Abstract The α-tomatine is a steroidal glycoalkaloid found in immature tomatoes (Lycopersicon esculentum) that has important biological functions including the inhibition of cancer cell growth and preventing metastasis. This study aimed to evaluate the effects of α-tomatine on cytotoxicity, cellular proliferation, apoptosis, and mRNA expression of APC, CCNA2, β-catenin, CASP9, BAK, BAX and BCL-XL in colorectal adenocarcinoma cell line HT-29. HT29 cells were treated with three concentrations of α-tomatine (0.1, 1 and 10 µg/mL), although only the 1 µg/mL concentration of α-tomatine was used to evaluate genetic expression patterns by real time-PCR. Results showed that α-tomatine was cytotoxic only at the 10 µg/mL concentration. Cell proliferation was significantly inhibited after the first 24 hours of treatment only with concentrations of 10 µg/mL. In contrast, there were no significant differences in apoptosis for any treatment. In the gene expression studies, only APC expression was significantly altered by α-tomatine treatment. In conclusion, α-tomatine has antiproliferative activity in the first 24h of treatment, does not induce apoptosis in this cell line and causes disruption of cell membranes, thereby increasing the expression of APC gene related to cell cycle.

Abstract The identification of antitumoral substances is the focus of intense biomedical research. Two structural analogues of thalidomide, LNO3 and L3, are two synthetic compounds that might possess such antitumor properties. We evaluated the toxicological effects of these substances, including cytotoxicity, genotoxicity and induction of apoptosis in HTC cells. Additionally, the production of free radicals (nitric oxide and superoxide) was investigated, and the expression of caspases genes 3, 8, and 9 were determined by RT-qPCR. The compounds exhibited cytotoxic effects that resulted in inhibited cell proliferation. LNO3 showed to be more effective and toxic than L3 in all assays. LNO3 stimulated the release of NO and superoxide, which was accompanied by the formation of peroxynitrite. Apoptosis was induced in a dose-dependent manner by both compounds; however, the expression of caspases 3, 8 and 9 was unchanged. These results suggested that L3 and LNO3 possess antiproliferative and pro-apoptotic effects in HTC cells. Additionally, although they exhibited cytotoxicity, L3 and LNO3 might be useful coadjuvants in tumor treatment studies.

β-glucan is a well-known polysaccharide for its chemopreventive effect. This study aimed to evaluate the chemopreventive ability of β-glucan in somatic and germ cells through the dominant lethal and micronucleus assays, and its influence on the reproductive performance of male mice exposed to cyclophosphamide. The results indicate that β-glucan is capable of preventing changes in DNA in both germ cells and somatic ones. Changes in germ cells were evaluated by the dominant lethal assay and showed damage reduction percentages of 46.46% and 43.79% for the doses of 100 and 150 mg/kg. For the somatic changes, evaluated by micronucleus assay in peripheral blood cells in the first week of treatment, damage reduction percentages from 80.63-116.32% were found. In the fifth and sixth weeks, the percentage ranged from 10.20-52.54% and -0.95-62.35%, respectively. Besides the chemopreventive efficiency it appears that the β-glucan, when combined with cyclophosphamide, is able to improve the reproductive performance of males verified by the significant reduction in rates of post-implantation losses and reabsorption in the mating of nulliparous females with males treated with cyclophosphamide.

Ample evidence suggests that cancer is triggered by mutagenic damage and diets or supplements capable of reducing such incidences can be related to the prevention of neoplasy development or to an improvement in life quality of patients who undergo chemotherapy. This research aimed to evaluate the antimutagenic and antigenotoxic activity of β-glucan. We set up 8 experimental groups: control (Group 1), cyclophosphamide (Group 2), Groups 3-5 to assess the effect of β-glucan administration, and Groups 6-8 to evaluate the association between cyclophosphamide and β-glucan. The intraperitonial concentrations of β-glucan used were 100, 150 and 200 mg/kg. Micronucleus and comet assays showed that within the first week of treatment β-glucan presented a damage reduction rate between 100-62.04% and 94.34-59.52% for mutagenic and genotoxic damages, respectively. This activity decreased as the treatment was extended. During the sixth week of treatment antimutagenicity rates were reduced to 59.51-39.83% and antigenotoxicity was not effective. This leads to the conclusion that the efficacy of β-glucan in preventing DNA damage is limited when treatment is extended, and that its use as a chemotherapeutic adjuvant need to be better clarified.

