Synthesis and characterization of metal nanoparticles templated chitosan-SiO2 catalyst for the reduction of nitrophenols and dyes.

Different metal nanoparticles (MNPs) templated on chitosan-silica (CH-SiO2) nanocomposite fiber were prepared via simple and fast method of the metal ions uptake by fiber and their subseqent reduction using strong reducing agent. The performance difference of CH-SiO2 templated with Cu, Co, Ag and Ni nanoparticles for both reduction of 4-nitroaniline (4-NA) and decolorization of congo red (CR) was investigated. The Cu nanoparticles loaded CH-SiO2 (Cu/CH-SiO2), showed high catalytic efficiencies in the reduction of 4-NA and CR, as compared to other loaded MNP fibers. The apparent rate constants of 6.17 × 10-3 s-1 and 1.68 × 10-2 s-1 and turnover frequencies (TOF) of 4.693 h-1 and 3.965 h-1 were observed for the reduction of 4-NA and CR, respectively. In addition, the catalytic activity of Cu/CH-SiO2 catalyst was also examined and found efficient in the reduction of nitrophenols (2-NP, 3-NP and 4-NP), and other dyes. Thus, Cu/CH-SiO2 with excellent catalytic activity can also be employed for other applications.

Chitosan coated cotton cloth supported zero-valent nanoparticles: Simple but economically viable, efficient and easily retrievable catalysts.

A simple, economically viable and fast method has been utilized for the preparation of highly active metal nanoparticles (MNPs) in coating layer of chitosan (CH) over cellulose microfibers of cotton cloth (CC). 2 wt% of CH solution was used for the coating of CC strips (CC-CH), and were kept in aqueous solutions of metal salts to adsorb metal ions. The CC-CH templated with metal ions were then treated with aqueous solution of NaBH4 to reduce the metal ions into zero-valent metal nanoparticles (M0). The CC-CH strips loaded with M0 were characterized by XRD, XPS, ATR-FTIR, FE-SEM and TGA, which indicates the successful synthesis of MNPs by this method. The M0/CC-CH strips were used as an efficient catalyst for the model reduction reaction of nitrophenol and toxic organic dyes. Among all the prepaped samples, Fe/CC-CH showed good catalytic activity for 4-NP and Rh-B dye reduction in the presence of NaBH4 with rate constants of 0.2937 min-1 and 0.3804 min-1, respectively. Moreover Fe/CC-CH has good catalytic reduction ability for MO and MB having rate constants equal to 0.1698 and 0.2802 min-1, respectively. Beside the good catalytic ability, it could be easily recoverable as compared to other available techniques. The recovery was completed by simply pulling the strip from the reaction matrix after completion of the reaction and can be used several times.

Cytotoxic Metabolites from Callyspongia siphonella Display Antiproliferative Activity by Inducing Apoptosis in HCT-116 Cells.

OBJECTIVES: To evaluate the antiproliferative effect of the isolated metabolites from Callyspongia siphonella. METHODS: Different chromatographic methods have been done on the organic extract of the marine sponge aiming at isolating the bioactive metabolites. The cytotoxicity of the isolated compounds has been evaluated against the human colorectal cancer cell line; HCT-116, employing SRB assay. The flow cytometry assay was applied to measure the cell cycle analysis. RESULTS: Six metabolites (1-6) were obtained. The compounds 4-6 exhibited IC50 values (µM ± SD) of 95.80± 1.34, 14.8 ± 2.33, and 19.8 ± 3.78, respectively. Cell cycle distribution analysis revealed that sipholenol A (5) and sipholenol L (6) induced G2/M and S phase arrest with concomitant increase in the pre-G cell population. Furthermore, 5 and 6 increased the nuclear expression of the pro-apoptotic protein-cleaved caspase-3 that effectively drives cellular apoptosis via caspase-3-dependent pathway. CONCLUSIONS: The antiproliferative activity of 5 and 6 can be recognized, at least partly, due to their ability to induce cellular apoptosis. SUMMARY: Several metabolites were isolated from the marine sponge Callyspongia siphonella. Sipholenol A and sipholenol L exhibited effective cytotoxicity against HCT-116 cells. The observed cytotoxicity involves induction of cellular apoptosis. Abbreviation used: A549 (human lung carcinoma), Caco-2 (Human ColonCarcinoma), CHCl3 (Chloroform), HCT 116 (Human Colon Carcinoma), HepG2 (Liver Hepatocellular Carcinoma), HT-29 (Human Colorectal Adenocarcinoma), MCF-7 (Michigan Cancer Foundation-7; Human Breast Adenocarcinoma), MeOH (Methanol), NMR Nuclear Magnetic Resonance), PBS (Phosphate Buffered Saline), PC-3 (Human Prostate Cancer), PTLC (Preparative Thin Layer Chromatography), RPMI-1640 (Roswell Park Memorial Institute medium), TLC (ThinLayer Chromatography).