Browsing by Author "Rojo, Leonel"

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    Part 1: Effect of vitamin C on the biological activity of two euryfurylbenzoquinones on TLT, a murine hepatoma cell line
    (ELSEVIER FRANCE-EDITIONS SCIENTIFIQUES MEDICALES ELSEVIER, 2008) Benites, Julio; Rojo, Leonel; Valderrama, Jaime A.; Taper, Henryk; Calderon, Pedro Buc
    2-Euryfuryl- and 2-euryfuryl-3-nitro-1,4-benzoquinone Q2 and Q3, prepared via oxidative coupling reactions of sesquiterpene euryfuran 1 to 2-nitro-1,4-benzoquinone and 1,4-benzoquinone, were tested for their cytotoxicity towards TLT cells (a murine hepatoma cell line) in the absence and in the presence of vitamin C. Their cytotoxic profile was completely different. In cells incubated with Q2 (from 1 to 50 mu g/ml), cell survival was not modified, both GSH and ATP were depleted to about 50% of control values (at 50 mu g/ml); and caspase-3 was activated in a dose-dependent manner. These effects were observed whatever cells were incubated or not in the presence of vitamin C. In the case of Q3, the cytotoxicity was rather unrelated to its concentration but the association of vitamin C plus the highest Q3 concentration (50 mu g/ml) results in a strong cell death (more than 60%). At such a concentration, a complete lack of caspase-3 activity was observed, probably due to cell lysis. At lower concentrations of Q3 (1 and 10 mu g/ml), caspase-3 activity was lower than that observed in the absence of vitamin C or even under control conditions. Both GSH and ATP were kept fairly constant as compared to control values but in the presence of vitamin C and Q3, at 50 mu g/ml, a decrease in their amounts was observed. (C) 2007 Elsevier Masson SAS. All rights reserved.
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    Roles of cholesterol and lipids in the etiopathogenesis of Alzheimer's disease
    (2006) Rojo, Leonel; Sjoberg, Marcela K.; Hernández, Paula; Zambrano, Cristian; Maccioni, Ricardo B.
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    Studies on quinones. Part 42: Synthesis of furylquinone and hydroquinones with antiproliferative activity against human tumor cell lines
    (PERGAMON-ELSEVIER SCIENCE LTD, 2008) Benites, Julio; Valderrama, Jaime A.; Rivera, Felipe; Rojo, Leonel; Campos, Nair; Pedro, Madalena; Jose Nascimento, Maria Saeo
    The preparation of furyl-1,4-quinone and hydroquinones by reaction of 2-furaldehyde N,N-dimethylhydrazone with benzo- and naphthoquinones is reported. Access to furylnaphthoquinones from unactivated quinones requires acid-induced conditions, however oxidative coupling reactions of activated quinones proceed under neutral conditions. The in vitro cytotoxic activity of the prepared compounds against a panel of three human cancer cell lines has been studied. Most of the furyl-1,4-quinones exhibited good antiproliferative activity (GI(50) = 6.5-33.5 mu m) against the MCF-7, NCI-H460, and SF-268 (CNS cancer) cell lines chosen for testing. (C) 2007 Elsevier Ltd. All rights reserved.