As frutas são importantes fontes de nutrientes na dieta humana e a Acerola (Malpighia glabra L.) é de particular interesse devido ao seu alto teor de antioxidantes. Dietas ricas em frutas e legumes protegem os indivíduos contra doenças e câncer, mas a ingestão excessiva de vitaminas pode atuar como pró-oxidante e gerar alterações no DNA. Para avaliar o efeito de diferentes concentrações da polpa in natura da Acerola (BAN) e congelada (BAF), e da vitamina C sintética na forma líquida (VC), em nível cromossômico e sobre o ciclo de divisão celular, foram utilizadas células meristemáticas de raiz de Allium cepa L. e células da medula óssea de ratos Wistar, Rattus norvegicus, como sistema teste. Em Allium cepa L., BAN, na maior concentração (0,4 mg.mL-1) e BAF, na menor concentração (0,2 mg.mL-1), houve inibição da divisão celular, e apenas para BAN houve recuperação da divisão celular após o período de recuperação em água. Em ratos Wistar, todos os tratamentos com Acerola, agudo ou subcrônico, não foram citotóxicos e mutagênicos, apenas a maior concentração de VC aumentou significativamente o percentual de anormalidades cromossômicas. Os dados obtidos são importantes porque reforçam o uso das frutas de Acerola na dieta.

Fruits are important sources of nutrients in human diet, and Barbados Cherry (Malpighia glabra L.) is of particular interest due to its high content of antioxidants. Diets rich in fruits and vegetables protect individuals against diseases and cancer, but excessive intake of vitamins may act as pro-oxidant and generate changes in DNA. To evaluate the effect of different in natura (BAN) and frozen (BAF) Barbados Cherry pulp concentrations and synthetic vitamin C in liquid form (VC) on the chromosome level and the cell cycle division, root meristeme cells of Allium cepa L. and bone marrow cells of Wistar rats Rattus norvegicus, were used as test system. In Allium cepa L., BAN, at the highest concentration (0.4 mg.mL-1) and BAF, at the lowest concentration (0.2 mg.mL-1), inhibited cell division, and there was recovery of cell division after the recovery period in water only for BAN. In the Wistar rats, all treatments with Barbados Cherry, either acute or subchronic, were not cytotoxic or mutagenic; only the highest concentration of VC increased significantly the rate of chromosomal abnormalities. The data obtained are important to reinforce the use of Barbados Cherry fruit in the diet.

A presente pesquisa avaliou a ação mutagênica e antimutagênica de um biopolímero de glucose extraído da Agrobacterium radiobacter (Biopolímero de Agrobacterium radiobacter). O experimento foi realizado com camundongos Swiss machos divididos em oito grupos. O tratamento com o biopolímero foi realizado por gavage em dose única concomitante a uma dose de solução tampão fosfato nos grupos de avaliação da mutagenicidade, ou ao agente indutor de danos no DNA, ciclofosfamida, na concentração de 50 mg/kg (peso corpóreo - p.c.), nos grupos de avaliação da antimutagenicidade. Utilizou-se o teste de micronúcleo em sangue periférico e a coleta de sangue foi realizada 24 e 48 h após a aplicação das substâncias-teste. A análise estatística demonstrou que o biopolímero não possui atividade mutagênica e que é efetivo em prevenir danos no DNA. As porcentagens de redução de danos nos grupos de antimutagenicidade foram de 83,9%, 89,1% e 103,1% em 24 h e 101,24%, 98,14% e 120,64% em 48 h para as doses de 75, 150 e 300mg/kg (p.c.), respectivamente. A alta porcentagem de redução de danos associada à ausência de efeitos mutagênicos indica, além da atividade quimioprotetora, a possibilidade do biopolímero ser um alimento funcional candidato à utilização como co-adjuvante na quimioterapia para prevenir efeitos colaterais.

