Osteoblastgenic and Osteogenic Effects of KY-273 with CDK8/19 Inhibitory Activity in Bone Marrow Mesenchymal Stem Cells and Female Rats.

Osteoporosis is caused by imbalance between osteogenesis and bone resorption, thus, osteogenic drugs and resorption inhibitors are used for treatment of osteoporosis. The present study examined the effects of (R)-4-(1-hydroxyethyl)-3-{4-[2-(tetrahydropyran-4-yloxy)ethoxy]phenoxy}benzamide (KY-273), a diphenyl ether derivative, on CDK8/19 activity, osteoblast differentiation and femoral bone using micro-computed tomography in female rats. KY-273 potently inhibited CDK8/19 activity, promoted osteoblast differentiation with an increase in alkaline phosphatase (ALP) activity, and gene expression of type I collagen, ALP and BMP-4 in mesenchymal stem cells (ST2 cells). In female rat femur, ovariectomy decreased metaphyseal trabecular bone volume (Tb.BV), mineral content (Tb.BMC), yet had no effect on metaphyseal and diaphyseal cortical bone volume (Ct.BV), mineral content (Ct.BMC) and strength parameters (BSPs). In ovaries-intact and ovariectomized rats, oral administration of KY-273 (10 mg/kg/d) for 6 weeks increased metaphyseal and diaphyseal Ct.BV, Ct.BMC, and BSPs without affecting medullary volume (Med.V), but did not affect Tb.BV and Tb.BMC. In ovariectomized rats, alendronate (3 mg/kg/d) caused marked restoration of Tb.BV, Tb.BMC and structural parameters after ovariectomy, and increased metaphyseal but not diaphyseal Ct.BV, Ct.BMC, and BSPs. In ovaries-intact and ovariectomized rats, by the last week, KY-273 increased bone formation rate/bone surface at the periosteal but not the endocortical side. These findings indicate that KY-273 causes osteogenesis in cortical bone at the periosteal side without reducing Med.V. In conclusion, KY-273 has cortical-bone-selective osteogenic effects by osteoblastogenesis via CDK8/19 inhibition in ovaries-intact and ovariectomized rats, and is an orally active drug candidate for bone diseases such as osteoporosis in monotherapy and combination therapy.

Discovery of Novel Chromenopyridine Derivatives as Readthrough-Inducing Drugs.

Hurler syndrome, a type of Mucopolysaccharidosis type I, is an inherited disorder caused by the accumulation of glycosaminoglycans (GAG) due to a deficiency in lysosomal α-L-iduronidase (IDUA), resulting in multiorgan dysfunction. In many patients with Hurler syndrome, IDUA proteins are not produced due to nonsense mutations in their genes; therefore, readthrough-inducing compounds, such as gentamycin, are expected to restore IDUA proteins by skipping the premature termination codon. In the present study, we synthesized a series of chromenopyridine derivatives to identify novel readthrough-inducing compounds. The readthrough-inducing activities of synthesized compounds were examined by measuring cellular IDUA activities and GAG concentrations in Hurler syndrome patient-derived cells. Compounds with a difluorophenyl group at the 2-position of chromenopyridine, a cyclobutyl group at the 3-position, and a basic side chain or basic fused ring exhibited excellent readthrough-inducing activities. KY-640, a chromenopyridine derivative with a tetrahydroisoquinoline sub-structure, increased the cellular IDUA activities of patient-derived cells by 3.2-fold at 0.3 µM and significantly reduced GAG concentrations, and also significantly increased enzyme activity in mouse models, suggesting its therapeutic potential in patients with Hurler syndrome.

Osteogenic Effects of KY-054, a Novel Coumarin Derivative on Femur Cortical Bone in Ovariectomized Female Rats.

