共查询到20条相似文献,搜索用时 421 毫秒
1.
The aim of the investigation was to prepare and characterize wheat germ agglutinin(WGA)-conjugated poly(d,l-lactic-co-glycolic) acid nanoparticles encapsulating mometasone furoate (MF) as a model drug and assess changes in its fate in terms
of cellular interactions. MF loaded nanoparticles were prepared using emulsion–solvent evaporation technique. WGA-conjugation
was done by carbodiimide coupling method. The nanoparticles were characterized for size, zeta potential, entrapment efficiency
and in-vitro drug release. The intracellular uptake of nanoparticles, drug cellular levels, and anti-proliferative activity studies of
wheat germ agglutinin-conjugated and unconjugated nanoparticles were assessed on alveolar epithelial (A549) cells to establish
cellular interactions. Prepared nanoparticles were spherical with 10–15 μg/mg of WGA conjugated on nanoparticles. The size
of nanoparticles increased after conjugation and drug entrapment and zeta potential reduced from 78 ± 5.5% to 60 ± 2.5% and
−15.3 ± 1.9 to −2.59 ± 2.1 mV respectively after conjugation. From the cellular drug concentration–time plot, AUC was found
to be 0.4745, 0.6791 and 1.24 for MF, MF-nanoparticles and wheat germ agglutinin-MF-nanoparticles respectively. The in-vitro antiproliferative activity was improved and prolonged significantly after wheat germ agglutinin-conjugation. The results
conclusively demonstrate improved availability and efficacy of antiasthmatic drug in alveolar epithelial cell lines. Hence,
a drug once formulated as mucoadhesive nanoparticles and incorporated in dry powder inhaler formulation may be used for targeting
any segment of lungs for more improved therapeutic response in other lung disorders as well. 相似文献
2.
In the present study attempt was made for preparation of isotretinoin-hydroxypropyl β cyclodextrin (HP-β-CD) inclusion complex
and encapsulate this complex in elastic liposomes to study the effect of dual carrier approach on skin targeting of isotretinoin.
The isotretinoin HP-β-CD complex was prepared by freeze-drying method and characterized by IR spectroscopy. The drug and drug-CD
complex loaded elastic liposomal formulation were prepared and characterized in vitro, ex-vivo and in vivo for shape, size, entrapment efficiency, no. of vesicles per cubic mm, in vitro skin permeation and deposition study, photodegradation and skin toxicity assay. The transdermal flux for different vesicular
formulations was observed between 10.5 ± 0.5 to 13.9 ± 1.6 μg/cm2/h. This is about 15-21 folds higher than that obtained from drug solution (0.7 ± 0.1 μg/cm2/h) and 4-5 folds higher than obtained with drug-CD complex solution (2.7 ± 0.1 μg/cm2/h). The amount of drug deposit was found to increase significantly (p < 0.05) by cyclodextrin complexation (30.1 ± 0.1 μg). The encapsulation of this complex in elastic liposomal formulation
further increases its skin deposition (262.2 ± 21 μg). The results of skin irritation study using Draize test also showed
the significant reduction in skin irritation potential of isotretinoin elastic liposomal formulation in comparison to free
drug. The results of the present study demonstrated that isotretinoin elastic liposomal formulation possesses great potential
for skin targeting, prolonging drug release, reduction of photodegradation, reducing skin irritation and improving topical
delivery of isotretinoin. 相似文献
3.
