Optimization of α‐Amylase Immobilization in Calcium Alginate Beads

Abstract

α‐Amylase enzyme was produced by Aspergillus sclerotiorum under SSF conditions, and immobilized in calcium alginate beads. Effects of immobilization conditions, such as alginate concentration, CaCl₂ concentration, amount of loading enzyme, bead size, and amount of beads, on enzymatic activity were investigated. Optimum alginate and CaCl₂ concentration were found to be 3% (w/v). Using a loading enzyme concentration of 140 U mL^?1, and bead (diameter 3 mm) amount of 0.5 g, maximum enzyme activity was observed. Beads prepared at optimum immobilization conditions were suitable for up to 7 repeated uses, losing only 35% of their initial activity. Among the various starches tested, the highest enzyme activity (96.2%) was determined in soluble potato starch hydrolysis for 120 min at 40°C.     

Investigation of antioxidant properties of some 6-(α-aminobenzyl)thiazolo[3,2-b]-1,2,4-triazole-5-ol compounds

Promising antiinflammatory activity together with low ulcerogenic properties of some Michael addition products of thiazolo[3,2-b]-1,2,4-triazole-5(6H)-ones which have been synthesized in our previous study, prompted us to investigate their antioxidant properties. Since compound Ib has both antioxidant and antiinflammatory activities beside the lowest ulcerogenic incidence, it was selected for investigation of its inhibitory effect on various cyclooxygenase ezymes. It was found that while it did not inhibit cyclooxygenase-1 (COX-1) enzyme, there was a small inhibitory effect (17%) on COX-2 enzyme. We concluded that the diminished harmful effects on the stomach of this novel antiinflammatory compound were related to its antioxidant properties since it is ineffective on COX-1 enzyme. In conclusion, the compounds having both antioxidant and antiinflammatory activities with a lack of COX-1 enzyme inhibitory effect may improve the gastrointestinal safety profile of such compounds.     

Fluconazole-, Amphotericin-B-, Caspofungin-, and Anidulafungin-Resistant <Emphasis Type="Italic">Candida ciferrii</Emphasis>: An Unknown Cause of Systemic Mycosis in a Child

Candida ciferrii, which is known as an agent of superficial yeast infection and onychomycosis, has rarely been isolated as an agent of candidemia. Limited reports have suggested different patterns of antifungal sensitivity. We report a rare candidemia case caused by c.ciferrii in an 8-year-old child in which isolated candida species were resistant to amphotericin-B (MIC > 1 μg/ml), fluconazole, (MIC ≥ 64 μg/ml), caspofungin (MIC ≥ 32 μg/ml), and anidulafungin (MIC ≥ 32 μg/ml) but sensitive to voriconazole (MIC ≤ 0.12 μg/ml). As far as we aware, this was the first recorded C. ciferrii candidemia case in children.     

Synthesis and biological evaluation of new N-(2-hydroxy-4(or 5)-nitro/aminophenyl)benzamides and phenylacetamides as antimicrobial agents

A new series of N-(2-hydroxy-4(or 5)-nitro/aminophenyl)benzamide and phenylacetamide derivatives (1a-1n, 2a-2n) were synthesized and evaluated for antibacterial and antifungal activities against Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae, Pseudomonas aeruginosa, Escherichia coli, Candida albicans, and their drug-resistant isolate. Microbiological results indicated that the compounds possessed a broad spectrum of activity against the tested microorganisms at MIC values between 500 and 1.95 microg/ml. Benzamide derivative 1d exhibited the greatest activity with MIC values of 1.95, 3.9, and 7.8 microg/ml against drug-resistant B. subtilis, B. subtilis, and S. aureus, respectively.     

Synthesis and antimicrobial activity of some new thiazolyl thiazolidine-2,4-dione derivatives

In this study, a series of thiazolyl thiazolidine-2,4-dione derivatives (Va-f and VIa-f) were synthesized and evaluated for their antibacterial and antifungal activities against Staphylococcus aureus (ATCC 25923), methicillin resistant S. aureus (MRSA ATCC 43300), methicillin resistant S. aureus (MRSA isolate), and Escherichia coli (ATCC 23556) and C. albicans (ATCC10145). All the compounds were found active against used microorganisms.     

