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1.
In situ forming biodegradable polymeric systems loaded with betamethasone (BTM) and betamethasone acetate (BTMA) were prepared using poly(DL ‐lactide‐co‐glycolide) (PLGA), ethyl heptanoate (EH), and N‐methyl‐2‐pyrrolidone (NMP) as the biodegradable polymer, additive, and solvent, respectively. The drug release studies were carried out in buffer (pH = 7.4, 37°C) using high performance liquid chromatography (HPLC). 1H‐NMR was used to determine the polymer degradation behavior, release mechanism, and interactions between the polymer and drug. The 1H‐NMR spectra showed that all interactions between the polymer and drug were hydrogen bonding. Hydroxyl groups and fluorine in drugs were involved in hydrogen bonding with PLGA polymer. In 1H‐NMR studies, we found that the degradation rate in the systems loaded with BTMA was higher than the systems loaded with BTM because BTMA is only slightly soluble and accelerates the hydrolysis of PLGA chains. The formulations loaded with BTM had obviously lower burst release compared with BTMA loaded samples. With respect to 1H‐NMR spectra, the mechanism of BTM release is controlled by two effective factors: solvent removal and polymer degradation. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

2.
Biodegradable in situ forming drug delivery systems for naltrexone release are promising for post‐treatment of drug addicts. The effect of two different additives, glycerol and ethyl heptanoate, on the naltrexone hydrochloride release and solvent removal from a poly(DL ‐lactide‐co‐glycolide) (PLGA) injectable implant is presented in this article. The experimental results showed that the in vitro initial release of the drug was decreased in the presence of these additives. Ethyl heptanoate was, however, more effective than glycerol and increasing the amount of additives in PLGA solution up to 5% (w/w) resulted in a decrease of initial naltrexone release rate up to 50%. The morphological evaluation of implants using scanning electron microscopy indicated that the additives generated a less porous structure together with a finger‐like to sponge‐like transition. The solvent removal profiles of injectable implants, which can be well described by thermogravimetric and morphological analysis, were in good agreement with drug release profiles. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   

3.
The purpose of this research was to develop polylactic-co-glycolic acid (PLGA) nanospheres surface modified with chitosan (CS). Mitoxantrone- (MTO-) loaded PLGA nanospheres were prepared by a solvent evaporation technique. The PLGA nanospheres surface was modified with CS by two strategies (adsorption and covalent binding). PLGA nanospheres of 248.4 ± 21.0 nm in diameter characterized by the laser light scattering technique, scanning electron microscopy (SEM) are spherical and its drug encapsulation efficiency is 84.1 ± 3.4%. Zeta potential of unmodified nanospheres was measured to be negative −21.21 ± 2.13 mV. The positive zeta potential of modified nanospheres reveals the presence of CS on the surface of the modified nanospheres. Modified nanospheres were characterized for surface chemistry by X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR). FT-IR spectra exhibited peaks at 3420 cm−1 and 1570 cm−1, XPS spectra shows the N 1s (atomic orbital 1s of nitrogen) region of the surface of the nanospheres, corresponding to the primary amide of CS. In vitro drug release demonstrated that CS-modified nanospheres have many advantages such as prolonged drug release property and decreased the burst release over the unmodified nanospheres, and the modified nanospheres by covalent binding method could achieve the release kinetics of a relatively constant release. These data demonstrate high potential of CS-modified PLGA nanospheres for the anticancer drug carrier.  相似文献   