Osteoporosis is treated with oral and parenteral bone resorption inhibitors such as bisphosphonates, and parenteral osteogenic drugs including parathyroid hormone (PTH) analogues and anti-sclerostin antibodies. In the present study, we synthesized KY-054, a 4,6-substituted coumarin derivative, and found that it potently promoted osteoblast differentiation with an increase in alkaline phosphatase (ALP) activity at 0.01-1 µM in mouse-derived mesenchymal stem cells (ST2 cells) and rat bone marrow-derived mesenchymal stem cells (BMSCs). In the ovariectomized (OVX) rats, KY-054 (10 mg/kg/d, 8 weeks) increased plasma bone-type ALP activity, suggesting in vivo promoting effects on osteoblast differentiation and/or activation. In dual-energy X-ray absorption (DEXA) scanning, KY-054 significantly increased the distal and diaphyseal femurs areal bone mineral density (aBMD) that was decreased by ovariectomy, indicating its beneficial effects on bone mineral contents (BMC) and/or bone volume (BV). In micro-computed tomography (micro-CT) scanning, KY-054 had no effect on metaphysis trabecular bone loss and microarchitecture parameters weakened by ovariectomy, but instead increased metaphysis and diaphysis cortical bone volume (Ct.BV) and cortical BMC (Ct.BMC) without reducing medullary volume (Med.V), resulting in increased bone strength parameters. It is concluded that KY-054 preferentially promotes metaphysis and diaphysis cortical bone osteogenesis with little effect on metaphysis trabecular bone resorption, and is a potential orally active osteogenic anti-osteoporosis drug candidate.

Synthesis and Evaluation of Novel Triaryl Derivatives with Readthrough-Inducing Activity.

The readthrough mechanism, which skips the premature termination codon and restores the biosynthesis of the defective enzyme, is an emerging therapeutic tactic for nonsense mutation-related diseases, such as Hurler syndrome, a type of mucopolysaccharidosis. In the present study, novel triaryl derivatives were synthesized and their readthrough-inducing activities were evaluated by a luciferase reporter assay with a partial α-L-iduronidase (IDUA) DNA sequence containing the Q70X nonsense mutation found in Hurler syndrome and by measuring the enzyme activity of IDUA knockout cells transfected with the mutant IDUA gene. KY-516, a representative compound in which the meta position carboxyl group of the left ring of the clinically used ataluren was converted to the para position sulfamoylamino group, the central ring to triazole, and the right ring to cyanobenzene, exhibited the most potent readthrough-inducing activity in the Q70X/luciferase reporter assay. In Q70X mutant IDUA transgenic cells, KY-516 significantly increased enzyme activity at 0.1 µM. After the oral administration of KY-516 (10 mg/kg), the highest plasma concentration of KY-516 was above 5 µM in rats. These results indicate that KY-516, a novel triaryl derivative, exhibits potent readthrough-inducing activity and has potential as a therapeutic agent for Hurler syndrome.

The role of CDK8 in mesenchymal stem cells in controlling osteoclastogenesis and bone homeostasis.

Bone marrow mesenchymal stem cells (MSCs) are critical regulators of postnatal bone homeostasis. Osteoporosis is characterized by bone volume and strength deterioration, partly due to MSC dysfunction. Cyclin-dependent kinase 8 (CDK8) belongs to the transcription-related CDK family. Here, CDK8 in MSCs was identified as important for bone homeostasis. CDK8 level was increased in aged MSCs along with the association with aging-related signals. Mouse genetic studies revealed that CDK8 in MSCs plays a crucial role in bone resorption and homeostasis. Mechanistically, CDK8 in MSCs extrinsically controls osteoclastogenesis through the signal transducer and transcription 1 (STAT1)-receptor activator of the nuclear factor κ Β ligand (RANKL) axis. Moreover, aged MSCs have high osteoclastogenesis-supporting activity, partly through a CDK8-dependent manner. Finally, pharmacological inhibition of CDK8 effectively repressed MSC-dependent osteoclastogenesis and prevented ovariectomy-induced osteoclastic activation and bone loss. These findings highlight that the CDK8-STAT1-RANKL axis in MSCs could play a crucial role in bone resorption and homeostasis.

Effects of KY-903, a Novel Tetrazole-Based Peroxisome Proliferator-Activated Receptor γ Modulator, in Male Diabetic Mice and Female Ovariectomized Rats.