Takashi Nemoto Taisuke Watanabe Yutaka Mizogami Jun-ichi Maruyama Katsuhiko Kitamoto 《Applied microbiology and biotechnology》2009,82(6):1105-1114
The recombinant Pichia pastoris harboring an improved methionine adenosyltransferase (MAT) shuffled gene was employed to biosynthesize S-adenosyl-l-methionine (SAM). Two l-methionine (l-Met) addition strategies were used to supply the precursor: the batch addition strategy (l-Met was added separately at three time points) and the continuous feeding strategies (l-Met was fed continuously at the rate of 0.1, 0.2, and 0.5 g l−1 h−1, respectively). SAM accumulation, l-Met conversion rate, and SAM productivity with the continuous feeding strategies were all improved over the batch addition
strategy, which reached 8.46 ± 0.31 g l−1, 41.7 ± 1.4%, and 0.18 ± 0.01 g l−1 h−1 with the best continuous feeding strategy (0.2 g l−1 h−1), respectively. The bottleneck for SAM production with the low l-Met feeding rate (0.1 g L−1 h−1) was the insufficient l-Met supply. The analysis of the key enzyme activities indicated that the tricarboxylic acid cycle and glycolytic pathway
were reduced with the increasing l-Met feeding rate, which decreased the adenosine triphosphate (ATP) synthesis. The MAT activity also decreased as the l-Met feeding rate rose. The reduced ATP synthesis and MAT activity were probably the reason for the low SAM accumulation when
the l-Met feeding rate reached 0.5 g l−1 h−1. 相似文献
4.
In order to develop a novel transdermal drug delivery system that facilitates the skin permeation of finasteride encapsulated
in novel lipid-based vesicular carriers (ethosomes)finasteride ethosomes were constructed and the morphological characteristics
were studied by transmission electron microscopy. The particle size, zeta potential and the entrapment capacity of ethosome
were also determined. In contrast to liposomes ethosomes were of more condensed vesicular structure and they were found to
be oppositely charged. Ethosomes were found to be more efficient delivery carriers with high encapsulation capacities. In vitro percutaneous permeation experiments demonstrated that the permeation of finasteride through human cadaver skin was significantly
increased when ethosomes were used. The finasteride transdermal fluxes from ethosomes containing formulation (1.34 ± 0.11 μg/cm2/h) were 7.4, 3.2 and 2.6 times higher than that of finasteride from aqueous solution, conventional liposomes and hydroethanolic
solution respectively (P < 0.01).Furthermore, ethosomes produced a significant (P < 0.01) finasteride accumulation in the skin, especially in deeper layers, for instance in dermis it reached to 18.2 ± 1.8 μg/cm2. In contrast, the accumulation of finasteride in the dermis was only 2.8 ± 1.3 μg/cm2 with liposome formulation. The study demonstrated that ethosomes are promising vesicular carriers for enhancing percutaneous
absorption of finasteride. 相似文献
5.
The purpose of this work was to develop and optimize gliclazide-loaded alginate–methyl cellulose mucoadhesive microcapsules
by ionotropic gelation using central composite design. The effect of formulation parameters like polymer blend ratio and cross-linker
(CaCl2) concentration on properties of gliclazide-loaded alginate–methyl cellulose microcapsules like drug encapsulation efficiency
and drug release were optimized. The optimized microcapsules were subjected to swelling, mucoadhesive, and in vivo studies. The observed responses coincided well with the predicted values from the optimization technique. The optimized microcapsules
showed high drug encapsulation efficiency (83.57 ± 2.59% to 85.52 ± 3.07%) with low T
50% (time for 50% drug release, 5.68 ± 0.09 to 5.83 ± 0.11 h). The in vitro drug release pattern from optimized microcapsules was found to be controlled-release pattern (zero order) with case II transport
release mechanism. Particle sizes of these optimized microcapsules were 0.767 ± 0.085 to 0.937 ± 0.086 mm. These microcapsules
also exhibited good mucoadhesive properties. The in vivo studies on alloxan-induced diabetic rats indicated the significant hypoglycemic effect that was observed 12 h after oral
administration of optimized mucoadhesive microcapsules. The developed and optimized alginate–methyl cellulose microcapsules
are suitable for prolonged systemic absorption of gliclazide to maintain lower blood glucose level and improved patient compliance. 相似文献
6.
