Oligosaccharides increase the genotoxic effect of colibactin produced by pks+ Escherichia coli strains.

BACKGROUND: Colibactin is a genotoxin that induces DNA double-strand breaks that may lead to carcinogenesis and is produced by Escherichia coli strains harboring the pks island. Human and animal studies have shown that colibactin-producing gut bacteria promote carcinogenesis and enhance the progression of colorectal cancer through cellular senescence and chromosomal abnormalities. In this study, we investigated the impact of prebiotics on the genotoxicity of colibactin-producing E. coli strains Nissle 1917 and NC101. METHODS: Bacteria were grown in medium supplemented with 20, 30 and 40 mg/mL of prebiotics inulin or galacto-oligosaccharide, and with or without 5 µM, 25 µM and 125 µM of ferrous sulfate. Colibactin expression was assessed by luciferase reporter assay for the clbA gene, essential for colibactin production, in E. coli Nissle 1917 and by RT-PCR in E. coli NC101. The human epithelial colorectal adenocarcinoma cell line, Caco-2, was used to assess colibactin-induced megalocytosis by methylene blue binding assay and genotoxicity by γ-H2AX immunofluorescence analysis. RESULTS: Inulin and galacto-oligosaccharide enhanced the expression of clbA in pks+ E. coli. However, the addition of 125 µM of ferrous sulfate inhibited the expression of clbA triggered by oligosaccharides. In the presence of either oligosaccharide, E. coli NC101 increased dysplasia and DNA double-strand breaks in Caco-2 cells compared to untreated cells. CONCLUSION: Our results suggest that, in vitro, prebiotic oligosaccharides exacerbate DNA damage induced by colibactin-producing bacteria. Further studies are necessary to establish whether oligosaccharide supplementation may lead to increased colorectal tumorigenesis in animal models colonized with pks+ E. coli.

Mutational spectra induced by flavonoid extracts from pepper tree (Schinus terebinthifolius, Raddi) stem bark.

Flavonoids are a diverse family of plant compounds that are involved in pigmentation, protection, and endogenous regulation. Flavonoids also have medicinal applications, suggesting that they may exert chemoprotective effects. However, some studies have shown, that some plant flavonoids have oxidative and toxic effects, including those produced by Schinus terebinthifolius. In Brazil, extracts of this plant are widely used for medical purposes. In this study, we analyzed the mutagenic potential of two flavonoid-enriched fractions from Brazilian pepper tree stem bark using Escherichia coli CC strains deficient and proficient in enzymes involved in the DNA repair of oxidative lesions. The highest mutagenic response was detected in the CC104mutMmutY strain but CC104mutY showed a higher mutation frequency than CC104mutM. The spectrum of mutations induced in plasmid DNA is composed of mutations typically caused by oxidative lesions. However, a new type of lesion must be occurred to explain the cytotoxicity, higher mutation rates in the CC104mutY strain, and the rare A:T → T:A and G:C → C:G transversions found in this work.

Potential Adverse Public Health Effects Afforded by the Ingestion of Dietary Lipid Oxidation Product Toxins: Significance of Fried Food Sources.

Exposure of polyunsaturated fatty acid (PUFA)-rich culinary oils (COs) to high temperature frying practices generates high concentrations of cytotoxic and genotoxic lipid oxidation products (LOPs) via oxygen-fueled, recycling peroxidative bursts. These toxins, including aldehydes and epoxy-fatty acids, readily penetrate into fried foods and hence are available for human consumption; therefore, they may pose substantial health hazards. Although previous reports have claimed health benefits offered by the use of PUFA-laden COs for frying purposes, these may be erroneous in view of their failure to consider the negating adverse public health threats presented by food-transferable LOPs therein. When absorbed from the gastrointestinal (GI) system into the systemic circulation, such LOPs may significantly contribute to enhanced risks of chronic non-communicable diseases (NCDs), e.g. cancer, along with cardiovascular and neurological diseases. Herein, we provide a comprehensive rationale relating to the public health threats posed by the dietary ingestion of LOPs in fried foods. We begin with an introduction to sequential lipid peroxidation processes, describing the noxious effects of LOP toxins generated therefrom. We continue to discuss GI system interactions, the metabolism and biotransformation of primary lipid hydroperoxide LOPs and their secondary products, and the toxicological properties of these agents, prior to providing a narrative on chemically-reactive, secondary aldehydic LOPs available for human ingestion. In view of a range of previous studies focused on their deleterious health effects in animal and cellular model systems, some emphasis is placed on the physiological fate of the more prevalent and toxic α,ß-unsaturated aldehydes. We conclude with a description of targeted nutritional and interventional strategies, whilst highlighting the urgent and unmet clinical need for nutritional and epidemiological trials probing relationships between the incidence of NCDs, and the frequency and estimated quantities of dietary LOP intake.

