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41.
42.
Production and characterization of pullulan from beet molasses using a nonpigmented strain of Aureobasidium pullulans in batch culture 总被引:2,自引:0,他引:2
Lazaridou A Biliaderis CG Roukas T Izydorczyk M 《Applied biochemistry and biotechnology》2002,97(1):1-22
The production of pullulan from beet molasses by a pigment-free strain of Aureobasidium pullulans on shake-flask culture was investigated. Combined pretreatment of molasses with sulfuric acid and activated carbon to remove
potential fermentation inhibitors present in molasses resulted in a maximum pullulan concentration of 24 g/L, a biomass dry
wt of 14 g/L, a pullulan yield of 52.5%, and a sugar utilization of 92% with optimum fermentation conditions (initial sugar
concentration of 50 g/L and initial pH of 7.0). The addition of other nutrients as carbon and nitrogen supplements (olive
oil, ammonium sulfate, yeast extract) did not further improve the production of the exopolysaccharides. Structural characterization
of the isolated polysaccharides from the fermentation broths by 13C-nuclear magnetic resonance spectroscopy and pullulanase digestion combined with size-exclusion chromatography confirmed
the identity of pullulan and the homogeneity (>93% dry basis) of the elaborated polysaccharides by the microorganism. Using
multiangle laser light scattering and refractive index detectors in conjunction with high-performance size-exclusion chromatography
molecular size distributions and estimates of the molecular weight (M
w
=2.1−4.1×105), root mean square of the radius of gyration (R
g
=30−38 nm), and polydispersity index (M
w
/M
n
=1.4−2.4) were obtained. The fermentation products of molasses pretreated with sulfuric acid and/or activated carbon were
more homogeneous and free of contaminating proteins. In the concentration range of 2.8−10.0 (w/v), the solution’s rheologic
behavior of the isolated pullulans was almost Newtonian (within 1 and 1200 s−1 at 20°C); a slight shear thinning was observed at 10.0 (w/v) for the high molecular weight samples. Overall, beet molasses
pretreated with sulfuric acid and activated carbon appears as an attractive fermentation medium for the production of pullulan
by A. pullulans. 相似文献
43.
Athina G. Nicolaou Maria C. Mavroudi Ioannis J. Stavrou Choyce A. Weatherly Constantina P. Kapnissi‐Christodoulou 《Electrophoresis》2019,40(4):539-546
The combined use of chiral ionic liquids (CILs) and conventional chiral selectors (CSs) in CE, to establish a synergistic system, has proven to be an effective approach for the separation of enantiomeric pairs. In this study, a new CE method was developed, employing a binary system of a CS, either a cyclodextrin (CD) or a cyclofructan (CF), and a chiral amino acid ester‐based ionic liquid (AAIL), for the chiral separation of four basic, acidic and zwitterionic drug compounds. In particular, the enantioseparation of two anticoagulants, warfarin (WAR) and coumachlor (COU), a non‐opioid analgesic, nefopam (NEF) and a third‐generation antihistamine, fexofenadine (FXD), was examined, by supporting the BGE with a CS and the chiral AAIL L‐alanine tert butyl ester lactate (L‐AlaC4Lac). Parameters, such as the type of the CS, the concentration of both the CS and L‐AlaC4Lac, and the BGE pH, were methodically examined in order to optimize the chiral separation of each analyte. It was observed that, in some cases, the addition of the AAIL into the BGE improved both resolution (Rs) and efficiency (N) significantly. In other cases, the synergistic effect enabled baseline separation of analyte enantiomers, at a much lower concentration of the CS. Finally, after optimization of separation conditions, baseline separations (Rs>1.5) of all four analytes were achieved in less than 5 min. 相似文献
44.