This study evaluated the mutagenic and ant mutagenic action of a biopolymer of glucose extracted from Agrobacterium radiobacter (Biopolymer of Agrobacterium radiobacter). The experiment was conducted with Swiss male mice divided into eight groups. Treatment with the biopolymer was performed in a single dose by gavage at a dose of concomitant phosphate buffer groups in the evaluation of mutagenicity, or the agent of inducing DNA damage, cyclophosphamide, the concentration of 50 mg/kg (body weight --b.w.), in groups of assessment ant mutagenic. We used the micronucleus test in peripheral blood. The blood sample was held 24 and 48 h after application of the test substances. Statistical analysis showed that the biopolymer has no mutagenic activity and it is effective in preventing damage to DNA. The percentages of damage reduction in groups of ant mutagenic were 83.9%, 89.1% and 103.1% in 24 h and 101.24%, 98.14% and 120.64% at doses of 48 to 75, 150 and 300 mg/kg (b.w.) respectively. The high percentage of damage reduction associated with the absence of mutagenic effects indicates the possibility of biopolymer chemoprotection action. It can also be considered a functional food candidate to be used as co-adjuvant chemotherapy to prevent side effects.

An aqueous extract of Rhizophora mangle L. bark is used as raw material in pottery making in the State of Espirito Santo, Brazil. This extract presents large quantities of tannins, compounds possessing antioxidant properties. Tannin antioxidant activity, as a plant chemical defense mechanism in the process of stabilizing free radicals, has been an incentive to studies on anti-mutagenicity. The present work aimed to evaluate possible antimutagenic activity of a R. mangle aqueous extract, using the Allium cepa test-system and micronuclear (MN) assay with blockage of cytokinesis in Chinese hamster ovary cells (CHO-K1). The Allium cepa test-system indicated antimutagenic activity against the damage induced by the mutagenic agent methyl methanesulfonate. A reduction in both MN cell frequency and chromosome breaks occurred in both the pre and post-treatment protocols. The MN testing of CHO-K1 cells revealed anti-mutagenic activity of the R. mangle extract against methyl methanesulfonate and doxorubicin in pre, simultaneous and post-treatment protocols. These results suggest the presence of phyto-constituents in the extract presenting demutagenic and bio-antimutagenic activities. Since the chemical constitution of Rhizophora mangle species presents elevated tannin content, it is highly probable that these compounds are the antimutagenic promoters themselves.

Polycyclic aromatic hydrocarbons (PAHs) are genotoxic chemicals commonly found in effluents from oil refineries. Bioassays using plants and cells cultures can be employed for assessing environmental safety and potential genotoxicity. In this study, the genotoxic potential of an oil refinery effluent was analyzed by means of micronucleus (MN) testing of Alium cepa, which revealed no effect after 24 h of treatment. On the other hand, primary lesions in the DNA of rat (Rattus norvegicus) hepatoma cells (HTC) were observed through comet assaying after only 2 h of exposure. On considering the capacity to detect DNA damage of a different nature and of these cells to metabolize xenobiotics, we suggest the association of the two bioassays with these cell types, plant (Allium cepa) and mammal (HTC) cells, for more accurately assessing genotoxicity in environmental samples.

The common everyday use of medicinal plants is an ancient, and still very widespread practice, whereby the need for studies on their possible toxicity and mutagenic properties. The species Coccoloba mollis has been much used in phytotherapy, mainly in cases involving loss of memory and stress. In order to investigate its genotoxic and mutagenic potential, ethanolic extracts from the leaves and roots underwent Salmonella/microsome assaying (TA98 and TA100 strains, with and without exogenous metabolism - S9), besides comet and micronucleus tests in vivo.There was no significant increase in the number of revertants/plate of Salmonella strains in any of the analyzed root-extract concentrations, although the extract itself was extremely toxic to the Salmonella TA98 strain in the tests carried out with S9 (doses varying from 0.005 to 0.5 µg/plate). On the other hand, the leaf-extract induced mutations in the TA98 strain in the absence of S9 in the highest concentration evaluated, although at very low mutagenic potency (0.004 rev/µg). Furthermore, there was no statistically significant increase in the number of comets and micronuclei, in treatments involving Swiss mice. It was obvious that extracts of Coccoloba mollis, under the described experimental conditions, are not mutagenic.