4.
Higher alcohols and esters are among the predominant classes of volatile organic compounds (VOCs) that influence the quality of beer. The concentrations of these compounds are determined through a specific yeast strain selection and fermentation conditions. The effect of yeast strains on the formation of higher alcohols and esters throughout fermentations (at 20°C) was investigated. Flavour-relevant esters (ethyl acetate, isoamyl acetate, ethyl hexanoate and ethyl octanoate) and higher alcohols (isoamyl alcohol, isobutyl alcohol and phenylethyl alcohol) were monitored throughout the fermentation using proton transfer reaction–time of flight–mass spectrometry (PTR-ToF-MS) coupled with an automated sampling system for continuous measurements. Compound identification was confirmed by analysis of samples using gas chromatography–mass spectrometry (GC–MS). Results demonstrated the specific time points where variation in higher alcohol and ester generation between yeast strains occurred. In particular, the concentrations of isoamyl acetate, ethyl octanoate and isoamyl alcohol between yeast strains were significantly different over the first 2 days of fermentation; whereas, after Day 3, no significant differences were observed. The two Saccharomyces pastorianus strains produced comparable concentrations of the key higher alcohols and esters. However, the key higher alcohol and ester concentrations varied greatly between the two S. cerevisiae strains. The use of PTR–ToF–MS to rapidly measure multiple yeast strains provides new insights on fermentation for brewers to modify the sensory profile and optimise quality.  相似文献   

5.
In this study, porous poly(lactide‐co‐glycolide) (PLGA) microparticles with low mass density and large particle size were developed for chronic obstructive pulmonary disease treatment using anticholinergic drug (tiotropium). The porous PLGA microparticles were prepared by the water‐in‐oil‐in‐water (W1/O/W2) multi‐emulsion method using PLGA polymer and ammonium bicarbonate (as a porogen). Herein, soluble starch was incorporated in porous PLGA microparticles for long‐term tiotropium release. In vitro drug release studies determined that the rapid release of tiotropium from porous PLGA microparticles was reduced because of the high viscosity of the incorporated starch. Tiotropium release from porous PLGA microparticles continued up to 3 days. Furthermore, the inhaled microparticles showed longer drug residence in in vivo lung epithelium. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   

6.
The volatile constituents of lulo del Chocó (Solanum topiro) fruit pulp obtained by liquid‐liquid extraction were analyzed by capillary GC and capillary GC‐MS. In total, 30 components were identified with methyl salicylate, hexadecanoic acid, hexanal, guaiacol, ethyl butanoate, and ethyl acetate being the major components. Chirospecific MDGC analysis revealed the predominance of (R)‐ethyl‐3‐hydroxybutanoate (ee 40%) and the presence of racemic mixtures both of δ‐octalactone and of δ‐decalactone. For γ‐hexalactone, γ‐octalactone, and γ‐decalactone enantiomeric distributions of 22.4 : 77.6, 22.9 : 77.1, and 20.0 : 80.0, (R) : (S), respectively, were determined. Glycosidically bound aroma compounds were identified by capillary GC and capillary GC‐MS after isolation of the glycosidic fraction obtained by Amberlite XAD‐2 adsorption and methanol elution followed by hydrolysis with a commercial pectinase enzyme. In total 13 bound aroma compounds (aglycones) were identified. These aglycones mainly consisted of compounds exhibiting aromatic structures. Additionally, with the aid of capillary GC and capillary GC‐MS (EI and NCI) of trifluoroacetylated derivatives we identified eight glucosides: the novel 3,6‐epoxy‐7‐megastigmen‐5,9‐diol β‐D‐glucopyranoside and the hexyl, benzyl, linalyl oxide (furanic), 2‐phenylethyl, vomifolyl (isomer 1), (6S,9R)‐vomifolyl, and scopoletin β‐D‐glucopyranosides.  相似文献   

7.
Gallic acid (GA)–loaded cellulose acetate (CA) nanofiber mats with 10 to 40 wt.% GA contents (based on the weight of CA) were fabricated by electrospinning. The effects of GA contents and applied potential on the morphology and the average diameters of fibers were studied. The electrospun fiber mats containing 20 and 40 wt.% GA were investigated for their potential use as carrier of GA in wound dressing application. The GA‐loaded CA films were prepared by solvent casting technique for use in comparative studies. Determination of the release characteristics of GA from the GA‐loaded fiber mats and films was carried out by the total immersion and the transdermal diffusion through a pig skin method in acetate buffer solution (pH 5.5) or normal saline (pH 7.0) at either 32 or 37°C, respectively. In the total immersion method, the maximum amounts of the GA released from the fiber mats containing 20 and 40 wt.% GA in the acetate buffer were approximately 97% and 71% (based on the weight of initial GA), while those of the GA released into the normal saline were approximately 96% and 81%, respectively. Lower values were observed in the experiments of the transdermal diffusion through a pig skin method. The corresponding GA‐loaded CA films showed the lower amounts of GA released into media. The as‐loaded and the as‐released GA remained its antioxidant activity as investigated by 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) assay. Lastly, the GA‐loaded CA fiber mats exhibited antibacterial activity against Staphylococcus aureus, which showed the potential for use as wound dressing materials.  相似文献   

