Synthesis and preliminary biological evaluation of a new pyridocarbazole derivative covalently linked to a thymidine nucleoside as a potential targeted antitumoral agent. I

The therapy of human cancer is one of the more pursued goals by medicinal chemistry research. Most of the compounds clinically used as a treatment owe their efficacy to their cytotoxic interaction (direct or indirect) with nuclear DNA. This interaction results in the inhibition of DNA synthesis and the degradation of nucleic strands. Ellipticine is a naturally occurring 6H-pyrido[4,3-b]carbazole alkaloid endowed with antitumor activity, and several ellipticine derivatives have been used in clinical trials. We previously reported some 1,4-dimethyl-9H-carbazole derivatives structurally related to ellipticine. The purpose of our research was to transform the pyridocarbazole in a prodrug so that it would have more penetration in the tumor cells and block their replication. Our prodrug is slowly hydrolyzed in human plasma in the corresponding acid. From these preliminary results, we deduce that our compound can block cellular replication. Our hypothesis is that the antitumoral activity is probably related to the induction of damage to DNA, without cellular lysis in the short term.     

Phosphine and Thiophene Cyclopalladated Complexes: Hydrolysis Reactions in Strong Acidic Media

The mechanisms for the hydrolysis of organopalladium complexes [Pd(CNN)R]BF₄ (R=P(OPh)₃, PPh₃, and SC₄H₈) were investigated at 25 °C by using UV/Vis absorbance measurements in 10 % v/v ethanol/water mixtures containing different sulphuric acid concentrations in the 1.3–11.7 M range. In all cases, a biphasic behavior was observed with rate constants k_1obs, which corresponds to the initial step of the hydrolysis reaction, and k_2obs, where k_1obs>k_2obs. The plots of k_1obs and k_2obs versus sulfuric acid concentration suggest a change in the reaction mechanism. The change with respect to the k_1obs value corresponds to 35 %, 2 %, and 99 % of the protonated complexes for R=PPh₃, P(OPh)₃, and SC₄H₈, respectively. Regarding k_2obs, the change occurred in all cases at about 6.5 M H₂SO₄ and matched up with the results reported for the hydrolysis of the 2‐acetylpyridinephenylhydrazone (CNN) ligand. By using the excess acidity method, the mechanisms were elucidated by carefully looking at the variation of k_i,_obs (i=1,2) versus ${c_{{\rm{H}}^ + } }$ . The rate‐determining constants, k_0,A‐1, k_0,A‐2, and k_0,A‐SE2 were evaluated in all cases. The R=P(OPh)₃ complex was most reactive due to its π‐acid character, which favors the rupture of the trans nitrogen–palladium bond in the A‐2 mechanism and also that of the pyridine nitrogen–palladium bond in the A‐1 mechanism. The organometallic bond exerts no effect on the relative basicity of the complexes, which are strongly reliant on the substituent.     

Pericyclic versus pseudopericyclic reactions. What the Laplacian of the charge density, inverted Delta2rho(r), has to say about it? The case of cycloaddition reactions

The pseudopericyclic character of a group of cycloaddition reactions is theoretically investigated with the quantum theory of atoms in molecules of Bader at B3LYP/6-311++G(d,p) and MP2/6-311++G(d,p) levels of theory. The analysis of the topology of the Laplacian of the charge density, inverted Delta2rho(r), along the reaction coordinate sets out a clear cut between pericyclic and pseudopericyclic processes and also allows one to account for intermediate cases.     

Thermodynamics and kinetics of the nickel(II)-salicylhydroxamic acid system. Phenol rotation induced by metal ion binding

The kinetics and the equilibria of Ni(II) binding to p-hydroxybenzohydroxamic acid (PHBHA) and salicylhydroxamic acid (SHA) have been investigated in an aqueous solution at 25 degrees C and I=0.2 M by the stopped-flow method. Two reaction paths involving metal binding to the neutral acid and to its anion have been observed. Concerning PHBHA, the rate constants of the forward and reverse steps are k1=(1.9+/-0.1)x10(3) M-1 s-1 and k-1=(1.1+/-0.1)x10(2) s-1 for the step involving the undissociated PHBHA and k2=(3.2+/-0.2)x10(4) M-1 s-1 and k-2=1.2+/-0.2 s-1 for the step involving the anion. Concerning SHA, the analogous rate constants are k1=(2.6+/-0.1)x10(3) M-1 s-1, k-1=(1.3+/-0.1)x10(3) s-1, k2=(5.4+/-0.2)x10(3) M-1 s-1, and k-2=6.3+/-0.5 s-1. These values indicate that metal binding to the anions of the two acids concurs with the Eigen-Wilkins mechanism and that the phenol oxygen is not involved in the chelation. Moreover, a slow effect was observed in the SHA-Ni(II) system, which has been put down to rotation of the benzene ring around the C-C bond. Quantum mechanical calculations at the B3LYP/lanL2DZ level reveal that the phenol group in the most stable form of the Ni(II) chelate is in trans position relative to the carbonyl oxygen, contrary to the free SHA structure, where the phenol and carbonyl oxygen atoms both have cis configuration. These results bear out the idea that the complex formation is coupled with phenol rotation around the C-C bond.     

