A Second Generation Prostanoid Receptor Antagonist Acting at Multiple Receptor Subtypes.

It has previously been reported that a prototypical compound (AGN 211377), which blocks pro-inflammatory prostanoid receptors (DP1, DP2, EP1, EP4, FP, TP) and leaves open IP and EP2 receptors so that their anti-inflammatory properties could be exerted, produced superior inhibitory effects on cytokine release from human macrophages compared to cyclooxygenase (COX) inhibitors. This favorable activity profile translated into animal studies, with AGN 211377 exceeding the level of inhibition afforded by COX inhibition. AGN 211377 was not, however, a practical drug candidate, having poor bioavailability and cost of goods concerns. Compound 1 (designated AGN 225660) represents a second-generation compound with an entirely different "druggable" core structure. Such a dramatic change in chemical scaffold created uncertainty with respect to matching the effects of AGN 211377. AGN 225660 inhibited RANTES, IL-8, and MCP-1 secretion by at least 50%, from TNFα activated human macrophages. Although AGN 225660 reduced TNFα-evoked MCP-1 release from human monocyte-derived macrophages, it increased LPS-induced MCP-1 secretion (up to 2-fold) from human monocyte-derived dendritic cells. However, AGN 225660 inhibited the release of IL12p 70 and IL-23 from human monocyte-derived dendritic cells stimulated by LPS by more than 70%. This effect of AGN 225660 was reproduced in part by the prototype compound AGN 211377 and a combination of selective DP1, EP1, EP4, FP, and TP antagonists. These findings suggest important effects on T cell skewing and disease modification by this class of therapeutic agents. AGN 225660 exhibited good ocular bioavailability and was active in reducing ocular inflammation associated with phacoemulsification surgery, LPS, and arachidonic acid induced uveitis.

FAAH-Catalyzed C-C Bond Cleavage of a New Multitarget Analgesic Drug.

The discovery of extended catalytic versatilities is of great importance in both the chemistry and biotechnology fields. Fatty acid amide hydrolase (FAAH) belongs to the amidase signature superfamily and is a major endocannabinoid inactivating enzyme using an atypical catalytic mechanism involving hydrolysis of amide and occasionally ester bonds. FAAH inhibitors are efficacious in experimental models of neuropathic pain, inflammation, and anxiety, among others. We report a new multitarget drug, AGN220653, containing a carboxyamide-4-oxazole moiety and endowed with efficacious analgesic and anti-inflammatory activities, which are partly due to its capability of achieving inhibition of FAAH, and subsequently increasing the tissue concentrations of the endocannabinoid anandamide. This inhibitor behaves as a noncompetitive, slowly reversible inhibitor. Autoradiography of purified FAAH incubated with AGN220653, opportunely radiolabeled, indicated covalent binding followed by fragmentation of the molecule. Molecular docking suggested a possible nucleophilic attack by FAAH-Ser241 on the carbonyl group of the carboxyamide-4-oxazole moiety, resulting in the cleavage of the C-C bond between the oxazole and the carboxyamide moieties, instead of either of the two available amide bonds. MRM-MS analyses only detected the Ser241-assisted formation of the carbamate intermediate, thus confirming the cleavage of the aforementioned C-C bond. Quantum mechanics calculations were fully consistent with this mechanism. The study exemplifies how FAAH structural features and mechanism of action may override the binding and reactivity propensities of substrates. This unpredicted mechanism could pave the way to the future development of a completely new class of amidase inhibitors, of potential use against pain, inflammation, and mood disorders.

In vivo studies validating multitargeting of prostanoid receptors for achieving superior anti-inflammatory effects.

The purpose of these studies was to test the hypothesis that a selected polypharmacological approach for treating the prostanoid-mediated component of inflammatory diseases would produce a therapeutic effect superior to global inhibition of prostaglandin (PG) biosynthesis by aspirin-like drugs. The compound studied was AGN 211377, which had been previously shown to produce a superior effect on cytokine release from human macrophages compared with cyclooxygenase (COX) inhibitors. AGN 211377 antagonizes prostanoid prostaglandin D2 (DP)1, DP2, prostaglandin E2 (EP)1, EP4, prostaglandin F2α, and thromboxane A2 receptors but not anti-inflammatory EP2, prostaglandin I2, or EP3 receptors. Established rodent models of ocular inflammatory diseases were used to determine therapeutic effects in living animals. The drugs were administered systemically after predetermination of their blood levels to ensure bioavailability at an appropriate dose level. Whereas compounds selective for a single prostanoid receptor typically exhibited modest but statistically significant inhibition, AGN 211377 profoundly inhibited S-antigen-induced uveitis and laser-induced retinal neovascularization. Consistent with previous polypharmacological studies on chemokine/cytokine release from human macrophages, the prostanoid EP1 receptor played a permissive role in suppressing neovascularization and inflammation in vivo Comparing AGN 211377 with a close structural congener lacking EP1 antagonism (AGN 197727), AGN 197727 was much less active than AGN 211377, but pronounced anti-inflammatory and angiostatic effects were achieved by adding the EP1 antagonist compound (SC-51322) to AGN 197727 in the systemic dosing regimen. Further, AGN 211377 produced superior anti-inflammatory activity compared with the nonsteroidal anti-inflammatory agent ketorolac. These results indicate the value of using a polypharmacological approach in the design of novel therapeutic agents in preference to compounds targeting a single receptor or enzyme. A compound such as AGN 211377 may represent more effective therapy than COX inhibitors in treating uveitis and ocular diseases where neovascularization is a significant part of the pathology.-Woodward, D. F., Wang, J. W., Ni, M., Bauer, A., Martos, J. L., Carling, R. W., Poloso, N. J. In vivo studies validating multitargeting of prostanoid receptors for achieving superior anti-inflammatory effects.

