Synergistic Antimicrobial Activity of Chitosan Hydrolysates derived fromthe Hydrolysis of High Molecular Weight Chitosan using Immobilized Enzyme

Chitosans represent a group of multifunctional drug excipients. Here, we aimed to estimate the impact of high-molecular weight chitosan on the physicochemical properties of clotrimazole–chitosan solid mixtures (CL–CH), prepared by grinding and kneading methods. We characterised these formulas by infrared spectroscopy, differential scanning calorimetry, and powder X-ray diffractometry, and performed in vitro clotrimazole dissolution tests. Additionally, we examined the antifungal activity of clotrimazole–chitosan mixtures against clinical Candida isolates under neutral and acid conditions. The synergistic effect of clotrimazole and chitosan S combinations was observed in tests carried out at pH 4 on Candida glabrata strains. The inhibition of C. glabrata growth reached at least 90%, regardless of the drug/excipient weight ratio, and even at half of the minimal inhibitory concentrations of clotrimazole. Our results demonstrate that clotrimazole and high-molecular weight chitosan could be an effective combination in a topical antifungal formulation, as chitosan acts synergistically with clotrimazole against non-albicans candida strains.

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Catalytic Degradation of Chitosan by Supported Heteropoly Acids in Heterogeneous Systems

Catalysts ◽

10.3390/catal10091078 ◽

2020 ◽

Vol 10 (9) ◽

pp. 1078

Author(s):

Hang Zhang ◽

Zhipeng Ma ◽

Yunpeng Min ◽

Huiru Wang ◽

Ru Zhang ◽

...

Keyword(s):

Hydrogen Peroxide ◽

Molecular Weight ◽

Catalytic Activity ◽

Activated Carbon ◽

Reaction Time ◽

High Molecular Weight ◽

Reaction Temperature ◽

Water Soluble ◽

High Catalytic Activity ◽

High Molecular Weight Chitosan

Several kinds of composite materials with phosphotungstic acid (PTA) as the catalyst were prepared with activated carbon as support, and their structures were characterized. According to the Box–Behnken central combination principle, the mathematical model of the heterogeneous system is established. Based on the single-factor experiments, the reaction temperature, the reaction time, the amount of hydrogen peroxide and the loading capacity of PTA were selected as the influencing factors to study the catalyzed oxidation of hydrogen peroxide and degradation of high molecular weight chitosan. The results of IR showed that the catalyst had a Keggin structure. The results of the mercury intrusion test showed that the pore structure of the supported PTA catalyst did not change significantly, and with the increase of PTA loading, the porosity and pore volume decreased regularly, which indicated that PTA molecules had been absorbed and filled into the pore of activated carbon. The results of Response Surface Design (RSD) showed that the optimum reaction conditions of supported PTA catalysts for oxidative degradation of high molecular weight chitosan by hydrogen peroxide were as follows: reaction temperature was 70 ℃, reaction time was 3.0 h, the ratio of hydrogen peroxide to chitosan was 2.4 and the catalyst loading was 30%. Under these conditions, the yield and molecular weight of water-soluble chitosan were 62.8% and 1290 Da, respectively. The supported PTA catalyst maintained high catalytic activity after three reuses, which indicated that the supported PTA catalyst had excellent catalytic activity and stable performance compared with the PTA catalyst.

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Biodegradation of low molecular weight polyacrylamide under aerobic and anaerobic conditions: effect of the molecular weight

Water Science & Technology ◽

10.2166/wst.2020.109 ◽

2020 ◽

Vol 81 (2) ◽

pp. 301-308 ◽

Cited By ~ 1

Author(s):

Wenzhe Song ◽

Yu Zhang ◽

Amir Hossein Hamidian ◽

Min Yang

Keyword(s):

Molecular Weight ◽

High Molecular Weight ◽

Carbon Chain ◽

Anaerobic Treatment ◽

Low Molecular Weight ◽

Amino Groups ◽

Molecular Weights ◽

Weight One ◽

Hydrolysis Of ◽

Aerobic And Anaerobic

Abstract The biodegradation of polyacrylamide (PAM) includes the hydrolysis of amino groups and cleavage of the carbon chain; however, the effect of molecular weight on the biodegradation needs further investigations. In this study, biodegradation of low molecular weight PAM (1.6 × 106 Da) was evaluated in two aerobic (25 °C and 40 °C) and two anaerobic (35 °C and 55 °C) reactors over 100 days. The removal of the low molecular weight PAM (52.0–52.6%) through the hydrolysis of amino groups by anaerobic treatment (35 °C and 55 °C) was much higher than that of the high molecular weight (2.2 × 107 Da, 11.2–17.0%) observed under the same conditions. The molecular weight was reduced from 1.6 × 106 to 6.45–7.42 × 105 Da for the low molecular weight PAM, while the high molecular weight PAM declined from 2.2 × 107 to 3.76–5.87 × 106 Da. The results showed that the amino hydrolysis of low molecular weight PAM is easier than that of the high molecular weight one, while the cleavage of its carbon chain is still difficult. The molecular weights of PAM in the effluents from the two aerobic reactors (25 °C and 40 °C) were further reduced to 4.31 × 105 and 5.68 × 105 Da by the biofilm treatment, respectively. The results would be useful for the management of wastewater containing PAM.