Synthesis of cyanophycin (multi-l-arginyl-poly-l-aspartic acid, CGP) in recombinant organisms is an important option to obtain sufficiently large amounts of this polymer
with a designed composition for use as putative precursors for biodegradable technically interesting chemicals. Therefore,
derivates of CGP, harbouring a wider range of constituents, are of particular interest. As shown previously, cyanophycin synthetases
with wide substrate ranges incorporate other amino acids than arginine. Therefore, using an organism, which produces the required
supplement by itself, was the next logical step. Former studies showed that Pseudomonas putida strain ATCC 4359 is able to produce large amounts of l-citrulline from l-arginine. By expressing the cyanophycin synthetase of Synechocystis sp. PCC 6308, synthesis of CGP was observed in P. putida ATCC 4359. Using an optimised medium for cultivation, the strain was able to synthesise insoluble CGP amounting up to 14.7 ± 0.7%
(w/w) and soluble CGP amounting up to 28.7 ± 0.8% (w/w) of the cell dry matter, resulting in a total CGP content of the cells of 43.4% (w/w). HPLC analysis of the soluble CGP showed that it was composed of 50.4 ± 1.3 mol % aspartic acid, 32.7 ± 2.8 mol % arginine,
8.7 ± 1.6 mol % citrulline and 8.3 ± 0.4 mol % lysine, whereas the insoluble CGP contained less than 1 mol % of citrulline.
Using a mineral salt medium with 1.25 or 2% (w/v) sodium succinate, respectively, plus 23.7 mM l-arginine, the cells synthesised insoluble CGP amounting up to 25% to 29% of the CDM with only a very low citrulline content. 相似文献
7.
M. Helanto K. Kiviharju T. Granström M. Leisola A. Nyyssölä 《Applied microbiology and biotechnology》2009,83(1):77-83
l-Ribose is a rare and expensive sugar that can be used as a precursor for the production of l-nucleoside analogues, which are used as antiviral drugs. In this work, we describe a novel way of producing l-ribose from the readily available raw material l-arabinose. This was achieved by introducing l-ribose isomerase activity into l-ribulokinase-deficient Escherichia coli UP1110 and Lactobacillus plantarum BPT197 strains. The process for l-ribose production by resting cells was investigated. The initial l-ribose production rates at 39°C and pH 8 were 0.46 ± 0.01 g g−1 h−1 (1.84 ± 0.03 g l−1 h−1) and 0.27 ± 0.01 g g−1 h−1 (1.91 ± 0.1 g l−1 h−1) for E. coli and for L. plantarum, respectively. Conversions were around 20% at their highest in the experiments. Also partially purified protein precipitates
having both l-arabinose isomerase and l-ribose isomerase activity were successfully used for converting l-arabinose to l-ribose. 相似文献
8.
Tumor cells have a high tolerance for acidic and hypoxic microenvironments, also producing abundant lactic acid through accelerated
glycolysis in the presence or absence of O2. While the accumulation of lactate is thought to be a major contributor to the reduction of pH-circumscribing aggressive
tumors, it is not known if other endogenous metabolic products contribute this acidity. Furthermore, anaerobic metabolism
in cancer cells bears similarity to homo-fermentative lactic acid bacteria, however very little is known about an alternative
pathway that may drive adenosine triphosphate (ATP) production independent of glycolysis. In this study, we quantify over
40 end-products (amines, acids, alcohols, aldehydes, or ketones) produced by malignant neuroblastoma under accelerated glycolysis
(+glucose (GLU) supply 1–10 mM) ± mitochondrial toxin; 1-methyl-4-phenylpyridinium (MPP+) to abate aerobic respiration to delineate differences between anaerobic vs. aerobic cell required metabolic pathways. The
data show that an acceleration of anaerobic glycolysis prompts an expected reduction in extracellular pH (pHex) from neutral to 6.7 ± 0.006. Diverse metabolic acids associated with this drop in acidity were quantified by ionic exchange
liquid chromatography (LC), showing concomitant rise in lactate (Ctrls 7.5 ± 0.5 mM; +GLU 12.35 ± 1.3 mM; +GLU + MPP 18.1 ± 1.8 mM),
acetate (Ctrl 0.84 ± 0.13 mM: +GLU 1.3 ± 0.15 mM; +GLU + MPP 2.7 ± 0.4 mM), fumarate, and a-ketoglutarate (<10 μM) while a
range of other metabolic organic acids remained undetected. Amino acids quantified by o-phthalaldehyde precolumn derivatization/electrochemical detection–LC show accumulation of l-alanine (1.6 ± .052 mM), l-glutamate (285 ± 9.7 μM), l-asparagine (202 ± 2.1 μM), and l-aspartate (84.2 ± 4.9 μM) produced during routine metabolism, while other amino acids remain undetected. In contrast, the
data show no evidence for accumulation of acetaldehyde, aldehydes, or ketones (Purpald/2,4-dinitrophenylhydrazine—Brady's
reagent), acetoin (Voges–Proskauer test), or alcohols (NAD+-linked alcohol dehydrogenase). In conclusion, these results provide preliminary evidence to suggest the existence of an active
pyruvate–alanine transaminase or phosphotransacetylase/acetyl-CoA synthetase pathway to be involved with anaerobic energy
metabolism of cancer cells. 相似文献
9.