8.
In present study, protein loaded poly (lactide-co-glycolide)/chitosan microspheres (PLGA/CS MSs) with spheres-in-sphere structure were prepared in order to weaken the burst release of protein from PLGA microspheres (PLGA MSs) and to buffer acidic micro-milieu. The PLGA MSs and PLGA/CS MSs were characterized in terms of their size distribution, morphology, drug-loading rate, zeta potential and physical-chemical properties. The incubation experiments of PLGA MSs and PLGA/CS MSs were manipulated in PBS solution at pH 7.4, 37 °C to monitor the release of BSA and the vehicles degradation. The release kinetic of BSA was illuminated mainly based on the degradation processes of the matrices. External CS crusts were proved to strikingly improve the release kinetic of the model protein by reducing initial burst release and extending continuous release while acting as a diffusion barrier. Moreover, using PLGA/CS MSs could avoid the decrease of pH value resulted from the acidic products of PLGA MSs because of the effective buffer action of the basic groups in CS. The results demonstrated that the spheres-in-sphere structure is an effective way to control the initial burst release of protein and to overcome the acidic problem of protein-loading PLGA MSs.  相似文献   

9.
A new hyperbranched poly (amine‐ester)‐poly (lactide‐co‐glycolide) copolymer (HPAE‐co‐PLGA) was synthesized by ring‐opening polymerization of D , L ‐lactide (DLLA) glycolid and branched poly (amine‐ester) (HPAE‐OHs) with Sn(Oct)2 as catalyst. The chemical structures of copolymers were determined by FT‐IR, 1H‐NMR(13C NMR), TGA and their molecular weights were determined by gel permeation chromatography (GPC). Paclitaxel‐loaded copolymer nanoparticles were prepared by the nanoprecipitation method. Their physicochemical characteristics, e.g. morphology and nanoparticles size distribution were then evaluated by means of fluorescence spectroscopy, environmental scanning electron microscopy (ESEM), and dynamic light scattering (DLS). Paclitaxel‐loaded nanoparticles assumed a spherical shape and have unimodal size distribution. It was found that the chemical composition of the nanoparticles was a key factor in controlling nanoparticles size, drug‐loading content, and drug release behavior. As the molar ratio of DL ‐lactide/glycolide to HPAE increased, the nanoparticles size and drug‐loading content increased, and the drug release rate decreased. The antitumor activity of the paclitaxel‐loaded HPAE‐co‐PLGA nanoparticles against human liver cancer H7402 cells was evaluated by 3‐(4, 5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide (MTT) method. The paclitaxel‐loaded HPAE‐co‐PLGA nanoparticles showed comparable anticancer efficacy with the free drug. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

10.
Environmental switches may be fabricated for the controlled release of pharmaceutical drug using a thermally responsive polymer with the intrinsic chemical and physical nature of stimuli‐sensitive smart materials. Particularly, much attention has been paid to the biomedical applications of poly(N‐isopropyl acrylamide) (PNIPAAm) because of its unique reversible transition at a specific lower critical solution temperature (LCST).Thermally sensitive block copolymers, poly(N‐isopropyl acrylamide‐b‐poly(L ‐lactide‐co‐glycolide) (PNIPAAm‐b‐PLGA), and polyethylene glycol‐poly (lactide‐co‐glycolide) (PEG‐PLGA) triblock copolymers with different compositions and length of PLGA block were synthesized via ring‐opening polymerization of lactide and glycolide in the presence of OH‐terminated PNIPAAm or PEG. The composition and structure of the polymer were determined by NMR and FTIR. The effect of important factors, such as ionic strength, pH, and polymer concentration on the phase transition behavior of temperature‐sensitive polymers, were investigated by cloud point measurements. The resulting thermosensitive polymers were used for the entrapment of a narcotic antagonist drug, naltrexone, as the model drug. The loading efficiency and drug release behavior of naltrexone‐loaded hydrogels were investigated. The naltrexone loaded thermosensitive polymers were able to sustain the release of naltrexone for different periods of time, depending on the polymer composition, and concentration. In vitro release studies showed that these thermosensitive polymers are able to deliver naltrexone in biologically active forms at a controlled rate for 3–8 weeks. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