Peroxisome proliferator-activated receptor γ (PPARγ) modulators are expected to exert anti-diabetic effects without PPARγ-related adverse effects, such as fluid retention, weight gain, and bone loss. The present study showed that the novel tetrazole derivative KY-903 exerted similar selective PPARγ partial agonist properties to INT-131, a known PPARγ modulator, in transactivation assays, and decreased plasma glucose and triglyceride levels with increases in adiponectin levels in diabetic KK-Ay mice. These effects were similar to those of pioglitazone. Pioglitazone, but not KY-903, increased adipose tissue and heart weights. In pre-adipocytes (3T3-L1), KY-903, in contrast to pioglitazone, increased adiponectin mRNA levels without adipocyte differentiation, indicating anti-diabetic effects via adiponectin without adipogenesis. In ovariectomized rats fed a high-fat diet (OVX/HFD), KY-903 and pioglitazone decreased plasma triglyceride and non-esterified fatty acid levels and increased adiponectin levels, indicating insulin sensitization via adiponectin. KY-903 reduced body weight gain and adipose tissue weight, while pioglitazone increased heart weight and markedly reduced bone mineral density. In mesenchymal stem cell-like ST2 cells, KY-903 slightly reduced osteoblast differentiation without adipocyte differentiation, while pioglitazone markedly reduced it with adipocyte differentiation. In conclusion, KY-903 is a novel PPARγ modulator that exerts anti-diabetic effects without body weight gain or cardiac hypertrophy in diabetic mice and anti-obesity effects with minor bone loss in OVX/HFD, possibly due to increases in adiponectin levels without adipogenesis.

Synthesis and Evaluation of a Novel Series of 2,7-Substituted-6-tetrazolyl-1,2,3,4-tetrahydroisoquinoline Derivatives as Selective Peroxisome Proliferator-Activated Receptor γ Partial Agonists.

A novel series of 7-substituted-2-[3-(2-furyl)acryloyl]-6-tetrazolyl-1,2,3,4-tetrahydroisoquinoline derivatives were synthesized to clarify structure-activity relationships for peroxisome proliferator-activated receptor γ (PPARγ) partial agonist activity and identify more efficacious PPARγ partial agonists with minor adverse effects. Among the derivatives synthesized, compound 26v with a 2-(2,5-dihydropyrrol-1-yl)-5-methyloxazol-4-ylmethoxy group at the 7-position of the tetrahydroisoquinoline structure exhibited stronger PPARγ agonist and antagonist activities (EC50 = 6 nM and IC50 = 101 nM) than previously reported values for compound 1 (EC50 = 13 nM and IC50 = 512 nM). Compound 26v had very weak protein tyrosine phosphatase 1B (PTP1B) inhibitory activity and showed higher oral absorption (Cmax = 11.4 µg/mL and area under the curve (AUC) = 134.7 µg·h/mL) than compound 1 (Cmax = 7.0 µg/mL and AUC = 63.9 µg·h/mL) in male Sprague-Dawley (SD) rats. A computational docking calculation revealed that 26v bound to PPARγ in a similar manner to that of compound 1. In male Zucker fatty rats, 26v and pioglitazone at 10 and 30 mg/kg for 4 weeks similarly reduced plasma triglyceride levels, increased plasma adiponectin levels, and attenuated increases in plasma glucose levels in the oral glucose tolerance test, while only pioglitazone decreased hematocrit values. In conclusion, 6-tetrazolyl-1,2,3,4-tetrahydroisoquinoline derivatives provide a novel scaffold for selective PPARγ partial agonists and 26v attenuates insulin resistance possibly by adiponectin enhancements with minor adverse effects.

CDK8 maintains stemness and tumorigenicity of glioma stem cells by regulating the c-MYC pathway.

Glioblastoma (GBM) is the most malignant form of glioma. Glioma stem cells (GSCs) contribute to the initiation, progression, and recurrence of GBM as a result of their self-renewal potential and tumorigenicity. Cyclin-dependent kinase 8 (CDK8) belongs to the transcription-related CDK family. Although CDK8 has been shown to be implicated in the malignancy of several types of cancer, its functional role and mechanism in gliomagenesis remain largely unknown. Here, we demonstrate how CDK8 plays an essential role in maintaining stemness and tumorigenicity in GSCs. The genetic inhibition of CDK8 by shRNA or CRISPR interference resulted in an abrogation of the self-renewal potential and tumorigenicity of patient-derived GSCs, which could be significantly rescued by the ectopic expression of c-MYC, a stem cell transcription factor. Moreover, we demonstrated that the pharmacological inhibition of CDK8 significantly attenuated the self-renewal potential and tumorigenicity of GSCs. CDK8 expression was significantly higher in human GBM tissues than in normal brain tissues, and its expression was positively correlated with stem cell markers including c-MYC and SOX2 in human GBM specimens. Additionally, CDK8 expression is associated with poor survival in GBM patients. Collectively, these findings highlight the importance of the CDK8-c-MYC axis in maintaining stemness and tumorigenicity in GSCs; these findings also identify the CDK8-c-MYC axis as a potential target for GSC-directed therapy.