The present research work was aimed to formulate clotrimazole encapsulated Cavamax W7 composite ethosomes by injection method
for improved delivery across epidermis. 32 factorial design was used to design nine formulations (F1-F9) and compared with ethosomal formulations (F10-F12). F9 with
vesicle size of 202.8 ± 4.8 nm, highest zeta potential (−83.6 ± 0.96 mV) and %EE of 98.42 ± 0.15 was selected as optimized
composite ethosome and F12 as reference ethosomal formulation. As revealed by transmission electron microscopy F9 vesicles
were more condensed, uniformly spherical in shape than F12 vesicles. Vesicular stability studies indicated F9 to be more stable
as compared to F12. Both F9 and F12 were incorporated in carbopol 934 gel base to get G1–G8 gel formulations and evaluated
for in vitro skin permeability. Cavamax W7 composite ethosomal optimized gel (G5) showed higher in vitro percent cumulative drug permeation (88.53 ± 2.10%) in 8 h and steady state flux (J
ss) of 3.39 ± 1.45 μg/cm2/min against the J
ss of 1.57 ± 0.23 μg/cm2/min for ethosomal gel (G1) and 1.13 ± 0.06 μg/cm2/min for marketed formulation. The J
ss flux of G5 was independent of amount of drug applied/unit area of skin. In vivo confocal laser scanning microscopic study of G5 depicted uniform and deeper penetration of rhodamine B (marker) in epidermis
from Cavamax W7 composite ethosomal gel in comparison to G1. Finally, G5 demonstrated better (p < 0.05) antifungal activity against Candida albicans and Aspergillus niger than G1 thus, signifying that Cavamax W7 composite ethosomes present a superior stable and efficacious vesicular system than
ethosomal formulation for topical delivery of clotrimazole. 相似文献
10.
Ribitsch D Karl W Wehrschütz-Sigl E Tutz S Remler P Weber HJ Gruber K Stehr R Bessler C Hoven N Sauter K Maurer KH Schwab H 《Applied microbiology and biotechnology》2009,81(5):875-886
In the course of a microbial screening of soil samples for new oxidases, different enrichment strategies were carried out.
With choline as the only carbon source, a microorganism was isolated and identified as Arthrobacter nicotianae. From this strain, a gene coding for a choline oxidase was isolated from chromosomal DNA. This gene named codA was cloned in Escherichia coli BL21-Gold and the protein (An_CodA) heterologously overexpressed as a soluble intracellular protein of 59.1 kDa. Basic biochemical characterization of
purified protein revealed a pH optimum of 7.4 and activity over a broad temperature range (15–70 °C). Specific activities
were determined toward choline chloride (4.70 ± 0.12 U/mg) and the synthetic analogs bis(2-hydroxyethyl)-dimethylammonium
chloride (0.05 ± 0.45 × 10–2 U/mg) and tris-(2-hydroxyethyl)-methylammonium methylsulfate (0.01 ± 0.12 × 10–2 U/mg). With increasing number of oxidizable groups, a significant decrease in activity was noted. Determination of kinetic
parameters in atmorspheric oxygen resulted in K
M = 1.51 ± 0.09 mM and V
max = 42.73 ± 0.42 mU/min for choline chloride and K
M = 4.77 ± 0.76 mM and V
max = 48.40 ± 2.88 mU/min for the reaction intermediate betaine aldehyde respectively. Nuclear magnetic resonance spectroscopic
analysis of the products formed during the enzyme reaction with choline chloride showed that in vitro the intermediate betaine
aldehyde exists also free in solution. 相似文献
11.
