Synthesis and Anticancer Activities of Novel Guanylhydrazone and Aminoguanidine Tetrahydropyran Derivatives.

In this paper we present the convenient syntheses of six new guanylhydrazone and aminoguanidine tetrahydropyran derivatives 2-7. The guanylhydrazone 2, 3 and 4 were prepared in 100% yield, starting from corresponding aromatic ketones 8a-c and aminoguanidine hydrochloride accessed by microwave irradiation. The aminoguanidine 5, 6 and 7 were prepared by reduction of guanylhydrazone 2-4 with sodium cyanoborohydride (94% yield of 5, and 100% yield of 6 and 7). The aromatic ketones 8a-c were prepared from the Barbier reaction followed by the Prins cyclization reaction (two steps, 63%-65% and 95%-98%). Cytotoxicity studies have demonstrated the effects of compounds 2-7 in various cancer and normal cell lines. That way, we showed that these compounds decreased cell viabilities in a micromolar range, and from all the compounds tested we can state that, at least, compound 3 can be considered a promising molecule for target-directed drug design.

Effects of curine in HL-60 leukemic cells: cell cycle arrest and apoptosis induction.

Curine is a natural alkaloid isolated from Chondrodendron platyphyllum and it has been reported that this alkaloid has vasodilatory and anti-inflammatory effects. The aim of this study is to analyze the cytotoxic effects of curine in cancer cell lines HL-60, K562, and HT-29, and in primary cultures of peripheral blood mononuclear cells (PBMC). Cells were treated with curine (from 3 to 15 µM) for 24 and 48 h. Cell viability was analyzed by the 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) test and flow cytometry with propidium iodide (PI) assay. To assess the type of cell death induced in HL-60, the cell cycle, morphological, and biochemical alterations were analyzed, which were determined by differential staining with acridine orange/ethidium bromide, and annexin V/PI double-labeling and change in mitochondrial membrane potential assays. Curine demonstrated a potent cytotoxic effect on leukemic cell lines (HL-60 and K562). Its cytotoxic effects in HL-60 cells was related to plasma membrane damage and cell cycle arrest at the G1 phase from 43.4 ± 1.0 to 56.7 ± 1.4 % (p < 0.05). Curine (15 µM) also increased the apoptotic cells number by around 60 % in HL-60 cells and caused phosphatidylserine externalization, inducing about 57 % of apoptosis. Moreover, this alkaloid provoked 20 % of mitochondrial membrane depolarization. We conclude that curine presented a cytotoxic effect and induced apoptosis in HL-60 cells. Thus, it can be considered a promising pharmacological drug.

Influence of fetal bovine serum on cytotoxic and genotoxic effects of lectins in MCF-7 cells.

Canavalia ensiformis (ConA), Canavalia brasiliensis (Conbr), and Cratylia floribunda (CFL) lectins have exhibited glucose-mannose binding specificity. We investigated the effect of fetal bovine serum (FBS) concentrations (1, 5, 10, and 20%) on the cytotoxic effect of these lectins against breast tumor cell line MCF-7. Cell viability was examined using the MTT reduction assay. When cells were grown in a medium supplemented with a higher serum concentration (10 or 20%), all lectins were much less toxic. When we used 1% FBS, it was possible to achieve a concentration-dependent activity by all examined lectins, with an IC(50) of 3.5, 25, and 60 µg/mL for ConA, Conbr, and CFL, respectively. All lectins incubated with 1% FBS induced apoptosis and DNA damage in MCF-7 cells. We conclude that ConA, Conbr, and CFL lectins' cytotoxic and genotoxic effects were observed only at low concentrations of serum.