In recent years, disorders like diabetes, hypertension, dyslipidemia and obesity which can be a risk factor for arteriosclerotic disorders have been rapidly increasing due to changes in life style with improvements in living standard, i.e., high calorie and high cholesterol type diet, obesity, lack of exercise, aging, and the like. It is known that, although being a risk factor independent of each other, overlap of the disorders can cause an occurrence of arteriosclerotic disorders at higher frequency or aggravation of the disorders. As such, with the understanding of a condition having a plurality of risk factors for arteriosclerotic disorders as metabolic syndrome, efforts have been made to elucidate the cause of the syndrome and to develop a therapeutic method therefor.
Angiotensin II (herein below, it may be also abbreviated as AII) is a peptide that is found to be an intrinsic pressor substance produced by renin-angiotensin system (i.e., RA system). It is believed that pharmacological inhibition of angiotensin II activity can lead to treatment or prevention of circulatory disorders like hypertension. Accordingly, an inhibitor for angiotensin converting enzyme (ACE) which inhibits the enzyme promoting the conversion of angiotensin I (AI) to angiotensin II has been clinically used as an inhibitory agent for RA system. Furthermore, an orally administrable AII receptor blocker (Angiotensin Receptor Blocker: ARB) has been developed, and losartan, candesartan, telmisartan, valsartan, olmesartan, and irbesartan, and the like are already clinically used as a hypotensive agent. It is reported by many clinical or basic studies that, as having not only a hypotensive activity but also other various activities including an anti-inflammatory activity, an endothelial function improving activity, a cardiovascular remodeling inhibiting activity, an oxidation stress inhibiting activity, a proliferation factor inhibiting activity, and insulin resistance improving activity, and the like, ARB is useful for cardiovascular disorders, renal diseases, and arteriosclerosis, and the like (Non-Patent Documents 1 and 2). Most recently, it is also reported that ARB particularly has a kidney protecting activity which does not depend on a hypotensive activity (Non-Patent Document 3).
Meanwhile, three isoforms, i.e., α, γ, and γ, have been identified so far as peroxisome proliferator-activated receptors (PPARγ) which belong to a nuclear receptor superfamily. Among them, PPARγ is an isoform that is most abundantly expressed in an adipose tissue and it plays an important role in differentiation of adipocytes or metabolism of glycolipids. Currently, thiazolidinedione derivatives (i.e., TZD) like pioglitazone or rosiglitazone are clinically used as a therapeutic agent for diabetes having PPARγ activation activity, and they are known to have an activity of improving insulin resistance, glucose tolerance, and lipid metabolism, and the like. Further, it is recently reported that, based on activation of PPARγ, TZD exhibits various activities including a hypotensive activity, an anti-inflammatory activity, an endothelial function improving activity, a proliferation factor inhibiting activity, and an activity of interfering RA system, and the like. It is also reported that, according to such multiple activities, TZD shows a kidney protecting activity particularly in diabetic nephropathy without depending on blood sugar control (Non-Patent Documents 4, 5, 6, 7, and 8). Meanwhile, there is also a concern regarding adverse effects of TZD caused by PPARγ activation like body fluid accumulation, body weight gain, peripheral edema, and pulmonary edema (Non-Patent Documents 9 and 10).
It has been recently reported that telmisartan has a PPARγ activation activity (Non-Patent Document 11). It has been also reported that the irbesartan has the same activity (Non-Patent Document 12). These compounds have both a RA system inhibiting activity and a PPARγ activation activity, and thus are expected to be used as an integrated agent for prevention and/or treatment of circulatory disorders (e.g., hypertension, heart diseases, angina pectoris, cerebrovascular disorders, cerebral circulatory disorders, ischemic peripheral circulatory disorders, and renal diseases, and the like) or diabetes-related disorders (e.g., Type II diabetes, diabetic complications, insulin resistant syndrome, metabolic syndrome, hyperinsulinemia, and the like) without increasing a risk of body fluid accumulation, body weight gain, peripheral edema, pulmonary edema, or congestive heart failure that are concerned over the use of TZD (Patent Document 1). Among them, for diabetic nephropathy, a synergistic prophylactic and/or therapeutic effect is expected from multiple kidney protecting activity based on activities of RA system inhibition and PPARγ activation.
As compounds having such activities, pyrimidine and triazine derivatives (Patent Document 1), imidazopyridine derivatives (Patent Document 2), indole derivatives (Patent Document 3), imidazole derivatives (Patent Document 4), and condensed ring derivatives (Patent Document 5) have been reported. However, the phenylpyridine derivative of the present invention is neither described nor suggested.
Meanwhile, Patent Document 6 discloses compounds represented by the following formula (A):
                [wherein, R1 represents a hydrocarbon residue that may be bonded through a heteroatom or substituted, R2 represents a 5 to 7-membered heterocyclic residue that may be substituted having as a ring constituting group, a carbonyl group, a thiocarbonyl group, a sulfur atom that can be oxidized, or a ring constituting group that can be converted thereto, X represents bonding of ring Y and ring W directly or through a spacer of 2 or less atom chains, W and Y represent an aromatic hydrocarbon residue or a heterocyclic residue that may be substituted or may contain a heteroatom, n represents an integer of 1 or 2, a and b, which constitute the heterocyclic residue, represent, independently from each other, one or two carbons or heteroatoms that may be substituted, c represents one carbon or heteroatom that may be substituted, and substituents on two adjacent ring constituting atoms in the group represented by the formula:        
                may bond to each other to form a 5 to 6-membered ring with the two ring constituting atoms]. Biphenyl is raised as a preferably example of the W—Y ring system, and the Examples specifically describe only a biphenyl derivative. These compounds disclosed in Patent Document 6 are different from the compound of the present invention in view of the ring to which the pyridinylmethyl group is bonded. Furthermore, in Patent Document 6, PPARγ activation activity as a pharmacological activity, or a treatment for diabetes, obesity or metabolic syndrome is neither described nor suggested.