Production of hexanoic acid from d-galactitol by a newly isolated Clostridium sp. BS-1 总被引:1,自引:0,他引:1
Byoung Seung Jeon Byung-Chun Kim Youngsoon Um Byoung-In Sang 《Applied microbiology and biotechnology》2010,88(5):1161-1167
In a study screening anaerobic microbes utilizing d-galactitol as a fermentable carbon source, four bacterial strains were isolated from an enrichment culture producing H2, ethanol, butanol, acetic acid, butyric acid, and hexanoic acid. Among these isolates, strain BS-1 produced hexanoic acid
as a major metabolic product of anaerobic fermentation with d-galactitol. Strain BS-1 belonged to the genus Clostridium based on phylogenetic analysis using 16S rRNA gene sequences, and the most closely related strain was Clostridium sporosphaeroides DSM 1294T, with 94.4% 16S rRNA gene similarity. In batch cultures, Clostridium sp. BS-1 produced 550 ± 31 mL L−1 of H2, 0.36 ± 0.01 g L−1 of acetic acid, 0.44 ± 0.01 g L−1 of butyric acid, and 0.98 ± 0.03 g L−1 of hexanoic acid in a 4-day cultivation. The production of hexanoic acid increased to 1.22 and 1.73 g L−1 with the addition of 1.5 g L−1 of sodium acetate and 100 mM 2-(N-morpholino)ethanesulfonic acid (MES), respectively. Especially when 1.5 g L−1 of sodium acetate and 100 mM MES were added simultaneously, the production of hexanoic acid increased up to 2.99 g L−1. Without adding sodium acetate, 2.75 g L−1 of hexanoic acid production from d-galactitol was achieved using a coculture of Clostridium sp. BS-1 and one of the isolates, Clostridium sp. BS-7, in the presence of 100 mM MES. In addition, volatile fatty acid (VFA) production by Clostridium sp. BS-1 from d-galactitol and d-glucose was enhanced when a more reduced culture redox potential (CRP) was applied via addition of Na2S·9H2O. 相似文献
12.
Gigartina skottsbergii is a commercially important carrageenan producer that has been suffering severe extraction pressure in Chile’s Magellan Region
and Cape Horn Archipelago since 1998. In order to create baseline information for its cultivation and repopulation, we studied
the effects of agricultural fertilizers on growth of G. skottsbergii early developmental stages. The culture media utilized were: a) seawater + Bayfoland, b) seawater + Superphosphate, c) seawater
+ Urea, d) seawater + Provasoli and e) seawater as a control. The culture conditions were: a) 12L:12D photoperiod; b) temperature
8 ± 1°C and c) irradiance at 45 μmol photons m−2 s−1. After 60 days, higher relative growth rates between treatments were observed; the treatments that included Bayfoland and
Provasoli showed greater growth (382 ± 55 and 378 ± 50 μm, respectively,) compared to Superphosphate (88 ± 16 μm), control
(78 ± 10 μm) and Urea (70 ± 11 μm) treatments, after 81 days. The Urea treatment and the control had inhibitory effects on
G. skottsbergii germlings growth and survival, as evidenced by progressive loss of pigmentation and death after 60 days. These results showed
that Bayfoland was an excellent alternative to develop cultures. 相似文献
13.
Glibenclamide (GL)-loaded microcapsules (MC) and transdermal patches (TDP) were formulated and in vitro and in vivo parameters compared to find out the best route of drug administration. The formulation TDP1 having a drug–polymer ratio 1:1
showed comparatively higher GL release and better permeation across mice skin (p < 0.05). From the comparative study, it was concluded that the transdermal system of GL produced better improvement compared
to oral microcapsule administration (p < 0.05). The transdermal system exhibited comparatively slow and continuous supply of GL at a desired rate to systemic circulation
avoiding metabolism, which improved day-to-day glycemic control in diabetic subjects. Transdermal system of GL exhibited better
control of hyperglycemia and prolonged plasma half-life by transdermal systems (9.6 ± 1.2 h) in comparison with oral microcapsule
(5.84 ± 2.1 h), indicating that the drug, when administered by transdermal systems, will remain in the body for a longer period.