Evidence for an Aneugenic Mechanism of Action for Micronucleus Induction by Black Cohosh Extract.

Black cohosh extract (BCE) is a popular botanical dietary supplement marketed to relieve symptoms of various gynecological ailments. Studies conducted by the National Toxicology Program (NTP) showed that BCE induces micronucleated erythrocytes in female rats and mice. Subsequently, the NTP showed that a variety of BCEs, including the sample that induced micronuclei (MN) in vivo ("NTP BCE") had a similar effect in human TK6 cells. Further testing with the MultiFlow® DNA Damage Assay revealed that TK6 cells exposed to NTP BCE, as well as a BCE reference material (BC XRM), exhibited a signature consistent with aneugenic activity in TK6 cells. Results from experiments reported herein confirmed these in vitro observations with NTP BCE and BC XRM. We extended these studies to include a novel test system, the MultiFlow Aneugen Molecular Mechanism Assay. For these experiments, TK6 cells were exposed to NTP BCE and BC XRM over a range of concentrations in the presence of fluorescent Taxol (488 Taxol). After 4 h, nuclei from lysed cells were stained with a nucleic acid dye and labeled with fluorescent antibodies against phospho-histone H3 (p-H3) and Ki-67. Whereas BCEs did not affect p-H3:Ki-67 ratios (a signature of aneugenic mitotic kinase inhibitors), 488 Taxol-associated fluorescence (a tubulin binder-sensitive endpoint) was affected. More specifically, 488 Taxol-associated fluorescence was reduced over the same concentration range that was previously observed to induce MN. These results provide direct evidence that BCEs destabilize microtubules in vitro, and this is the molecular mechanism responsible for the aneugenicity findings. Environ. Mol. Mutagen. 2019. © 2019 The Authors. Environmental and Molecular Mutagenesis published by Wiley Periodicals, Inc. on behalf of Environmental Mutagen Society.

Antigenotoxic and antimutagenic effects of Myrciaria dubia juice in mice submitted to ethanol 28-day treatment.

Myrciaria dubia is a native plant from the Amazon region which produces red-purplish fruit rich in antioxidant compounds such as ascorbic acid, carotenoids, and phenolic. M. dubia fruit is used to prepare juices considered to possess high nutritional content providing health benefits. The aim of this study was to examine the ability of M. dubia juice to protect DNA against genomic instability induced by sub-acute ethanol consumption attributed to oxidative stress. Mice were treated for 28 days with juice at 25% and 50% diluted in distilled water or with the diluted combination juice plus ethanol (5 g/kg). The genotoxic/antigenotoxic and mutagenic/antimutagenic effects were assessed using comet assay in blood, liver, and kidney and micronucleus (MN) test with bone marrow. In addition, the mutagenicity was also evaluated using Salmonella/microsome assay. Phytochemical compounds were determined using HPLC/PDA/MS/MS. The juice did not induce genotoxic effects in blood, kidney, and liver cells at both doses. In combination with ethanol, the juice reduced the alcohol-mediated DNA damage in all tissues analyzed. Further, the juice did not produce mutagenic effects and decreased mutagenicity induced by ethanol in the bone marrow. The anthocyanins were major compounds detected by HPLC/PDA/MS/MS, which modulated genotoxic and mutagenic effects initiated by ethanol and at least in part appeared responsible for the observed antigenotoxic and antimutagenic effects of M. dubia juice.

