Structural basis for human monoglyceride lipase inhibition.

Monoglyceride lipase (MGL) is a serine hydrolase that hydrolyses 2-arachidonoylglycerol (2-AG) into arachidonic acid and glycerol. 2-AG is an endogenous ligand of cannabinoid receptors, involved in various physiological processes in the brain. We present here the first crystal structure of human MGL in its apo form and in complex with the covalent inhibitor SAR629. MGL shares the classic fold of the alpha/beta hydrolase family but depicts an unusually large hydrophobic occluded tunnel with a highly flexible lid at its entry and the catalytic triad buried at its end. Structures reveal the configuration of the catalytic triad and the shape and nature of the binding site of 2-AG. The bound structure of SAR629 highlights the key interactions for productive binding with MGL. The shape of the tunnel suggests a high druggability of the protein and provides an attractive template for drug discovery.

Synthesis and SAR of 3- and 4-substituted quinolin-2-ones: discovery of mixed 5-HT(1B)/5-HT(2A) receptor antagonists.

Quinolin-2-ones bearing a heteroaryl-piperazine linked by a two carbon chain at the 3- or 4-position were synthesised and evaluated as mixed 5-HT(1B)/5-HT(2A) receptor antagonists. Potent mixed antagonists were obtained with thieno[3,2-c]pyridine derivatives. In this series, compound 2.1 (SL 65.0472) proved to be functional antagonist at both the 5-HT(2A) receptor (rat in vivo 5-HT-induced hypertension model) and the 5-HT(1B) receptor (dog in vitro saphenous vein assay).

Pharmacological profile of SL 59.1227, a novel inhibitor of the sodium/hydrogen exchanger.

1. The NHE1 isoform of the Na(+)/H(+) exchanger plays an important role in the regulation of intracellular pH and in cardiac cell injury caused by ischaemia and reperfusion. SL 59.1227 is a novel imidazolypiperidine Na(+)/H(+) antiport inhibitor which is structurally unrelated to previously described acylguanidine inhibitors such as cariporide. 2. Recovery of pH(i) following an intracellular acid load was measured in CCL39-derived PS120 variant cells, selectively expressing either NHE1 or NHE2 isoforms of the Na(+)/H(+) exchanger. pH(i) recovery was potently and selectively slowed by SL 59.1227 in NHE1-expressing cells (IC(50) 3.3+/-1.3 nM) versus NHE2-expressing cells (2.3+/-1.0 microM). The respective IC(50) values for cariporide were 103+/-28 nM (NHE1) and 73+/-46 microM (NHE2). 3. In anaesthetized rats following left coronary artery occlusion (7 min) and reperfusion (10 min) SL 59.1227 (10 - 100 microg kg(-1) min(-1) i.v.) inhibited ischaemia-mediated ventricular tachycardia (71 - 100%) and reperfusion-induced ventricular fibrillation (75 - 87%) and prevented mortality. Bolus i.v. administration of SL 59.1227 (1 mg kg(-1)) produced anti-arrhythmic effects when administered either before or during ischaemia. 4. Cardiac infarct size was determined in anaesthetized rabbits following left coronary artery occlusion (30 min) and reperfusion (120 min). Infarct size measured as a percentage of the area at risk was 36.2+/-3.4% (control group) versus 15.3+/-3.9% (SL 59.1227 0.6 mg kg(-1) i.v.). 5. SL 59.1227 is the first example of a potent and NHE1-selective non-acylguanidine Na(+)/H(+) exchanger inhibitor. It possesses marked cardioprotective properties.

Effects of SL 65.0472, a novel 5-HT receptor antagonist, on 5-HT receptor mediated vascular contraction.

5-hydroxytryptamine (5-HT) contracts vascular smooth muscle and pharmacological and molecular biological data suggest that these effects are mediated primarily by stimulation of 5-HT(1B) and 5-HT(2A) receptor subtypes. We have studied the properties of 7-fluoro-2-oxo-4-[2-[4-(thieno[3,2-c] pyridin-4-yl) piperazin-1-yl] ethyl]-1,2-dihydroquinoline-1-acetamide (SL 65.0472 ), a novel 5-HT receptor antagonist, in isolated vascular preparations contracted by 5-HT or sumatriptan. In canine isolated saphenous vein strips (putatively 5-HT(1B)-mediated contraction), SL 65.0472 antagonised sumatriptan-induced contractions in a competitive manner (pA(2) 8. 17+/-0.36). 5-HT contracts rabbit aorta by stimulation of 5-HT(2A) receptors. SL 65.0472 displaced the 5-HT concentration response curve in rabbit aorta rightwards with a significant reduction in maximum. The apparent pK(B) value was 8.58+/-0.18. 5-HT-induced contractions of human coronary arteries are mediated by a mixed population of 5-HT(1B) and 5-HT(2A) receptors. SL 65.0472 produced rightward parallel shifts of the 5-HT concentration response curves in all tissues studied (pA(2) 8.8+/-0.14, n=7). In conclusion, SL 65. 0472 is a potent antagonist of vascular smooth muscle contraction in vitro mediated by 5-HT receptor stimulation.