A new method for the chemical modification of chitosan sulfate was used to prepare
N-propanoyl-,
N-hexanoyl- and
N,
O-quaternary substituted chitosan sulfate. Structural analysis by elemental ...analysis, FTIR,
13C NMR, and
1H NMR spectroscopy, and gel-permeation chromatography showed that these methods could conveniently be used for the introduction of functional groups. The influences of the acyl or quaternary groups on the anticoagulant activity of the polysaccharides were studied with respect to activated partial thromboplastin time (APTT) thrombin time (TT), and prothrombin time (PT). The propanoyl and hexanoyl groups increased the APTT activity, and the propanoyl groups also increased the TT anticoagulant activity slightly, while the
N,
O-quaternary chitosan sulfate showed only a slight TT coagulant activity.
Chitosan sulfate from chitosan was chemically modified to get propanoylated, hexanoylated or quarternized derivatives. The influences of these groups on the anticoagulant activity are discussed.
Sulfonated crosslinked chitosan resins (SCCRs) were prepared by firstly crosslinking chitosan to crosslinked chitosan resins (CCRs) using a reverse emulsion crosslinking method, followed by ...sulfonating CCRs with concentrated H.sub.2SO.sub.4 as the sulfonation agent. The properties and application of SCCRs as solid acid catalysts were studied. The acidic sites in SCCRs, including C.sub.6-O and C.sub.2-N sulfate groups, are all weak acidic sites. SCCRs of higher crosslinking degrees have a higher sulfonation rate of the C.sub.6 primary hydroxyl groups, thus more C.sub.6-O sulfate groups. High-temperature treatment and TG analysis verified that the crosslinking can improve the thermostability of both SCCR backbone and its acidic groups, and a higher crosslinking degree leads to better thermostability. Catalytic esterification of citric acid with butanol and propionic acid with n-butyl alcohol demonstrated that SCCRs have good catalytic activity and can be repetitively used as efficient solid acid catalysts.Key words:sulfonated crosslinked chitosan resin, solid acid catalyst, chitosan sulfate, crosslinked chitosan resin
A new method of introduction carboxyl groups to chitosan sulfate by the acylation reaction between hydroxyethyl chitosan sulfates and butane dioic anhydride in homogeneous solution was used to obtain ...carboxybutyrylated hydroxyethyl chitosan sulfates. The structures of the derivatives were characterized by element analysis, FT-IR,
13C-NMR, and gel permeation chromatography. The content and position of the carboxyl groups could be controlled favorably. Their anticoagulant activity was determined for human plasma with respect to activated partial thromboplastin time (APTT), thrombin time (TT), and prothombin time (PT). The introducing of carboxyl groups to amino groups greatly prolonged the APTT and TT. The best result occurred when the degree of substitution of the carboxyl groups was about 0.4/unit that prolonged APTT and TT with about 5 and 1.5 times compared to that of the uncarboxylated hydroxyethyl chitosan sulfates; another conclusion is that introducing of carboxyl groups into
N,
O-position gave better results than that just into
N-positions. Low S% chitosan sulfate and 6-
O-desulfated chitosan sulfate showed little anticoagulant activity but their
N,
O-carboxybutyrylated derivatives (0.6/unit ds) showed increased APTT or TT, while their
N-carboxybutyrylated derivatives (0.6/unit ds) gave no improvement. Generally, the introducing of carboxyl groups could not increase PT in spite of the position introduced.
A new approach to prepared chemically modified chitosan sulfate derivatives was reported, from which chitosan sulfate was prepared from chitosan first. Then N-acyl or N,O-quaternary ammonium groups ...were introduced by the reaction of chitosan sulfate with caproic anhydride, propanoic anhydride, or 2,3-epoxypropyl trimethylammonium. The structures of the derivatives were characterized by elemental analysis, FT-IR,
13C NMR,
1H NMR and gel permeation chromatography. The antibacterial activities against
Escherichia coli, which is a gram-negative bacterium, and
Staphylococcus aureus, which is a gram-positive bacterium, have been investigated by optical density method. It was found that the chitosan sulfate showed no inhibition against
E. coli, while at concentration below 10
2 μg/ml its inhibition against
S. aureus was higher than phenic acid, a widely used biocide. The quaternized derivatives of the chitosan sulfate also showed
S. aureus inhibition but no
E. coli inhibition. The acylated chitosan sulfates were found to be not only increasing the
S. aureus inhibition activities but also exhibiting some inhibition towards the growth of
E. coli slightly. The activities of
N-acyl chitosan sulfates seem to be related to the structures of the covalently bonded acyl moieties, among which the N-hexanoyl moiety was more effective in enhancing the
E. coli inhibition activities. The antibacterial mechanism of the chitosan sulfate and its derivatives was also simply discussed.
