Ángel Ramos-Organillo

Antioxidant Activity of Butyl- and Phenylstannoxanes Derived from 2-, 3- and 4-Pyridinecarboxylic Acids

In vitro antioxidant activity for 12 stannoxanes derived from Ph3SnCl (compounds 1-3), Ph2SnCl2 (compounds 4-6), Bu3SnCl (compounds 7-9), and Bu2SnCl2 (compounds 10-12), was assayed qualitatively by the chromatographic profile with 1,1-diphenyl-2-picrylhydrazil (DPPH) method and by two quantitative methods: the DPPH radical scavenging activity and Ferric-Reducing Antioxidant Power (FRAP) assays. The results were compared with those obtained with the starting materials 2-pyridine- carboxylic acid (I), 3-pyridinecarboxylic acid (II) and 4-pyridinecarboxylic acid (III), as well as with standard compounds, such as vitamin C and vitamin E, respectively. The in vitro antiradical activity with DPPH of diphenyltin derivative 5 showed a very similar behavior to vitamin C at a 20 μg/mL concentration, whereas according to the FRAP method, compound 8 was better. This difference is due to the mechanism of the antioxidant process. The Structure-Activity Relationships (SAR) for both methods is also reported.

NMR study of the coordinating behavior of 2,6‐bis(benzimidazol‐2′‐yl)pyridine

The coordination sites of 2,6- bis(benzimidazol-2-yl)pyridine (1) toward protons and the diamagnetic metal ions Li ,N a , and Co 3 were investigated by NMR spectroscopy. Variable tem- perature 1 H and 13 C NMR experiments were performed on 1 in order to evaluate the tautomeric equilibrium and hydrogen bonding. Imidazole dicoordinated aro- matic nitrogen atoms were protonated by trichloroa- cetic acid and the three N-dicoordinated atoms by fuming H2SO4. Reactions of the ligand 1 and benzim- idazole 2 with metallic sodium or LiH afforded an- ionic species; the alkali metal ions appeared solvated by THF, but not by the ligands 1 or 2. In contrast, reaction of 1 with Co(III) produces the stable cation (Co(1-H)2) with cobalt ion coordinated by two mol- ecules of the monodeprotonated ligand. 2000 John Wiley & Sons, Inc. Heteroatom Chem 11:392-398, 2000

The zwitterion of 4-nitro-2-{(E)-[2-(piperidin-1-yl)ethyl]iminomethyl}phenol.

The title Schiff base compound, 4-nitro-1-oxo-2-{(E)-[2-(piperidin-1-yl)ethyl]iminiomethyl}cyclohexadienide, C(14)H(19)N(3)O(3), exists as a zwitterion, with the H atom of the phenol group being transferred to the imine N atom. The C=O, C(Ar)-C(Ar) and C-N bond lengths are in agreement with the oxocyclohexadienide-iminium zwitterionic form. The iminium H atom is engaged in a strong intramolecular hydrogen bond with the O atom of the keto group (N(+)-H...O) to form an S(6) motif. Soft C-H...O interactions in the ac plane lead to the development of hydrogen-bonded tapes, which are pi-stacked through the oxocyclohexadienide ring and iminium group. The significance of this study is in providing crystallographic evidence, supported by NMR and IR data, of the predominance of the oxocyclohexadienide-iminium zwitterion form over the noncharged canonical form in the title Schiff base.

Synthesis and Biological Screening of Silicon-Containing Ibuprofen Derivatives: A Study of Their NF-κβ Inhibitory Activity, Cytotoxicity, and Their Ability to Bind IKKβ

The synthesis and characterisation of new silicon-containing amides and esters derived from ibuprofen is reported. These compounds were tested against nuclear transcription factor κβ (NF-κβ). Higher inhibition values than those of ibuprofen were achieved by the new amides 10a–10d; ester derivatives did not show inhibitory activity. The cytotoxicity of these new derivatives was screened; none of them displayed significant toxicity at the screened doses. A molecular docking calculation on IKKβ (an enzyme related to NF-κβ activation) was carried out and the results showed that the amides interact better than ibuprofen with key residues, which are important to the inhibition of IKKβ.

Silicon containing ibuprofen derivatives with antioxidant and anti-inflammatory activities: An in vivo and in silico study

ABSTRACT There are many chronic diseases related with inflammation. The chronic inflammation can produce other problems as cancer. Therefore, it is necessary to design drugs with better anti‐inflammatory activity than those in the clinic. Likewise, these could be used in chronic treatments with minimum adverse effects. The amide or ester functionality in combination with the insertion of a silyl alkyl moiety is able to improve some drug properties. In this context, the evaluation of a group of silicon containing ibuprofen derivatives (SCIDs) as antioxidants and anti‐inflammatory agents is reported. Antioxidant activity was evaluated by the 2,2‐Diphenyl‐1‐picrylhydrazyl (DPPH‐), 2,2′‐Azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic) acid (ABTS•+) and the Fe(II) chelating ability methods. The anti‐inflammatory activity was determined by using the carrageenan induced rat paw edema. The gastrotoxic profile of the SCIDs that displayed significant anti‐inflammatory activity was determined by the indomethacin induced ulceration method. The SCIDs performed better than ibuprofen as chelating agents for Fe(II) and as scavengers for the free radicals DPPH• and ABTS•+. On the anti‐inflammatory test, compound 4a inhibited the edema up to 87%, while 4d & 10b achieved significant inflammation inhibition at a lower effective dose 50 (ED50) than ibuprofens. None of the SCIDs endowed with anti‐inflammatory activity, showed significant gastrotoxic effects with respect to those displayed by ibuprofen. Based on the experimental results and aided by the theoretical docking approach, it was possible to rationalize how the SCIDs may bind to cyclooxygenase isoforms and helped to explain their reduced gastrotoxicity. The evaluated effects were improved in SCIDs with respect to ibuprofen. Graphical abstract Figure. No Caption available.

A new sulfate acid polymorph of 1,3-dihydrobenzotriazole.

A new sulfate acid polymorph of 1,3-dihydrobenzotriazole, viz. 1,3-dihydrobenzotriazolium hydrogensulfate, C(6)H(6)N(3)+.HSO4-, differs from an existing polymorph in that the polymeric interaction between the HSO4- anions, together with different classical (D-H...A) and nonclassical (C-H...A) interactions, changes the space group.

Aminosilanes derived from 1H-benzimidazole-2(3H)-thione.

In two trimethylsilyl-substituted 1H-benzimidazole-2(3H)-thiones, noncovalent C—H⋯π interactions between the centroid of the benzmidazole system and the SiMe3 groups form helicoidal arrangements in one, and dimerization results in the formation of (8) rings via N—H⋯S interactions, along with parallel π–π interactions between imidazole and benzene rings, in the second compound.