Multitargeting of selected prostanoid receptors provides agents with enhanced anti-inflammatory activity in macrophages.

A polypharmacologic approach to prostanoid based anti-inflammatory therapeutics was undertaken in order to exploit both the anti- and proinflammatory properties attributed to the various prostanoid receptors. Multitargeting of selected prostanoid receptors yielded a prototype compound, compound 1 (AGN 211377), that antagonizes prostaglandin D2 receptors (DPs) DP1 (49) and DP2 (558), prostaglandin E2 receptors (EPs) EP1 (266) and EP4 (117), prostaglandin F2α receptor (FP) (61), and thromboxane A2 receptor (TP) (11) while sparing EP2, EP3, and prostaglandin I2 receptors (IPs); Kb values (in nanomoles) are given in parentheses. Compound 1 evoked a pronounced inhibition of cytokine/chemokine secretion from lipopolysaccharide or TNF-α stimulated primary human macrophages. These cytokine/chemokines included cluster of designation 40 receptor (CD40), epithelial-derived neutrophil-activating protein 78 (ENA-78), granulocyte colony stimulating factor (G-CSF), granulocyte macrophage colony stimulating factor (GM-CSF), IL-8, IL-18, monocyte chemotactic protein-1 (CCL2) (MCP-1), tissue plasminogen activator inhibitor (PAI-1), and regulated on activation, normal T cell expressed and secreted (RANTES). In contrast, the inhibitory effects of most antagonists selective for a single receptor were modest or absent, and selective EP2 receptor blockade increased cytokine release in some instances. Compound 1 also showed clear superiority to the cyclooxygenase inhibitors diclofenac and rofecoxib. These findings reveal that blockade of multiple prostanoid receptors, with absent antagonism of EP2 and IP, may provide more effective anti-inflammatory activity than global suppression of prostanoid synthesis or highly selective prostanoid receptor blockade. These investigations demonstrate the first working example of prostanoid receptor polypharmacology for potentially safer and more effective anti-inflammatory therapeutics by blocking multiple proinflammatory receptors while sparing those with anti-inflammatory activity.

Bimatoprost, prostamide activity, and conventional drainage.

PURPOSE: Despite structural similarity with prostaglandin F(2 alpha), the ocular hypotensive agent bimatoprost (Lumigan; Allergan, Inc., Irvine, CA) shows unique pharmacology in vitro and functional activity in vivo. Unfortunately, the precise mechanisms that underlie bimatoprost's distinctive impact on aqueous humor dynamics are unclear. The purpose of the present study was to investigate the effects of bimatoprost and a novel prostamide-selective antagonist AGN 211334 on human conventional drainage. METHODS: Two model systems were used to test the consequences of bimatoprost and/or AGN 211334 treatment on conventional drainage. Human anterior segments in organ culture were perfused at a constant flow rate of 2.5 microL/min while pressure was recorded continuously. After stable baseline facilities were established, segments were treated with drug(s), and pressure was monitored for an additional 3 days. In parallel, the drugs' effects on hydraulic conductivity of human trabecular meshwork (TM) cell monolayers were evaluated. Pharmacological properties of AGN 211334 were characterized in isolated feline iris preparations in organ culture and heterologously expressed G-protein-coupled receptors were examined in vitro. RESULTS: Bimatoprost increased outflow facility by an average of 40% +/- 10% within 48 hours of treatment (n = 10, P < 0.001). Preincubation or coincubation with AGN 211334 significantly blunted bimatoprost's effects by 95% or 43%, respectively. Similar results were obtained in cell culture experiments in which bimatoprost increased hydraulic conductivity of TM cell monolayers by 78% +/- 25%. Pretreatment with AGN 211334 completely blocked bimatoprost's effects, while coincubation decreased its effects on average by 74%. In both models, AGN 211334 alone significantly decreased fluid flux across trabecular tissues and cells. CONCLUSIONS: The findings indicate that bimatoprost interacts with a prostamide receptor in the trabecular meshwork to increase outflow facility.