Pteridium aquilinum and its ptaquiloside toxin induce DNA damage response in gastric epithelial cells, a link with gastric carcinogenesis

Sixty years of research on bracken fern (Pteridium spp.) toxins: Environmental exposure, health risks and recommendations for bracken fern control

Bracken fern (Pteridium spp.) is a highly problematic plant worldwide due to its toxicity in combination with invasive properties on former farmland, in deforested areas and on disturbed natural habitats. The carcinogenic potential of bracken ferns has caused scientific and public concern for six decades. Its genotoxic effects are linked to illudane-type glycosides (ITGs), their aglycons and derivatives. Ptaquiloside is considered the dominating ITG, but with significant contributions from other ITGs. The present review aims to compile evidence regarding environmental pollution by bracken fern ITGs, in the context of their human and animal health implications. The ITG content in bracken fern exhibits substantial spatial, temporal, and chemotaxonomic variation. Consumption of bracken fern as food is linked to human gastric cancer but also causes urinary bladder cancers in bovines browsing on bracken. Genotoxic metabolites are found in milk and meat from bracken fed animals. ITG exposure may also take place via contaminated water with recent data pointing to concentrations at microgram/L-level following rain events. Airborne ITG-exposure from spores and dust has also been documented. ITGs may synergize with major biological and environmental carcinogens like papillomaviruses and Helicobacter pylori to induce cancer, revealing novel instances of chemical and biological co-carcinogenesis. Thus, the emerging landscape from six decades of bracken research points towards a global environmental problem with increasingly complex health implications.

Determination of ptaquiloside in ten species of Pteris in northwestern Argentina

The toxic effect of ferns of the genus of Pteris in bovines is caused by ptaquiloside, the main carcinogenic toxin. In this study, ten species of Pteris fern in different phenologic stages and plant conditions were collected in northwest Argentina. The phytochemical analysis showed the presence of Pt in the recent collected samples (adults and young plants) but not in the herbarium specimens. The results show a great variation of Pt concentration that depends on the phenologic stage, plant condition, and collection site. Pt was measured in 6-4326 μg/g concentration, with a mean concentration of 644 μg/g. No Pt was detected in eight species of Pteris collected from herbarium samples; such results may be a false negative. It is important to notice that analysis of herbarium samples for Pt may not be a reliable method to determine its presence. It is important to further understand the potential toxicity caused by these ferns because of their effect on animals, public health, and the environment.

Meat and dairy products intake is associated with gastric cancer: Case-control study findings

Countries experiencing a significant shift toward Western lifestyle are facing an increased risk of gastric cancer (GC). While many studies have explored the link between diet and GC, the role of meat and dairy consumption remains uncertain. To delve deeper into this association, we conducted a case-control study in Jordan involving 173 GC cases and 314 controls, matched by age and marital status. Using a validated food frequency questionnaire, we assessed the intake of different dairy and meat products. The adjusted odds ratios and corresponding 95% confidence intervals indicated a strong correlation between high intake of red meat, milk, and buttermilk and GC. Our multinomial logistic regression analysis revealed that daily consumption of red meat (≥1 serving/day; OR, 3.34 [95% CI 1.85-6.03, p value of trend <.001], ≥1 serving/day) and weekly intake of milk (2-3 servings/week; OR, 2.04 [95% CI 1.14-3.64, p value of trend = .041]) and buttermilk (2-3 servings/week; OR, 2.07 [95% CI 1.12-3.83, p value of trend = .018], per 2-3 servings/week) were significantly associated with an increased risk of GC. Furthermore, consuming cooked eggs daily (OR = 2.44, 95% CI 1.24-4.79, p trend <.001) or weekly (OR, 3.34, 95% CI 1.58-7.10, p value of trend <.001) was also associated with an increased risk of GC. These findings highlight the potential health risks associated with excessive meat and some dairy products consumption and suggest that a balanced intake of these products, along with eggs, may help prevent GC.

Food-Borne Chemical Carcinogens and the Evidence for Human Cancer Risk

Commonly consumed foods and beverages can contain chemicals with reported carcinogenic activity in rodent models. Moreover, exposures to some of these substances have been associated with increased cancer risks in humans. Food-borne carcinogens span a range of chemical classes and can arise from natural or anthropogenic sources, as well as form endogenously. Important considerations include the mechanism(s) of action (MoA), their relevance to human biology, and the level of exposure in diet. The MoAs of carcinogens have been classified as either DNA-reactive (genotoxic), involving covalent reaction with nuclear DNA, or epigenetic, involving molecular and cellular effects other than DNA reactivity. Carcinogens are generally present in food at low levels, resulting in low daily intakes, although there are some exceptions. Carcinogens of the DNA-reactive type produce effects at lower dosages than epigenetic carcinogens. Several food-related DNA-reactive carcinogens, including aflatoxins, aristolochic acid, benzene, benzo[a]pyrene and ethylene oxide, are recognized by the International Agency for Research on Cancer (IARC) as causes of human cancer. Of the epigenetic type, the only carcinogen considered to be associated with increased cancer in humans, although not from low-level food exposure, is dioxin (TCDD). Thus, DNA-reactive carcinogens in food represent a much greater risk than epigenetic carcinogens.

