349 resultados para cytotoxic assay
Bioinformatical and in vitro approaches to essential oil-induced matrix metalloproteinase inhibition
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Trans-dehydrocrotonin, the major diterpene isolated from the bark of Croton cajucara, has good antiulcerogenic activity which, however, is accompanied by toxic effects. on the basis of these results, a semi-synthetic crotonin, named 4SRC, was prepared to determine whether this substance has similar antiulcerogenic activity with lower or no toxicity. The natural crotonin was also isolated from the bark of C. cajucara but was not used due to the small amount obtained. The cytotoxic effect of semi-synthetic crotonin, expressed as cell viability, was assessed in (a) lung fibroblast cell line (V79) derived from Chinese hamsters, a system commonly used for cytotoxicity studies, and (b) rat hepatocytes isolated from male Wistar rats. After treatment, cell viability was determined by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide reduction (MTT reduction), total acid content and neutral red uptake assays. To evaluate V79 cell viability, different concentrations of semi-synthetic crotonin were incubated with the cells. To evaluate the antiulcerogenic effects of semi-synthetic crotonin (50, 100 and 200 mg/kg), we used the models of gastric ulcer induced by ethanol/HCl, stress, indomethacin/bethanechol, and ethanol in male Swiss mice and male Wistar rats. The substance had an IC50 = 500 muM in the neutral red uptake and MTT reduction tests and an IC50 = 200 muM in the nucleic acid content test. With regard to hepatocyte viability after treatment with semi-synthetic crotonin at different concentrations, semi-synthetic crotonin had an IC50 = 10-500 muM in the nucleic acid content and MTT reduction tests and an IC50 = 120 muM in the neutral red uptake test. In another experiment, V79 cells were incubated with the metabolites produced by hepatocytes treated with different concentrations of semi-synthetic crotonin. After a 4-h incubation, semi-synthetic crotonin had an IC50 = 500 muM in the MTT reduction and neutral red uptake tests and an IC50 = 370 muM in nucleic acid content test. The substance had significant antiulcerogenic activity in all models studied, suggesting the presence of a possible antisecretory effect combined with a cytoprotective effect. For this reason, the effect of semi-synthetic crotonin was also evaluated on biochemical parameters of gastric juice and gastric wall mucus, both obtained from pylorus-ligated mice. No significant differences were observed in these parameters between semi-synthetic crotonin-treated and control animals. The results obtained with semi-synthetic crotonin are promising, with a significant preventive effect against gastric ulcer induced by different agents. Our data also show that semi-synthetic crotonin was less toxic than dehydrocrotonin and that the cytotoxic effects decreases with the time that isolated hepatocytes were in culture. (C) 2003 Elsevier B.V. B.V. All rights reserved.
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To study the 'in vivo' importance of vitamin D on the natural killer (NK) activity, rats were submitted to privational rickets induced by a diet deficient in vitamin D and phosphorus (D-P-). Thirty days after the beginning of treatment the animals showed low body weight, changes in the bone development, and decreased levels of 25-hydroxyvitamin D-3 (25-OH D-3). NK activity, evaluated using a cytotoxicity assay against Cr-51-labeled Yac.1 target cells, was not modified by the rickets-inducing treatment during the first 30 days. Following a long-term treatment (60 days) the rachitic rats (D-P-) exhibited higher NK activity than control animals (D + P +) (P < 0.05). on the other hand, D - P + animals showed higher cytotoxic activity than D - P - and D + P + groups. Feed replacement to the rachitic rats by a complete diet (D - P - /D + P +) led to a partial recuperation of growth, bone development, and 25-OH D-3 scrum. levels. The NK activity was also influenced by vitamin D intake, decreasing after treatment. (C) 2002 Elsevier B.V. B.V. All rights reserved.
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Objectives Propolis is a honeybee product used extensively in traditional medicine for its antioxidant, anti-inflammatory, immunomodulatory and anticancer effects. Propolis exhibits a broad spectrum of biological activities because it is a complex mixture of natural substances. In this review, the antitumour effects of propolis extracts and its constituents (e. g. flavonoids, terpenes and caffeic acid phenethyl ester) are discussed.Key findings The effect of propolis on experimental carcinogenesis is discussed, as well as its possible mechanisms of action against tumours, involving apoptosis, cell cycle arrest and interference on metabolic pathways. Propolis seems to be efficient against different tumour cells both in vitro and in vivo, which suggests its potential in the development of new anticancer drugs.Summary Propolis extracts may be important economically and would allow a relatively inexpensive cancer treatment. Preclinical investigations are needed to further elucidate the benefits of propolis and its antitumour properties.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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The ovary of the Rhipicephalus sanguineus dog tick female is structurally formed by oocytes in five different stages of development (from I to V) and attached to the gonad by the pedicel. The present study evaluated possible toxic effects of the acaricide fipronil (Frontline (R)) on ovaries of semi-engorged ticks. Sixty partially fed females of R. sanguineus tick were distributed into four groups of 15 specimens each: I - non-treated; II, III and IV - treated with 1, 5 and 10 ppm of fipronil, respectively. The acaricide induced structural changes in the oocytes of individuals of the different treated groups ranging from the presence of a few small vacuoles to cellular death. In conclusion, germinative cells of semi-engorged R. sanguineus tick female are affected by different concentrations of fipronil leading to the reduction of tick fertility. (c) 2008 Elsevier Ltd. All rights reserved.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