Molecular analysis of glycosylphosphatidylinositol anchor deficient aerolysin resistant isolates in gulf war i veterans exposed to depleted uranium.

During the First Gulf War (1991) over 100 servicemen sustained depleted uranium (DU) exposure through wound contamination, inhalation, and shrapnel. The Department of Veterans Affairs has a surveillance program for these Veterans which has included genotoxicity assays. The frequencies of glycosylphosphatidylinositol anchor (GPIa) negative (aerolysin resistant) cells determined by cloning assays for these Veterans are reported in Albertini RJ et al. (2019: Environ Mol Mutagen). Molecular analyses of the GPIa biosynthesis class A (PIGA) gene was performed on 862 aerolysin-resistant T-lymphocyte recovered isolates. The frequencies of different types of PIGA mutations were compared between high and low DU exposure groups. Additional molecular studies were performed on mutants that produced no PIGA mRNA or with deletions of all or part of the PIGA gene to determine deletion size and breakpoint sequence. One mutant appeared to be the result of a chromothriptic event. A significant percentage (>30%) of the aerolysin resistant isolates, which varied by sample year and Veteran, had wild-type PIGA cDNA (no mutation). As described in Albertini RJ et al. (2019: Environ Mol Mutagen), TCR gene rearrangement analysis of these isolates indicated most arose from multiple T-cell progenitors (hence the inability to find a mutation). It is likely that these isolates were the result of failure of complete selection against nonmutant cells in the cloning assays. Real-time studies of GPIa resistant isolates with no PIGA mutation but with a single TCR gene rearrangement found one clone with a PIGV deletion and several others with decreased levels of GPIa pathway gene mRNAs implying mutation in other GPIa pathway genes. Environ. Mol. Mutagen. 60:470-493, 2019. © 2019 Wiley Periodicals, Inc.

Longitudinal study of t-cell somatic mutations conferring glycosylphosphatidylinositol-anchor deficiency in gulf war I veterans exposed to depleted uranium.

Fifty Veterans of the first Gulf War in 1991 exposed to depleted uranium (DU) were studied for glycosylphosphatidylinositol-anchor (GPIa) deficient T-cell mutants on three occasions during the years 2009, 2011, and 2013. GPIa deficiency was determined in two ways: cloning assays employing aerolysin selection and cytometry using the FLAER reagent for positive staining of GPIa cell surface proteins. Subsequent molecular analyses of deficient isolates recovered from cloning assays (Nicklas JA et al. [2019]: Environ Mol Mutagen) revealed apparent incomplete selection in some cloning assays, necessitating correction of original data to afford a more realistic estimate of GPIa deficient mutant frequency (MF) values. GPIa deficient variant frequencies (VFs) determined by cytometry were determined in the years 2011 and 2013. A positive but nonsignificant association was observed between MF and VF values determined on the same blood samples during 2013. Exposure to DU had no effect on either GPIa deficient MF or VFs. Environ. Mol. Mutagen. 60:494-504, 2019. © 2019 Wiley Periodicals, Inc.

Preclinical safety evaluation of the ethanolic extract from Campomanesia pubescens (Mart. ex DC.) O.BERG (guavira) fruits: analysis of genotoxicity and clastogenic effects.

Genotoxicity studies of plants with medicinal and nutritional properties are recommended by international regulatory agencies as part of the risk assessment. Due to their consumption as food, nutraceutical use and ethnopharmacological relevance, Campomanesia pubescens represents one of these plants to be studied. The aim of the present study was to evaluate the genotoxic, cytotoxic potential and clathogenic effects of the ethanolic extract obtained from the pulp of C. pubescens (EEFCP) fruits on rats submitted to experimental genotoxicity models and through the SMART test performed in Drosophila melanogaster. The comet assay and the micronucleus test were performed on peripheral and bone marrow blood, respectively, of Wistar rats orally treated with EEFCP at doses of 125, 250, 500 and 1000 mg per kg per bw for 28 days. In the SMART test, the standard cross between three mutant D. melanogaster strains was used. Larvae were treated with EEFCP at different concentrations and the wings of adult flies were evaluated for the presence/frequency of mutant spots and compared to the negative control group. Phytochemical analysis of EEFCP indicated high levels of flavonoids. The tests performed in rats showed that EEFCP did not present significant genotoxic or clastogenic effects. The biotransformation metabolites of EEFCP did not present genotoxic activity, as demonstrated by the SMART test. Together, all results indicate that, under the experimental conditions used, EEFCP did not reveal any preclinical genetic toxicity. Therefore, the safe consumption can be fomented increasing, consequently, the economic liquidity in the industrial market from the fruits of guavira.

