The antigenotoxic activity of latex from Himatanthus articulatus

Himatanthus articulatus (Vahl) Woodson (Apocynaceae) is a native plant to the Amazon popularly used to treat ulcers, tumors, inflammations, cancer, syphilis and malaria. The aim of the present study was to investigate the in vivo genotoxic/antigenotoxic and mutagenic potential of this plant, using the comet and the micronucleus assays in mice. Female and male adult mice were treated with different doses of H. articulatus latex by gavage for two consecutive days. For the experiments, the latex was serially diluted with water to 1:2 (D1); 1:4 (D½) and 1:8 (D») and administered to the animals. The blood slides were exposed to hydrogen peroxide (ex vivo) to evaluate antigenotoxic effect. Under the experimental conditions used in this study, the latex of H. articulatus did not increase the frequency of DNA damage as measured by the comet assay and micronucleus test in treated mice, indicating a non-genotoxic and non-mutagenic activity. In relation to the antigenotoxicity, latex exerted protective effect against DNA damage induced by hydrogen peroxide. Therefore, our results add new information about the antigenotoxic potential of H. articulatus latex, which is popularly used in the Amazon to treat different pathologies.

Occupational genotoxicity among copper smelters.

Occupational exposure in a copper smelting industry may produce various adverse health effects including cancer. Despite a number of well-documented studies reporting an increased risk of cancer among copper smelter workers, the data on genotoxic effects in this industry are scarce. In view of the above, an assessment of DNA damage in peripheral blood leukocytes by Comet assay from copper smelter workers was undertaken. Additionally, the proton-induced X-ray emission (PIXE) analysis was assessed to determine the metal content of samples. The study was conducted with all workers from a copper smelter (males; n = 11), and a control group (n = 11) was recruited. The results of our study showed a significant increase (p < 0.001; Mann-Whitney test) in DNA damage in peripheral blood lymphocytes of smelter workers, compared to the controls (p < 0.001; Mann-Whitney test). No correlation between DNA damage or metal concentration and age mean or time of exposure was found under study. Our findings indicate that copper smelter workers have increased levels of DNA damage in somatic cells, suggesting a potential health risk for the workers. PIXE results show the presence of copper, iron, and other metals.

UVA/UVB-induced genotoxicity and lesion repair in Colossoma macropomum and Arapaima gigas Amazonian fish.

Ultraviolet radiation is known to cause adverse effects to aquatic species and aquatic environments. The fish Colossoma macropomum (tambaqui) and Arapaima gigas (pirarucu) live in the Amazon basin, near the Equator, and thus receive high intensity of ultraviolet radiation. Deforestation further aggravates the situation by reducing shade at ground level. The aim of this study was to evaluate the genotoxic effects of UVA and UVB radiation on erythrocytes of tambaqui and pirarucu fish using Micronuclei test and Comet assay. Our study showed that UV radiation caused DNA damage in both species as detected by Comet assay. In addition, there were differences in response to genotoxicity between both species, which are possibly related to their evolutionary history. Tambaqui fish exposed to ultraviolet radiation for different periods presented clear dose-response in DNA damage profile. Significant damage repair was observed 24h after cessation of ultraviolet radiation exposure. At the test conditions used, no significant increase in micronucleated cells was observed in tambaqui and pirarucu fish. Tambaqui proved to be more sensitive to ultraviolet radiation than Pirarucu, as detected by Comet assay, showing statistically higher baseline DNA damage. The present results demonstrated that alkaline Comet assay was very sensitive for detecting the UV-induced genotoxicity during the short exposure period in our study. In addition, the present study also suggests that tambaqui and pirarucu fish are useful sentinel organisms, as their UV sensitivity allows them to be effective monitors of biological hazards in the Amazon region.

Protective effects of three extracts from Antarctic plants against ultraviolet radiation in several biological models.

The photoprotective effect of the methanolic extracts of three Antarctic plant species - Deschampsia antarctica Desv., Colobanthus quitensis (Kunth) Bartl., and Polytrichum juniperinum Hedw. against UV-induced DNA damage was investigated in hamster lung fibroblasts (V79 cells) and in a biomonitor organism Helix aspersas, using comet assay. The protective, mutagenic, and antimutagenic profiles of these extracts were also evaluated using haploid strains of the simple eukaryote Saccharomyces cerevisiae, and antioxidant activity were investigated using the 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging assay, as well as the hypoxanthine/xanthine oxidase assay. At the concentration range employed, the extracts were not cytotoxic or mutagenic to S. cerevisiae. In addition, the treatment with these extracts enhanced survival, and decreased induced reverse, frameshift, and forward mutations in a dose-response manner in all UVC doses employed. The plants extracts did not generate DNA strand breaks in V79 cells, and the treatment significantly decreased DNA damage induced by UVC. Extracts significantly decreased UVC-induced lipid peroxidation in V79 cells, showing a clear antioxidant property. Moreover, results of comet assay in V79 cells, employing Fpg, Endo III, and Endo V enzymes, demonstrated significant reduction of UVC-induced DNA damage after pre-incubation with these extracts. The treatment with all tested extracts were much less efficient against UVC-induced cytotoxicity in the yeast strain defective in photolyase as compared to the wild type strain, suggesting that this DNA repair pathway is stimulated by substances present in the extracts. All extracts showed a significant inhibitory effect in the hypoxanthine/xanthine oxidase assay, and they had the ability to scavenge DPPH. In H. aspersas, the treatment was able to protect against UVC-induced damage. In conclusion, D. antarctica, C. quitensis, and P. juniperinum extracts present photoprotective properties, which can be attributed to molecules, such as flavonoids and carotenoids, which act as UV-absorbing molecules and as antioxidants, as well as stimulate DNA-repair processes.