Health Risk Assessment of Workers' Exposure to Organic Compounds in a Tire Factory

This study focuses on a health risk assessment related to chemical exposure via inhalation for workers in a tire factory. Specifically, several volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) were measured in the four different points of the vulcanization unit. A chemical transport model was developed in order to better represent the workers' exposure to the chemicals. Then, a risk assessment methodology was employed to evaluate the potential adverse health effects of the chemicals according to their carcinogenicities. Concentrations measured near the milling machine and press in the vulcanization unit were generally higher than the respective occupational exposure limit values. The corresponding estimated cumulative cancer risks for the carcinogens at the each sampling point were higher than the designated acceptable risk level of 1 × 10^{? 4}. With respect to non-carcinogenic risks, the hazard indexes, both individually and cumulatively, were lower than the specified level of one. The high cancer risk estimated in this study suggests that the VOCs and SVOCs exposure for workers in the vulcanization unit should not be neglected. The results obtained in this study are valuable to plant managers, government officials, and regulators in the risk evaluation process.     

Mitigation of salinity stress in cucumber seedlings by exogenous hydrogen sulfide

Journal of Plant Research - This research hypothesized that tolerance of cucumber seedlings to salinity stress could be increased by hydrogen sulfide (H2S) treatments. In pot experiments, the...     

Apoptotic effects and glucose-6-phosphate dehydrogenase responses in liver and gill tissues of rainbow trout treated with chlorpyrifos

We investigated apoptotic effects and changes in glucose-6-phosphate dehydrogenase (G6PD) enzyme activity in liver and gill tissues of fish exposed to chlorpyrifos. Three different chlorpyrifos doses (2.25, 4.5 and 6.75 μg/L) were administrated to rainbow trout at different time intervals (24, 48, 72 and 96 h). Acute exposure to chlorpyrifos showed time dependent decrease in G6PD enzyme activity at all concentrations (p < 0.05). Immunohistochemical results showed that chlorpyrifos caused mucous cell loss in gill tissue and apoptosis via caspase-3 activation in fish. The present study suggested that chlorpyrifos inhibits G6PD enzyme and causes mucous cell loss in gill and apoptosis in gill and liver tissues.     

Studies on the antioxidant activities of some new chromone compounds

Recent reviews evidence that the naturally occurring compounds containing the chromone skeleton exhibit antiradical activities, providing protection against oxidative stress. The antioxidant activities of 13 new synthesized chromonyl‐2,4‐thiazolidinediones, chromonyl‐2,4‐imidazolidinediones and chromonyl‐2‐thioxoimidzolidine‐4‐ones were evaluated using in vitro antioxidant assays, including superoxide anion radical (), hydroxyl radical (), 2,2‐diphenyl‐1‐picryl‐hydrazyl free radical (DPPH^?) scavenging capacity and total antioxidant capacity ferric ion reducing activity. Superoxide anion radical was produced using potassium superoxide/18‐crown‐6‐ether dissolved in dimethylsulfoxide, and the Fenton‐like reaction (Fe(II) + H₂O₂) was a generator of hydroxyl radicals. Chemiluminescence, spectrophotometry, electron paramagnetic resonance (EPR) and 5,5‐dimethyl‐1‐pyrroline‐N‐oxide (DMPO) as the spin trap were the measurement techniques. The results showed that the majority of the chromone derivatives tested showed a strong scavenging effect towards free radicals, similar to the chemiluminescence reaction with superoxide anion radical with a high activity, inhibition of the DMPO‐OOH radical EPR signal (24–58%), the DMPO‐OH radical EPR signal (4–75%) and DPPH radical EPR signal (6–100%) at 1 mmol/L. Several of the examined compounds exhibited the high reduction potentials. The results obtained show that the new synthesized chromone derivatives may directly scavenger reactive oxygen species and thus may play a protective role against oxidative damage. Copyright © 2014 John Wiley & Sons, Ltd.