Novel sulfonylurea derivatives as H3 receptor antagonists. Preliminary SAR studies

The combination of antagonism at histamine H3 receptor and the stimulation of insulin secretion have been proposed as an approach to new dual therapeutic agents for the treatment of type 2 diabetes mellitus associated with obesity. We have designed and synthesized a new series of non-imidazole derivatives, based on a basic amine ring connected through an alkyl spacer of variable length to a phenoxysulfonylurea moiety. These compounds were initially evaluated for histamine H3 receptor binding affinities, suggesting that a propoxy chain linker between the amine and the core ring could be essential for optimal binding affinity. Compound 56, 1-(naphthalen-1-yl)-3-[(p-(3-pyrrolidin-1-ylpropoxy)benzene)]sulfonylurea exhibited the best H3 antagonism affinity. However, since all these derivatives failed to block KATP channels, the link of these two related moieties should not be considered a good pharmacophore for obtaining new dual H3 antagonists with insulinotropic activity, suggesting the necessity to propose a new chemical hybrid prototype

Synthesis of quinoxaline 1,4-di-N-oxide derivatives on solid support using room temperature and microwave-assisted solvent-free procedures

We describe the synthesis of 12 new ethyl and methyl quinoxaline-7-carboxylate 1,4-di-N-oxide derivatives on solid supports with room temperature and microwave-assisted solvent-free procedures. Results show that solid supports have good catalytic activity in the formation of quinoxaline 1,4-di-N-oxide derivatives. We found that florisil and montmorillonite KSF and K10 could be used as new, easily available, inexpensive alternatives of catalysts. Additionally, room temperature and microwave-irradiation solvent-free synthesis was more efficient than a conventional procedure (Beirut reaction), reducing reaction time and increasing yield

Substitutions of fluorine atoms and phenoxy groups in the synthesis of quinoxaline 1,4-di-N-oxide derivatives.

The unexpected substitution of fluorine atoms and phenoxy groups attached to quinoxaline or benzofuroxan rings is described. The synthesis of 2-benzyl- and 2-phenoxy- 3-methylquinoxaline 1,4-di-N-oxide derivatives was based on the classical Beirut reaction. The tendency of fluorine atoms linked to quinoxaline or benzofuroxan rings to be replaced by a methoxy group when dissolved in an ammonia saturated solution of methanol was clearly demonstrated. In addition, 2-phenoxyquinoxaline 1,4-di-N-oxide derivatives became 2-aminoquinoxaline 1,4-di-N-oxide derivatives in the presence of gaseous ammonia

New quinoxaline derivatives as potential MT₁ and MT₂ receptor ligands.

Ever since the idea arose that melatonin might promote sleep and resynchronize circadian rhythms, many research groups have centered their efforts on obtaining new melatonin receptor ligands whose pharmacophores include an aliphatic chain of variable length united to an N-alkylamide and a methoxy group (or a bioisostere), linked to a central ring. Substitution of the indole ring found in melatonin with a naphthalene or quinoline ring leads to compounds of similar affinity. The next step in this structural approximation is to introduce a quinoxaline ring (a bioisostere of the quinoline and naphthalene rings) as the central nucleus of future melatoninergic ligand

1,4-Di-N-oxide quinoxaline-2-carboxamide: Cyclic voltammetry and relationship between electrochemical behavior, structure and anti-tuberculosis activity

To gain insight into the mechanism of action, the redox properties of 37 quinoxaline-2-carboxamide 1,4-di-N-oxides with varying degrees of anti-tuberculosis activity were studied in dimethylformamide (DMF) using cyclic voltammetry and first derivative cyclic voltammetry. For all compounds studied, electrochemical reduction in DMF is consistent with the reduction of the N-oxide functionality to form a radical anion. The influence of molecular structure on reduction potential is addressed and it can be said that a general relationship exists between reduction potential and reported antimicrobial activity. For those compounds which have demonstrated promising biological activity, the more active the compound the less negative the reduction potential typically is. The results suggest the possible participation of charge transfer processes in the mechanism of action of quinoxaline di-N-oxides against tuberculosis and offer new insights into the design of future antitubercular drugs

Gliotoxin contamination in and pre- and postfermented corn, sorghum and wet brewer's grains silage in Sao Paulo and Rio de Janeiro State, Brazil

