloroethylene and 1,1,2-trichloroethene, from a seven-component solution on to activated carbon are presented. The experimental results were described using the equilibrium model. The application of this model allows to determine the location of the midpoint of the breakthrough profile.

9.
J Colloid Interface Sci ; 290(1): 83-90, 2005 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-15939433

RESUMO

The mass transfer and effective intraparticle diffusion coefficients were determined in the adsorption process of 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chloroform, carbon tetrachloride, 1,1-dichloroethene, perchloroethene, and 1,1,2-trichloroethene from seven-component aqueous solution onto a thin layer of activated carbon. A modified constant-volume method was used in the studies. A correlation between similarity numbers in the form of Sh=2+1.54Re(0.66)Sc(0.33) was derived for a range of the Reynolds numbers in(1-15). Based on the Biot number, it was found that within the range of Reynolds numbers <14 the mass transport through a film decides the adsorption rate.

10.
J Colloid Interface Sci ; 285(2): 518-24, 2005 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-15837467

RESUMO

The desorption of 1,2-dichloroethane from a bed of DTO activated carbon after adsorption from aqueous solution has been investigated. The desorption process was carried out using steam. The basic characteristics of the process were determined. The studies were performed in the temperature range 100-160 degrees C. A steam consumption indicator reduces with an increase of temperature from 100 to 140 degrees C. An elevation of temperature above 140 degrees C does not cause an improvement in the desorption efficiency. The number of performed cycles does not reduce the adsorption capacity of used activated carbon. Studies on the regeneration of the bed saturated with a seven-component mixture of chloroorganic compounds at temperature of 140 degrees C were carried out. The degree of removal of the sum of chloro-derivatives exceeded 0.96 at a volume ratio of steam (recalculated on the condensate) to bed of about 10. It was found that the dechlorination proceeds during desorption at elevated temperature. The quantitative ratio of chloro-derivatives in the desorbate was changed in comparison to the composition of wastewater directed to the adsorption.

11.
J Colloid Interface Sci ; 265(2): 276-82, 2003 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-12962661

RESUMO

The adsorption capacities of five chlorinated organic compounds, chloroform (CHCl3), 1,1,2,2-tetrachloroethane (S-TET), 1,1,2,2-tetrachloroethylene (PER), 1,2-dichloropropane (DCP), and bis(1-chloroisopropyl) ether (BCIPE) for DTO, WD-EXTRA, and AG-5 activated carbons were investigated. Moreover, the effective molecular diameters of investigated chlorocompounds were calculated. The Freundlich and Langmuir equations of adsorption isotherms describe the experimental data with good correlation for each studied system. The equilibrium data were also analyzed using the equations of Dubinin and Radushkevich and of Dubinin and Astakhov. The degree of filling of the micropores and the average free energy for adsorption in the investigated systems were determined based on these models. It was found that the highest adsorption capacity in relation to all investigated compounds is exhibited by DTO activated carbon. For DTO activated carbon the adsorption affinity of the compounds decreases in the order BCIPE>PER approximately S-TET>DCP>CHCl3, whereas for WD-EXTRA S-TET>BCIPE>PER>DCP>CHCl3 and for AG-5 S-TET>PER>BCIPE>DCP>CHCl3. The obtained adsorption isotherms are generally L-type according to the Giles classification.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...