Amberlite IRC-718 ion chelating resin extraction of hazardous metal Cr (VI) from aqueous solutions: equilibrium and theoretical modeling.

Under varied conditions, the IRC 718 ion-exchange resin is used to extract chromium (VI) ions from aqueous solutions. On chromium (VI) removal effectiveness, the effects of adsorption dosage, contact time, beginning metal concentration, and pH were examined. The batch ion exchange process reached equilibrium after around 90 minutes of interaction. With an initial chromium (VI) concentration of 0.5 mg/dm3, the pH-dependent ion-exchange mechanism revealed maximal removal in the pH 2.0-10 range. The adsorption mechanism occurs between Cr (VI) determined as the electron acceptor, and IRC 718 determined as the electron donor. The equilibrium ion-exchange potential and ion transfer quantities for Amberlite IRC 718 were calculated using the Langmuir adsorption isotherm model. The overall ion exchange capacity of the resin was determined to be 187.72 mg of chromium (VI)/g of resin at an ideal pH of 6.0.

Benzimidazolium- and Benzimidazolilydene-Capped Cyclodextrins: New Perspectives in Anion Encapsulation and Gold-Catalyzed Cycloisomerization of 1,6-Enynes.

A new way of introducing a N-heterocyclic carbene cap onto cyclodextrins has been devised. The benzimidazolium intermediates were found to behave as receptors towards cavity matching anions. The corresponding C1 - and C2 -symmetrical regioisomeric carbene gold(I) complexes have been tested in a benchmark asymmetric cycloisomerization of 1,6-enynes. Up to 50 % ee was achieved for the enantioselective cycloisomerization of N-allyl-4-methyl-N-(3-phenylprop-2-yn-1-yl)benzenesulfonamide.

Formation of Mono- and Polynuclear Luminescent Lanthanide Complexes based on the Coordination of Preorganized Phosphonated Pyridines.

A series of polynuclear assemblies based on ligand L (1,4,7-tris[hydrogen (6-methylpyridin-2-yl)phosphonate]-1,4,7-triazacyclononane) has been developed. The coordination properties of ligand L with LnIII (Ln = La, Eu, Tb, Yb, Lu) have been studied in water (pH = 7.0) and in D2O (pD = 7.0) by UV-absorption spectrometry, spectrofluorimetry, 1H and 31P NMR, DOSY, ESI-mass spectrometry, and X-ray diffraction. This nonadentate ligand forms highly stable mononuclear complexes in water and provides a very efficient shielding of the Ln cations, as emphasized by the very good luminescence properties of the Yb complex in D2O, especially regarding its lifetime (τD2O = 10.2 µs) and quantum yield (ϕD2O = 0.42%). In the presence of excess LnIII cation, polynuclar complexes of [(LnL)2Ln x] stoichiometry (x = 1 and x = 2) are observed in solution. In the solid state, a dinuclear complex of La could be isolated and structurally characterized by X-ray diffraction, unraveling the presence of strong hydrogen bonding interactions between a La(H2O)93+ cation and the [LaL]3- complex.

Development of prohibitin ligands against osteoporosis.

Current therapeutic approaches to osteoporosis display some potential adverse effects and a limited efficacy on non-vertebral fracture reduction. Some sulfonylamidines targeting the scaffold proteins prohibitins-1 and 2 (PHB1/2) have been showed to inhibit the formation of osteoclasts in charge of bone resorption. Herein, we report the development of a second generation of anti-osteoclastic PHB ligands. The most potent compound, IN45, showed 88% inhibition at the low concentration of 5 µM, indicates that it might serve as a basis for the development of new antiosteoporotic drugs.

Targeting prohibitin with small molecules to promote melanogenesis and apoptosis in melanoma cells.

Prohibitins 1 and 2 (PHB1/2) are scaffold proteins that are involved in both melanogenesis and oncogenic pathways. We hypothesized that a PHB1 ligand, melanogenin, may display anti-cancer effects in addition to its known melanogenic activity in melanocytes. Here, we disclose a convenient synthesis of melanogenin, and its analogs. We found that, among 57 new melanogenin analogs, two (Mel9 and Mel41) significantly promoted both melanogenesis in melanocytes by activating one of the PHB2-interacting proteins, microtubule-associated protein light chain 3 (LC3), and upregulating the expression of microphthalmia associated transcription factor (MITF). These analogs also activate ERK. Besides, in addition to their promelanogenic activities, we uncovered that melanogenin and its active analogs induce apoptosis in several cancer cell lines, including melanoma cells, and that this effect is caused by an inhibition of AKT survival pathway. Our findings present a new putative function for PHBs as regulators of LC3/ERK/MITF melanogenic signaling, and suggest that Mel9 and Mel41 may provide the basis for the development of new drugs candidates to treat melanoma and other types of cancers.

Cancer wars: natural products strike back.

Natural products have historically been a mainstay source of anticancer drugs, but in the 90's they fell out of favor in pharmaceutical companies with the emergence of targeted therapies, which rely on antibodies or small synthetic molecules identified by high throughput screening. Although targeted therapies greatly improved the treatment of a few cancers, the benefit has remained disappointing for many solid tumors, which revitalized the interest in natural products. With the approval of rapamycin in 2007, 12 novel natural product derivatives have been brought to market. The present review describes the discovery and development of these new anticancer drugs and highlights the peculiarities of natural product and new trends in this exciting field of drug discovery.

A comparison of the acidity and the complexing ability of (o-hydroxyphenyl) bis- and (o-hydroxyphenyl) mono-methylenephosphonic acids towards lanthanide(III) ions.

The characterization of the acid-base properties of a family of three phenoldimethylenephosphonic acids differently substituted by auxo- or chromophoric groups was studied. These ligands may be considered as pentaacids. Their pK(a) were determined in aqueous solution at 25 degrees C and constant ionic strength 0.1 mol dm(-3) by potentiometry and UV-visible spectrophotometry. Eventually, the complexing power of these molecules with lanthanide cations, Ce(3+), Pr(3+), Nd(3+), Sm(3+) and Eu(3+), was studied keeping in view the possible application to the treatment of radioactive liquid waste. The number, the nature of the species in solution, their stability constants and their individual electronic spectra as restored by computation have been determined. In all cases, complexes of 1:1 stoichiometry accompanied by hydroxy and protonated species are postulated. The comparison of tri- and pentaacids confirms that the acids having the methyl group at the para position with respect to the phenolic OH, have the highest complexing power.