The induction of oxidative stress in cervix carcinoma cells by levoglucosenone derived 4-S-salicyl derivative and (1–4)-S-thio-disaccharides. Part 4

New N-Adducts of Thiadiazole and Thiazoline with Levoglucosenone and Evaluation of Their Significant Cytotoxic (Anti-Cancer) Activity

The conjugate N-adducts of thio-1,3,4-diazole and 2-thiazoline with levoglucosenone were synthesized via a stereoselective, base-catalyzed conjugate N-Michael addition to levoglucosenone at C-4. Structural assignments were established using 1H and 13C NMR analysis, and X-ray single-crystal analysis for one of the compounds. The biological properties of the novel compounds were tested on a cell model. Cytotoxicity was analyzed via colorimetric assay. Two distinct types of cell death, apoptosis and necrosis, were analyzed by determining the phosphatidylserine levels from the outer leaflet of the plasma membrane, caspase activation, and lactate dehydrogenase release. We also evaluated DNA damage using an alkaline comet assay. The level of oxidative stress was measured with a modified comet assay and an H2DCFDA probe. The thio-1,3,4-diazole adduct (FCP23) and the 2-thiazoline adduct (FCP26) exhibit similar cytotoxicity values for cancer cells (ovarian (A2780), breast (MCF-7), cervix (HeLa), colon (LoVo), and brain (MO59J and MO59K)), but their mechanism of action is drastically different. While FCP23 induces oxidative stress, DNA damage, and necrosis, FCP26 induces apoptosis through caspase activation.

Biological properties of (1-4)-thio disaccharides

Thio sugars are carbohydrate derivatives in which one or more oxygen atoms have been replaced with sulfur. Thio sugars are effective inhibitors of glycosylases, have considerable therapeutic potential, and are used as drugs in the treatment of diabetes and infectious diseases. The development of this branch of carbohydrate chemistry would not be possible without the development of novel methods for its synthesis and the analysis of their biochemical properties. In this Review Article, we summarize our findings on the biological properties of a collection of thio sugars and their derivatives synthesized by the Witczak and Bielski team using their original methods based on the Michael addition of sugar thiols to levoglucosenone.

Design, synthesis and evaluation of novel levoglucosenone derivatives as promising anticancer agents

A series of levoglucosenone-derived 1,2,3-triazoles and isoxazoles featuring a flexible spacer between the heteroaromatic and anhydropyranose cores have been designed and synthesized following an hetero Michael // 1,3-dipolar cycloaddition path. The use of a design of experiments approach allowed the optimization of the oxa-Michael reaction with propargyl alcohol as nucleophile, a key step for the synthesis of the target compounds. All of the compounds were tested for their anticancer activity on MDA-MB-231 cells, featuring mutant p53. The results highlighted the importance of the introduction of the flexible spacer as well as the higher activity of oxa-Michael isoxazole-derivatives. The most prominent compounds also showed anti-proliferative activities against lung and colon cancer cell lines. The compounds showed enhanced cytotoxic effects in the presence of mutant p53, determined both by endogenous mutant p53 knock down (R280K) and by reintroducing p53 R280K in cells lacking p53 expression.

(1-4)-Thiodisaccharides as anticancer agents. Part 5. Evaluation of anticancer activity and investigation of mechanism of action

(1-4)-Thiodisaccharides, thiosugars with the 1-4-thio bridge, were recently shown to induce oxidative stress, as well as, apoptosis in cancer cells in the low micromolar range; however, the detailed mechanism of their anticancer action still remains unknown. In order to clarify the mechanism of (1-4)- thiodisaccharides action, we performed a series of tests including cytotoxic, clonogenic and apoptosis assays using an in vitro glioma cancer model with one ATCC cell line U87 and two novel glioma cell lines derived from cancer patients - H6PX and H7PX. We also evaluated the ability of (1-4)-thiodisaccharides to interfere with protein folding and synthesis processes, as well as, the thioredoxin system. (1-4)-thiodisaccharides induced glioma cell death, which were found to be accompanied with endoplasmic reticulum stress, inhibition of global protein synthesis, reduced overall cellular thiol level and thioredoxin reductase activity. We also performed a RT-PCR and Elisa analysis of (1-4)-thiodisaccharides-treated glioma cells to identify any changes within the pathway affected by (1-4)-thiodisaccharides. We observed a significant increase of expression in key markers of endoplasmic reticulum stress and pro-apoptotic protein, FASLG. We proposed that (1-4)-thiodisaccharides react with cellular thiols and disturb any cellular thiol-depended processes like thioredoxin system or protein folding.