Functional food investigations have demonstrated the presence of substances that could be beneficial to human health when consumed. However, the toxic effects of some substances contained in foods have been determined. Reported medicinal and nutritive properties have led to the extensive commercialization of the basidiomycete fungi Agaricus blazei Murrill (sensu Heinemann), also known as Agaricus brasiliensis Wasser et al., Agaricus subrufescens Peck or the Brazilian medical mushroom (BMM). Different methanolic extract fractions (ME) of this mushroom were submitted to the cytokinesis-block micronucleus (CBMN) clastogenic assay and the hypoxanthine-guanine phosphoribosyl transferase locus (HGPRT) assay for gene mutation, both using Chinese hamster ovary cells clone K1 (CHO-K1). The results suggest that all the fractions tested possess cytotoxic and mutagenic potential but no clastogenic effects. Further information is needed on the biochemical components of the A. blazei methanol fractions to identify any substances with cytotoxic and/or mutagenicity potential. These findings indicate that A. blazei methanolic extract should not be used due to their genotoxicity and care should be taken in the use of A. blazei by the general population until further biochemical characterization of this fungi is completed.

Cytotoxicity of metals is important because some metals are potential mutagens able to induce tumors in humans and experimental animals. Chromium can damage DNA in several ways, including DNA double strand breaks (DSBs) which generate chromosomal aberrations, micronucleus formation, sister chromatid exchange, formation of DNA adducts and alterations in DNA replication and transcription. In our study, water samples from three sites in the Córrego dos Bagres stream in the Franca municipality of the Brazilian state of São Paulo were subjected to the comet assay and micronucleus test using erythrocytes from the fish Oreochromis niloticus. Nuclear abnormalities of the erythrocytes included blebbed, notched and lobed nuclei, probably due to genotoxic chromium compounds. The greatest comet assay damage occurred with water from a chromium-containing tannery effluent discharge site, supporting the hypothesis that chromium residues can be genotoxic. The mutagenicity of the water samples was assessed using the onion root-tip cell assay, the most frequent chromosomal abnormalities observed being: c-metaphases, stick chromosome, chromosome breaks and losses, bridged anaphases, multipolar anaphases, and micronucleated and binucleated cells. Onion root-tip cell mutagenicity was highest for water samples containing the highest levels of chromium.

The comet assay was used to study the sensitivity of the widely distributed freshwater bivalve mollusk Corbicula fluminea to the DNA-damaging alkylating-agent methylmethane sulfonate (MMS). This study was undertaken to ascertain if C. fluminea is a good bioindicator of pollutants in aquatic environments and identify which C. fluminea tissue is most effective and practical for genotoxicity studies. The mollusks were exposed to 0.6, 1.2 or 2.4 X 10-4 M MMS for 40 min and their hemolymph, gill tissue and digestive gland tissue assessed for the level of DNA damage and the time needed for the tissues to recovery. Regression analysis showed a direct linear dose-response relationship between MMS concentration and the number of damaged cells for hemolymph and digestive gland tissue but a quadratic relationship for gill tissue, which made the interpretation the gill tissue results difficult. The basal level of DNA damage to gill tissue was very high, possibly because gill is the organs most directly exposed to environmental toxins and mutagenic agents. Although all three types of tissue produced useful results, hemolymph and digestive gland tissue produced more reproducible and reliable results. Hemolymph was the best sample type in that it was easy to obtain and handle, while gill tissue required more manipulation to obtain cell suspensions. Our results indicate that C. fluminea is an optimal bioindicator for the determination genotoxic contaminants in aquatic environments.