Black cohosh extracts and powders induce micronuclei, a biomarker of genetic damage, in human cells.

Black cohosh extract (BCE) is a widely used dietary supplement marketed to women to alleviate symptoms of gynecological ailments, yet its toxicity has not been well characterized. The National Toxicology Program (NTP) previously reported significant increases in micronucleated erythrocytes in peripheral blood of female Wistar Han rats and B6C3F1/N mice administered 15-1,000 mg BCE/kg/day by gavage for 90 days. These animals also developed a dose-dependent nonregenerative macrocytic anemia characterized by clinical changes consistent with megaloblastic anemia. Both micronuclei (MN) and megaloblastic anemia can arise from disruption of the folate metabolism pathway. The NTP used in vitro approaches to investigate whether the NTP's test lot of BCE, BCEs from various suppliers, and root powders from BC and other cohosh species, were genotoxic in general, and to gain insight into the mechanism of action of BCE genotoxicity. Samples were tested in human TK6 lymphoblastoid cells using the In Vitro MicroFlow® MN assay. The NTP BCE and a BC extract reference material (XRM) were tested in the MultiFlow® DNA Damage assay, which assesses biomarkers of DNA damage, cell division, and cytotoxicity. The NTP BCE and several additional BCEs were tested in bacterial mutagenicity assays. All samples induced MN when cells were grown in physiological levels of folic acid. The NTP BCE and BC XRM produced activity patterns consistent with an aneugenic mode of action. The NTP BCE and five additional BCEs were negative in bacterial mutagenicity tests. These findings show that black cohosh preparations induce chromosomal damage and may pose a safety concern. Environ. Mol. Mutagen. 59:416-426, 2018. © 2018 Published 2018. This article is a US Government work and is in the public domain in the USA.

A battery of assays as an integrated approach to evaluate fungal and mycotoxin inhibition properties and cytotoxic/genotoxic side-effects for the prioritization in the screening of thiosemicarbazone derivatives.

Aflatoxins represent a serious problem for a food economy based on cereal cultivations used to fodder animal and for human nutrition. The aims of our work are two-fold: first, to perform an evaluation of the activity of newly synthesized thiosemicarbazone compounds as antifungal and anti-mycotoxin agents and, second, to conduct studies on the toxic and genotoxic hazard potentials with a battery of tests with different endpoints. In this paper we report an initial study on two molecules: S-4-isopropenylcyclohexen-1-carbaldehydethiosemicarbazone and its metal complex, bis(S-4-isopropenylcyclohexen-1-carbaldehydethiosemicarbazonato)nickel (II). The outcome of the assays on fungi growth and aflatoxin production inhibition show that both molecules possess good antifungal activities, without inducing mutagenic effects on bacteria. From the assays to ascertain that the compounds have no adverse effects on human cells, we have found that they are cytotoxic and, in the case of the nickel compound, they also present genotoxic effects.

Setting Occupational Exposure Limits for Genotoxic Substances in the Pharmaceutical Industry.

In the pharmaceutical industry, genotoxic drug substances are developed for life-threatening indications such as cancer. Healthy employees handle these substances during research, development, and manufacturing; therefore, safe handling of genotoxic substances is essential. When an adequate preclinical dataset is available, a risk-based decision related to exposure controls for manufacturing is made following a determination of safe health-based limits, such as an occupational exposure limit (OEL). OELs are calculated for substances based on a threshold dose-response once a threshold is identified. In this review, we present examples of genotoxic mechanisms where thresholds can be demonstrated and OELs can be calculated, including a holistic toxicity assessment. We also propose a novel approach for inhalation Threshold of Toxicological Concern (TTC) limit for genotoxic substances in cases where the database is not adequate to determine a threshold.

