9 research outputs found
Chemoenzymatic synthesis, nanotization and anti- aspergillus activity of optically enriched fluconazole analogues
Despite recent advances in diagnostic and therapeutic advances in antifungal research, aspergillosis still remains a leading cause of morbidity and mortality. One strategy to address this problem is to enhance the activity spectrum of known antifungals, and we now report the first successful application of Candida antarctica lipase (CAL) for the preparation of optically enriched fluconazole analogs. Anti-Aspergillus activity was observed for an optically enriched derivative, (-)-S-2-(2’ ,4’ -difluorophenyl)-1-hexyl-amino-3-(1‴,2‴,4‴) triazol-1‴-yl-propan-2-ol, which exhibits MIC values of 15.6 μg/mL and 7.8 μg/disc in microbroth dilution and disc diffusion assays, respectively. This compound is tolerated by mammalian erythrocytes and cell lines (A549 and U87) at concentrations of up to 1000 μg/mL. When incorporated into dextran nanoparticles, the novel, optically enriched fluconazole analog exhibited improved antifungal activity against Aspergillus fumigatus (MIC = 1.63 μg/mL). These results not only demonstrate the ability of biocatalytic approaches to yield novel, optically enriched fluconazole derivatives but also suggest that enantiomerically pure fluconazole derivatives, and their nanotised counterparts, exhibiting anti-Aspergillus activity may have reduced toxicity
Synthesis of substituted 2,6-dioxabicyclo[3.1.1]heptanes. 1,3-Anhydro-2,4,6-tri-O-benzyl- and 1,3-anhydro-2,4,6-tri-O-(p-bromobenzyl)-.beta.-D-mannopyranose
Electrical surface conductivity of fluorinated polymer films after chemical surface treatment
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Cyclitol-Based Metal-Complexing Agents. Effect of the Relative Orientation of Oxygen Atoms in the Ionophoric Ring on the Cation-Binding Ability of myo
CELLULASES FROM PENICILLIUM JANTHINELLUM MUTANTS: SOLID-STATE PRODUCTION AND THEIR STABILITY IN IONIC LIQUIDS
The cellulase production by P. janthinellum mutants on lignocellulosic material such as cellulose or steam exploded bagasse (SEB) in combination with wheat bran was studied in solid state fermentation (SSF). One of the mutants, EU2D21, produced the highest levels of endoglucanase (3710 IU g-1 carbon source) and β-glucosidase (155 IU g-1 carbon source). Ionic liquids are so-called green solvents that have become attractive for biocatalysis. Stability of mutant cellulases was tested in 10-50% of the ionic liquid 1-butyl-3-methylimidazolium chloride ([bmim]Cl). FPA and CMCase were significantly stable in 10% ionic liquid after 5h. β-glucosidase showed 85% of its original activity after 5 h incubation in 30% ionic liquid and retained 55% of its activity after 24 h. This enzyme preparation hydrolyzed ionic-liquid-treated SEB completely in 15 h in the presence of 20% ionic liquid. These studies revealed that there is no need of regenerating cellulose after ionic liquid treatment, since cellulase of mutant strain was found to be significantly stable in the ionic liquid
Biodegradation of Styrene-Butadiene-Styrene Coploymer via Sugars Attached to the Polymer Chain
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Facile Synthesis of Unique Cellulose Triacetate Based Flexible and High Performance Gel Polymer Electrolyte for Lithium Ion Batteries
Lithium
ion batteries (LIBs) with polymer based electrolytes have attracted
enormous attention due to the possibility of fabricating intrinsically
safer and flexible devices. However, economical and eco-friendly sustainable
technology is an oncoming challenge to fulfill the ever increasing
demand. To circumvent this issue, we have developed a gel polymer
electrolyte (GPE) based on renewable polymers like cellulose triacetate
and polyÂ(polyethylene glycol methacrylate) pÂ(PEGMA) using a photo
polymerization technique. Cellulose triacetate offers good mechanical
strength with improved ionic conductivity, owing to its ether and
carbonyl functional groups. It is observed that the presence of an
open network has a critical impact on lithium ion transport. At room
temperature, GPE PC exhibits an optimal ionic conductivity of 1.8 ×
10<sup>–3</sup> S cm<sup>–1</sup> and transference number
of 0.7. Interestingly, it affords an excellent electrochemical stability
window up to 5.0 V vs Li/Li<sup>+</sup>. GPE PC shows a discharge
capacity of 164 mAhg<sup>–1</sup> after the first cycle when
evaluated in a Li/GPE/LiFePO<sub>4</sub> cell at 0.5 C-rate. Interfacial
compatibility of GPE PC with lithium metal improves the overall cycling
performance. This system provides a guiding principle toward a future
renewable and flexible electrolyte design for flexible LIBs (FLIBs)
Biocatalytic Synthesis of Novel Partial Esters of a Bioactive Dihydroxy 4-Methylcoumarin by Rhizopus oryzae Lipase (ROL)
Highly regioselective acylation has been observed in 7,8-dihydroxy-4-methylcoumarin (DHMC) by the lipase from Rhizopus oryzae suspended in tetrahydrofuran (THF) at 45 °C using six different acid anhydrides as acylating agents. The acylation occurred regioselectively at one of the two hydroxy groups of the coumarin moiety resulting in the formation of 8-acyloxy-7-hydroxy-4-methylcoumarins, which are important bioactive molecules for studying biotansformations in animals, and are otherwise very difficult to obtain by only chemical steps. Six monoacylated, monohydroxy 4-methylcoumarins have been biocatalytically synthesised and identified on the basis of their spectral data and X-ray crystal analysis