The Different Facets of Triclocarban: A Review

In the late 1930s and early 1940s, it was discovered that the substitution on aromatic rings of hydrogen atoms with chlorine yielded a novel chemistry of antimicrobials. However, within a few years, many of these compounds and formulations showed adverse effects, including human toxicity, ecotoxicity, and unwanted environmental persistence and bioaccumulation, quickly leading to regulatory bans and phase-outs. Among these, the triclocarban, a polychlorinated aromatic antimicrobial agent, was employed as a major ingredient of toys, clothing, food packaging materials, food industry floors, medical supplies, and especially of personal care products, such as soaps, toothpaste, and shampoo. Triclocarban has been widely used for over 50 years, but only recently some concerns were raised about its endocrine disruptive properties. In September 2016, the U.S. Food and Drug Administration banned its use in over-the-counter hand and body washes because of its toxicity. The withdrawal of triclocarban has prompted the efforts to search for new antimicrobial compounds and several analogues of triclocarban have also been studied. In this review, an examination of different facets of triclocarban and its analogues will be analyzed.     

Transferred plasma jet as a tool to improve the wettability of inner surfaces of polymer tubes

The wettability of the inner surfaces of vinyl, polyurethane, and silicone tubes was modified using an atmospheric pressure plasma jet operated in argon. A specific plasma jet configuration, transferred plasma jet, developed at Sao Paulo State University was utilized. It has been shown that it is possible to homogeneously alter the inner wall wettability of 1-m-long tubes, while providing safe plasma source usage for the operator. The water contact angle for three tube materials, i.e., vinyl, polyurethane, and silicone, changed from 98°, 86°, and 109° to 55°, 45°, and 40°, respectively.     

A novel synthesis of methyl cis-(3-thienyl)glycidate with 2-aminothiophenol and the synthesis of [1,5]benzothiazepine derivatives

The synthesis of cis-2,3-dihydro-3-hydroxy-2-(3-thienyl)[1,5]benzothiazepin-4(5H)-one derivatives is described starting from 2-aminothiophenol and methyl cis-(3-thienyl)glycidate. The structures were confirmed by ¹H-nmr spectroscopy.     

Synthesis of [1,5]benzothiazepine derivatives

Various derivatives of 2,3-dihydro[1,5]benzothiazepin-4(5H)-ones were synthesized. Alternative route for the synthesis of 5-dimethylaminoethyl-2,3-dihydro[1,5]benzothiazepin-4(5H)-ones and 4-dimethylaminopro-poxy-(2H,5H)-[1,5]benzothiazepines are described.     

Acrylic copolymers with pendant 1,2,4‐triazole moieties as colorimetric sensory materials and solid phases for the removal and sensing of cations from aqueous media

Linear water‐soluble polymers and nets with gel‐like behavior were prepared for use as colorimetric sensors and selective extracting agents for naked eye detection and solid–liquid removal of heavy‐metal cations from aqueous environments. Triazole is a well‐known, heavy‐metal cation host. A water‐insoluble methacrylamide containing a 1,2,4‐triazole receptor derivative was copolymerized with highly hydrophilic and water‐soluble methacrylamides to yield a water‐soluble polymer or a cross‐linked network as a powder or a dense membrane. In powder form, the material selectively removed Hg²⁺, Pb²⁺, and Ag⁺ from aqueous media. In the form of swelled dense membranes or films, the material acted as colorimetric sensor for Fe³⁺. When the membrane was soaked in a yellow aqueous solution of Fe³⁺, the former colorless, transparent membrane became reddish (but retained its transparency), and the solution became colorless. Aqueous conductivity studies confirmed that both the extraction and the sensing phenomena arose from the interaction of the cations with the triazole moieties. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011