[THE EFFECT OF PLANT EXTRACTS ON THE CYCLOPHOSPHAMIDE INDUCTION OF MICRONUCLEUS IN RED BLOOD CELLS OF OUTBRED WHITE MICE].

Antimutagenic properties flavonoids extracts of the three plants Gratiola officinalis L., Helichrysum arenarium L., anthocyanin forms Zea mays L. were investigated. Analysis was performed by counting the micronucleus in peripheral blood erythrocytes outbred white mice; the mutagen was cyclophosphamide. Selected extracts reduce the number of micronucleus. Gratiola officinalis L. extract reduces the mutagenic action of cyclo- phosphamide at a dose of 200 mg/kg, Helichrysum arenarium L. extract--at doses of 100 and 200 mg/kg (maximum protective effect was observed at a dose of 200 mg/kg), anthocyanin forms Zea mays L. extract at doses of 50, 100 and 200 mg/kg (a dose of 50 mg/kg--maximum antimutagenic effect).

Broccoli seed extract: Genotoxicity and subchronic toxicity studies.

Potential health benefits have been attributed to broccoli consumption. Hence, there is potential for use of broccoli seed extract (BSE) in food or for use as a dietary supplement. To assess the potential safety of a BSE product, three genotoxicity experiments, including an Ames, in vivo mouse micronucleus, and in vivo mouse sperm abnormality assay, were carried out. BSE was subject to an acute oral toxicity test and was evaluated in a 30-day feeding study in rats. BSE showed no mutagenic activity in the Ames assay and no evidence of genotoxic potential in the in vivo assays at doses up to 10 g/kg body weight (bw). The LD50 of BSE in rats was >10 g/kg bw/d. In the 30-day feeding study, in which BSE was administered in the diet to provide doses of 0, 0.3, 1.0, or 3.0 g/kg bw/d, no toxicological significant effects were noted on body weight, body weight gain, organ weights, or on the results of hematological, clinical chemistry and histopathological evaluations. The no-observed-adverse-effect level was considered to be 3.0 g/kg bw/d, the highest dose tested. Collectively, these results support the safe use of BSE as a food ingredient or product.

In vivo evaluation of the genetic toxicity of Rubus niveus Thunb. (Rosaceae) extract and initial screening of its potential chemoprevention against doxorubicin-induced DNA damage.

ETHNOPHARMACOLOGICAL RELEVANCE: Rubus niveus Thunb. plant belongs to Rosaceae family and have been used traditionally to treat wounds, burns, inflammation, dysentery, diarrhea and for curing excessive bleeding during menstrual cycle. The present study was undertaken to investigate the in vivo genotoxicity of Rubus niveus aerial parts extract and its possible chemoprotection on doxorubicin (DXR)-induced DNA damage. In parallel, the main phytochemicals constituents in the extract were determined. MATERIALS AND METHODS: The animals were exposed to the extract for 24 and 48 h, and the doses selected were 500, 1000 and 2000 mg/kg b.w. administered by gavage alone or prior to DXR (30 mg/kg b.w.) administered by intraperitoneal injection. The endpoints analyzed were DNA damage in bone marrow and peripheral blood cells assessed by the alkaline alkaline (pH>13) comet assay and bone marrow micronucleus test. RESULTS AND CONCLUSION: The results of chemical analysis of the extract showed the presence of tormentic acid, stigmasterol, quercitinglucoronide (miquelianin) and niga-ichigoside F1 as main compounds. Both cytogenetic endpoints analyzed showed that there were no statistically significant differences (p>0.05) between the negative control and the treated groups with the two higher doses of Rubus niveus extract alone, demonstrating absence of genotoxic and mutagenic effects. Aneugenic/clastogenic effect was observed only at 2000 mg/kg dose. On the other hand, in the both assays and all tested doses were observed a significant reduction of DNA damage and chromosomal aberrations in all groups co-treated with DXR and extract compared to those which received only DXR. These results indicate that Rubus niveus aerial parts extract did not revealed any genotoxic effect, but presented some aneugenic/clastogenic effect at higher dose; and suggest that it could be a potential adjuvant against development of second malignant neoplasms caused by the cancer chemotherapic DXR.

