(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

Abstract

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=13nM, maximal response 30%) and very weak protein tyrosine phosphatase 1B (PTP1B) inhibition (IC50=1100nM), 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 30mg/kg for 7d significantly reduced plasma glucose levels, but not triglyceride levels. The effects of 20g were similar to those of pioglitazone at 10mg/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.