Identification of novel benzimidazole derivatives as highly potent AMPK activators with anti-diabetic profiles.

Diabetes is a global healthcare problem that affects more than 400 million people worldwide. Treatment for type 1 and 2 diabetes is expected by targeting adenosine monophosphate activated protein kinase, AMPK, a well-known master regulator of glucose. Many pharmaceutical companies have tried to identify AMPK activators but few direct AMPK activators with high potency for the ß2-AMPK isoform, which is important for glucose homeostasis, have been found. In addition, their chemical structure is limited to benzimidazole or indole derivatives bearing an aromatic substituent at the C5 position of the core structure. We describe herein our efforts to identify novel benzimidazole derivatives that directly activate the ß2-AMPK isoform. Our newly designed activator 14d bearing a 1-amino indanyl moiety at the C5 position of the core exhibited high in vitro potency and good pharmacokinetic profiles. A single oral dosing of 14d showed dose-dependent activation of AMPK and blood-glucose-lowering effects was observed in a diabetic animal model. In addition, chronic AMPK activation with 14d led to dose-dependent reduction in HbA1c of the animal model.

Discovery and structure-activity relationship study of 2-piperazinyl-benzothiazole derivatives as potent and selective PPARδ agonists.

Peroxisome proliferator-activated receptor δ (PPARδ) is considered to be a target for treating metabolic syndrome, whereas there is no PPARδ agonist in clinical use. Previously, we have reported the discovery of 2-(1-piperidinyl)-1,3-benzothiazole derivatives as a new series of PPARδ agonists using docking-based virtual screening techniques. In this study, we performed the further optimization study of the lead compound 1 focusing on improvement of hydrophobic interactions in the binding site to enhance agonist efficacy for PPARδ and subtype selectivity, thereby discovering a novel PPARδ agonist 5g which exhibited high in vitro agonist activity (hPPARδ, EC50 = 4.1 nM) and sufficiently high selectivity ratio over PPARα and PPARγ. Moreover, 5g revealed a significant upregulation of high-density lipoprotein cholesterol level in vivo.

Discovery and structure-based design of a new series of potent and selective PPARδ agonists utilizing a virtual screening method.

Novel PPARδ agonists, 2-(1-piperidinyl)-1,3-benzothiazole derivatives were discovered by our proprietary docking-based virtual screening technique. Compound 1 as the initial hit was effectively modified to acquire PPARδ agonist activity, resulting in the discovery of compound 12 with high agonistic potency for PPARδ and selectivity over PPARα and PPARγ. Compound 12 also had good ADME profiles and showed in vivo efficacy as a lead.

Identification of novel indole derivatives as highly potent AMPK activators with anti-diabetic profiles.

AMP-activated protein kinase (AMPK) has been shown to play an important role in the beneficial effects of exercise on glucose and lipid metabolism in skeletal muscle and liver. Therefore, activation of AMPK has been proposed as an attractive strategy for the treatment of metabolic disorders, such as type 2 diabetes. Many of existing AMPK activators bearing diverse chemical structure were reported. However, there have been few reports of direct AMPK activator with high potency for ß2-AMPK isoform, which is thought to be important for glucose homeostasis, and their chemical structure is limited to benzimidazole core. We describe herein our efforts for identification of novel AMPK activator. Our newly designed 4-azaindole derivative 16g exhibited single-digit nM in vitro activity, and chronic treatment with 16g led to dose-dependent improvement in HbA1c as well as decrease in hepatic lipid accumulation in diabetic animal model.

Design, Synthesis, and Anti-Inflammatory Evaluation of a Novel PPARδ Agonist with a 4-(1-Pyrrolidinyl)piperidine Structure.

Peroxisome proliferator-activated receptor δ (PPARδ) is considered to be a pharmaceutical target to treat metabolic diseases including atherosclerosis, but there is no PPARδ agonist available for clinical use. We have previously reported the discovery of piperidinyl/piperazinyl benzothiazole derivatives as a new series of PPARδ agonists using docking-based virtual screening methods. In the present study, we found that introduction of a pyrrolidine group into the 4-position of their central piperidine rings enhances hPPARδ activity and subtype selectivity. This led to the discovery of 21 having strong PPARδ agonist activity (EC50 = 3.6 nM) with excellent ADME properties. Furthermore, 21 significantly suppressed atherosclerosis progression by 50-60% with reduction of the serum level of MCP-1 in LDLr-KO mice.

Cadmium activates extracellular signal-regulated kinase 5 in HK-2 human renal proximal tubular cells.

