This study is the first in the literature to focus attention on the possible immunotoxic effect of integerrimine N-oxide content in the butanolic residue (BR) of Senecio brasiliensis, a poisonous hepatotoxic plant that contains pyrrolizidine alkaloids (PAs). PAs have been reported as a pasture and food contaminant and as herbal medicine used worldwide and are responsible for poisoning events in livestock and human beings. After the plant extraction, BR extracted from Senecio brasiliensis was found to contain approximately 70% integerrimine N-oxide by elemental and spectral analyses ((1)H and (13)C NMR), which was administered to adult male Wistar Hannover rats at doses of 3, 6 and 9 mg/kg for 28 days. Body weight gain, food consumption, lymphoid organs, neutrophil analysis, humoural immune response, cellular immune response and lymphocyte analysis were evaluated. Our study showed that integerrimine N-oxide could promote an impairment in the body weight gain, interference with blood cell counts and a reducing T cell proliferative activity in rats; however, no differences in the neutrophil activities, lymphocytes phenotyping and humoural and cellular immune responses were observed. It is concluded that doses of integerrimine N-oxide here employed did not produce marked immunotoxic effects.

Reports of cyanobacterial blooms developing worldwide have considerably increased, and, in most cases, the predominant toxins are microcystins. The present study reports a cyanobacterial bloom in Lake Violão, Torres, Rio Grande do Sul State, in January 2005. Samples collected on January 13, 2005, were submitted to taxonomical, toxicological, and chemical studies. The taxonomical analysis showed many different species of cyanobacteria, and that Microcystis protocystis and Sphaerocavum cf. brasiliense were dominant. Besides these, Microcystis panniformis, Anabaena oumiana, Cylindrospermopsis raciborskii, and Anabaenopsis elenkinii f. circularis were also present. The toxicity of the bloom was confirmed through intraperitoneal tests in mice, and chemical analyses of bloom extracts showed that the major substance was anabaenopeptin F, followed by anabaenopeptin B, microcystin-LR, and microcystin-RR.

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Livestock poisoning by plants is a frequent occurrence which determines severe losses, such as the fall in the milk and meat production, the cost of expensive treatments, the state of immunosuppression, or even the animal's death. Cattle ingest toxic plants only when there is food shortage, when they cannot select what they eat, or when they ingest food for preference, which is the case of Hovenia dulcis fruits, very rich in sucrose. This plant is widely distributed in the southern and southeastern Brazilian regions. In literature, there are some cases of severe human liver injury associated with a long-term of H. dulcis leaf and fruit tea intake, and only one report regarding spontaneous poisoning of goats caused by this plant ingestion. However, its toxic effects associated with spontaneous ingestion by cattle have never been reported. This paper reports the first case of spontaneous poisoning in cattle by H. dulcis, which occurred in a dairy farm in southwest Paraná, Brazil. Three cattle individuals showed anorexia, ruminal atony, severe diarrhea and neurological tournament, head pressing, blindness, ataxia, and circling. The necropsy of the animals was done, and the remaining alterations were restricted to the digestive system and brain. The clinical signs presented by the animals are characteristic of polioencephalomalacia (PEM), caused by changes in the thiamine metabolism. Furthermore, clinical signs, gross, and microscopic lesions as well as the large amount of the plant throughout the digestive segment led to a diagnosis.

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-(Loss of toxicity by Pseudanabaena galeata in culture). Pseudanabaena galeata, a well-known toxin-producer, is commonly found in water supplies. In order to assess potential risks associated with oral exposure to this cyanobacterium, mouse toxicological studies were carried out with the monoespecific strain P. galeata CCIBt 3082, which has been kept in culture since 1996. In our studies, the acute oral lethal dose has been estimated to be 5,000 mg kg -1 bw and, in the oral sub-chronic assays, the animals showed a decrease in weight and presented microscopic intestinal lesions, results that did not correspond to statements by other authors. In their studies, oral administration of the extract, whose acute lethal dose has been established to be 1,000 mg kg -1 bw, led to severe intoxication and promoted hepatic and renal lesions. Toxicity loss of this strain may be the result of reductive evolution that can occur in organisms that remain in static environments for long periods. Keywords: adaptive process, changes in culture, cyanobacteria, toxicity loss RESUMO -(Perda de toxicidade de Pseudanabaena galeata em cultura). Pseudanabaena galeata, produtora de toxina letal, é encontrada frequentemente em reservatórios de água para abastecimento. Para avaliar o potencial risco associado à exposição, por via oral, a esta cianobactéria, foram realizados estudos toxicológicos em camundongos com a cepa uniespecífica P. galeata CCIBt 3082, mantida em cultura desde 1996. Em nossos estudos, a dose oral letal aguda foi de 5.000 mg kg -1 pc e o teste oral subcrônico mostrou diminuição do peso e lesões microscópicas nos intestinos, resultados que contrastaram com os experimentos levados a efeito com esta cepa, em períodos anteriores. Nesses estudos, a administração oral do extrato causou severa intoxicação e lesões hepáticas e renais e a dose letal oral média foi de 1.000 mg kg -1 pc. A perda de toxicidade dessa cepa pode ser resultado de evolução redutiva, fenômeno que ocorre em organismos que permanecem em ambientes estáticos por longos períodos. Palavras-chave: cianobactéria, mudanças em cultura, perda de toxicidade, processos adaptativos

A methodology for the production of a saxitoxin (STX) standard from cyanobacteria (Raphydiopsis brookii strain SPC 338) was developed. The cyanobacterium was cultured in 5-litre culture bottles in ASM-1 medium, pH 7.4 at 22±1°C, under continuous light at an irradiance of 45-50 mmol m-2 s-1 and moderate aeration rate. The cells were grown until the late-exponential growth phase (approximately 3 weeks), at which point the culture was harvested. The cultured material was lyophilized, extracted with 0.1 M acetic acid and ultrasonication, and centrifuged. The supernatant was lyophilized and subjected to purification by chromatographic methods. STX purity was determined by HPLC-FLD analysis. Male Swiss-Webster mice were injected intraperitoneally with crude extract and with fractions obtained from all purification steps, all diluted in sterile 0.9% NaCl solution (the bio-guided assay). Time to death, signs of poisoning, and other symptoms were observed up to 72 h after injection. STX extracted from R. brookii showed 95% purity, which is similar to STX standards obtained from mussels. The cyanobacterium standard contains only STX, whereas the standard obtained from mollusks contains both STX and an analog. By selecting another cyanobacteria species, it may be possible to obtain different analogues at a lower price. The biomass is easily obtained in culture, its production is not seasonal, and no special storage equipment is required. Thus, this method represents an excellent option for obtaining STX standards.

Forty male rats were equally divided into 4 groups and administered with saxitoxin (STX) at 0, 10, 30 and 90 µg/kg body weight by gavage for 28 days. Bone marrow, lymphocyte proliferation and histopathology of selected tissues were analysed after euthanasia. It was shown that body weight gain, food intake, lymphoid organ weights, lymphocyte proliferation, and histological analyses were not significantly different between groups.