No abstract

Positive allosteric modulators of ionotropic glutamate receptors are potential compounds for treatment of cognitive disorders, e.g., Alzheimer's disease. The modulators bind within the dimer interface of the ligand-binding domain (LBD) and stabilize the agonist-bound conformation, thereby slowing receptor desensitization and/or deactivation. Here we describe the synthesis and pharmacological testing at GluA2 of a new generation of 3,4-dihydro-2H-1,2,4-benzothiadiazine 1,1-dioxides. The most potent modulator 3 in complex with GluA2-LBD-L483Y-N754S was subjected to structural analysis by X-ray crystallography, and the thermodynamics of binding was studied by isothermal titration calorimetry. Compound 3 binds to GluA2-LBD-L483Y-N754S with a Kd of 0.35 μM (ΔH = -7.5 kcal/mol and -TΔS = -1.3 kcal/mol). This is the first time that submicromolar binding affinity has been achieved for this type of positive allosteric modulator. The major structural factor increasing the binding affinity of 3 seems to be interactions between the cyclopropyl group of 3 and the backbone of Phe495 and Met496.

Ticagrelor reversibly inhibits the platelet adenosine diphosphate P2Y 12 receptor (P2Y 12). 1 It is approved for prevention of cardiovascular events in patients with atherosclerotic cardiovascular disease and shows evidence of superior clinical performance compared with other P2Y 12 inhibitors. A post hoc analysis of the Comparison of Ticagrelor (AZD6140) and Clopidogrel in Patients With Acute Coronary Syndrome (PLATO) trial 2 revealed that patients treated with ticagrelor had a lower risk of infection-related death than those treated with clopidogrel bisulfate. 3 More recently, in the Targeting Platelet-Leukocyte Aggregates in Pneumonia With Ticagrelor (XANTHIPPE) study, ticagrelor was associated with improved lung function in patients hospitalized for pneumonia. 4 We therefore questioned whether ticagrelor or its metabolites could possess antimicrobial properties. Methods | Tic agrelor and its major metabolites (M5 AR-C133913, M7, M8 AR-C124910) 5 were synthetized and tested in time-kill assays against gram-positive methicillinresistant Staphylococcus epidermidis RP62A (MRSE) (ATCC 35984); methicillin-sensitive Staphylococcus aureus (MSSA) (ATCC 25904, ATCC 6538); glycopeptide intermediate S aureus (GISA) Mu-50 (ATCC 700699); methicillin-resistant S aureus (MRSA) (ATCC BAA-1556); Enterococcus faecalis (ATCC 29212); vancomycin-resistant E faecalis (VRE) (ATCC BAA-2365); and Streptococcus agalactiae (ATCC 12386) and against gram-negative Escherichia coli (ATCC 8739) and Pseudomonas aeruginosa (PAK laboratory strain). Biofilm formation was assessed in vitro with crystal violet staining and in a mouse model of S aureus polyurethane-implant infection using Xen-29 bacteria (Perkin Elmer). Infected disks were implanted in specific pathogen-free BALB/cAnCrl mice (Charles River). The mouse protocol was approved by the ethical committee of Liège University.

3-(Alkylamino)-7-halo-4H-1,2,4-benzothiadiazine 1,1-dioxides were synthesized, and their activity on rat-insulin-secreting cells and rat aorta rings was compared to that of the K(ATP) channel activators diazoxide and pinacidil. Structure-activity relationships indicated that an improved potency and selectivity for the pancreatic tissue was obtained by introducing a fluorine atom in the 7-position and a short linear (preferably ethyl) or cyclic (preferably cyclobutyl) hydrocarbon chain on the nitrogen atom in the 3-position. By contrast, strong myorelaxant activity was gained by the introduction of a halogen atom different from the fluorine atom in the 7-position and a bulky branched alkylamino chain in the 3-position. Thus, 3-(ethylamino)-7-fluoro-4H-1,2,4-benzothiadiazine 1,1-dioxide (11) expressed a marked inhibitory activity on pancreatic B-cells (IC(50) = 1 microM) associated with a weak vasorelaxant effect (ED(50) > 300 microM), whereas 7-chloro-3-(1,1-dimethylpropyl)amino-4H-1,2,4-benzothiadiazine 1,1-dioxide (27), which was only slightly active on insulin-secreting cells (IC(50) > 10 microM), was found to be very potent on vascular smooth muscle cells (ED(50) = 0.29 microM). Radioisotopic and electrophysiological investigations performed with 7-chlorinated, 7-iodinated, and 7-fluorinated 3-alkylamino-4H-1,2,4-benzothiadiazine 1,1-dioxides confirmed that the drugs activated K(ATP) channels. The present data revealed that subtle structural modifications of 3-(alkylamino)-7-halo-4H-1,2,4-benzothiadiazine 1,1-dioxides can generate original compounds activating K(ATP) channels and exhibiting different in vitro tissue selectivity profiles.