From the glucose tolerance test, transdermal route effectively maintained the normoglycemic levels in contrast to the oral
group (MC1), which produced remarkable hypoglycemia ranging from −12.6 ± 2.1% to −18 ± 2.3%. The significantly high (p < 0.05) area under the curve values observed with transdermal system (1,346.2 ± 92.3 ng ml−1 h−1) also indicate increased bioavailability of the drug from these systems compared to the oral route (829.8 ± 76.4 ng ml−1 h−1). 相似文献
14.
An DS Cui CH Sung BH Yang HC Kim SC Lee ST Im WT Kim SG 《Applied microbiology and biotechnology》2012,94(3):673-682
The gene encoding an α-l-arabinofuranosidase that could biotransform ginsenoside Rc {3-O-[β-d-glucopyranosyl-(1–2)-β-d-glucopyranosyl]-20-O-[α-l-arabinofuranosyl-(1–6)-β-d-glucopyranosyl]-20(S)-protopanaxadiol} to ginsenoside Rd {3-O-[β-d-glucopyranosyl-(1–2)-β-d-glucopyranosyl]-20-O-β-d-glucopyranosyl-20(S)-protopanaxadiol} was cloned from a soil bacterium, Rhodanobacter ginsenosidimutans strain Gsoil 3054T, and the recombinant enzyme was characterized. The enzyme (AbfA) hydrolyzed the arabinofuranosyl moiety from ginsenoside
Rc and was classified as a family 51 glycoside hydrolase based on amino acid sequence analysis. Recombinant AbfA expressed
in Escherichia coli hydrolyzed non-reducing arabinofuranoside moieties with apparent K
m values of 0.53 ± 0.07 and 0.30 ± 0.07 mM and V
max values of 27.1 ± 1.7 and 49.6 ± 4.1 μmol min−1 mg−1 of protein for p-nitrophenyl-α-l-arabinofuranoside and ginsenoside Rc, respectively. The enzyme exhibited preferential substrate specificity of the exo-type
mode of action towards polyarabinosides or oligoarabinosides. AbfA demonstrated substrate-specific activity for the bioconversion
of ginsenosides, as it hydrolyzed only arabinofuranoside moieties from ginsenoside Rc and its derivatives, and not other sugar
groups. These results are the first report of a glycoside hydrolase family 51 α-l-arabinofuranosidase that can transform ginsenoside Rc to Rd. 相似文献
15.
Characteristics of Se-Enriched Mycelia by Stropharia rugoso-annulata and its Antioxidant Activities in vivo 总被引:1,自引:0,他引:1
Zhen Song Le Jia Feng Xu Fanyun Meng Peng Deng Keming Fan Xiaonan Liu 《Biological trace element research》2009,131(1):81-89
Selenium (Se) is an essential trace element for humans and animals. Stropharia rugoso-annulata is a nutritional and functional mushroom containing many kinds of bioactive ingredients. The aims of this study were to investigate
the Se-enrichment characteristics of S. rugoso-annulata in submerged culture and evaluate the antioxidant activities of Se-enriched mycelia in vivo in terms of the values of glutathione
peroxidase (GSH-Px), superoxide dismutase (SOD), and malondialdehyde (MDA). The optimum parameters of Se-enrichment under
the optimal Se concentration (150 μg/mL) in media were as follows: biomass 8.11 ± 0.25 g/L, Se content in mycelia 4,727.68 ± 13 μg/g,
Se-accumulated rate 24.68 ± 1.67%, and percentage of organic Se 96.27 ± 3.26%. The mainly subsistent forms of selenium in
Se-enriched mycelia were selenoprotein and selenium-polysaccharide. The contents of total amino acids (TAA) and essential
amino acids (EAA) in Se-enriched mycelia were increased by 13.5 ± 1.09% and 12.8 ± 0.89%, respectively. It was efficient for
Se-enriched mycelia to elevate GSH-Px and SOD activities and decrease MDA content. These results indicated that Se-enriched
mycelia of S. rugoso-annulata represent a novel dietary source of bioavailable supplemental selenium. 相似文献
16.
