Synthesis and dopaminergic activity of some 3-(1,2,3,6-tetrahydro-1-pyridylalkyl)indoles. A novel conformational model to explain structure-activity relationships.

The synthesis and dopaminergic properties of a novel type of dopamine agonist is described. The number and kind of essential structural elements differ significantly from that of the rigid apomorphine-type dopamine agonists. Using standard molecular modeling techniques, a conformational model is developed proposing a U-shaped conformation which might be energetically preferred through aromatic pi-pi-interactions between both of the electron rich aromatic structural elements of this class of compounds.

Conformation-based design of two cyclic physalaemin analogues.

Two new cyclic analogues of physalaemin were designed on the basis of the conformation found in DMSO solution. Glp-Ala-cyclo(-Asp-Pro-Asn-Lys-)-Phe-Tyr-Gly-Leu-Met-NH2 (1) was synthesized by cyclization of physalaemin. In 2 the Asp residue was replaced by Glu.

4-Heterocyclyloxy-2H-1-benzopyran potassium channel activators.

The reaction of 2,4-dihydroxypyridine (2) with 3,4-epoxy-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-6-carbonitrile (1) yielded the 4-[(1,2-dihydro-2-oxo-4-pyridyl)oxy] compound 3a, accompanied by small amounts of the isomeric 4-(1,2-dihydro-4-hydroxy-2-oxo-1-pyridyl) compound 4. This could also be prepared by hydrogenation of the benzyloxy derivative 5. Reaction of 3,6-pyridazinediol (10) with 1 (R = CN) gave the 4-[(1,6-dihydro-6-oxo-3-pyridazinyl)oxy] compound 11a, which in turn rearranged on heating with NaH in DMSO into the 4-(1,6-dihydro-3-hydroxy-6-oxo-1-pyridazinyl) compound 12.

Prevention of phalloidin-induced lesions on isolated rat hepatocytes by novel synthetic analogues of somatostatin.

Exposure of freshly isolated hepatocytes to phalloidin produced blebs on their surfaces: this phenomenon was time- and dose-dependent and irreversible. When hepatocytes were pretreated with somatostatin or with some of its synthetic analogues, formation of blebs was dramatically reduced. This cytoprotective effect was dose-dependent: the dose-response profiles enabled the determination of the CD50 values, i.

Modified somatostatins as inhibitors of a multispecific transport system for bile acids and phallotoxins in isolated hepatocytes.

Somatostatin inhibits the uptake of phallotoxins and of cholic acid in isolated liver cells in a concentration-dependent manner. The inhibition is independent on the preincubation period and fully reversed by switching to a somatostatin-free buffer. Concentrations needed for 50% inhibition decreased 30-80-fold when somatostatin was modified by variation of its amino acid sequence.