Synthesis and oral hypoglycemic properties of two 4-oxo-4,5,6,7-tetrahydroindole-3-acetic acids.

Condensation of beta-acetyl-2-hydroxy-4,4-dimethyl-6-oxo-1-cyclohexene-1-propionic acid (3) with n-butyl and isobutylamines affords the title acids 4 and 5, respectively, which show good oral hypoglycemic activity in normal rats. Acids 4 and 5, are also active in streptozocin-induced diabetic rats. Results of extensive pharmacological and acute toxicity tests are reported.

Rat parathyroid hormone-(1-34) fragment: renal adenylate cyclase activity and receptor binding properties in vitro.

The rat PTH molecule contains five sequence differences from either the bovine or the human hormone within the biologically active 1-34 region. A synthetic rat 1-34 peptide was tested for activity by in vitro activation of canine and rat renal adenylate cyclase and binding to canine renal membrane receptors. The mean potency of 21,400 Medical Research Council units/mg in the canine adenylate cyclase system and 24,900 in the rat system was 8- to 10-fold higher than human 1-34 and 2- to 4-fold greater than bovine 1-34. These values represent the highest potency we have observed to date for a PTH preparation by these assay systems. In contrast, receptor binding of the rat fragment was comparable to that of bovine and human 1-34. Half-maximal inhibition of radioligand binding occurred at 1.7- 2.0 X 10(-9) M with all synthetic hormones. Hence, the amino acid substitutions in rat 1-34 appear to affect the cyclase-activating sequence domain without increasing avidity for the receptor. Analogs combining the rat sequence with modifications known to enhance receptor binding and/or retard enzymatic degradation offer a promising approach to the preparation of still more potent parathyroid agonists.