NaH-mediated one-pot cyclocondensation of 6-nitroquinoline with aromatic hydrazones to form

[reaction: see text] 6-Nitroquinoline undergoes direct cyclocondensation with aromatic hydrazones in the presence of sodium hydride in DMF at -10 degrees C, giving the corresponding 3-aryl-1(3)H-pyrazolo[3,4-f]quinolines and/or 3-aryl[1.2.4]triazino[6,5-f]quinolines in low to moderate yield. The mode of cyclocondensation is considerably dependent on the electronic nature of ring substituent of hydrazones, an electron-donating substituent favoring the formation of the latter heterocycles.

Differential effects of sulfate and sulfobutyl ether of beta-cyclodextrin on erythrocyte membranes in vitro.

The hemolytic activity of beta-cyclodextrin (beta-CyD) on rabbit erythrocytes was reduced by the introduction of negatively-charged groups onto the hydroxyls of beta-CyD; the membrane disrupting abilities decreased in the order of beta-CyD > 2-hydroxypropyl-beta-CyD (HP-beta-CyD) > sulfobutyl-beta-CyD (SB-beta-CyD) >> beta-CyD sulfate (S-beta-CyD). Under pre-hemolytic concentrations, both beta-CyD and SB-beta-CyD induced shape changes of membrane invagination on the erythrocytes. In sharp contrast, S-beta-CyD showed biphasic effect on the shape of the erythrocytes; i.e. the crenation at relatively low concentrations and the invagination at higher concentrations. The S-beta-CyD-induced membrane crenation arose from a direct action on the membranes rather than cell metabolism-mediated effects. Unlike beta-CyD, S-beta-CyD was found to bind to the erythrocytes and may be confined to the outer surface of the membrane bilayer, which may expand the exterior layer relative to the cytoplasmic half, thereby inducing the cells to crenate. On the other hand, the membrane invagination mediated by the three beta-CyDs was initiated by extracting specific membrane lipids from the cells, depending upon their inclusion abilities, subsequently leading to the lysis of the cells. These results indicate that SB-beta-CyD and S-beta-CyD interact with the erythrocyte membranes in a differential manner and possess lower membrane disrupting abilities than the parent beta-CyD and HP-beta-CyD.

Characterization of the inclusion mode of beta-cyclodextrin sulfate and its effect on the chlorpromazine-induced hemolysis of rabbit erythrocytes.

The inclusion mode of beta-cyclodextrin sulfate (beta-CyD-sul) with a cationic drug, chlorpromazine, was investigated, and the effect of beta-CyD-sul on the hemolytic activity of chlorpromazine was compared with that of parent beta-CyD. The interaction of beta-CyD-sul with chlorpromazine was weaker than that of parent beta-CyD, probably because of the steric or electrostatic repulsion between anionic sulfate groups and hydrophobic phenothiazine moiety. Spectroscopic studies, including pH- and salt-effects, as well as thermodynamic parameters, suggested that both electrostatic and hydrophobic interactions are operative in the inclusion complexation of beta-CyD-sul with chlorpromazine. The inhibiting effect of parent beta-CyD on the chlorpromazine-induced hemolysis of rabbit erythrocytes was accounted for by the decreased fraction of free drug through the complexation. In the case of beta-CyD-sul, the hemolysis and binding of the drug to the erythrocyte membrane was higher than those estimated from the fraction of free drug, probably due to the increased hydrophobicity of the drug through the complexation. However, the chlorpromazine-induced shape change of the erythrocytes was significantly suppressed by beta-CyD-sul, and its inhibiting effect was greater than that of beta-CyD, because of the counterbalance of the opposite effects, i.e., internalization and externalization induced by chlorpromazine and beta-CyD-sul, respectively.