Protective effect of naringenin-7-O-glucoside against oxidative stress induced by doxorubicin in H9c2 cardiomyocytes

Doxorubicin (DOX) is one of the most effective chemotherapeutic agents, but cardiotoxicity limits its clinical use. Although the mechanisms are not entirely understood, reactive oxygen species (ROS) and cardiomyocyte apoptosis appear to be involved in DOX cardiotoxicity. Protection or alleviation of DOX cardiotoxicity can be achieved by administration of natural phenolic compounds via activating endogenous defense systems and antiapoptosis. Naringenin-7-O-glucoside (NARG), isolated from Dracocephalum rupestre Hance, could protect from cardiomyocyte apoptosis and induce endogenous antioxidant enzymes against DOX toxicity, but the effects on intracellular ROS generation and cell membrane stability were not demonstrated. In the present study, we investigated the effects of NARG on H9c2 cell morphology, viability, lactate dehydrogenase (LDH) and creatine kinase (CK) leakage, glutathine peroxidase (GSH-Px) activity, intracellular Ca2+ concentration, and ROS generation. Compared with DOX alone treatment group, the morphological injury of the cells in groups treated by DOX plus NARG was alleviated, cell viability was increased, the amount of released LDH and CK was significantly decreased, the activity of GSH-Px was increased, the content of intracellular Ca2+ and ROS generation was lowered remarkably. These results suggest that NARG could prevent cardiomyocytes from DOX-induced toxicity by their property of stabilizing the cell membrane and reducing ROS generation.

Flavopiridol, the first cyclin-dependent kinase inhibitor: recent advances in combination chemotherapy

The cell cycle is the series of events necessary for the division and duplication of a cell. The dysregulation of the cell cycle can promote the development of cancer. A group of proteins, cyclin-dependent kinases (CDKs), that control the cell cycle, provide new targets for treating cancer. As a result, cyclin-dependent kinase inhibitors (CDKIs) represent a novel class of chemotherapeutic agents. Of these, flavopiridol, a semisynthetic flavonoidal alkaloid, emerged as the first CDKI to enter clinical trials. Preclinical data indicate that flavopiridol could block the proliferation of neoplastic cells and induce programmed cell death as a single agent. Furthermore, recent emerging data revealed that flavopiridol can potentiate, generally in a dose- and sequence-dependent manner, the anti-tumor effects of many established chemotherapeutic agents. This review is primarily focused on the role of flavopiridol in combination with various therapeutic agents that are in or near clinical development.

Stereoselective metabolism of silybin diastereoisomers in the glucuronidation process

A separation method for the hepatoprotective drug silybin and its metabolites by RP-HPLC was described. Based on this separation, the stereoselectivity of the metabolism of silybin was investigated by incubation of the drug and its two diastereoisomers with bovine liver microsomes. Information about the structures of these metabolites was obtained, using UV, HPLC/MS and NMR spectra. Four major metabolites (M(1), M(4) of silybin A and M(2), M(5) of silybin B), were prepared by preparative HPLC, and their configurations were accomplished by NMR spectra. A HPLC method was used to quantify the metabolites. The results showed that silybin was extensively metabolized and the major sites for glucuronidation were the C-20, C-7, at phenolic OH groups. Furthermore, the results obtained reveal that there was significant stereoselectivity in the glucuronidation process of silybin. Silybin B was glucuronidated at a more efficient rate than its diastereoisomer, and glucuronidation of silybin B was much preferred at the 20 position, while that of silybin A was similar at both 7 and 20 position.

