Biomedical subjects
Publications and source records attributed to R Pellicciari.
The 7,7-diethoxycarbonylnorcarane (III), obtained by a catalytic decomposition of diethyldiazomalonate (I a) in cyclohexene, was condensed with urea to give the 5-spiro-7'-(bicyclo(4.1.0.)heptane)barbituric acid (IV).
In connection with a program, the purpose of which is to aim at the synthesis of molecules containing the residual phenylethylamine in a rigid structure, the synthesis of 1-methylaminoisotiocromane (IV) starting from isotiocromane (I) is hereby described.
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A side chain derivative of ursodeoxycholic acid, 23-methylursodeoxycholic acid, was synthesized and the effect of i.v. infusion of the acid at different doses (0.75, 1.5, 3.0 and 6.0 mumoles per min per kg body weight over 1 hr) on bile flow, on its hepatic biotransformations and on biliary lipid secretion has been studied in bile fistula rats. The results were compared with those of ursodeoxycholic and cholic acid administered under similar conditions. 23-Methylursodeoxycholic acid is poorly secreted into bile and poorly taurine and glycine conjugated, at all infusion doses. Ursodeoxycholic acid is quantitatively recovered at low doses and recovered less at high infusion rates. Cholic acid is almost entirely recovered at all infusion doses. Ursodeoxycholic acid conjugation pattern is dependent on the dose, and glucuronidation and sulfation operate at high doses. Cholic acid is taurine conjugated at low doses; at high doses, large amounts of unconjugated bile acids are observed. Methylursodeoxycholic acid presents a delayed secretion and hypercholeresis. Ursodeoxycholic acid presents similar results at high infusion rates, possibly by reaching a high intrahepatic concentration of free form. The octanol/water partition coefficients of ursodeoxycholic acid and 23-methylursodeoxycholic acid are similar and higher than that of cholic acid. A chole-hepatic shunting of 23-methylursodeoxycholic acid may explain both the low recovery in bile and hypercholeresis and is consistent with its hydrophilicity of cholic acid, on the contrary, makes possible its high recovery in bile. The effect on biliary lipid secretion is unpredictable and affected by the dose and, in consequence, by the conjugation pattern of the bile acid.(ABSTRACT TRUNCATED AT 250 WORDS)
alpha-Diazo-beta-hydroxy esters 3, obtained by condensation of ketones 1 with ethyl diazo(lithio)acetate 2, are efficiently converted into the corresponding beta-ketoesters 4 by exposure to dirhodium (II) tetraacetate. Application of this two-step sequence to 3 beta-acetoxy-5-androstene-17-one 5b and to 3-acetoxy estrone 10b afforded regiospecifically and in very high overall yield the corresponding ethyl 17a-oxo-D-homo-steroid-17-carboxylates 7a,b and 12a,b, which were decarboalkoxylated to give, respectively, 3 beta-hydroxy-D-homo-5-androstene-17a-one 8 and D-homoestrone 13.
Metabotropic glutamate receptors (mGluRs) constitute an attractive target for the development of potential neuroprotective agents. Recent advances in the elucidation of the peculiar molecular architecture of mGluRs and in the design and synthesis of subtype selective ligands are discussed.
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Two new spirobicyclophosphonate isomers (19 and 20), conformationally constrained analogues of the potent competitive NMDA antagonist CGS 19755 (4), have been designed and synthetized with the aim of gaining insight into the conformational preference of the crucial distal phosphonate moiety at the antagonist NMDA binding site. The preliminary biological evaluation reveals that the activity as NMDA antagonist resides only in the (1R,5S,7R)-isomer (19), characterized by a (-)-gauche disposition around the C1-C5 bond, thus confirming previously reported pharmacophore models.