Samvel N. Sirakanyan Athina Geronikaki Viktor G. Kartsev Elmira K. Hakobyan Anush A. Hovakimyan 《合成通讯》2019,49(10):1262-1276
Taking into account previously obtained biological results on some polyheterocyclic compounds (containing different heteroatoms) and in particular on several 8-amino-5-isopropyl-2,2-dimethyl-10-(methylthio)-1,4-dihydro-2H-pyrano[4’’,3’’:4’,5’]pyrido[3’,2’:4,5]thieno[3,2-d]pyrimidines Ia-v we have carried out the synthesis of twentyone 8-amino-5-isobutyl-2,2-dimethyl-10-(methylthio)-1,4-dihydro-2H-pyrano[4’’,3’’:4’,5’]pyrido[3’,2’:4,5]thieno[3,2-d]pyrimidines 6. Therefore we have slightly modified the structure of the previously studied I introducing at C-5 an isobutyl group instead of the previously examined isopropyl ones in order to see if this variation (changing a little the lipophilicity) will affect the biological activity. Furthermore thieno[3,2-d]pyrimidine-8-thione 7 and their S-alkylated 8 were synthesized. Finally by alkylation of 5-isobutyl-2,2-dimethyl-10-thioxo-1,4,10,11-tetrahydro-2H-pyrano[4'',3'':4',5']pyrido[3',2':4,5]thieno[3,2-d]pyrimidin-8(9H)-one 3 with alkyl dichlorides (bifunctional reagents) we realized the cyclization of a thiazole or thiazine ring on the [b] side of the pyrimidine ring with formation of the new condensed pentaheterocyclic systems: pyrano[4'',3'':4',5']pyrido[3',2':4,5]thieno[3,2-d][1,3]thiazolo[3,2-a]pyrimidin-8-one 11 and pyrano[4''',3''':4'',5'']pyrido[3'',2'':4',5']thieno[3',2':4,5]pyrimido[2,1-b][1,3]thiazin-8-one 12. It was found that some of the synthesized compounds showed interesting antimicrobial activity (by agar diffusion method) against some gram-positive and gram-negative bacilli strains. 相似文献
45.
Briassoulis G Karabatsou I Gogoglou V Tsorva A 《Journal of immune based therapies and vaccines》2005,3(1):1
Background
The protection, which some BCG vaccines could confer against the development of tuberculosis (TB) in childhood, might be indirectly reflected by the subsequent development of BCG immune response. The objectives of the study were to examine effectiveness and possible differences of post-vaccination reaction to a lyophilized BCG at different age groups and to evaluate its protection against TB in a decade's period. 相似文献46.
Athina Mageira 《Mathematical Physics, Analysis and Geometry》2008,11(3-4):381-398
We apply the theory of C*-algebras graded by a semilattice to crossed products of C*-algebras. We establish a correspondence between the spectrum of commutative graded C*-algebras and the spectrum of their components. This will allow us to compute the spectrum of some commutative examples of graded C*-algebras. 相似文献
47.
Samvel N. Sirakanyan Domenico Spinelli Athina Geronikaki Anush A. Hovakimyan Azat S. Noravyan 《Tetrahedron》2014
By exploiting the reactivity of 7-alkyl-3-chloro-4-cyano-1-hydrazino-5,6,7,8-tetrahydro-2,7-naphthyridines 5 some 7-alkyl-1-azido-3-chloro-4-cyano-5,6,7,8-tetrahydro-2,7-naphthyridines 6 were synthesized. Looking at their chemical properties we have ascertained that in these compounds the azide/tetrazole equilibrium is completely shifted towards the azido form (both in solid state and in solution). Their behaviour with some amines was tested as well. Moreover by exploiting the reactivity of the chlorine and of the nitrile group we have fused on the pyridine system two new rings (pyrazole or thiophene), thus obtaining previously unknown heterocyclic systems (10 and 11). Interestingly, in these new systems, the position of the above equilibrium is reversed. 相似文献
48.
