Modifications of flexible nonyl chain and nucleobase head group of (+)-erythro-9-(2's-hydroxy-3's-nonyl)adenine [(+)-EHNA] as adenosine deaminase inhibitors.

A series of terminal nonyl chain and nucleobase modified analogues of (+)-EHNA (III) were synthesized and evaluated for their ability to inhibit adenosine deaminase (ADA). The constrained carbon analogues of (+)-EHNA, 7a-7h, 10a-c, 12, 13, 14 and 17a-c appeared very potent with Ki values in the low nanomolar range. Thio-analogues of (+)-EHNA 24a-e wherein 5'C of nonyl chain replaced by sulfur atom found to be less potent compared to (+)-EHNA. Docking of the representative compounds into the active site of ADA was performed to understand structure-activity relationships. Compounds 7a (Ki: 1.1nM) 7b (Ki: 5.2nM) and 26a (Ki: 5.9nM) showed suitable balance of potency, microsomal stability and demonstrated better pharmacokinetic properties as compared to (+)-EHNA and therefore may have therapeutic potential for various inflammatory diseases, hypertension and cancer.

Discovery of liver-directed glucokinase activator having anti-hyperglycemic effect without hypoglycemia.

Glucokinase activators (GKAs) are among the emerging drug candidates for the treatment of type 2 diabetes (T2D). Despite effective blood glucose lowering in clinical trials, many pan-GKAs "acting both in pancreas and liver" have been discontinued from clinical development mainly because of their potential to cause hypoglycemia. Pan-GKAs over sensitize pancreatic GK, resulting in insulin secretion even at sub-normoglycemic level which might be a possible explanation for hypoglycemia. An alternative approach to minimize the risk of hypoglycemia is to use liver-directed GKAs, which are reported to be advancing well in clinical development. Here, we report the discovery and structure-activity relationship (SAR) studies on a novel 2-phenoxy-acetamide series with the aim of identifying a liver-directed GKA. Incorporation of a carboxylic acid moiety as an active hepatocyte uptake recognizing element at appropriate position of 2-phenoxy-acetamide core led to the identification of 26, a potent GKA with predominant liver-directed pharmacokinetics in mice. Compound 26 on oral administration significantly reduced blood glucose levels during an oral glucose tolerance test (oGTT) performed in diet-induced obese (DIO) mice, while showing no sign of hypoglycemia in normal C57 mice over a 10-fold dose range, even when dosed at fasted condition. Together, these data demonstrate a liver-directed GKA has beneficial effect on glucose homeostasis with reduced risk of hypoglycemia.

Potent and Selective Inhibitors of Long Chain l-2-Hydroxy Acid Oxidase Reduced Blood Pressure in DOCA Salt-Treated Rats.

l-2-Hydroxy acid oxidase (Hao2) is a peroxisomal enzyme with predominant expression in the liver and kidney. Hao2 was recently identified as a candidate gene for blood pressure quantitative trait locus in rats. To investigate a pharmacological role of Hao2 in the management of blood pressure, selective Hao2 inhibitors were developed. Optimization of screening hits 1 and 2 led to the discovery of compounds 3 and 4 as potent and selective rat Hao2 inhibitors with pharmacokinetic properties suitable for in vivo studies in rats. Treatment with compound 3 or 4 resulted in a significant reduction or attenuation of blood pressure in an established or developing model of hypertension, deoxycorticosterone acetate-treated rats. This is the first report demonstrating a pharmacological benefit of selective Hao2 inhibitors in a relevant model of hypertension.

Efficacy of new retinoids in the prevention of mammary cancers and correlations with short-term biomarkers.

A number of retinoid X receptor (RXR) agonists have proven to be highly effective in preventing methylnitrosourea (MNU) induced mammary cancers. However, these agonists have side effects; particularly causing an increase in serum triglyceride levels. A series of ligands for RXR were designed based on computer modeling to the ligand binding domain (LBD) of the RXR receptors and on structure-activity relationships. The chemopreventive effects of these retinoids were evaluated in the relatively long-term MNU model. As a short-term assay to predict their efficacy, the ability of the retinoids to modulate cell proliferation and apoptosis was also determined in mammary cancers after only 7 days of treatment. The five UAB retinoids evaluated included two Class I UAB retinoids (UAB20, UAB112) and three Class II UAB retinoids (UAB30, 4-methyl-UAB30 and the benzosuberone-analog of UAB30). The previously evaluated RXR agonist targretin and the pan-agonist 9-cis-retinoic acid (9-cis-RA), which interacts with both RAR and RXR receptors, were included as positive agonists known to prevent cancer in the MNU model. In the prevention studies, in which the agents were administered beginning 5 days after MNU until the end of the study, targretin (150 mg/kg diet) and 4-methyl-UAB30 (200 mg/kg diet) were highly effective in decreasing cancer numbers by 75-85%. UAB30 (200 mg/kg diet) and 9-cis-RA (60 mg/kg diet) gave intermediate inhibitions of 60 and 45%, respectively. Targretin (15 mg/kg diet), UAB20 (200 mg/kg diet) and the benzosuberone analog of UAB30 (200 mg/kg diet) showed limited activity by decreasing cancer multiplicity 25-30%, while UAB112 had no effect on mammary cancer multiplicity. A direct correlation was observed between the long-term chemopreventive efficacy of these agents and their ability to decrease cell proliferation in mammary cancers after short-term treatment. Furthermore, the highly effective agents (4-methyl-UAB30 and targretin at 150 mg/kg diet) increased apoptosis 3-5 times, while agents with moderate or limited preventive efficacy failed to significantly increase apoptosis. Although the more effective retinoid treatments increased serum triglycerides 2.5- to 4.0-fold, one moderately effective agent (UAB30) had no significant effect on lipid levels. In summary, a short-term in vivo method has been identified for screening newly synthesized retinoids both for chemopreventive efficacy and for their adverse effect on serum triglycerides.