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The aim of the study was to examine whether antioxidant properties of 3,4,4',5-tetramethoxystilbene (DMU-212) contribute to its anticarcinogenic activity and whether DMU-212 affects the expression of apoptosis-related genes. Two-stage model of hepatocarcinogenesis was used; male Wistar rats were challenged with N-nitrosodiethylamine (NDEA), 200 mg/kg body weight (b.w.), intraperitoneal, then phenobarbital (PB) in drinking water (0.05%) was administered. Simultaneously, DMU-212 was given per os at a dose 20 or 50 mg/kg b.w. two times a week for 16 weeks. DMU-212 caused a moderate decrease in hepatic thiobarbituric acid reactive substances and protein carbonyls concentration elevated in rats treated with NDEA/PB. The activity of antioxidant enzymes examined reduced by NDEA/PB treatment was not restored in rats coadministered with DMU-212. Effects of DMU-212 on messenger RNA (mRNA) expression of antioxidant enzymes in rats challenged with NDEA/PB were diversified; no changes in their protein expression were noted in any of the groups. The expression of 17,000 genes was analyzed by Affymetrix® Rat Gene 1.1 ST Array; 15 apoptosis-related genes were selected and validated by RT-q PCR. The combined treatment with NDEA/PB and DMU-212 increased the mRNA level of some genes driving mitochondria-mediated apoptosis, whereas the mRNA expression of some anti-apoptotic genes triggering receptor-mediated apoptosis was reduced. The expression of genes encoding caspases-4, -8, -9, and -12 was also increased in rats treated with DMU-212. Although antioxidant effect of DMU-212 in rats challenged with NDEA/PB was moderate, its potential anticarcinogenic properties were demonstrated as evidenced by modulation of apoptosis-related genes.

In this study we compared the antioxidant and DNA protective activity of tannic acid and stilbene derivatives, resveratrol, 3,5,4(')-trimethoxystilbene (TMS) and pterostilbene in human neutrophils stimulated to oxidative burst by 12-O-tetradecanoyl-phorbol-13-acetate (TPA) in relation to apoptosis induction. All polyphenols within the concentration range 1-100 μM reduced the intracellular ROS and H2O2 production in the TPA-stimulated cells. Tannic acid was the most effective polyphenol in protection against DNA damage induced by TPA. In the resting neutrophils resveratrol and to lesser extent other polyphenols increased DNA damage and increased the level of p53. Pretreatment of the TPA-stimulated cells with tannic acid or stilbenes led to the induction of apoptosis. The most significant effect was observed as a result of treatment with TMS and resveratrol. These compounds appeared the most effective inducers of p53 in the TPA-challenged neutrophils, what may suggest that pro-apoptotic activity of these stilbenes might be related to p53 activation. Overall, the results of our present study demonstrate that tannic acid and stilbenes modulate the ROS production, ultimately leading to cell apoptosis in human neutrophils stimulated to oxidative burst. In resting neutrophils they exhibit pro-oxidant activity, which is accompanied by p53 induction., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Cyclic pyrazoles exhibit cytotoxicity to human cancer cells through apoptosis induction. We investigated the proapoptotic activities of two novel synthetic pyrazoles: 5-(p-toluenesulfonyl)pyrazolo[4,3-f]quinoline (tospyrquin) and 5-chloro-3-(p-toluenesulfonyl)indazole (tosind) in HT29 colon cancer cells which are characterised by point mutation (G/A in codon 273) in the p53 gene, which causes the lack of functionality of the p53 protein. Cell viability was evaluated in the MTT assay, cell morphology was assessed by DAPI staining, flow cytometry was used to study the cell cycle, Western blot techniques were applied for measurements of the Bax, Bcl-2, caspase-8, caspase-9 and PARP-1 proteins and DNA damage was evaluated in the Comet assay. Tospyrquin or tosind in a concentration range of 2.5 μM-15 μM caused an approximately 20% diminishment in cell growth, but in higher concentrations (25-100 μM) the observed effect depended on the pyrazole structure and time of treatment. In cell cycle analysis, tosind caused 23.7% of apoptotic death and tospyrquin - 14.9%. These data were supported by an increased level of the pro-apoptotic protein Bax, a decreased level of the anti-apoptotic Bcl-2 and enhanced caspase-8, caspase-9, PARP-1 cleavage. DNA damage was dose-dependent for both tested compounds. The results suggest that the pro-apoptotic activity of tospyrquin and tosind is probably regulated by the extrinsic and the intrinsic pathways.

Citrus flavonoids are dietary antioxidants that may protect against oxidative stress linked to inflammation and reduce the risk of macromolecule damage caused by free radicals. Three citrus flavonoids - naringin, naringenin and hesperidin - have been examined for their ability to activate caspase-3, a marker of apoptosis execution, in human polymorphonuclear neutrophils in vitro, stimulated and non-stimulated with phorbol 12-myristate 13-acetate. The flavonoid potency to reduce reactive oxygen species generation was also assessed in measurements of superoxide radical and luminol dependent chemiluminescence. The caspase-3 activity depended on the time of flavonoid treatment and was increased markedly in phorbol-treated cells incubated with flavonoids for 24 h. Hesperidin at a concentration of 100 microm exerted the strongest stimulating effect on the enzyme (137% of control). Flavonoids inhibited the neutrophil ability to generate superoxide radical and 10-100 microM hesperidin appeared the most active phytochemical. The antioxidant capacity of the examined flavonoids was most prominently expressed in the chemiluminescent measurements. The obtained results suggest that reactive oxygen species may inhibit apoptosis via caspase-3 inhibition and the antioxidant action of citrus flavonoids may reverse this process., ((c) 2008 John Wiley & Sons, Ltd.)