11.
The principal purpose of the present work is to characterize the aroma, aroma‐active, and anthocyanin profiles of Okuzgozu wines and to observe the effect of the pomace pressing technique on these parameters. A total of 58 and 59 volatile compounds were identified and quantified in free‐run juice wine (FRW) and pressed pomace wine (PW). Alcohols were found as the most dominant group among aroma compounds followed by esters and acids. However, among all these compounds, only 11 and 13 of them could be considered as key odorants in aromatic extracts of FRW and PW, respectively. According to GC‐MS‐O analysis, ethyl octanoate (fruity), phenyl ethyl acetate (fruity), and 2‐phenyl ethanol (flowery) were found as the main contributors to the overall scent of both wines. Beyond the aroma profiles, anthocyanin contents of both types of wines were also investigated, and total 14 and 15 anthocyanins were identified and quantified in FRW and PW. Malvidin‐3‐glycoside and its acetyl and coumaroyl forms were identified as the dominant anthocyanins in both wines. It is worth noting the pressing application (2.0 atm) led to an increase of some unpleasant notes in the aroma providing chemical, pharmacy, and fermented aromas in wine. On the other hand, the wines produced with pressed pomace presented higher amounts of anthocyanins.  相似文献   

12.
Oral delivery of proteins and peptides is one of the main challenges in pharmaceutical drug development. Microdevices have the possibility to protect the therapeutics until release is desired, avoiding losses by degradation. One type of microdevice is polymeric microcontainers. In this study, lysozyme is chosen as model protein and loaded into microcontainers with the permeation enhancer sodium decanoate (C10). The loaded microcontainers are sealed and functionalized by applying polymeric lids onto the cavity of the devices. The first lid is poly(lactic‐co‐glycolic) acid (PLGA) and on top of this either polyethylene glycol (PEG) or chitosan is applied (PLGA+PEG or PLGA+chitosan, respectively). The functionalization is evaluated in vitro for morphology, drug release, and mucoadhesive properties. These are coupled with in vitro and ex vivo studies using Caco‐2 cells, Caco‐2/HT29‐MTX‐E12 co‐cultures, and porcine intestinal tissue. PLGA+chitosan shows slower release compared to PLGA+PEG or only PLGA in buffer and the transport of lysozyme across cell cultures is not enhanced compared to the bulk powder. Microcontainers coated with chitosan or PEG demonstrate a three times stronger adhesion during ex vivo mucoadhesion studies compared to samples without coatings. Altogether, functionalized microcontainers with mucoadhesive properties and tunable release for oral protein delivery are developed and characterized.  相似文献   

13.
A facile procedure for the synthesis of 2,4,5-triarylimidazoles is being reported starting from benzil, aromatic aldehyde and ammonium acetate. The reactions were carried out with catalyst-free, solvent-free and under microwave irradiation conditions in high yield (80–99%) with short time (3–5 min) and environmental benign, as well as convenient operation. The structures of the compounds have been confirmed on the basis of their IR, 1H NMR, and/or 13C NMR, MS, and elemental analyzer.  相似文献   