(S)-1,2,3,4-Tetrahydroisoquinoline Derivatives Substituted with an Acidic Group at the 6-Position as a Selective Peroxisome Proliferator-Activated Receptor γ Partial Agonist.

A novel series of 2,6,7-substituted 3-unsubstituted 1,2,3,4-tetrahydroisoquinoline derivatives were synthesized to find a peroxisome proliferator-activated receptor γ (PPARγ) partial agonist. Among the derivatives, (E)-7-[2-(cyclopent-3-eny)-5-methyloxazol-4-ylmethoxy]-2-[3-(2-furyl)acryloyl]-6-(1H-tetrazol-5-yl)-1,2,3,4-tetrahydroisoquinoline (20g) exhibited potent partial agonist activity (EC50 = 13 nM, maximal response 30%) and very weak protein tyrosine phosphatase 1B (PTP1B) inhibition (IC50 = 1100 nM), indicating a selective PPARγ partial agonist. A computational docking calculation revealed that 20g bound to PPARγ in a similar manner to that of known partial agonists. In male and female KK-Ay mice with insulin resistance and hyperglycemia, 20g at 30 mg/kg for 7 d significantly reduced plasma glucose levels, but not triglyceride levels. The effects of 20g were similar to those of pioglitazone at 10 mg/kg. In conclusion, the 2,6,7-substituted 1,2,3,4-tetrahydroisoquinoline with an acidic group at the 6-position provides a novel scaffold for selective PPARγ partial agonists and 20g exerted anti-diabetic effects via the partial activation of PPARγ.

[A Novel Oral Anti-osteoporosis Drug with Osteogenesis-promoting Effects via Osteoblast Differentiation].

Osteoporosis increases the risk of bone fractures (e.g., the femur), reduces a person's activities of daily living (ADL) and increases the likelihood of being bedridden. Therapeutic drugs for osteoporosis include oral bisphosphonates and intravenous receptor activator of nuclear factor-κB ligand (RANKL) antibodies, both of which suppress osteoclast activity, as well as the subcutaneously administered recombinant human parathyroid hormone (PTH), which activates osteoblasts. However, there is currently no oral osteogenesis-promoting drug. In the present study, we found a low-molecular-weight compound, KY-273, with osteogenesis promoting effects. KY-273 induced osteoblast differentiation in ST2 cells and in rat bone marrow-derived mesenchymal stem cells at a dose of 0.1 µM. On the other hand, KY-273 did not clearly exert differentiation effects in osteoclasts, chondrocytes, adipocytes, or myoblasts. In ovariectomized rats, KY-273 clearly increased serum bone alkaline phosphatase (ALP) by at a dose of 3 mg/kg for 8 weeks, and increased both the cortical bone volume and medullary volume of the diaphyseal and epiphyseal regions of femoral bone, but did not affect trabecular bone. Although alendronate (used to decrease bone loss) increased trabecular bone, it did not have any significant effects on cortical bone. PTH increased epiphysis cortical and trabecular bone volume, and reduced medullary volume. KY-273 also displayed good oral absorption in rats. In conclusion, KY-273 is a promising candidate for use as an oral anti-osteoporosis drug with osteogenesis promoting effects.

2-Acyl-3-carboxyl-tetrahydroisoquinoline Derivatives: Mixed-Type PTP1B Inhibitors without PPARγ Activation.