We examined the effects of cadmium chloride (CdCl(2)) exposure on the phosphorylation and functionality of extracellular signal-regulated kinase 5 (ERK5), a recently identified member of the mitogen-activated protein kinase (MAPK) family, in HK-2 human renal proximal tubular cells. Following exposure to CdCl(2), ERK5 phosphorylation increased markedly, but the level of total ERK5 was unchanged. ERK5 phosphorylation following CdCl(2) exposure was rapid and transient, similar to the time course of ERK1/2 phosphorylation. Treatment of HK-2 cells with the MAPK/ERK kinase 5 inhibitor, BIX02189, suppressed CdCl(2)-induced ERK5 but not ERK1/2 phosphorylation. The CdCl(2)-induced increase of phosphorylated cAMP response element-binding protein (CREB) and activating transcription factor-1 (ATF-1), as well as the accumulation of mobility-shifted c-Fos protein, were suppressed by BIX02189 treatment. Furthermore, BIX02189 treatment enhanced cleavage of poly(ADP-ribose) polymerase and increased the level of cytoplasmic nucleosomes in HK-2 cells exposed to CdCl(2). These findings suggest that ERK5 pathway activation by CdCl(2) exposure might induce the phosphorylation of cell survival-transcription factors, such as CREB, ATF-1, and c-Fos, and may exert a partial anti-apoptotic role in HK-2 cells.

Combining symmetry elements results in potent naphthyridinone (NTD) HIV-1 integrase inhibitors.

A series of naphthyridinone HIV-1 integrase strand-transfer inhibitors have been designed based on a psdeudo-C2 symmetry element present in the two-metal chelation pharmacophore. A combination of two distinct inhibitor binding modes resulted in potent inhibition of the integrase strand-transfer reaction in the low nM range. Effects of aryl and N1 substitutions are disclosed including the impact on protein binding adjusted antiviral activity.

CT Hounsfield Unit Is a Good Predictor of Growth in Meningiomas.

Predicting the growth rate of meningiomas is important in treatment planning. Although calcification may be an important sign of slow growth in meningiomas, the developmental process and its relation to the tumor growth pattern have not been elucidated. We retrospectively examined the location and degree of calcification in 150 meningiomas (131 asymptomatic tumors) using computed tomography (CT) scans and mean Hounsfield units (mHU). Tumor growth was evaluated using serial imaging studies wherein we calculated tumor doubling time (Td) and identified the growth curve pattern as exponential, intermediate, or decelerating. Tumors in women more frequently had calcification and showed higher mHU than those in men. The mHU was measured at least twice in 57 tumors. Tumors in women showed greater mHU increases than those in men. We found a significant correlation between Td and mHU (R = 0.49). Tumors in men and those in patients in the younger age group grew significantly faster. Multivariate analysis revealed that mHU was the only significant factor affecting Td (P <0.0001). The growth pattern was significantly related to calcification (n = 61, P = 0.0042). Tumors with decelerating growth more frequently showed calcification and had higher mHU than those with exponential growth. Receiver operating characteristic curve analysis revealed that mHU was a better predictor of growth pattern change compared with calcification on CT scan. Meningiomas with high mHU, even without calcification, were likely to show growth deceleration. Mean Hounsfield unit correlated with Td and may be a good quantitative indicator of the growth rate and pattern.

Circumstances, activities, and events precipitating aneurysmal subarachnoid hemorrhage.

Medical records of 513 patients with aneurysmal subarachnoid hemorrhage were reviewed to analyze the factors precipitating aneurysmal rupture. There was no seasonal difference in incidence. A significantly higher incidence was observed during 6:00 AM to 9:00 AM and 6:00 PM to 9:00 PM when engaging in daily routines such as defecation/micturition, brushing teeth/washing face/dressing, eating/drinking, and taking a bath. These activities are associated with a Valsalva maneuver that results in sudden pressure changes across the aneurysmal wall precipitating aneurysmal rupture. Aneurysmal rupture occurred most frequently during talking, chatting, watching television, or staying home without any strenuous physical activity. Considering the time spent, the highest incidence rate was found during defecation/micturition. There was no significant difference between men and women or between younger and older age groups regarding activities or events preceding aneurysmal rupture. Hypertension was the most common pre-existing medical problem. The main results are the same as those of the previous study except for aging of the patients.

Intracranial localized Castleman's disease. Case report.

A 68-year-old woman presented with generalized clonic seizure following a 2-month history of initiative loss, incoherent speech, headache, and left hemiparesis. No systemic signs or symptoms were seen and laboratory studies were within normal range. Computed tomography and magnetic resonance imaging demonstrated a well-delineated small mass with homogeneous enhancement in the right parietal convexity, associated with unusually extensive perifocal edema compared to the size of the mass. Cerebral angiography showed a faint stain fed by the middle meningeal artery. These imaging features were very similar to those of meningioma. Full recovery from the symptoms was achieved by total removal of the lesion and no recurrence was found after 3 years. Histological examination identified the hyaline-vascular type of angiofollicular lymph node hyperplasia (Castleman's disease). Castleman's disease involving the central nervous system is rare, with only 12 previous cases, but should be considered in the diagnosis of intracranial meningeal tumors. The treatment of choice for localized Castleman's disease is complete surgical resection, which is curative in most of the cases.