Soria F Ellenrieder G Oliveira GB Cabrera M Carvalho LB 《Applied microbiology and biotechnology》2012,93(3):1127-1134
α-l-Rhamnosidase from Aspergillus terreus was covalently immobilized on the following ferromagnetic supports: polyethylene terephthalate (Dacron-hydrazide), polysiloxane/polyvinyl
alcohol (POS/PVA), and chitosan. The powdered supports were magnetized by thermal coprecipitation method using ferric and
ferrous chlorides, and the immobilization was carried out via glutaraldehyde. The activity of the Dacron-hydrazide (0.53 nkat/μg
of protein) and POS/PVA (0.59 nkat/μg of protein) immobilized enzyme was significantly higher than that found for the chitosan
derivative (0.06 nkat/μg of protein). The activity–pH and activity–temperature profiles for all immobilized enzymes did not
show difference compared to the free enzyme, except the chitosan derivative that presented higher maximum temperature at 65 °C.
The Dacron-hydrazide derivative thermal stability showed a similar behavior of the free enzyme in the temperature range of
40–70 °C. The POS/PVA and chitosan derivatives were stable up to 60 °C, but were completely inactivated at 70 °C. The activity
of the preparations did not appreciably decrease after ten successive reuses. Apparent K
m of α-l-rhamnosidase immobilized on magnetized Dacron-hydrazide (1.05 ± 0.22 mM), POS/PVA (0.57 ± 0.09 mM), and chitosan (1.78 ± 0.24 mM)
were higher than that estimated for the soluble enzyme (0.30 ± 0.03 mM). The Dacron-hydrazide enzyme derivative showed better
performance than the free enzyme to hydrolyze 0.3% narigin (91% and 73% after 1 h, respectively) and synthesize rhamnosides
(0.116 and 0.014 mg narirutin after 1 h, respectively). 相似文献
17.
Morphological and Genetic Characterization of <Emphasis Type="Italic">Saimiri boliviensis</Emphasis>
Eliana Ruth Steinberg Mariela Nieves Marina Sofía Ascunce Ana María Palermo Marta Dolores Mudry 《International journal of primatology》2009,30(1):29-41
The taxonomy of Saimiri is controversial because morphological characteristics, traditionally used for identification, are insufficient to distinguish
species and subspecies. Genetic studies of specimens become relevant for captive management, especially considering their
frequently unknown geographical origin. We analyzed phenotypic and genetic parameters in Saimiri spp. in Argentinean zoological gardens and biological stations to provide a more accurate taxonomic identification. We studied
27 males and 19 females of Saimiri spp. The cytogenetic analysis in mitotic metaphases corroborated a modal number of 2N = 44, XX/XY, and FN = 75 for males
and FN = 76 for females. G- and C-bands, fluorescence in situ hybridization (FISH) and the pelage coloration pattern of all the specimens corresponded to Saimiri boliviensis boliviensis. We characterized for the first time the sperm cell morphology and morphometry (mean ± SE): total length: 71.39 ± 5.40 μm;
head length: 5.71 ± 0.81 μm; head width: 3.76 ± 0.70 μm; acrosome length: 3.70 ± 0.82 μm; midpiece length: 12.20 ± 2.22 μm.
Researchers can use the characterization of the sperm morphology as another parameter for taxonomic identification that, together
with cytogenetic and molecular ones, would allow a more precise identification of individual Saimiri boliviensis boliviensis. 相似文献
18.
Chuong MC Palugan L Su TM Busano C Lee R Di Pretoro G Shah A 《AAPS PharmSciTech》2010,11(4):1650-1661
Vitamin B3 is made up of niacin (nicotinic acid) and its amide, niacinamide. Both have equivalent vitamin activity, but only niacin
(not niacinamide) is effective in lowering elevated low-density lipoprotein cholesterol and triglyceride levels in the blood.