Toxicologic assessment of Paecilomyces tenuipes in rats: renal toxicity and mutagenic potential.

Paecilomyces tenuipes is entomogenous fungus that is called snow-flake Dongchunghacho in Korea. Although it is widely used in traditional medicines, its safety has not yet been comprehensively investigated. Therefore, the aim of this study was to evaluate the genotoxicity, acute and subchronic toxicity of P. tenuipes. The acute oral LD50 of P. tenuipes extract in rats was estimated to be greater than 2000mg/kg of body weight. In the subchronic study, the oral treatment of rats with 500, 1000 or 2000mg/kg P. tenuipes extract daily for 13weeks did not induce any dose-related changes (body weight, food consumption, clinical observation, urinalysis, hematology, clinical chemistry and organ weight). In contrast, histopathological observation revealed that P. tenuipes extract induced karyomegaly in outer medulla of kidney in all treated rats. Importantly, P. tenuipes extract exerted the mutagenic potential in Ames assay. Since karyomegalic alterations have been known to be associated with carcinogenicity, our finding on the mutagenicity of P. tenuipes extract supports the possibility on the potential involvement of P. tenuipes in carcinogenicity at least partially. In conclusion, the subchronic oral exposure of P. tenuipes may induce kidney abnormality at the concentration higher than 500mg/kg body weight, although further studies using other animal models are needed to identify the toxicity of P. tenuipes.

Safety of biological therapies for psoriasis: effects on reproductive potential and outcomes in male and female patients.

The effects of biological therapies for psoriasis on pregnancy outcomes and lactation, and male fertility and mutagenicity are common concerns in the clinical setting. There is relatively little evidence to guide the clinician and patient. Here, we review the safety profile of the commonly used biological therapies for psoriasis in individuals of reproductive potential. Safety data were derived from large-scale registries, adverse event reporting databases, clinical trials and case reports. We assessed the effect of each therapy on adverse pregnancy outcomes including congenital malformations, and lactation with maternal administration, and male fertility and potential mutagenicity with paternal administration. We provide applicable guidance to inform clinician and patient before and after conception.

Cytotoxicity and mutagenicity of fluoxetine hydrochloride (Prozac), with or without vitamins A and C, in plant and animal model systems.

Fluoxetine, commonly known as Prozac, is the first representative of the so-called new generation of antidepressants that promise efficacy, with few side effects, against deep depression, nervous bulimia, and anxiety. As there is a growing number of people suffering from anxiety and depression; consequently, the use of fluoxetine is also increasing. Verifying absence of drug effects such as cytotoxicity or mutagenicity is of great importance. Certain vitamins, such as vitamin A (retinol, retinoids) and vitamin C (ascorbic acid) protect and are extremely active against mutagens. We evaluated the cytotoxic and mutagenic activity of fluoxetine, with and without concomitant administration of vitamin A or C, in Allium cepa meristem cells and Wistar rat bone marrow cells. The A. cepa meristem cells showed fluoxetine cytotoxicity; concomitant treatment with vitamin A or C proved non-protective. Treatment of Wistar rats with fluoxetine intraperitoneally or via gavage did not affect cell division or cause clastogenic effects. Vitamin A and C did not affect the cytotoxicity or mutagenicity of fluoxetine in the rat cells.

Dissimilar effects of ß-lapachone- and hydroxyurea-induced DNA replication stress in root meristem cells of Allium cepa.

