The -3 polyunsaturated fatty acid docosahexaenoic acid (DHA) possesses potent anti-inflammatory properties and has shown therapeutic benefit in numerous inflammatory diseases. However, the molecular mechanisms of these anti-inflammatory properties are poorly understood. DHA is highly susceptible to peroxidation, which yields an array of potentially bioactive lipid species. One class of compounds are cyclopentenone neuroprostanes (A 4 /J 4 -NPs), which are highly reactive and similar in structure to anti-inflammatory cyclopentenone prostaglandins. Here we show

Phenotypic screening of a quinoxaline library against replicating Mycobacterium tuberculosis led to the identification of lead compound Ty38c (3-((4-methoxybenzyl)amino)-6-(trifluoromethyl)quinoxaline-2-carboxylic acid). With an MIC99 and MBC of 3.1 μM, Ty38c is bactericidal and active against intracellular bacteria. To investigate its mechanism of action, we isolated mutants resistant to Ty38c and sequenced their genomes. Mutations were found in rv3405c, coding for the transcriptional repressor of the divergently expressed rv3406 gene. Biochemical studies clearly showed that Rv3406 decarboxylates Ty38c into its inactive keto metabolite. The actual target was then identified by isolating Ty38c-resistant mutants of an M. tuberculosis strain lacking rv3406. Here, mutations were found in dprE1, encoding the decaprenylphosphoryl-d-ribose oxidase DprE1, essential for biogenesis of the mycobacterial cell wall. Genetics, biochemical validation, and X-ray crystallography revealed Ty38c to be a noncovalent, noncompetitive DprE1 inhibitor. Structure-activity relationship studies generated a family of DprE1 inhibitors with a range of IC50's and bactericidal activity. Co-crystal structures of DprE1 in complex with eight different quinoxaline analogs provided a high-resolution interaction map of the active site of this extremely vulnerable target in M. tuberculosis.

SummaryTo combat the emergence of drug-resistant strains of Mycobacterium tuberculosis, new antitubercular agents and novel drug targets are needed. Phenotypic screening of a library of 594 hit compounds uncovered two leads that were active against M. tuberculosis in its replicating, non-replicating, and intracellular states: compounds 7947882 (5-methyl-N-(4-nitrophenyl)thiophene-2-carboxamide) and 7904688 (3-phenyl-N-[(4-piperidin-1-ylphenyl)carbamothioyl]propanamide). Mutants resistant to both compounds harbored mutations in ethA (rv3854c), the gene encoding the monooxygenase EthA, and/or in pyrG (rv1699) coding for the CTP synthetase, PyrG. Biochemical investigations demonstrated that EthA is responsible for the activation of the compounds, and by mass spectrometry we identified the active metabolite of 7947882, which directly inhibits PyrG activity. Metabolomic studies revealed that pharmacological inhibition of PyrG strongly perturbs DNA and RNA biosynthesis, and other metabolic processes requiring nucleotides. Finally, the crystal structure of PyrG was solved, paving the way for rational drug design with this newly validated drug target.

Cyclopentenone isoprostanes (IsoPs), A(2)/J(2)-IsoPs, are one class of IsoPs formed via the free radical-initiated peroxidation of arachidonic acid. These compounds, which are structurally similar to cyclooxygenase-derived PGA(2) and PGJ(2), contain highly reactive alpha,beta-unsaturated carbonyl moieties. A(2)/J(2)-IsoPs are generated in vivo in humans esterified in glycerophospholipids. Unlike other classes of IsoPs, however, cyclopentenone IsoPs cannot be detected in the free form; we postulated that this might be due to their rapid adduction to various thiol-containing biomolecules via Michael addition. Recently, we reported that the A-ring IsoP, 15-A(2t)-IsoP, is efficiently conjugated with glutathione in vitro by certain human and rat glutathione transferases (GSTs), with the isozyme GSTA4-4 displaying the highest activity. Herein, we examined the metabolic disposition of 15-A(2t)-IsoP in HepG2 cells. We report that 15-A(2t)-IsoP is primarily metabolized by these cells via conjugation to glutathione. Within 6 h, approximately 60% of 15-A(2t)-IsoP added to HepG2 cells was present in the form of a water soluble conjugate(s). Structural characterization of the adduct(s) by liquid chromatography-tandem mass spectrometry revealed four major conjugates. These include the intact 15-A(2t)-IsoP-GSH conjugate, the GSH conjugate in which the carbonyl at C-9 of 15-A(2t)-IsoP is reduced, and the corresponding cysteine conjugates. These studies thus show that the primary pathway of metabolic disposition of endogenously derived cyclopentenone IsoPs occurs via conjugation with thiols.

Whereas the anti-inflammatory properties and mechanisms of action of long chain ω3 PUFAs have been abundantly investigated, research gaps remain regarding the respective contribution and mechanisms of action of their oxygenated metabolites collectively known as oxylipins. We conducted a dose-dependent and comparative study in human primary macrophages aiming to compare the anti-inflammatory activity of two types of DHA-derived oxylipins including the well-described protectins (NPD1 and PDX), formed through lipoxygenase pathway and the neuroprostanes (14-A- and 4-F-NeuroP) formed through free-radical mediated oxygenation and expected to be new anti-inflammatory mediators. Considering the potential ability of these DHA-derived oxylipins to bind PPARs and knowing the central role of these transcription factors in the regulation of macrophage inflammatory response, we performed transactivation assays to compare the ability of protectins and neuroprostanes to activate PPARs. All molecules significantly reduced mRNA levels of cytokines such as IL-6 and TNF-α, however not at the same doses. NPD1 showed the most effect at 0.1µM (-14.9%, p<0.05 for IL-6 and -26.7%, p<0.05 for TNF-α) while the three other molecules had greater effects at 10µM, with the strongest result due to the cyclopentenone neuroprostane, 14-A-NeuroP (-49.8%, p<0.001 and -40.8%, p<0.001, respectively). Part of the anti-inflammatory properties of the DHA-derived oxylipins investigated could be linked to their activation of PPARs. Indeed, all tested oxylipins significantly activated PPARγ, with 14-A-NeuroP leading to the strongest activation, and NPD1 and PDX also activated PPARα. In conclusion, our results show that neuroprostanes and more especially cyclopentenone neuroprostanes have potent anti-inflammatory activities similar or even more pronounced than protectins supporting that neuroprostanes should be considered as important contributors to the anti-inflammatory effects of DHA.

