A. A. Shishkina

Insulin secretion-stimulating activity of certain derivatives of the C-terminal tetrapeptide of cholecystokinin

The tetrapeptide amide, possessing amino acid sequence H-Trp-Met-Asp-Phe-Nh 2 (I, CCK-4, trimafam) is a C-terminal structural fragment of gastrin, secretin, and cholecystokinin, and, as we discovered previously [2], has a pronounced stimulating effect on the secretion of insulin, glucagon, and somatostatin. According to the data of [5], the insulin-stimulating effect of tetrapeptide I is substantially more pronounced than that of other larger fragments of cholecystokinin. These investigations open up theoretically new possibilities in the treatment of diabetes mellitus using previously unknown oligopeptide compounds that activate insulin secretion in the pancreas.

Synthesis of new structural analogs of tetragastrin

In connection with a study of the structural-functlonal organization of peptlde hormones, we have performed the synthesis of new structural analogs of tetragastrin (synonym: fragment 14-17 of gastrln; fragment 30-33 of cholecystoklnin, trimafam, CCK-4)[I-3], which consists of a tetrapeptlde with the structure (I). It was the previously unknown analogs (II-IV) differing from natural tetragastrln (I) by the replacement of the L-tryptophan residue in position i by L-ornithine, D-ornithlne, and L-alanine residues, respectively, that were synthesized.

Synthesis and properties of 2-substituted estra-4, 9-dien-17β-ol-3-one derivatives

Reaction of II with formaldehyde in the presence of potassium carbonate [6] and subsequent treatment with aluminum oxide gives the 2-methylene (III) in satisfactory yield. In spite of the presence of five trigonal carbon atoms in one cyclohexene ring, III is a moderately stable compound, considerably more stable than the analogous derivatives described in [3]. Ths structure of III is confirmed by spectral data (Tables 1 and 2). Compared with I, the UV spectrum of III shows a bathochromic shift of 25 nm in the long-wave absorption maximum, due to the additional cross-conjugated double bond [7]. The H I NMR spectrum of the corresponding acetate (IIIa) has signals for three vinyl protons with the expected chemical shifts and multiplicity (see Table i). The signals from the protons in the I-CH2 group are split by geminal coupling with a coupling constant 2j = 20 Hz, which is characteristic of methylene groups with two adjacent double bonds [8].

Synthesis and properties of condensed heterocyclic derivatives of estra-4,9-dien-17β-ol-3-one

Steroid he te rocyc les somet imes possess high anabolic activity and cer ta in of them have found use in medicine [1,2]. In the course of a study of the relat ion between s t ructure and activity in the e s t r a -4 ,9 -d i en -17~-o l -3 -one (I) ser ies [3] it appeared of interest to synthesize steroid isoxazoles and pyrazoles based on the lat ter with five t r igonal carbon atoms in ring A of the steroid, the more so as s imi la r compounds have only once been reported in the patent l i terature [4].