Structure-activity relationships of a novel class of endothelin-A receptor antagonists and discovery of potent and selective receptor antagonist, 2-(benzo[1,3]dioxol-5-yl)-6-isopropyloxy-4-(4-methoxyphenyl)-2H-chromene-3-carboxylic acid (S-1255). 1. Study on structure-activity relationships and basic structure crucial for ET(A) antagonism.

A novel series of endothelin-A (ET(A)) selective receptor antagonists having a 2H-chromene skeleton are described. A lead compound, 2-(benzo[1,3]dioxol-5-yl)-2H-chromene-3-carboxylic acid (3), was found by modifications of our own angiotensin II antagonist. A structure-activity relationship (SAR) study of 3 reveals that the structural requirements essential for potent and selective ET(A) receptor binding affinity are the m,p-methylenedioxyphenyl, carboxyl, and isopropoxy groups at the 2-, 3-, and 6-positions, respectively, on the (R)-2H-chromene skeleton. The substituent at the 4-position is also important for improving the activity, and various hydrophobic functional groups of 6-9 A such as liner, branched, and cyclic aliphatic groups, unsubstituted and substituted aryl groups, and even halogen atoms were acceptable. These results suggest that (R)-2-(benzo[1,3]dioxol-5-yl)-6-isopropoxy-2H-chromene-3-carboxylic acid, formula 108, is the crucial basic structure to be recognized by the ET(A) receptor. The most potent compound is (R)-48 (S-1255), which binds to the ET(A) receptor with an IC(50) value of 0.19 nM and is 630-fold selective for the ET(A) receptor than for the ET(B) receptor. This compound has 55% oral bioavailability in rats. On the basis of the SAR, the roles of each substituent in the receptor binding are discussed.

A novel class of endothelin-A receptor antagonists, (R)-2-(benzo[1,3]dioxol-5-yl)-6-isopropyloxy-2H-chromene-3-carboxylic acids (S-1255). Conformational analysis of basic structure, crucial for ET(A) antagonism, in solution and solid states.

Conformational studies of potent and selective endothelin-A (ET(A)) receptor antagonists, 4-substituted (R)-2-(benzo[1,3]-dioxol-5-yl)-6-isopropoxy-2H-chromene-3-carboxylic acids, are reported. X-ray crystallography and NMR studies of the 4-anisyl derivative 2 (S-1255), the stable atropisomers 3 and the 4-n-butyl derivative 4 reveal that the A-, B- and C-rings in these compounds adopt a L-like conformation in both solution and solid states. Molecular mechanics calculation shows that this L-like conformation is an inevitable conformation as determined by intramolecular steric repulsions. These 2H-chromene derivatives bound to an ET(A) receptor with IC(50) values of less than 1 nM, whereas the dihydro compounds 7 and 9 not having the L-like conformation showed weaker affinities. These results suggest that the L-like conformation is specifically recognized by the active site of the ET(A) receptor. The roles of the L-like conformation in the receptor binding are discussed.

Practical enantioselective synthesis of endothelin antagonist S-1255 by dynamic resolution of 4-methoxychromene-3-carboxylic acid intermediate.

A practical multikilogram-scale synthesis of enantiomerically pure S-1255 (1), a potent and orally active ET(A) receptor antagonist, is described. Utilizing readily available starting materials and reagents, the entire sequence of reactions starting from 2,5-dihydroxyacetophenone 8 proceeded under mild conditions to give 1 in an excellent chemical yield (8 steps, 41% overall yield) and in a high enantiopurity (98% ee). The crucial step of the synthesis is a dynamic resolution of key intermediate 16. (R)-Methoxy acid (R)-16 having 97-99% ee was obtained in 83-84% yield from racemic 16 as a crystalline (1S,2R)-(+)-norephedrine or (+)-cinchonine salt by the dynamic resolution comprising concurrent crystallization and in situ racemization. A mechanism of the dynamic resolution through a ring-opened zwitterionic intermediate is discussed. In the final synthetic step, an effective carbon-carbon bond formation between the C4 carbon and the p-anisyl group was accomplished by a conjugate addition-elimination reaction of Grignard reagent 3 to (R)-16 to give 1 having 98% ee. Owing to high efficiencies of functional group transformations, carbon-carbon bond formations, and the dynamic resolution, the synthesis required no chromatographic purification and was amenable to a multikilogram-scale preparation. Several kilograms of 1 for clinical trials were successfully prepared by this process.