Two anticancer drugs, ß-lapachone (ß-lap, a naphthoquinone) and hydroxyurea (HU, an inhibitor of ribonucleotide reductase), differently affect nuclear morphology and cell cycle control mechanisms in root meristem cells of Allium cepa. The 18 h treatment with 100 µM ß-lap results in a lowered number of M-phase cells, increased occurrence of mitotic abnormalities, including over-condensation of chromosomes, their enhanced stickiness, formation of anaphase bridges, micronucleation and reduced mitotic spindles. Following prolonged incubations using high doses of ß-lap, cell nuclei reveal dark-red fluorescence evenly distributed in chromatin surrounding the unstained regions of nucleoli. Both drugs generate H2O2 and induce DNA double strand breaks, which is correlated with γ-phoshorylation of H2AX histones. However, the extent of H2AX phosphorylation (including the frequency of γ-H2AX foci and the relative number cells creating phospho-H2AX domains) is considerably reduced in root meristem cells treated jointly with the ß-lap/HU mixture. Furthermore, various effects of caffeine (an inhibitor of ATM/ATR cell cycle checkpoint kinases) on ß-lap- and HU-induced γ-phoshorylation of H2AX histones and the protective activity of HU against ß-lap suggest that their genotoxic activities are largely dissimilar. ß-Lap treatment results in the induction of apoptosis-like programmed cell death, while HU treatment leads to cell adaptation to replication stress and promotion of abnormal nuclear divisions with biphasic interphase/mitotic states of chromatin condensation.

The in vitro genotoxic effect of Tucuma (Astrocaryum aculeatum), an Amazonian fruit rich in carotenoids.

Tucuma (Astrocaryum aculeatum) is an Amazonian fruit that presents high levels of carotenoids and other bioactive compounds such as quercetin. The extracts of tucuma peel and pulp present strong antioxidant activity which illustrate an elevated concentration that causes cytotoxic effects in human peripheral blood mononuclear cells (PBMCs). This study performed additional investigations to analyze the potential genotoxic effects of the tucuma extracts on PBMCs. The genotoxicity was evaluated by DNA fragmentation, Comet assay, and chromosomal instability G-band assays. The acute tucuma extract treatment showed genoprotective effects against DNA denaturation when compared with untreated PBMC cells. However, in the experiments with 24 and 72 h treatments to tucuma treatments, we observed low genotoxicity through a concentration of 100 µg/mL, some genotoxic effects related to intermediary concentrations (100-500 µg/mL), and more pronounced genotoxic effects on higher tucuma extract concentrations. After 24 h of treatment, the reactive oxygen species were similar among treatments and PBMC control groups. However, the caspase-1 activity related to the apoptosis and pyroptosis process increased significantly in higher tucuma concentrations. In summary, tucuma extracts, despite their higher antioxidant content and antioxidant activity, would present PBMCs genotoxic effects that are dependent on concentration and time exposition. These results need to be considered in future in vitro and in vivo studies of tucuma effects.

A novel p53 mutant found in iatrogenic urothelial cancers is dysfunctional and can be rescued by a second-site global suppressor mutation.

Exposure to herbal remedies containing the carcinogen aristolochic acid (AA) has been widespread in some regions of the world. Rare A→T TP53 mutations were recently discovered in AA-associated urothelial cancers. The near absence of these mutations among all other sequenced human tumors suggests that they could be biologically silent. There are no cell banks with established lines derived from human tumors with which to explore the influence of the novel mutants on p53 function and cellular behavior. To investigate their impact, we generated isogenic mutant clones by integrase-mediated cassette exchange at the p53 locus of platform (null) murine embryonic fibroblasts and kidney epithelial cells. Common tumor mutants (R248W, R273C) were compared with the AA-associated mutants N131Y, R249W, and Q104L. Assays of cell proliferation, migration, growth in soft agar, apoptosis, senescence, and gene expression revealed contrasting outcomes on cellular behavior following introduction of N131Y or Q104L. The N131Y mutant demonstrated a phenotype akin to common tumor mutants, whereas Q104L clone behavior resembled that of cells with wild-type p53. Wild-type p53 responses were restored in double-mutant cells harboring N131Y and N239Y, a second-site rescue mutation, suggesting that pharmaceutical reactivation of p53 function in tumors expressing N131Y could have therapeutic benefit. N131Y is likely to contribute directly to tumor phenotype and is a promising candidate biomarker of AA exposure and disease. Rare mutations thus do not necessarily point to sites where amino acid exchanges are phenotypically neutral. Encounter with mutagenic insults targeting cryptic sites can reveal specific signature hotspots.