Structure-based drug design to overcome species differences in kallikrein 7 inhibition of 1,3,6-trisubstituted 1,4-diazepan-7-ones.

A series of 1,3,6-trisubstituted 1,4-diazepan-7-ones were prepared as kallikrein 7 (KLK7, stratum corneum chymotryptic enzyme) inhibitors. Previously reported compounds 1-3 were potent human KLK7 inhibitors; however, they did not exhibit inhibitory activity against mouse KLK7. Comparison of the human and mouse KLK7 structures reveals the cause of this species differences; therefore, compounds that could inhibit both KLK7s were designed, synthesized, and evaluated. Through this structure-based drug design, compound 22g was identified as an inhibitor against human and mouse KLK7, and only one of the enantiomers, (-)-22g, exhibited potent inhibitory activity. Furthermore, the crystal structure of mouse KLK7 complexed with 22g enabled the elucidation of structure-activity relationships and justified 22g as a valuable compound to overcome the species differences.

Structure-based drug design of 1,3,6-trisubstituted 1,4-diazepan-7-ones as selective human kallikrein 7 inhibitors.

A novel series of 1,3,6-trisubstituted 1,4-diazepan-7-ones were investigated as human kallikrein 7 (KLK7, stratum corneum chymotryptic enzyme) inhibitors. Based on the X-ray co-crystal structure of compound 1 bound to human KLK7, the derivatives of this scaffold were designed, synthesized, and evaluated. Through structure-activity relationship studies focused on the side chain located in the prime site region of the enzyme, representative compounds 15, 33a, and 35a were identified as highly potent and selective inhibitors of human KLK7.

Discovery and dimeric approach of novel Natriuretic Peptide Receptor A (NPR-A) agonists.

Novel agonists of the Natriuretic Peptide Receptor A (NPR-A) were obtained through random screening and subsequent structural modification of triazine derivatives. The key structural feature to improve in vitro activity was the dimerization of triazine monomer derivatives. The non peptide derivative 7c and 13a showed highly potent NPR-A agonistic activity in vitro and diuretic activity in vivo. These results implied that non-peptidic small molecules open the possibility of new therapy for congestive heart failure.

Small-molecule inhibition of PTPRZ reduces tumor growth in a rat model of glioblastoma.

Protein tyrosine phosphatase receptor-type Z (PTPRZ) is aberrantly over-expressed in glioblastoma and a causative factor for its malignancy. However, small molecules that selectively inhibit the catalytic activity of PTPRZ have not been discovered. We herein performed an in vitro screening of a chemical library, and identified SCB4380 as the first potent inhibitor for PTPRZ. The stoichiometric binding of SCB4380 to the catalytic pocket was demonstrated by biochemical and mass spectrometric analyses. We determined the crystal structure of the catalytic domain of PTPRZ, and the structural basis of the binding of SCB4380 elucidated by a molecular docking method was validated by site-directed mutagenesis studies. The intracellular delivery of SCB4380 by liposome carriers inhibited PTPRZ activity in C6 glioblastoma cells, and thereby suppressed their migration and proliferation in vitro and tumor growth in a rat allograft model. Therefore, selective inhibition of PTPRZ represents a promising approach for glioma therapy.

ASB14780, an Orally Active Inhibitor of Group IVA Phospholipase A2, Is a Pharmacotherapeutic Candidate for Nonalcoholic Fatty Liver Disease.

We have previously shown that high-fat cholesterol diet (HFCD)-induced fatty liver and carbon tetrachloride (CCl4)-induced hepatic fibrosis are reduced in mice deficient in group IVA phospholipase A2 (IVA-PLA2), which plays a role in inflammation. We herein demonstrate the beneficial effects of ASB14780 (3-[1-(4-phenoxyphenyl)-3-(2-phenylethyl)-1H-indol-5-yl]propanoic acid 2-amino-2-(hydroxymethyl)propane-1,3-diol salt), an orally active IVA-PLA2 inhibitor, on the development of fatty liver and hepatic fibrosis in mice. The daily coadministration of ASB14780 markedly ameliorated liver injury and hepatic fibrosis following 6 weeks of treatment with CCl4. ASB14780 markedly attenuated the CCl4-induced expression of smooth muscle α-actin (α-SMA) protein and the mRNA expression of collagen 1a2, α-SMA, and transforming growth factor-ß1 in the liver, and inhibited the expression of monocyte/macrophage markers, CD11b and monocyte chemotactic protein-1, while preventing the recruitment of monocytes/macrophages to the liver. Importantly, ASB14780 also reduced the development of fibrosis even in matured hepatic fibrosis. Additionally, ASB14780 also reduced HFCD-induced lipid deposition not only in the liver, but also in already established fatty liver. Furthermore, treatment with ASB14780 suppressed the HFCD-induced expression of lipogenic mRNAs. The present findings suggest that an IVA-PLA2 inhibitor, such as ASB14780, could be useful for the treatment of nonalcoholic fatty liver diseases, including fatty liver and hepatic fibrosis.

Design, synthesis, and biological evaluation of 3-(1-Aryl-1H-indol-5-yl)propanoic acids as new indole-based cytosolic phospholipase A2α inhibitors.

This article describes the design, synthesis, and biological evaluation of new indole-based cytosolic phospholipase A2α (cPLA2α, a group IVA phospholipase A2) inhibitors. A screening-hit compound from our library, (E)-3-{4-[(4-chlorophenyl)thio]-3-nitrophenyl}acrylic acid (5), was used to design a class of 3-(1-aryl-1H-indol-5-yl)propanoic acids as new small molecule inhibitors. The resultant structure-activity relationships studied using the isolated enzyme and by cell-based assays revealed that the 1-(p-O-substituted)phenyl, 3-phenylethyl, and 5-propanoic acid groups on the indole core are essential for good inhibitory activity against cPLA2α. Optimization of the p-substituents on the N1 phenyl group led to the discovery of 56n (ASB14780), which was shown to be a potent inhibitor of cPLA2α via enzyme assay, cell-based assay, and guinea pig and human whole-blood assays. It displayed oral efficacy toward mice tetradecanoyl phorbol acetate-induced ear edema and guinea pig ovalbumin-induced asthma models.