Dr. Richard Whitfield Dr. Glen R. Jones Dr. Nghia. P. Truong Dr. Lewis E. Manring Prof. Athina Anastasaki 《Angewandte Chemie (International ed. in English)》2023,62(38):e202309116
Although controlled radical polymerization is an excellent tool to make precision polymeric materials, reversal of the process to retrieve the starting monomer is far less explored despite the significance of chemical recycling. Here, we investigate the bulk depolymerization of RAFT and ATRP-synthesized polymers under identical conditions. RAFT-synthesized polymers undergo a relatively low-temperature solvent-free depolymerization back to monomer thanks to the partial in situ transformation of the RAFT end-group to macromonomer. Instead, ATRP-synthesized polymers can only depolymerize at significantly higher temperatures (>350 °C) through random backbone scission. To aid a more complete depolymerization at even lower temperatures, we performed a facile and quantitative end-group modification strategy in which both ATRP and RAFT end-groups were successfully converted to macromonomers. The macromonomers triggered a lower temperature bulk depolymerization with an onset at 150 °C yielding up to 90 % of monomer regeneration. The versatility of the methodology was demonstrated by a scalable depolymerization (≈10 g of starting polymer) retrieving 84 % of the starting monomer intact which could be subsequently used for further polymerization. This work presents a new low-energy approach for depolymerizing controlled radical polymers and creates many future opportunities as high-yielding, solvent-free and scalable depolymerization methods are sought. 相似文献
49.
Andrea Angeli Victor Kartsev Anthi Petrou Mariana Pinteala Volodymyr Brovarets Roman Vydzhak Svitlana Panchishin Athina Geronikaki Claudiu T. Supuran 《Molecules (Basel, Switzerland)》2021,26(22)
A series of benzenesulfonamides incorporating pyrazole- and pyridazinecarboxamides decorated with several bulky moieties has been obtained by original procedures. The new derivatives were investigated for the inhibition of four physiologically crucial human carbonic anhydrase (hCA, EC 4.2.2.1.1) isoforms, hCA I and II (cytosolic enzymes) as well as hCA IX and XII (transmembrane, tumor-associated isoforms). Examples of isoform-selective inhibitors were obtained for all four enzymes investigated here, and a computational approach was employed for explaining the observed selectivity, which may be useful in drug design approaches for obtaining inhibitors with pharmacological applications useful as antiglaucoma, diuretic, antitumor or anti-cerebral ischemia drugs. 相似文献
50.
Christophe Tratrat Anthi Petrou Athina Geronikaki Marija Ivanov Marina Kosti Marina Sokovi Ioannis S. Vizirianakis Nikoleta F. Theodoroula Michelyne Haroun 《Molecules (Basel, Switzerland)》2022,27(6)
Herein, we report computational and experimental evaluations of the antimicrobial activity of twenty one 2,3-diaryl-thiazolidin-4-ones. All synthesized compounds exhibited an antibacterial activity against six Gram-positive and Gram-negative bacteria to different extents. Thus, the MIC was in the range of 0.008–0.24 mg/mL, while the MBC was 0.0016–0.48 mg/mL. The most sensitive bacterium was S. Typhimurium, whereas S. aureus was the most resistant. The best antibacterial activity was observed for compound 5 (MIC at 0.008–0.06 mg/mL). The three most active compounds 5, 8, and 15, as well as compound 6, which were evaluated against three resistant strains, MRSA, P. aeruginosa, and E. coli, were more potent against all bacterial strains used than ampicillin. The antifungal activity of some compounds exceeded or were equipotent with those of the reference antifungal agents bifonazole and ketoconazole. The best activity was expressed by compound 5. All compounds exhibited moderate to good drug-likeness scores ranging from −0.39 to 0.39. The docking studies indicated a probable involvement of E. coli Mur B inhibition in the antibacterial action, while CYP51 inhibition is likely responsible for the antifungal activity of the tested compounds. Finally, the assessment of cellular cytotoxicity of the compounds in normal human MRC-5 cells revealed that the compounds were not toxic. 相似文献