A novel series of 2-acyl-3-carboxyl-tetrahydroisoquinoline derivatives were synthesized and biologically evaluated. Among them, (S)-2-{(E)-3-furan-2-ylacryloyl}-7-[(2E,4E)-5-(2,4,6-trifluorophenyl)penta-2,4-dienyloxy]-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (compound 17u) was identified as a potent protein tyrosine phosphatase 1B (PTP1B) inhibitor without peroxisome proliferator-activated receptor (PPAR) γ activation: PTP1B inhibition IC50=0.19 µM and PPARγ ΕC50>10 µM. Compound 17u exhibited mixed-type inhibition for PTP1B, and this mode of inhibition was rationalized by computational ligand docking into the catalytic and allosteric sites of PTP1B. Compound 17u also showed high oral absorption at 10 mg/kg (per os (p.o.), Cmax=4.67 µM) in rats, significantly reduced non-fasting plasma glucose and triglyceride levels with no side effects at 30 mg/kg/d (p.o.) for 4 weeks, and attenuated elevations in plasma glucose levels in the oral glucose tolerance test performed 24 h after its final administration in db/db mice. In conclusion, the substituted 2-acyl-3-carboxyl-tetrahydroisoquinoline is a novel scaffold of mixed-type PTP1B inhibitors without PPARγ activation, and compound 17u has potential as an efficacious and safe anti-diabetic drug as well as a useful tool for investigations on the physiological and pathophysiological effects of mixed-type PTP1B inhibition.

Therapeutic effects of the allosteric protein tyrosine phosphatase 1B inhibitor KY-226 on experimental diabetes and obesity via enhancements in insulin and leptin signaling in mice.

The anti-diabetic and anti-obesity effects of the allosteric protein tyrosine phosphatase 1B (PTP1B) inhibitor 4-(biphenyl-4-ylmethylsulfanylmethyl)-N-(hexane-1-sulfonyl)benzoylamide (KY-226) were pharmacologically evaluated. KY-226 inhibited human PTP1B activity (IC50 = 0.28 µM), but did not exhibit peroxisome proliferator-activated receptor γ (PPARγ) agonist activity. In rodent preadipocytes (3T3-L1), KY-226 up to 10 µM had no effects on adipocyte differentiation, whereas pioglitazone, a PPARγ agonist, markedly promoted it. In human hepatoma-derived cells (HepG2), KY-226 (0.3-10 µM) increased the phosphorylated insulin receptor (pIR) produced by insulin. In db/db mice, the oral administration of KY-226 (10 and 30 mg/kg/day, 4 weeks) significantly reduced plasma glucose and triglyceride levels as well as hemoglobin A1c values without increasing body weight gain, while pioglitazone exerted similar effects with increases in body weight gain. KY-226 attenuated plasma glucose elevations in the oral glucose tolerance test. KY-226 also increased pIR and phosphorylated Akt in the liver and femoral muscle. In high-fat diet-induced obese mice, the oral administration of KY-226 (30 and 60 mg/kg/day, 4 weeks) decreased body weight gain, food consumption, and fat volume gain with increases in phosphorylated STAT3 in the hypothalamus. In conclusion, KY-226 exerted anti-diabetic and anti-obesity effects by enhancing insulin and leptin signaling, respectively.

Novel Non-carboxylate Benzoylsulfonamide-Based Protein Tyrosine Phosphatase 1B Inhibitors with Non-competitive Actions.

A novel series of benzoylsulfonamide derivatives were synthesized and biologically evaluated. Among them, 4-(biphenyl-4-ylmethylsulfanylmethyl)-N-(hexane-1-sulfonyl)benzamide (compound 18K) was identified as a protein tyrosine phosphatase 1B (PTP1B) inhibitor with potent and selective inhibitory activity against PTP1B (IC50=0.25 µM). Compound 18K functioned as a non-competitive inhibitor and bound to the allosteric site of PTP1B. It also showed high oral absorption in mice (the maximum drug concentration (Cmax)=45.5 µM at 30 mg/kg), rats (Cmax=53.6 µM at 30 mg/kg), and beagles (Cmax=37.8 µM at 10 mg/kg), and significantly reduced plasma glucose levels at 30 mg/kg/d (per os (p.o.)) for one week with no side effects in db/db mice. In conclusion, the substituted benzoylsulfonamide was shown to be a novel scaffold of a non-competitive and allosteric PTP1B inhibitor, and compound 18K has potential as an efficacious and safe anti-diabetic drug as well as a useful tool for investigations of the physiological and pathophysiological effects of allosteric PTP1B inhibition.

