Preparation,antitumor activity in mice,pharmacokinetics and tissue distribution in rats of di‐n‐butyl‐di‐(4‐chlorobenzohydroxamato)tin(IV) liposome

Di‐n‐butyl‐di‐(4‐chlorobenzohydroxamato)tin(IV) (DBDCT) is an antitumor compound with high activity and relatively low bioavailability. In order to improve the pharmacokinetic characteristics and raise its therapeutic index, a liposome of DBDCT (DBDCT‐L) was prepared for the first time. A study of the pharmacokinetics and tissue distribution after intravenous administration of DBDCT‐L compared with free DBDCT to rats was investigated. DBDCT‐L showed a slower clearance, increased half‐time and a larger AUC value than those of free DBDCT, which demonstrated that DBDCT‐L could significantly alter the tissue distribution pattern of DBDCT in rats. The highest concentration distribution for DBDCT‐L was detected in liver, which may be associated with the enhanced antitumor activity in vivo against hepatocellular carcinoma H₂₂ and possible target release of the compound. Acute toxicity assay showed that the LD₅₀ value of DBDCT‐L was higher than that of free DBDCT. Further in vivo antitumor test showed that DBDCT‐L displayed higher antitumor activity against the hepatocellular carcinoma H₂₂ than free DBDCT, indicating that the liposome could prolong the action time of DBDCT in the system circulation, change its distribution in rats, reduce acute toxicity and finally increase antitumor activity. Copyright © 2014 John Wiley & Sons, Ltd.     

Immobilization of Xylanase on Poly (Ethylene Glycol) Methyl Ether 5000 and its Self-Extractive Bioconversion for the Production of Xylo-Oligosaccharides

Endo-β-1,4-xylanase derived from Trichoderma reesei was covalently immobilized on poly (ethylene glycol) methyl ether 5000 (mPEG5000), and the resulting immobilized enzyme had a residual activity of 72.4 % with 82.9 % of PEGylated amino groups. Compared with the free enzyme, the immobilized xylanase was stable at pH values in the range of 4.0–6.0 and temperatures in the range of 50–65 °C. A self-extractive bioconversion system composed of immobilized xylanase, mPEG5000, and sodium citrate was used to produce xylo-oligosaccharides and provided a better distribution of the xylo-oligosaccharides than the free enzyme. Furthermore, the immobilized xylanase could be effectively recovered in situ following the hydrolysis reaction.     

Electrochemical reduction of selenium on a silver electrode and its determination in river water

A new, simple, and fast method is described for determining selenium based on a silver wire electrode flow-through voltammetric detector. A comparison was done between the sensitivity of disk silver, mercury-modified glassy carbon, and mercury-modified gold electrodes. The response of the flow-through voltammetric detector was evaluated with respect to each electrode’s operating potential and pH in direct current mode. The limit of detection (3s) for Se(IV) was below 0.01 mg/L. The flow-through system does not need deposition times and the organic matter does not need to be removed before determining selenium in river water.