A novel carbohydrate derived compound FCP5 causes DNA strand breaks and oxidative modifications of DNA bases in cancer cells

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.

Valorization of the Photo-Protective Potential of the Phytochemically Standardized Olive (Olea europaea L.) Leaf Extract in UVA-Irradiated Human Skin Fibroblasts

Leaves of Olea europaea are a by-product of the olive oil industry and a dietary supplement with acknowledged antioxidant and anti-inflammatory activity but underestimated photoprotective potential. We investigated the protective effects of the LC-PDA-MS/MS standardized ethanol-water extract of olive leaves (OLE), containing 26.2% total phenols and 22.2% oleuropein, with underlying mechanisms against the UVA-induced oxidative damage in human dermal fibroblasts. Hs68 cells were pre-treated (24 h) with OLE (2.5-25 μg/mL) or the reference antioxidants, quercetin and ascorbic acid (25 μg/mL), followed by irradiation (8 J/cm²). OLE significantly reduced the UVA-induced DNA damage and reactive oxygen species (ROS) overproduction and increased the thioredoxin reductase (TrxR) expression and post-radiation viability of fibroblasts by inhibiting their apoptosis. Both intrinsic and extrinsic apoptotic signaling pathways appeared to be inhibited by OLE, but the activity of caspase 9 was the most reduced. We hypothesized that the TrxR up-regulation by OLE could have prevented the UVA-induced apoptosis of Hs68 cells. In addition, a significant decrease in UVA-induced secretion levels of tumor necrosis factor (TNF-α) and interleukin-2 (IL-2) was shown in human lymphocyte culture in response to OLE treatment. In summary, our results support the beneficial effect of OLE in an in vitro model and indicate its great potential for use in the cosmetic and pharmaceutical industry as a topical photoprotective, antioxidant, and anti-inflammatory agent.

Responses of human colon and breast adenocarcinoma cell lines (LoVo, MCF7) and non-tumorigenic mammary epithelial cells (MCF-10A) to the acellular fraction of packed red blood cells in the presence and absence of cisplatin

Perioperative blood transfusion in colorectal and some other cancer patients has been linked to the increased risk for recurrence, but a causal mechanism remains unclear. During the preparation and storage of packed red blood cells (PRBCs) bio-active substances accumulate in the acellular fraction (supernatant). Viability, proliferation, reactive oxygen species (ROS) levels, and DNA damage of colon (LoVo) and breast (MCF7) adenocarcinoma cells and non-tumorigenic MCF-10A cell line were determined in response to the supernatants of fresh and long-stored (day 42) PRBCs, leukoreduced (LR) or non-leukoreduced (NLR). The effect of supernatants on the cytotoxicity of cisplatin (cisPt) towards the cells was also examined. Supernatants, especially from a day 1 PRBCs, both LR and NLR, reduced the viability and inhibited proliferation of tumor cells (LoVo, MCF7), accompanying by the excessive ROS production, but these were not the case in MCF-10A. Moreover, supernatants had no effect on the cytotoxicity of cisPt against LoVo and MCF7 cells, while caused increased drug resistance in MCF-10A cells. The findings suggest the acellular fraction of PRBCs does not exhibit any pro-proliferative activity in the cancer cell lines studied. However, these are pioneering issues and require further research.

(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.

Evaluation of the Mycobactericidal Effect of Thio-functionalized Carbohydrate Derivatives

Sugars with heteroatoms other than oxygen have attained considerable importance in glycobiology and in drug design since they are often more stable in blood plasma due to their resistance to enzymes, such as glycosidases, phosphorylases and glycosyltransferases. The replacement of oxygen atoms in sugars with sulfur forms thio-sugars, which are potentially useful for the treatment of diabetes and some bacterial and viral infections. Here, we evaluated the antibacterial activity of thio-functionalized carbohydrate derivatives. A set of 21 compounds was screened against acid-fast Mycobacterium tuberculosis (Mtb), gram-negative Escherichia coli and gram-positive Staphylococcus aureus. The tested carbohydrate derivatives were most effective against tubercle bacilli, with as many as five compounds (thioglycoside 6, thiosemicarbazone 16A, thiosemicarbazone 20, aminothiadiazole 23, and thiazoline 26) inhibiting its growth with MIC₅₀ ≤ 50 µM/CFU. Only two compounds (aminothiadiazole 23 and thiazoline 26) were able to inhibit the growth of E. coli at concentrations below 1 mM, and one of them, aminothiadiazole 23, inhibited the growth of S. aureus at a concentration ≤1 mM. The five compounds affecting the growth of mycobacteria were either thiodisaccharides (6, 16A, and 20) or thioglycosides (23 and 26). All of these compounds (6, 16A, 20, 23, and 26) were able to inhibit the growth of Mtb deposited within human macrophages. However, three of the five selected compounds (6, 23, and 26) exhibited relatively high cytotoxicity in mouse fibroblasts at micromolar concentrations. The selected thio-sugars are very promising compounds, thus making them candidates for further modifications that would decrease their cytotoxicity against eukaryotic cells without affecting their antimycobacterial potential.

A comparative study on the radioprotective potential of the polyphenolic glycoconjugates from medicinal plants of Rosaceae and Asteraceae families versus their aglycones

Radioprotective potential of the polyphenolic glycoconjugates, isolated from flowers of Sanguisorba officinalis L. (So) and Erigeron canadensis L. (Ec), and from leaves of Fragaria vesca L. (Fv) and Rubus plicatus Whe. Et N. E. (Rp) as well as their aglycones (SoA, EcA, FvA and RpA, respectively), against γ-radiation-induced lipid peroxidation in human plasma and DNA damage in lymphocytes, were investigated in vitro. These properties were assessed by measuring the concentration of thiobarbituric acid reactive substances (TBARS) and using the alkaline comet assay, and were compared to the protective effects of rutin (R) and quercetin (Q). Cytotoxicity of the glycoconjugates/aglycones towards L929 mouse fibroblasts and human lymphocytes were also measured. Plant products from S. officinalis, similar to Q, were able to reduce the most radiation-induced lipid peroxidation as well as DNA damage and extent of oxidative damage to the DNA basis. Contrary to the pure flavonoids, where Q was shown to be significantly more effective than its glycoside R, the results did not show more benefit with application of SoA/EcA over So/Ec in terms of lipid peroxidation inhibition. Moreover, glycoconjugates Ec and So showed much higher capacity in protecting lymphocytes against radiation-induced genotoxicity which may suggest that between the polyphenolic and polysaccharide parts exist some synergistic effects. There were no significant differences between Fv versus FvA or Rp versus RpA in terms of the provided radioprotection. Summarizing, plant glycoconjugates isolated by the multi-step method offered sufficient radioprotection. In addition, they possess many advantages, compared to the synthetic polyphenolic compounds or the plant extracts, such as water-solubility and minor toxicity.