14.
Eleven compounds were successfully separated from Asteris souliei by using a two‐step high‐performance counter‐current chromatography method. The first step involved a reversed phase isocratic counter‐current chromatography separation using hexane/ethyl acetate/methanol/water (1:0.8:1:1 v/v/v/v), which produced three fractions, the first two of which were mixtures. The second step used step‐gradient reversed‐phase counter‐current chromatography with hexane/butanol/ethyl acetate/methanol/water (1:0.5:3.5:1:4 v/v/v/v/v) initially followed by hexane/ethyl acetate/methanol/water (1:2:1:2 v/v/v/v) to separate Fraction 1 into seven compounds; and hexane/ethyl acetate/methanol/water (1:1:1:1.2 v/v/v/v) to separate Fraction 2 into three further compounds. The chemical structures of the separated compounds were identified by ESI‐MS and NMR spectroscopy (1H and 13C). Baicalin ( 5 ), eriodictyol ( 7 ), apigenin‐7‐glycoside ( 8 ), quercetin ( 9 ), luteolin ( 10 ), and apigenin ( 11 ) showed obvious inhibitory effects on lipopolysaccharide‐induced nitric oxide production in RAW264.7 cells at a concentration of 10 μg/mL.  相似文献   

15.
Naturally derived materials are becoming widely used in the biomedical field. Soy protein has advantages over the various types of natural proteins employed for biomedical applications due to its low price, nonanimal origin, and relatively long storage time and stability. In the current study, novel drug‐eluting soy‐protein films for wound healing applications were developed and studied. The films were prepared using the solvent casting technique. The analgesic drug bupivacaine and two types of wide range antibiotics (gentamicin and clindamycin) were incorporated into the soy‐protein films. The effect of drug incorporation and plasticizers content on the films' mechanical properties, drug release profiles, and cell viability was studied. Drug incorporation had a softening effect of the films, lowering mechanical strength and increasing ductility. Release profiles of bupivacaine and clindamycin exhibited high burst release of 80% to 90% of encapsulated drug within 6 hours, followed by continuous release in a decreasing rate for a period of 2 to 4 days. Gentamicin release was prolonged, probably due to interaction between the gentamicin and the polymer chains. Hybrid soy‐protein/poly (Dl‐lactic‐co‐glycolic acid) (PDLGA) microspheres structure showed potential for long and sustained release of bupivacaine. Films with no drugs and films loaded with gentamicin were found to be noncytotoxic for human fibroblasts, while bupivacaine and clindamycin were found to have some effect on cell growth. In conclusion, our new drug‐loaded soy‐protein films combine good mechanical properties and biocompatibility, with desired drug release profiles, and can therefore be potentially very useful as burn and ulcer dressings.  相似文献   

16.
Five terpenoids, including two new ones, 3,7‐dioxo‐tirucalla‐8,24‐dien‐21‐oic acid ( 2 ) and 3α‐acetoxyl‐7‐oxo‐tirucalla‐8,24‐dien‐21‐oic acid ( 3 ), and three known ones, boscartol A ( 1 ), 11‐keto‐β‐boswellic acid ( 4 ), and acetyl‐11‐keto‐boswellic acid ( 5 ), have been extracted by the ultrapressure extraction and purified by pH‐zone‐refining countercurrent chromatography and high‐speed countercurrent chromatography from olibanum. For ultrapressure extraction, the optimal condition including 200 MPa of extraction pressure, ethyl acetate of extraction solvent, 1:20 (g/mL) of solid/liquid ratio, and 2 min of extraction time were obtained. For the separation, from 1.5 g of the terpenoid extract, 220.1 mg of 4 , 255.5 mg of 5 , and 212.3 mg of the mixture of 1 , 2 , and 3 were obtained by pH‐zone‐refining countercurrent chromatography under the solvent system of chloroform/ethyl acetate/methanol/water (3:1:3:2, v/v/v/v) with aqueous ammonia and trifluoroacetic acid as retention and eluter agents. The enriched mixture (210 mg) was further separated by conventional high‐speed countercurrent chromatography with petroleum ether/ethyl acetate/methanol/water (1:0.8:1.1:0.6, v/v/v/v), yielding 30.1 mg of 1 , 35.5 mg of 2 , 12.3 mg of 3 . The structures of these five terpenoids were elucidated by extensive spectroscopic methods.  相似文献   