Scavenging activity of hydroxyethyl chitosan sulfate (HCS) against 2,2-diphenyl-1-picrylhydrazyl (DPPH), hydroxyl and carbon-centered radical species were studied using electron spin resonance (ESR) ...spectroscopy. In addition, its antioxidant activity to retard lipid peroxidation was also evaluated in a linoleic acid model system. HCS could scavenge DPPH (33.78%, 2.5
mg/mL) and carbon-centered radicals (67.74%, 0.25
mg/mL) effectively. However, chitosan sulfate did not exhibit any scavenging activity against hydroxyl radicals, but increased its generation. This was different from the published literature and was presumed due to the loss of chelating ability on Fe
2+. This assumption could further confirm from the results obtained for Fe
2+-ferrozine method that upon sulfation chitooligosaccharides lost its chelation properties. Therefore, HCS can be identified as antioxidant that effectively scavenges carbon centered radicals to retard lipid peroxidation.
Strongly adsorbing hydrophobic cationic polyelectrolyte, Eudragit RS, containing ∼2.5
mol% of pendent hydrophilic trimethylammonium (TMA) groups irreversibly adsorbs from its methylene chloride (MCl) ...solution at the MCl/water interface and forms solid-like adsorption layers (ALs). Submitted to periodic dilational deformations with the standard radial frequency
ω
0
=
0.63
rad/s, these ALs exhibit relatively high dilational storage modulus
E′
∼
20
mN/m and practically zero loss modulus
E′′ at the bulk concentration
C
Eud
=
4
×
10
−3
g/L. The frequency scanning of these ALs in the diapason
ω
=
0.01–0.63
rad/s and the approximation of the experimental dependences
E′(
ω) and
E′′(
ω) by two relaxation times rheological model makes it possible to estimate the crossing frequency of these ALs determined from the condition
E′(
ω
c)
=
E′′(
ω
c) as
ω
c
∼
5
×
10
−4
rad/s. Upon dissolving the hydrophilic anionic polyelectrolyte, chitosan sulfate (ChS), in the water phase (
C
ChS
=
3
×
10
−2
g/L) the electrostatic interpolyelectrolyte complexes form at the MCl/water interface. The elasticity moduli
E′ and
E′′ of these mixed AL did not undergo remarkable variations, but the crossing frequency is sharply increased by ∼10 times becoming equal to
ω
c
≅
3
×
10
−3
rad/s. The increase of
ω
c certifies for the liquefaction of mixed Eudragit RS/ChS adsorption layers. A remarkable decrease of the storage modulus down to
E′
=
8
mN/m and simultaneous increase of the crossing frequency up to
ω
c
≅
10
−2
rad/s occurs upon increasing the concentrations of both components, Eudragit RS and ChS, up to 0.1
g/L. The liquefaction effect in the mixed ALs of oppositely charged polyelectrolytes was explained on the basis of the proposed relaxation mechanism. The effect of the liquefaction of adsorption layers of strongly adsorbing hydrophobic polyelectrolytes by formation of interpolyelectrolyte complexes with hydrophilic polyelectrolytes must be taken into account in the production of nano-capsules and nano-fibers.
Introduction:
Amphiphilic copolymers are capable of forming core shell-like structures at the critical micellar concentration (CMC); hence, they can serve as drug carriers. Thus, in the present work, ...polymeric micelles based on novel chitosan derivative were synthesized.