Novel 2,7-Substituted (S)-1,2,3,4-Tetrahydroisoquinoline-3-carboxylic Acids: Peroxisome Proliferator-Activated Receptor γ Partial Agonists with Protein-Tyrosine Phosphatase 1B Inhibition.

A novel series of 2,7-substituted 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid derivatives were synthesized and biologically evaluated. (S)-2-(2-Furylacryloyl)-7-[2-(2-methylindane-2-yl)-5-methyloxazol-4-yl]methoxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid tert-butylamine salt (13jE) was identified as a potent human peroxisome proliferator-activated receptor γ (PPARγ)-selective agonist (EC50=85 nM) and human protein-tyrosine phosphatase 1B (PTP-1B) inhibitor (IC50=1.0 µM). Compound 13jE partially activated PPARγ, but not PPARα or PPARδ, and antagonized farglitazar, a full PPARγ agonist. Cmax after the oral administration of 13jE at 10 mg/kg was 28.6 µg/mL (53 µM) in male Sprague-Dawley (SD) rats. Repeated administration of 13jE and rosiglitazone for 14 d at 10 mg/kg/d decreased plasma glucose and triglyceride levels significantly in male KK-A(y) mice. Rosiglitazone, but not 13jE, significantly increased the plasma volume and liver weight. In conclusion, 13jE showed stronger hypoglycemic and hypolipidemic effects and weaker hemodilution and hepatotoxic effects than rosiglitazone, suggesting that its safer efficacy may be due to its partial PPARγ agonism and PTP-1B inhibition.

Insulin sensitization by a novel partial peroxisome proliferator-activated receptor γ agonist with protein tyrosine phosphatase 1B inhibitory activity in experimental osteoporotic rats.

The pharmacological profile of (S)-7-(2-{2-[(E)-2-cyclopentylvinyl]-5-methyloxazol-4-yl}-ethoxy)-2-[(2E,4E)-hexadienoyl]-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (KY-201), a peroxisome proliferator-activated receptor (PPAR) γ agonist, was compared with that of rosiglitazone in ovariectomized rats. The serum triglyceride and non-esterified fatty acid reducing effects of KY-201 at 3 and 10 mg/kg per day for 6 weeks were similar to those of rosiglitazone despite its weaker PPARγ agonistic activity. KY-201 had no effects on body weight gain, blood volume, or heart and adipose weights, while rosiglitazone at 10 mg/kg per day increased them. KY-201 had few effects on bone mineral density (BMD) or fat in marrow (FM), whereas rosiglitazone strongly decreased BMD and increased FM. The PPARγ agonistic activity of KY-201 was weaker than that of rosiglitazone in ST-2 cells, and KY-201 reduced osteoblast differentiation and increased adipocyte differentiation less potently than rosiglitazone in rat bone marrow-derived mesenchymal stem cells. KY-201, but not rosiglitazone inhibited protein tyrosine phosphatase 1B (PTP1B) and increased phosphorylation of the insulin receptor in HepG2 cells. These results suggest that the hypolipidemic effects of KY-201 are similar to those of rosiglitazone, but with less adverse effects, due to the combination of PPARγ partial activation and PTP1B inhibition. KY-201 would be useful for treatments of diabetic patients at high risk of osteoporosis, cardiovascular disease, and/or obesity.

Novel (S)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acids: peroxisome proliferator-activated receptor γ selective agonists with protein-tyrosine phosphatase 1B inhibition.

A novel series of 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid derivatives were synthesized and (S)-2-[(2E,4E)-hexadienoyl]-7-(2-{5-methyl-2-[(1E)-5-methylhexen-1-yl]oxazol-4-yl}ethoxy)-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (14i) was identified as a potent human peroxisome proliferator-activated receptor γ (PPARγ) selective agonist (EC(50)=0.03 µM) and human protein-tyrosine phosphatase 1B (PTP-1B) inhibitor (IC(50)=1.18 µM). C(max) after oral administration of 14i at 10mg/kg was 2.2 µg/ml (4.5 µM) in male SD rats. Repeated administration of 14i and rosiglitazone for 14 days dose-dependently decreased plasma glucose levels, ED(50)=4.3 and 23 mg/kg/day, respectively, in male KK-A(y) mice. In female SD rats, repeated administration of 14i at 12.5-100mg/kg/day for 28 days had no effect on the hematocrit value (Ht) and red blood cell count (RBC), while rosiglitazone significantly decreased them from 25mg/kg/day. In conclusion, 14i showed about a fivefold stronger hypoglycemic effect and fourfold or more weaker hemodilution effect than rosiglitazone, indicating that 14i is 20-fold or more safer than rosiglitazone. Compound 14i is a promising candidate for an efficacious and safe anti-diabetic drug targeting PPARγ and PTP-1B.