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Ca2+-Induced Cleavage of Human Platelet Polypeptides Mediated by the Calcium Ionophore A-23187

10.1055/s-0039-1682815 ◽

1977 ◽

Author(s):

Milica Jakábová ◽

David R. Phillips

Keyword(s):

Molecular Weight ◽

High Molecular Weight ◽

Proteolytic Activity ◽

Platelet Activation ◽

Human Platelet ◽

Calcium Ionophore ◽

Lactic Dehydrogenase ◽

Actin Binding ◽

A 23187 ◽

Hydrolysis Of

The effect of calcium on human platelet polypeptides was investigated. When lysed platelets were incubated with mM Ca++, two major intracellular polypeptides (Mr = 255,000 and 230,000) were found to rapidly disappear. A similar phenomenon was also observed when intact platelets were treated with the calcium ionophore A-23187 in the presence of mM Ca++. Determinations of lactic dehydrogenase activity in supernatant fractions demonstrated that these losses occurred before platelet lysis. Investigations into the identity of the high molecular weight polypeptides revealed that one (Mr = 255,000) had similar properties to actin binding protein. The loss of the high molecular weight polypeptides was accompanied by formation of lower molecular weight polypeptides (Mr = 135,000, 93,000 and 48,000), indicating that Ca++ activates a polypeptide cleavage mechanism. The Ca++-activated polypeptide cleavages were rapid, with significant changes being observed within the first 0.5 min of incubation. An obvious explanation for these effects is. that there is Ca++-activated proteolytic activity within platelets. The Ca++-activated proteolytic activity was determined by the hydrolysis of the artificial substrate azocasein. We found that more than 90% of the proteolytic activity in lysed platelets was due to Ca++-activated proteases. These studies show that Ca++-activated proteases may play an important role in platelet activation.

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Resveratrol encapsulation in high molecular weight chitosan-based nanogels for applications in ocular treatments: Impact on human ARPE-19 culture cells

International Journal of Biological Macromolecules ◽

10.1016/j.ijbiomac.2020.09.234 ◽

2020 ◽

Vol 165 ◽

pp. 804-821 ◽

Cited By ~ 2

Author(s):

Florencia Solana Buosi ◽

Agustina Alaimo ◽

Mariana Carolina Di Santo ◽

Fernanda Elías ◽

Guadalupe García Liñares ◽

...

Keyword(s):

Molecular Weight ◽

High Molecular Weight ◽

Culture Cells ◽

High Molecular Weight Chitosan

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"Colloidal" Phosphorus Errors in Gel Chromatography

Canadian Journal of Fisheries and Aquatic Sciences ◽

10.1139/f83-187 ◽

1983 ◽

Vol 40 (10) ◽

pp. 1614-1621 ◽

Cited By ~ 2

Author(s):

B. Kent Burnison

Keyword(s):

Molecular Weight ◽

Acid Hydrolysis ◽

High Molecular Weight ◽

Gel Chromatography ◽

Chemical Analyses ◽

Molybdophosphoric Acid ◽

Molybdenum Blue ◽

Soluble Reactive Phosphate ◽

Colloidal Phosphorus ◽

Hydrolysis Of

Gel chromatography has been used for the separation of 32PO4 and a high molecular weight "colloidal" 32P-labeled fraction from 32PO4-labeled lakewater. When the labeled filtrate is treated with reagents required for the molybdenum blue method for orthophosphate analysis, only a small fraction of the "colloidal" peak is hydrolyzed to orthophosphate. As the reduced molybdophosphoric acid is strongly adsorbed to the dextran gel, quantitative elution of 32PO4 can be achieved with 0.05 mol∙L−1 NaOH and 0.3% NaCl. In hardwater lakes, care must be taken to eliminate the possibility of orthophosphate precipitation at higher pH. In these lakes, it is unlikely that the discrepancy between 32PO4 bioassays and chemical analyses can be solely attributed to acid hydrolysis of "colloidal" phosphorus. Microparticulate apatite also has the potential to release soluble reactive phosphate when the acidic molybdenum blue method is used.

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