Methods:
Block copolymer of palmitoyl glycol chitosan sulfate (PGCS) was prepared by grafting palmitoyl and sulfate groups serving as hydrophobic and hydrophilic fractions, respectively. Then, fourier transform infrared spectra (FTIR) and spectral changes in iodine/iodide mixture were carried out.
Results:
FTIR studies confirmed the formation of palmitoyl glycol chitosan sulfate (PGCS) and spectral changes in iodine/iodide mixture indicated CMC which lies in the range of 0.003-0.2 mg/ml.
Conclusion:
Therefore, our study indicated that polymeric micelles based on palmitoyl glycol chitosan sulphate could be used as a prospective carrier for water insoluble drugs.
The present work aimed to synthesis of chitin, chitosan and sulfation of chitosan from cuttlebone of cuttlefish Sepia kobiensis. Principally chitin was extracted through sequential processes of ...demineralisation and deproteinzation. Then chitosan was synthesized by a deacetylation and finally sulfated at semi-heterogeneous condition using chlorosulfonic acid in N,N-dimethylformamide. The synthesized macromolecules were characterized for its structural, physical and thermal (CHN, DDA, FT-IR, NMR, XRD, Viscometric analysis, SEM and DSC) properties. Apart from anticoagulant potential of the sulfated chitosan was tested using human plasma by means of activated partial thromboplastin time (APTT) and prothrombin time (PT). Further sulfated chitosan was tested for antibacterial potential by well diffusion method against eleven human pathogenic clinical isolates of both Gram positive and Gram-negative strains and minimum inhibitory concentrations (MIC) was calculated accordingly. The results of this study revealed the effectiveness of the sulfated chitosan at semi-heterogeneous conditions as a potent antibacterial and anticoagulant molecule.
Ten dextran sulphates and six chitosan sulphates of variable Mr and extent of sulphate substitution have been examined for their ability to inhibit human leukocyte elastase (HLE). All were potent ...partial non-competitive inhibitors of this enzyme, highest activity being obtained with compounds of large molecular weight and maximum sulphate incorporation (Ki = 5.0 X 10(-10)M. In all cases, the dextran sulphates were more effective inhibitors than chitosan sulphates of similar size and charge, but both classes were inactive against bovine trypsin, chymotrypsin and porcine pancreatic elastase at concentrations less than 10(-4)M. The data suggest that drug binding to HLE occurs by stereospecific electrostatic interactions at site(s) removed from the catalytic reaction centre.
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The strategy in this work was loading Melatonin (MEL), the powerful antioxidant photosensitive molecule, in novel Pickering emulsions (PEs) stabilized by chitosan-dextran sulphate ...nanoparticles (CS-DS NPs) and enhanced by lecithin, for treatment of androgenic alopecia (AGA). Biodegradable CS-DS NPs dispersion was prepared by polyelectrolyte complexation and optimized for PEs stabilization. PEs were characterized for droplet size, zeta potential, morphology, photostability and antioxidant activity. Ex-vivo permeation study through rat full thickness skin was conducted with optimized formula. Differential tape stripping trailed by cyanoacrylate skin surface biopsy was executed, for quantifying MEL in skin compartments and hair follicles. In-vivo evaluation of MEL PE hair growth activity was performed on testosterone induced AGA rat model. Visual inspection followed by anagen to telogen phase ratio (A/T) and histopathological examinations were conducted and compared with marketed 5% minoxidil spray “Rogaine ®”. Data showed that PE improved MEL antioxidant activity and photostability. Ex-vivo results displayed MEL PE high follicular deposition. In-vivo study demonstrated that MEL PE treated testosterone induced AGA rat group, restored hair loss and produced maximum hair regeneration along with prolonged anagen phase amongst tested groups. The histopathological examination revealed that MEL PE prolonged anagen stage, increased follicular density and A/T ratio by 1.5-fold. The results suggested that lecithin-enhanced PE stabilized by CS-DS NPs was found to be an effective approach to enhance photostability, antioxidant activity and follicular delivery of MEL. Thus, MEL-loaded PE could be a promising competitor to commercially marketed Minoxidil for treatment of AGA.
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