The aim of this study was to determine total fungal counts and the relative density of Aspergillus fumigatus and related species in silage samples intended for bovines before and after fermentation as well as to monitor the natural occurrence of gliotoxin in silage samples (pre- and postfermentation). Methods and methods: The survey was performed in farms located in São Paulo and Rio de Janeiro States in Brazil. In addition, the ability of A. fumigatus strains and related species strains to produce gliotoxin was also evaluated. A total of 300 samples were taken, immediately after opening of the silo (3-5 months) and during the ensiling period. Fungal counts were done by the surface-spread method. Gliotoxin production ability of isolates and natural contamination were determined by HPLC. Results: All postfermented samples had a total number of moulds exceeding 1 × 10 4 CFU g -1, with Aspergillus sp. as the most prevalent genus. Frequency of strains, among A. fumigatus and related species, was able to produce gliotoxin was similar in pre- and postfermented samples, except for sorghum, which showed differences between both kinds of samples. The highest toxin levels were produced by strains isolated from postfermented samples. More than 50% of the samples showed gliotoxin contamination levels that exceeded concentrations known to induce immunosuppressive and apoptotic effects in cells. Conclusions: The present data suggest that care should be taken because gliotoxin contamination in feedstuffs could affect productivity and also present a health risk for herds. Significance and Impact of the Study: Gliotoxin was found at quite important concentrations levels in pre- and postfermented substrates and its presence could therefore probably affect the productivity and health of herds. Current conservation and management practices do not avoid contamination with A. fumigatus on silage. Therefore, farm workers should be adequately protected during its handling. © 2012 The Authors. Journal of Applied Microbiology © 2012 The Society for Applied Microbiology.Fil: Keller, Luiz Antonio Moura. Universidade Federal Rural do Rio de Janeiro; BrasilFil: Keller, Kelly Moura. Universidade Federal Rural do Rio de Janeiro; BrasilFil: Monge, Maria del Pilar. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigación en Micología y Micotoxicología. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación en Micología y Micotoxicología; ArgentinaFil: Pereyra, Carina Maricel. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Alonso, Veronica Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología; ArgentinaFil: Cavaglieri, Lilia Reneé. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas, Fisicoquímicas y Naturales. Departamento de Microbiología e Inmunología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Chiacchiera, Stella Maris. Universidad Nacional de Río Cuarto. Facultad de Ciencias Exactas Fisicoquímicas y Naturales. Instituto de Investigación en Micología y Micotoxicología. - Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigación en Micología y Micotoxicología; ArgentinaFil: R Rosa, C. A.. Universidade Federal Rural do Rio de Janeiro; Brasi

Quinoxalinas como potenciales agentes Antimycobacterium tuberculosis: una revisión

La tuberculosis requiere nuevos tratamientos frente a su compleja resistencia como MDR-TB y XDR-TB. Las quinoxalinas presentan una amplia variedad de propiedades biológicas antichagásica, antimalarial,antileishmanial, antifungal, antimicobacteriana, antiviral, antitumoral, anticancerosa, analgésica, antiinflamatoria, antioxidante, antihipertensiva y antitrombótica. En esta revisión se muestra las propiedades y nuevas aproximaciones de derivados de 1,4-di-N-óxido de quinoxalina como potenciales agentes con actividad antimicobacterial. Tuberculosis requires of new treatments against their complex resistance as MDR-TB and XDR-TB. Quinoxalines present a wide variety of biological properties as antichagasic, antimalarial, antileishmanial, antifungal, antibacterial, antiviral, antitumor, anticancer, analgesic, antiinflammatory, antioxidant, antithrombotic and antihypertensive. This review shows the properties and new approaches for 1,4-di-N-oxide quinoxaline derivatives as potential antimycobacterial active agents

Synthesis and biological evaluation of new quinoxaline derivatives as antioxidant and anti-inflammatory agents

We report the synthesis, anti-inflammatory and antioxidant activities of novel quinoxaline and quinoxaline 1,4-di-N-oxide derivatives. Microwave assisted methods have been used in order to optimize reaction times and to improve the yields. The tested compounds presented important scavenging activities and promising in vitro inhibition of soybean lipoxygenase. Two of the best lipoxygenase inhibitors (compounds 7b and 8f) were evaluated as in vivo anti-inflammatory agents using the carrageenin-induced edema model. One of them (compound 7b) showed important in vivo anti-inflammatory effect (41%) similar to that of indomethacin (47%) used as the reference drug