Discovery of Balovaptan, a Vasopressin 1a Receptor Antagonist for the Treatment of Autism Spectrum Disorder.

We recently reported the discovery of a potent, selective, and brain-penetrant V1a receptor antagonist, which was not suitable for full development. Nevertheless, this compound was found to improve surrogates of social behavior in adults with autism spectrum disorder in an exploratory proof-of-mechanism study. Here we describe scaffold hopping that gave rise to triazolobenzodiazepines with improved pharmacokinetic properties. The key to balancing potency and selectivity while minimizing P-gp mediated efflux was fine-tuning of hydrogen bond acceptor basicity. Ascertaining a V1a antagonist specific brain activity pattern by pharmacological magnetic resonance imaging in the rat played a seminal role in guiding optimization efforts, culminating in the discovery of balovaptan (RG7314, RO5285119) 1. In a 12-week clinical phase 2 study in adults with autism spectrum disorder balovaptan demonstrated improvements in Vineland-II Adaptive Behavior Scales, a secondary end point comprising communication, socialization, and daily living skills. Balovaptan entered phase 3 clinical development in August 2018.

A new DNA gyrase inhibitor subclass of the cyclothialidine family based on a bicyclic dilactam-lactone scaffold. Synthesis and antibacterial properties.

The DNA gyrase inhibitor cyclothialidine had been shown to be a valuable lead structure for the discovery of new antibacterial classes able to overcome bacterial resistance to clinically used drugs. Bicyclic lactone derivatives containing in their 12-14-membered ring a thioamide functionality were reported previously to exhibit potent antibacterial activity against gram-positive bacteria. Moderate in vivo efficacy, however, was demonstrated only for derivatives bearing hydrophilic substituents, which were found to have a favorable impact on pharmcokinetics, and to reduce metabolic degradation, in particular glucuronidation. The incorporation of an additional amide unit into the 14-membered monolactam-lactone scaffold of cyclothialidine analogues provided a new "dilactam" subclass of DNA gyrase inhibitors of inherently higher polarity. After adjusting their lipophilicity by methyl-halogen exchange at the benzene ring, compounds of this series did not require the thioamide functionality to exert a decent antibacterial potency and consequently exhibited improved pharmacokinetic properties resulting in a pronounced in vivo efficacy in a mouse septicaemia infection model.

Synthesis and characterization of 1,3-dihydro-benzo[b][1,4]diazepin-2-one derivatives: Part 4. In vivo active potent and selective non-competitive metabotropic glutamate receptor 2/3 antagonists.

This study completes a series of papers devoted to the characterization of the non-competitive mGluR2/3 antagonist properties of 1,3-dihydro-benzo[b][1,4]diazepin-2-one derivatives with particular emphasis on derivatizations compatible with brain penetration and in vivo activity. Especially the compounds bearing a para-pyridine consistently showed in vivo activity in rat behavioral models after oral administration, for example, blockade of the mGluR2/3 agonist LY354740-induced hypoactivity and improvement of a working memory deficit induced either by LY354740 or scopolamine in the delayed match to position task (DMTP). Moreover, combination studies with a cholinesterase inhibitor show apparent synergistic effects on working memory impairment induced by scopolamine.

Synthesis and characterization of 1,3-dihydro-benzo[b][1,4]diazepin-2-one derivatives: Part 3. New potent non-competitive metabotropic glutamate receptor 2/3 antagonists.

A series of 1,3-dihydro-benzo[b][1,4]diazepin-2-one derivatives was evaluated as non-competitive mGluR2/3 antagonists. Replacement of the (2-aryl)-ethynyl-moiety in 8-position with smaller less lipophilic substituents produced compounds inhibiting the binding of [3H]-LY354740 to rat mGluR2 with low nanomolar affinity and consistent functional effect at both mGluR2 and mGluR3. These compounds were able to reverse LY354740-mediated inhibition of field excitatory postsynaptic potentials in the rat dentate gyrus and in vivo activity could be demonstrated by reversal of the LY354740-induced hypoactivity in mice after oral administration.

Synthesis and characterization of 8-ethynyl-1,3-dihydro-benzo[b][1,4]diazepin-2-one derivatives: part 2. New potent non-competitive metabotropic glutamate receptor 2/3 antagonists.

A series of 1,3-dihydro-benzo[b][1,4]diazepin-2-one derivatives was evaluated as non-competitive mGluR2/3 antagonists. Replacement of a cyano group by a five-membered heterocycle produced compounds inhibiting the binding of [(3)H]-LY354740 to rat mGluR2 with low nanomolar affinity and consistent functional effect at both mGluR2 and mGluR3. Further modification to improve the physicochemical properties led eventually to compounds with the ability to reverse LY354740-mediated inhibition of field excitatory postsynaptic potentials in the rat dentate gyrus.

New antibacterial agents derived from the DNA gyrase inhibitor cyclothialidine.

Cyclothialidine (1, Ro 09-1437) is a potent DNA gyrase inhibitor that was isolated from Streptomyces filipinensis NR0484 and is a member of a new family of natural products. It acts by competitively inhibiting the ATPase activity exerted by the B subunit of DNA gyrase but barely exhibits any growth inhibitory activity against intact bacterial cells, presumably due to insufficient permeation of the cytoplasmic membrane. To explore the antibacterial potential of 1, we developed a flexible synthetic route allowing for the systematic modification of its structure. From a first set of analogues, structure-activity relationships (SAR) were established for different substitution patterns, and the 14-hydroxylated, bicyclic core (X) of 1 seemed to be the structural prerequisite for DNA gyrase inhibitory activity. The variation of the lactone ring size, however, revealed that activity can be found among 11- to 16-membered lactones, and even seco-analogues were shown to maintain some enzyme inhibitory properties, thereby reducing the minimal structural requirements to a rather simple, hydroxylated benzyl sulfide (XI). On the basis of these "minimal structures" a modification program afforded a number of inhibitors that showed in vitro activity against Gram-positive bacteria. The best activities were displayed by 14-membered lactones, and representatives of this subclass exhibit excellent and broad in vitro antibacterial activity against Gram-positive pathogens, including Staphylococcus aureus, Streptococcus pyogenes, and Enterococcus faecalis, and overcome resistance against clinically used drugs. By improving the pharmacokinetic properties of the most active compounds (94, 97), in particular by lowering their lipophilic properties, we were able to identify congeners of cyclothialidine (1) that showed efficacy in vivo.

New anti-MRSA and anti-VRE carbapenems; synthesis and structure-activity relationships of 1beta-methyl-2-(thiazol-2-ylthio)carbapenems.

Discovery of novel antimicrobial agents effective against infections caused by drug-resistant pathogens is an important objective. In order to find a new parenteral carbapenem antibiotic, which has potent antibacterial activity especially against methicillin-resistant staphylococci, vancomycin-resistant enterococci and penicillin-resistant Streptococcus pneumoniae, a series of 1beta-methylcarbapenems with thiazol-2-ylthio groups at the C-2 position have been synthesized. Structure-activity relationships were investigated which led to SM-197436 (27), SM-232721 (44) and SM-232724 (41), being selected for further evaluation.