Administration of an extended-release (ER) oral tablet would frequently encounter food. If hydrogel is used to formulate the
matrix of a biopharmaceutical classification system I drug (high solubility and high permeability), the dosage form absorbs
water and swells.. The softened outer layer may be slashed off by food present in the stomach, thus, exposing the core tablet
more readily for water absorption and speeding up drug release from its original designed rate. This project aimed to formulate
niacin CR pellets made of hydrophobic inert matrix. After niacin was melted with excipients and cooled, the mass was extruded
and spheronized into pellets. Size distribution and flowability were determined before pellets were filled into hard gelatin
capsule. The USP dissolution study revealed that a candidate formulation of 250 mg in strength released similar amount of
niacin as its commercial reference, niacin controlled-release 500 mg tablet, in 6 h (223.9 ± 23.8 mg, n = 4 versus 259.4 ± 2.6 mg, n = 3). The differential scanning calorimetry study of the pellets in capsules stored in 40°C for 4 weeks, and the content
assay of capsules in 40°C up to 6 months suggested that niacin was stable within the innovative formulation. In vitro release from this innovative ER capsules stored at 40°C up to 4 weeks were also investigated. 相似文献
19.
Syntheses of l-dopa 1a glucoside 10a,b and dl-dopa 1b glycosides 10–18 with d-glucose 2, d-galactose 3, d-mannose 4, d-fructose 5, d-arabinose 6, lactose 7, d-sorbitol 8 and d-mannitol 9 were carried out using amyloglucosidase from Rhizopus mold, β-glucosidase isolated from sweet almond and immobilized β-glucosidase. Invariably, l-dopa and dl-dopa gave low to good yields of glycosides 10–18 at 12–49% range and only mono glycosylated products were detected through glycosylation/arylation at the third or fourth
OH positions of l-dopa 1a and dl-dopa 1b. Amyloglucosidase showed selectivity with d-mannose 4 to give 4-O-C1β and d-sorbitol 8 to give 4-O-C6-O-arylated product. β-Glucosidase exhibited selectivity with d-mannose 4 to give 4-O-C1β and lactose 7 to give 4-O-C1β product. Immobilized β-glucosidase did not show any selectivity. Antioxidant and angiotensin converting enzyme inhibition
(ACE) activities of the glycosides were evaluated glycosides, out of which l-3-hydroxy-4-O-(β-d-galactopyranosyl-(1′→4)β-d-glucopyranosyl) phenylalanine 16 at 0.9 ± 0.05 mM and dl-3-hydroxy-4-O-(β-d-glucopyranosyl) phenylalanine 11b,c at 0.98 ± 0.05 mM showed the best IC50 values for antioxidant activity and dl-3-hydroxy-4-O-(6-d-sorbitol)phenylalanine 17 at 0.56 ± 0.03 mM, l-dopa-d-glucoside 10a,b at 1.1 ± 0.06 mM and dl-3-hydroxy-4-O-(d-glucopyranosyl)phenylalanine 11a-d at 1.2 ± 0.06 mM exhibited the best IC50 values for ACE inhibition.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
20.
Julie Marmet Benoît Pisanu Jean-Louis Chapuis 《European Journal of Wildlife Research》2009,55(5):497-504
Home range size, range overlap, and multiyear site fidelity were investigated for introduced Siberian chipmunks (Tamias sibiricus) in a French suburban forest from bimonthly trapping sessions for 4 years (2004–2007). Annual home range sizes (100% minimum
convex polygon, ±SE) were estimated from 39 trapping histories of 28 different adult residents. Males (N = 13, 1.86 ± 0.32 ha) had a home range 2.5 times larger than females (N = 26, 0.71 ± 0.08 ha); a male home range included significantly more trapping centers (arithmetic mean of capture locations)
of females (5.5 ± 0.7) than of males (2.3 ± 0.5). Chipmunks exhibited strong multiyear site fidelity: mean distance between
annual trapping centers of individuals trapped over two successive years was small (N = 82, 26 ± 2 m) compared to the largest home range length (ranging from 36 to 281 m); overlap between annual home range sizes
of residents was 84 ± 5% (N = 11). These results improve our understanding of the space occupation of this unknown species in a novel environment. 相似文献