A combined bioprocess for integrated removal of copper and organic pollutant from copper-containing municipal wastewater

Heavy metal-containing wastewater is difficult to treat by most of the bioprocess due to its toxicity to microorganism in activated sludge. In this study, a combined bioprocess consisting of biosorption section that contained magnetite immobilized Pseudomonas putida 5-x cell as biosorbent followed by sequence batch reactor (SBR) was developed to treat Cu(2+)-containing municipal wastewater. The production techniques of Pseudomonas putida 5-x cell as biosorbent, such as optimal cell harvest period and cell pretreatment techniques were studied. Experimental results showed, considering both cell biomass and cell adsorption capacity to Cu(2+), 36 h is the optimal harvest period in the course of culturing Pseudomonas putida 5-x cells as biosorbent, and 0.1-0.3 mol L(-1) HCl is an optimal cell pretreating eluant to improve Cu(2+) adsorption capacity. The performances of the combined bioprocess for treating Cu(2+) containing wastewater were assessed. Experimental results showed that after treatment by biosorption, the Cu(2+) level in wastewater was reduced to level that did not inhibit COD removal efficiency of subsequent SBR activated sludge process, although it still affected the COD adsorption capacity of activated sludge. In terms of COD removal, the biosorption section was efficient for reducing Cu(2+) concentration to provide biodegradable wastewater for subsequent SBR activated sludge process.

The biodegradation of 1,3-dichlorobenzene by an adapted strain Bacillus cereus PF-11 derived from town-gas industrial effluent

In the present study, an adapted bacterium PF-11 with high 1,3-dichlorobenzene degradation capability was isolated from town-gas industrial effluent through continuous introducing of N-methyl-N'-nitro-N-nitrosoquanidine (NTG). In suitable condition, a degradation rate of 32 mg L(-1) d(-1) of 1,3-dichlorobenzene was obtained by strain PF-11 with effective chlorion release. Strain PF-11 was tentatively identified as gram-positive Bacillus cereus. The substrate specificity of the strain PF-11 was relatively low, and the degradation rate for different chlorobenzenes was in the order of monochlorobenzene > 1,3-dichlorobenzene > 1,2-dichlorobenzene. Initial oxidation step was molecular oxygen attacking chlorobenzene ring catalyzed by dioxygenase.

[Expression and characterization of human pulmonary surfactant-associated protein A1 in Saccharomyces cerevisiae]

The cDNA encoding pulmonary surfactant-associated protein A1 (SP-A1) derived from healthy adult's lung was cloned into the pVT102U/alpha, expression vector of Saccharomyces cerevisiae, which contains the yeast alpha-factor signal sequence, leading to the secretion of expressed protein, and then transformed into Saccharomyces cerevisiae S-78 (leu2, ura3, rep4) by electroporation. After 2-3 days culture in adequate pH, the expressed SP-A1 accumulated up to 400 mg/L in supernatant. The pure proteins were obtained by Sephadex G-25, G-75, Sepharose 4B. The expressed recombinant products, 62 kD and 32 kD, reacted to specific antibody using ELISA and Western blot. The SP-A1 protein expressed in Saccharomyces cerevisiae was efficient in enhancing the phagocytosis of E. coli J5 by alveolar macrophages.

[Cloning, expression of a segment of hTERT gene and detection of telomerase and hTERT by anti-hTERT polyclonal antibody]

Telomerase is an important biomarker in cancer cells. It is active in germline cells, most of cancer tissues and cell lines, but not in most somatic tissues. Telomerase is composed of two components, and while hTER is present in normal and tumor cells, expression of hTERT appears to be highly regulated and correlates with telomerase activity. In order to detect the telomerase enzyme and hTERT protein, anti-hTERT polyclonal antibodies were produced in this study. A segment of hTERT cDNA was amplified by RT-PCR and cloned into the multi-cloning site of the GST gene fusion vector pGEX-5X-3. After the recombinant plasmid was expressed in E. coli BL21, the fusion protein was purified for immunization. Extracts from several cultured cells were analyzed by Western blot, and the results indicated that telomerase enzyme and hTERT protein could be specifically detected by this anti-hTERT antibod'. Thus, a simple and effective method was primarily established for the immunodetection of telomerase enzyme and hTERT protein.