KR 31372, a benzopyran derivative, inhibits oxidized LDL-stimulated proliferation and migration of vascular smooth muscle cells

Construction of 6-amino-2,2-dimethyl-3,4,6-trisubstituted-2H-1-benzopyran library by solid phase synthesis

We report the solid-phase library construction of 2000 analogues of 6-amino-2,2-dimethyl-3,4,6-trisubstituted-2H-1-benzopyran. The polymer-bound hydroxyalkoxychromanes 5, produced by nucleophilic reactions with various alcohols on epoxides generated in situ, served as key intermediates for subsequent diversification. Further reactions on these hydroxyalkoxychromanes 5 with various electrophiles, such as alkyl halides and acid halides, produced the desired 6-amino-2,2-dimethyl-3,4,6-trisubstituted-2H-1-benzopyran analogues 9, 10, and 11. The progress of reactions could be monitored as solid-bound intermediates by ATR-FTIR or HR-MAS-NMR spectroscopy. The final compounds, obtained in good yields and high purity upon cleavage from the resins, were characterized by LC/MS, HRMS, (1)H NMR, and (13)C NMR spectroscopy.

Antiangiogenic effect of KR-31372 by apoptosis via mediation of mitochondrial KATP channel opening and the phosphatase and tensin homolog deleted from chromosome 10 phosphorylation

Antiangiogenic action of (2R,3R,4S)-N"-cyano-N-(6-nitro-3,4-dihydro-hydroxy-2-methyl-2-dimethoxymethyl-2H-1-benzopyran-4yl)-N'-benzyl guanidine (KR-31372) was examined with its proapoptotic action in human umbilical vein endothelial cells (HUVECs) compared with diazoxide. KR-31372 as well as diazoxide significantly suppressed the neovascularization in mice induced by the Matrigel-containing recombinant human vascular endothelial growth factor (VEGF)165 in vivo and the basal tube formation of HUVECs in vitro with suppression of proliferation of HUVECs stimulated by VEGF165. KR-31372 and diazoxide enhanced DNA fragmentation associated with increase in phosphatase and tensin homolog deleted from chromosome 10 (PTEN) and decrease in serine/threonine kinase phosphorylation, which were accompanied by augmented Bax and cytochrome c release, and suppressed Bcl-2 in HUVECs. In the U87-MG cells, when transfected with expression vectors for sense PTEN, KR-31372 enhanced DNA fragmentation, but not in naive U87-MG cells. The suppression by KR-31372 and diazoxide of these variables was significantly antagonized by 5-hydroxydecanoic acid, a mitochondrial KATP channel blocker. Taken together, KR-31372 strongly inhibited angiogenesis in HUVECs by proapoptotic mechanism via mediation of 5-hydroxydecanoic acid-inhibitable mitochondrial KATP channel opening and PTEN phosphorylation.

KR-31372 inhibits KDR/Flk-1 tyrosine phosphorylation via K+(ATP) channel opening in its antiangiogenic effect

The aim of this study was to identify the signaling pathway of the antiangiogenesis by (2R,3R,4S)-N-cyano-N-(6-nitro-3,4-dihydro-hydroxy-2-methyl-2-dimethoxymethyl 2H-1-benzopyran-4yl)-N'-benzylguanidine (KR-31372). KR-31372 inhibited the in vitro basal tube formation using Matrigel-coated plate and in vivo neovascularizations in mice induced by Matrigel containing vascular endothelial growth factor (VEGF(165), 5 ng/ml). VEGF(165) markedly increased cell proliferation using 5-bromo-2'-deoxyuridine incorporation and chemotactic migration using transwell chamber in human umbilical vein endothelial cells, those of which were significantly suppressed by pretreatment with KR-31372 and levcromakalim concentration dependently. The suppression of all these variables were strongly antagonized by glibenclamide, ATP-sensitive K(+) channel blocker. KR-31372 (10(-6)-10(-4) M) and levcromakalim (10(-5) M) concentration-dependently suppressed the VEGF(165)-induced increases in KDR/Flk-1 tyrosine phosphorylation as well as the extracellular signal-related kinase 1/2 (ERK1/2), p38 MAK and p125(FAK) tyrosine phosphorylation. These variables were significantly antagonized by glibenclamide. In conclusion, KR-31372 significantly inhibited the KDR/Flk-1 tyrosine phosphorylation-linked ERK1/2, p38 MAPK and p125(FAK) tyrosine phosphorylation via mediation of K(+)(ATP) channel opening, thereby resulting in antiangiogenesis.