Synthesis and biological evaluation of new 1,2-dihydro-4-hydroxy-2-oxo-3-quinolinecarboxamides for treatment of autoimmune disorders: structure-activity relationship.

Roquinimex-related 3-quinolinecarboxamide derivatives were prepared and evaluated for treatment of autoimmune disorders. The compounds were tested in mice for their inhibitory effects on disease development in the acute experimental autoimmune encephalomyelitis model and selected compounds in the beagle dog for induction of proinflammatory reaction. Structure-activity relationships are discussed. Compound 8c, laquinimod, showed improved potency and superior toxicological profile compared to the lead compound roquinimex (1b, Linomide) and was selected for clinical studies (currently in phase II).

Inhibition of human DHODH by 4-hydroxycoumarins, fenamic acids, and N-(alkylcarbonyl)anthranilic acids identified by structure-guided fragment selection.

A strategy that combines virtual screening and structure-guided selection of fragments was used to identify three unexplored classes of human DHODH inhibitor compounds: 4-hydroxycoumarins, fenamic acids, and N-(alkylcarbonyl)anthranilic acids. Structure-guided selection of fragments targeting the inner subsite of the DHODH ubiquinone binding site made these findings possible with screening of fewer than 300 fragments in a DHODH assay. Fragments from the three inhibitor classes identified were subsequently chemically expanded to target an additional subsite of hydrophobic character. All three classes were found to exhibit distinct structure-activity relationships upon expansion. The novel N-(alkylcarbonyl)anthranilic acid class shows the most promising potency against human DHODH, with IC(50) values in the low nanomolar range. The structure of human DHODH in complex with an inhibitor of this class is presented.

Selective determination of acidic pharmaceuticals in wastewater using molecularly imprinted solid-phase extraction.

The determination of acidic pharmaceuticals, such as non-steroidal anti-inflammatory drugs NSAIDs and clofibric acid (metabolite of clofibrate), at low ngL(-1) levels in wastewater requires highly selective and sensitive analytical procedures. The removal of matrix components during sample preparation results in significant benefits towards reducing the matrix effects during LC-MS analysis. Therefore this work describes a simple method to enrich and clean up NSAIDs and clofibric acid from sewage water using molecularly imprinted solid-phase extraction (MISPE). Final analysis was performed by liquid chromatography-tandem mass spectrometry. The performance of this method has been evaluated in fortified tap and sewage water in terms of recovery, precision, linearity, and method quantification limit. Recovery for all compounds ranged in all matrices between 84 and 116% with intra-day R.S.D. values below 11.5%. Matrix effect evaluation demonstrated that even complex sample matrixes, such as pond or sewage water did not showed significant ion suppression/enhancement compared to tap water. The performance of the method was further emphasized by the study of pond water, which receives treated water from a sewage treatment plant in south Sweden. Raw sewage and treated water were also tested. In those samples, all acidic pharmaceuticals were detected in concentration above method quantification limits ranging from 5.1 to 5153.0ngL(-1).

Synthesis and reactivity of laquinimod, a quinoline-3-carboxamide: intramolecular transfer of the enol proton to a nitrogen atom as a plausible mechanism for ketene formation.

5-Chloro-N-ethyl-1,2-dihydro-4-hydroxy-1-methyl-2-oxo-N-phenyl-3-quinolinecarboxamide (laquinimod, 2) is an oral drug in clinical trials for the treatment of multiple sclerosis. The final step in the synthesis of 2 is a high-yielding aminolysis reaction of ester 1 with N-ethylaniline. An equilibrium exists between 1 and 2, and removal of formed methanol during the reaction is a prerequisite for obtaining high yields of 2 from 1. The reactivity of 1 and 2 is explained by a mechanistic model that involves a transfer of the enol proton to the exocyclic carbonyl substituent with concomitant formation of ketene 3. This proton transfer is especially facilitated for 2 because the intramolecular hydrogen bond to the carbonyl oxygen is weakened due to steric interactions. Both 1 and 2 undergo solvolosis reactions that obey first-order reaction kinetics, further supporting the theory that these two molecules are able to decompose unimolecularly into ketene 3. The solvent-dependent spectroscopic features of 2 indicate that the molecule mainly resides in two conformations. One conformation is favored in nonpolar solvents and is likely the result of intramolecular hydrogen bonding. The other conformation is favored in polar solvents and probably exhibits less intramolecular hydrogen bonding.