The development of efficienta nd mild methods for the synthesis of organofluorine compounds is of foremost interest in various fields of chemistry.Adirect pyrimidine-based selective meta-CÀHp erfluoroalkenylationo f arenes involving several commerciallya vailable perfluoroolefins is described. The synthetic versatility of the protocol is demonstrated by an extensive substrate scopei ncludingd ifferent benzylsulfonyl, alkylarene and phenylacetic acid scaffolds. The generality of this methodology includingt he meta-CÀHp erfluoroalkenylation of Ibuprofen, the facile cleavageo ft he directing group and gram-scale reactions are presented.Fluorine-containingc ompounds are knownt op lay ap ivotal role in pharmaceutical/medicinal chemistry,b ut also in agrochemicala nd material sciences.F luorinea nd in particular the incorporation of CÀFb onds into organic molecules strongly influence their properties such as thermals tability,h igh chemical inertness ands olubility in organic solvents. [1] Bioavailability and metabolic stabilitya re commonlyi ncreased by substitution with fluorine atoms. [2] Alkenes and aromatic moieties bearing perfluorinated tails are widely used as as table isosterica nd isoelectronic mimics of the amide bond, and bioisosteres in structure-activity relationships tudies. [3] Althougho fg reat importance,t he synthesiso fp erfluoroalkenylated arenes through the incorporationo ff luoroalkyl chains has remained an out-standingc hallenge. Few strategies for the preparation of these structuralm otifs, such as the classical cross-couplingr eaction have been shown to be effective. [4,5] The existing methods usually require prefunctionalization of substrates or employment of non-readilya vailable starting materials, and these methods often suffer from low regio-or stereoselectivity and poor functionalg roup toleranced ue to the employmento fs ensitive reagents. [6] Therefore, new synthetic strategies featuring high efficiency and mild conditions are highly desirable.Over the past decades, transition-metal-catalyzed CÀHb ond functionalization has been establisheda sa ne ffectives trategy in late-stage functionalization of pharmaceuticals and bioactive molecules. [7] To achieve site-selective CÀHb ond functionalization at ad esired position, directing group (DG) approaches [8] have been employede xtensively for the ortho-CÀHb ond, [9] whereasd istal meta-a nd para-CÀHb onds have been much less addressed. In the past few years, meta-selective CÀHf unctionalizations of arenes have been accomplishedb ye xploiting the inherent steric and electronic properties of substrates, or by designing suitablet emplates. [10] In this context, direct CÀH perfluoroalkenylation of arenes is an important route in terms of both atom and step economy.V ery recently,L oh, Wang, and Ackermann elegantly reported ortho-CÀHf luoroalkenylation of arenest hrough CÀFb ond activation. [11] Intriguingly,t he metafunctionalization of arenes using sterically demanding electrophilic perfluoroalkenes remainsad ifficult task, due to th...

The cyclopentenone isoprostanes (A 2 /J 2 -IsoPs) are formed in significant amounts in humans and rodents esterified in tissue phospholipids. Nonetheless, they have not been detected unesterified in the free form, presumably because of their marked reactivity. A 2 /J 2 -IsoPs, similar to other electrophilic lipids such as 15-deoxy-⌬ 12,14 -prostaglandin J 2 and 4-hydroxynonenal, contain a highly reactive ␣,␤-unsaturated carbonyl, which allows these compounds to react with thiol-containing biomolecules to produce a range of biological effects. We sought to identify and characterize in rats the major urinary metabolite of 15-A 2t -IsoP, one of the most abundant A 2 -IsoPs produced in vivo, in order to develop a specific biomarker that can be used to quantify the in vivo production of these molecules. Following intravenous administration of 15-A 2t -IsoP containing small amounts of [ 3 H 4 ]15-A 2t -IsoP, 80% of the radioactivity excreted in the urine remained in aqueous solution after extraction with organic solvents, indicating the formation of a polar conjugate(s). Using high pressure liquid chromatography/mass spectrometry, the major urinary metabolite of 15-A 2t -IsoP was determined to be the mercapturic acid sulfoxide conjugate in which the carbonyl at C9 was reduced to an alcohol. The structure was confirmed by direct comparison to a synthesized standard and via various chemical derivatizations. In addition, this metabolite was found to be formed in significant quantities in urine from rats exposed to an oxidant stress. The identification of this metabolite combined with the finding that these metabolites are produced in in vivo settings of oxidant stress makes it possible to use this method to quantify, for the first time, the in vivo production of cyclopentenone prostanoids.

Endogenous nitro-fatty acids, acting as partial agonist of PPARγ, are able to lower the insulin and glucose levels without the side effects associated with common antidiabetic drugs. (E)-12-Nitrooctadec-12-enoic acid, a potent activator of this peroxisome receptor, was synthesized in a very efficient sequence via a Henry-retro-Claisen ring fragmentation, followed by a novel enzymatic cleavage of methyl esters. The latter method was then applied in the last step of the synthesis of a few labile natural products, such as prostaglandins, isoprostanes, and phytoprostanes.