17.
This letter reports on the fabrication of hollow,porous and non-porous poly(D,L-lactide-co-glycolide) (PLGA) microspheres(MSs) for the controlled release of protein and promotion of cell compatibility of tough hydrogels.PLGA MSs with different structures were prepared with modified double emulsion methods,using bovine serum albumin(BSA) as a porogen during emulsification.The release of the residual BSA from PLGA MSs was investigated as a function of the MS structure.The hollow PLGA MSs show a faster protein release than the porous MSs,while the non-porous MSs have the slowest protein release.Compositing the PLGA MSs with poly(vinyl alcohol)(PVA) hydrogels promoted chondrocyte adhesion and proliferation on the hydrogels.  相似文献   

18.
A 2(5H)‐furanone bearing two furyl rings was synthesized. The behavior of this furanone toward some nitrogen nucleophiles, namely, hydrazine hydrate, benzylamine, and ammonium acetate, was studied. The nitrile group at position‐3 of the furanone was utilized to construct thiazolidine ring by the action of thioglycollic acid. The acid hydrazide synthesized from the previous step was allowed to react with some carbonyl compounds, namely, acetonylacetone, acetylacetone, ethyl acetoacetate, ethyl cinnamate, diethylmalonate, phthalic anhydride, benzil, and 4‐methoxybenzaldehyde, to form pyrrole, pyrazole, and pyrazolopyridazine ring systems bearing two furyl groups. The structures of all the products obtained were illustrated from their analytical and spectral data.  相似文献   

19.
Gastrodia rhizome, a dried and steamed tuber of Gastrodia elata Blume (Orchidaceae), has been traditionally used in Korea, China and Japan for the treatment of neurological and nervous disorders such as headaches, dizziness, vertigo and convulsive illnesses. The ethyl acetate and water extracts of G. elata stimulated plasmin activity. The active ethyl acetate fraction was subjected to centrifugal partition chromatography (CPC) with a two‐phase solvent system, composed of n‐hexane–ethyl acetate–methanol–water (3:7:4:6, v/v) followed by semi‐preparative HPLC purification to separate active compounds and the water fraction was purified by Diaion HP‐20 resin and semi‐preparative HPLC. In ethyl acetate extract, 4‐hydroxybenzyl alcohol (1), 4‐hydroxybenzoic acid (2), 4‐hydroxybenzaldehyde (3), 4‐ethoxymethylphenol (4), 4,4′‐oxybis(methylene)diphenol (5) and 4,4′‐methylenediphenol (6) were obtained with high purities. Parishin (7) and parishin B (8) were isolated from water extract. Among isolated compounds, 4‐hydroxybenzyl alcohol (1), 4‐hydroxybenzaldehyde (3) and 4‐ethoxymethylphenol (4) significantly stimulated plasmin activity. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   

20.
A study of the mechanism of the catalytic transformation of mixed ethyl acetate (EA) + methyl acetate (MA) (50:50 v/v) to hydrocarbons over HZSM‐5 (Si/Al ratio of 9) catalyst was conducted. The reaction was carried out in a continuous fixed‐bed reactor under atmospheric pressure and in the temperature range 250–390°C and with weight hourly space velocity of 3.2 and 4.6 h?1. The distribution of products including monoaromatics, fused ring aromatics and oxygenates was determined using GC‐MS. The product distribution was controlled by temperature. The oxygenate components (kinetically controlled products) were transformed into aromatics (thermodynamically controlled products) with an increase in temperature. The effluents were benzene‐free or with low content of benzene and toluene. Two intermediates were proposed for this conversion to hydrocarbons over HZSM‐5: cyclobutane‐1,3‐dione and/or acetic acid (AA) as ketene source. Furthermore, AA and mesityl oxide (MO) were selected as potential intermediates in the transformation of mixed EA + MA into hydrocarbons over HZSM‐5. It is suggested that ketene dimerization, the phenolic pool and the condensation reaction between ketene and MO are the probable mechanism routes for AA conversion. Aldol condensation, Michael addition, cracking, isomerization and ketene formation are the presumable pathways for MO conversion over HZSM‐5.  相似文献   

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