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 gamma (PPAR gamma) selective agonist (EC(50) = 0.03 mu M) and human protein-tyrosine phosphatase 1B (PTP-1B) inhibitor (IC(50) = 1.18 mu M). C(max) after oral administration of 14i at 10 mg/kg was 2.2 mu g/ml (4.5 mu M) 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 12.5-100 mg/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 25 mg/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 PPAR gamma and PTP-1B. (C) 2011 Elsevier Ltd. All rights reserved.