Agaricus blazei Murrill, popularly known as the sun mushroom, is a native mushroom in SP, Brazil, that has been widely used in the treatment of cancer and many other pathologies in different parts of the world. A water-soluble protein-polysaccharide complex (1 -> 6)beta-D-glucan has been isolated from its fruiting body that showed immune-modulation activity. From organic extracts, linoleic acid has been isolated and determined to be the main substance with antimutagenic activity. Using both the micronucleus (MN) and comet (single cell microgel electrophoresis) assays, this study determined the genotoxic and antigenotoxic potential of A. blazei (AB) obtained from commercial sources or the following strains: a) strains AB 97/29 (young and sporulated phases); b) a mixture taken from AB 96/07, AB 96/09 and AB 97/11 strains; and c) commercial mushrooms from Londrina, PR and Piedade, SP, designated as AB PR and AB SP, respectively. The extracts from these mushrooms were isolated in chloroform:methanol (3:1) and used in vitro at three different concentrations. V79 cells (Chinese hamster lung cells) were exposed to the extracts under pre-, simultaneous and post-treatment conditions, combined with methyl methanesulfonate (MMS). Under the circumstances of this study, these organic extracts did not show any genotoxic or mutagenic effects, but did protect cells against the induction of micronuclei by MMS.

The effects of clastogenic or mutagenic agents have rarely been studied in neotropical fish species exposed to contaminated water. In this study, the genetic damage caused by lead in the widely distributed South American fish, Hoplias malabaricus, was assessed using the comet (SCGE) assay and by testing for chromosomal aberrations. Eighteen specimens were acclimatized to laboratory conditions and then chronically exposed to contaminated food by feeding prey (Cyprinus sp.) injected intraperitoneally with doses of inorganic lead adjusted to give a contamination level of 21 mg of Pb2+.g-1 net weight of H. malabaricus. Three fish were sampled for chromosomal analysis after four doses (18 days) and another three after eight doses (41 days) of lead and the results then compared with three untreated controls kept under lead-free conditions. An additional six treated fish and three controls were sampled for the comet assay after 13 doses (64 days). Exposure to lead significantly increased the frequency of chromosomal aberrations and the frequency of tailed cell nuclei, the latter indicating DNA damage. These results show that H. malabaricus is a useful biological model for screening the clastogenic effects of lead and possibly other xenobiotics. The genetic damage seen here illustrates the need to investigate the potential effects of heavy metals on fish species in South America.

The use of medicinal plants by the general population is an old and still widespread practice, which makes studies of their genotoxicity essential. Psidium guajava L. and Achillea millefolium L. are examples of plants commonly used in popular medicine. P. guajava L. is indicated for diarrhea and also as an antiseptic, while A. millefolium L. is indicated as an analgesic, antispasmodic, digestive, diuretic, antiseptic, astringent, emollient, wound healer and hemorrhoid medication. The aim of this study was to determine the effects of the infusions of these two plant species on chromosomes and the cell cycle. Leaves from the plants were used to prepare infusions, in the same manner as teas, but at two different concentrations. Allium cepa L. root-tip cells (P. guajava L. - 2.62 and 26.2 mg/mL, and A. millefolium L. - 3.5 and 35.0 mg/mL) and Wistar rat bone marrow cells (P. guajava L. - 2.62 and 26.2 mg/100g body weight, and A. millefolium L. - 3.5 and 35.0 mg/100g body weight) were used as in vivo plant and animal test systems, respectively. Human peripheral blood lymphocytes (P. guajava L. - 0.262 and 2.62 mg/mL culture medium, and A. millefolium L. - 0.35 and 3.5 mg/mL culture medium) were used as in vitro test system. The P. guajava L. infusion at the higher concentration caused a statistically significant inhibition of cellular division in the onion root-tip cells, not observed in onion root-tip cells treated with A. millefolium L. No statistically significant alterations were found, as compared to untreated controls, in either the cell cycle or the number of chromosome alterations, after treatments with either plant, in rat cells or in cultured human lymphocytes. These results regarding the cytotoxicity and mutagenicity of these plants provide valuable information about the safety of using them as therapeutic agents.