Nucleic acid components and their analogs: Design and synthesis of novel cytosine thioglycoside analogs

The synthesis of a new category of novel cytosine 4-thioglycoside analogs has been first accomplished. The main step of this strategy is the synthesis of sodium pyrimidine-4-thiolate through the condensation of 2-cyano-N-arylacetamides with sodium cyanocarbonimidodithioate, followed by coupling with α-bromo-sugars to afford the corresponding cytosine 4-thioglycoside analogs. The free thioglycosides were also prepared. Subsequent studies on the application of this strategy for the preparation of other potent pyrimidine thioglycosides are reported.     

Protective effect of Echinops galalensis against CCl4-induced injury on the human hepatoma cell line (Huh7)

Phytochemical investigation of the flowering aerial parts of Echinops galalensis (Asteraceae) led to the isolation of a new taraxasteryl triterpene, 3β-acetoxy-taraxast-12, 20(30)-diene-11α-21α-diol (1), together with nine known metabolites, α-amyrin (2), β-sitosterol (3), erythrodiol (4), lup-20(29)-ene-1,3-diol (5), 1,5-dicaffeoylquinic acid (6), 3,5-dicaffeoylquinic acid (7), 3,4-dicaffeoylquinic acid (8), 4,5-dicaffeoylquinic acid (9) and apigenin-7-O-β-d-glucoside (10). The structure of the new compound was determined by comprehensive analyses of their 1D and 2D NMR, mass spectral (HR-EI) data and comparison with previously known analogs. The effect of the methanol extract of E. galalensis, its fractions as well as compounds (1–10) on human hepatoma cell line (Huh7) was evaluated according to aspartate aminotransferase (AST), alanine transaminase (ALT), superoxide dismutase (SOD) activities and malondialdehyde (MDA) level before and after exposure of the cells to carbon tetrachloride (CCl₄). It was found that pre-treatment of human hepatoma cell line (Huh7) with the tested samples (100 μg/ml) prior to CCl₄ challenge protected against cell injury. The protective effect of E. galalensis was suggested to be mediated, at least partly, by its antioxidant activity.     

Gene transfer into insect brain and cell-specific expression of bombyxin gene

 A transgene reporter consisting of the bombyxin gene promoter and the green fluorescent protein coding region was introduced into intact brains of the silkworm Bombyx mori by in vitro electroporation. After in vitro culture of the brains, the fluorescence derived from the introduced reporter gene was observed in all cases in eight neurosecretory cells that had previously been identified as bombyxin-producing cells (BPCs). Although the fluorescence was not always observed in all cells, it was specific to BPCs, indicating that the reporter was under the control of the bombyxin gene promoter in a BPC-specific manner. Electroporatical introduction of a reporter gene was therefore found to be a suitable method for analyzing cell-specific expression in intact tissues and to be substitute for germ-line transmission of reporters in the transgenic system. Application of this technique enables us to analyze the cell-specific expression of transgene reporters within a few days and treat more than several dozens of the reporters within 1 month, which is difficult to do with the transgenic system. Received: 8 December 1998 / Accepted: 8 March 1999