A novel series of (S)-2,7-substituted-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acids: peroxisome proliferator-activated receptor α/γ dual agonists with protein-tyrosine phosphatase 1B inhibitory activity.

Novel 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid derivatives were synthesized and (S)-7-(2-{2-[(E)-2-cyclopentylvinyl]-5-methyloxazol-4-yl}ethoxy)-2-[(2E,4E)-hexadienoyl]-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (14c) was identified as a peroxisome proliferator-activated receptor (PPAR) α/γ dual agonist. The transactivation activity of 14c was comparable to that of rosiglitazone in human PPARγ (EC50=0.14 µM) and was much higher than in human PPARα (EC50=0.20 µM). In addition, 14c, but not rosiglitazone, showed human protein-tyrosine phosphatase 1B (PTP-1B) inhibitory activity (IC50=1.85 µM). 14c showed about 10-fold stronger hypoglycemic and hypotriglyceridemic effects than rosiglitazone by repeated application for 14 d in male KK-Ay mice. Furthermore, 14c, but not rosiglitazone, increased hepatic peroxisome acyl CoA oxidase activity at 30 mg/kg/d for 7 d in male Syrian hamsters, probably due to its PPARα agonist activity. 14c did not affect plasma volume at 100 mg/kg/d for 14 d in male ICR mice, while rosiglitazone significantly increased it. In conclusion, 14c is a promising candidate for an efficacious and safe anti-diabetic drug with triple actions as a PPARα/γ dual agonist with PTP-1B inhibitory activity.

2-Acyl-tetrahydroisoquinoline-3-carboxylic acids: lead compounds with triple actions, peroxisome proliferator-activated receptor α/γ agonist and protein-tyrosine phosphatase 1B inhibitory activities.

2-Acyl-tetrahydroisoquinoline-3-carboxylic acid derivatives were synthesized and biologically evaluated. (S)-2-(2,4-Hexadienoyl)-7-[2-(5-methyl-2-phenyloxazol-4-yl)ethoxy]-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (14) showed peroxisome proliferator-activated receptor γ (PPARγ) and PPARα agonist activities and protein-tyrosine phosphatase 1B (PTP-1B) inhibitory activities. PPARγ agonist activity of 14 was comparable to that of rosiglitazone, and PTP-1B inhibitory activity was about 10-fold weaker than that of ertiprotafib, a PTP-1B inhibitor. Compound 14 showed high oral absorption in rats and potent hypoglycemic effects in KK-A(y) mice. In conclusion, 14 would be an excellent lead compound for a new type of anti-diabetic drug with triple actions.

Novel prodrugs of meropenem with two lipophilic promoieties: synthesis and pharmacokinetics.

To improve the oral absorption of meropenem (MEPM), we synthesized and evaluated a series of its double-promoiety prodrugs, in which lipophilic promoieties were introduced into carboxyl and pyrrolidinyl groups. Among these prodrugs, pivaloyloxymethyl (1R,5S,6S)-2-[(3S,5S)-5-(N,N-dimethylcarbamoyl)-1-(isobutyryloxymethyloxycarbonyl)pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate (4) and 1-ethylpropyloxycarbonyloxymethyl (1R,5S,6S)-2-[(3S,5S)-5-(N,N-dimethylcarbamoyl)-1-(isobutyryloxymethyloxycarbonyl)pyrrolidin-3-ylthio]-6-[(1R)-1-hydroxyethyl]-1-methylcarbapen-2-em-3-carboxylate (8) were chosen for further evaluation. Compounds 4 and 8 were well absorbed after oral administration to rats and beagles (bioavailability 18.2-38.4%), and expected to show potent therapeutic efficacy in patients infected with various pathogens, such as penicillin-resistant S. pneumoniae and ß-lactamase-negative ampicillin-resistant H. influenzae.