Terminal velocity of fern and lycopod spores is affected more by mass and ornamentation than by size

PREMISE

Terminal velocity (Vt) is an important factor for the dispersal of biological particles but has scarcely been studied for anemochorous fern spores, and the influence of spore characteristics on Vt has not been evaluated. Here, we measured the Vt of 1234 spores of 18 fern species and two Selaginella microspores using videoimaging analysis and evaluated the effects of mass, size, and ornamentation on Vt.

METHODS

We designed a sedimentation tower with a graduated microtelescope attached to a high-speed video camera to record falling particles and measure the Vt of fern spores using video-image processing software. Spores were measured for each species and their size correlated with Vt.

RESULTS

The Vt of fern spores ranged from 4.7 cm·s^-1 (Cyathea costaricensis) to 18.85 cm·s^-1 (Acrostichum danaeifolium). The method is accurate and reliable as predicted by Stokes model for glass beads of known density and size. In addition, Vt had a higher correlation coefficient with mass (ρ = 0.72) than size (ρ = 0.20), and ornamental appendages reduced Vt.

CONCLUSIONS

The reported values of Vt of fern spores are within the range of different biological airborne particles such as moss spores and pollen grains of seed plants. The results showed that spore ornamentation is directly related to Vt rather than spore size and may increase or decrease the drag. This method will aid future aerobiological research on biological particles.

Occurrence and stability of ptesculentoside, caudatoside and ptaquiloside in surface waters

The illudane glycosides ptesculentoside (PTE), caudatoside (CAU) and ptaquiloside (PTA) are found in bracken ferns (Pteridium sp.). PTA is known to contaminate water bodies adjacent to bracken ferns and hence contribute to water toxicity. This study for the first time reports the presence of PTE and CAU in surface waters with concentrations up to 5.3 μg L^-1 and outlines their stability under semi-natural conditions using water of two diverse lakes at their natural pH or pH adjusted to 6.5, with temperature controlled at 5 or 15 °C, and in the presence or absence of microbial activity. Under the same set of tested conditions the three illudane glycosides degraded at similar rates: with half-lives of approximately two days at pH 7.4 and 15 °C, and approximately 12 days at pH 5.2-6.5 and 5 °C. The water origin had significant influence on the degradation rates, but only due to its difference in pH. In most cases, the degradation rates of all the three illudane glycosides could be predicted using the existing first-order model for PTA hydrolysis. As PTE and CAU exhibit the same leaching pattern and stability as PTA, previous predictions of bracken environmental impact are likely underestimated, as PTE and CAU have not been monitored and included in the risk assessment.

Ethnoveterinary for food-producing animals and related food safety issues: A comprehensive overview about terpenes

Alternatives to the use of conventional veterinary drugs in food-producing animals have gained attention, such as the use of natural products (NPs), mainly to soften the risks to the animal, the environment, and consumer's health. Although NPs have consistent advantages over conventional drugs, they cannot be considered risk free under food safety matters. In this way, this document presents a comprehensive overview of the importance of considering both the pharmacological and toxicological properties of the constituents of a NP from plants intending the standardization and regulation of its use in food-producing animals. Terpenes are the most diverse class of natural substances present in NP of vegetal origin with a broad range of biological activities that can be explored in veterinary science; however, certain plants and terpenes also have significant toxic effects, a fact that can harm the health of animals and consequently generate economic losses and risks for humans. In this context, this review gathered scientific data of vegetal species of importance to ethnoveterinary for food-producing animals, which produce terpenes, its biological effects, and their implications on food safety issues for consumers. For this, more than 300 documents were selected from different online scientific databases. The present data and discussion may contribute to the rational commercial exploration of this class of NPs in veterinary medicine.

A Novel Method for Determination of the Natural Toxin Ptaquiloside in Ground and Drinking Water

Ptaquiloside (PTA) is a carcinogenic compound naturally occurring in bracken ferns (Pteridium aquilinum). It is highly water soluble and prone to leaching from topsoil to surface and groundwaters. Due to possible human exposure via drinking water, PTA is considered as an emerging contaminant. We present a sensitive and robust method for analysis of PTA and its degradation product pterosin B (PtB) in groundwater. The method comprises two steps: sample preservation at the field site followed by sample pre-concentration in the laboratory. The preservation step was developed by applying a Plackett–Burman experimental design testing the following variables: water type, pH, filtering, bottle type, storage temperature, transportation conditions and test time. The best sample preservation was obtained by using amber glass bottles, unfiltered solutions buffered at pH 6, transported without ice, stored at 4 °C and analysed within 48 h. The recovery was 94% to 100%. The sample purification step had a pre-concentration factor of 250, and the recovery percentages of the entire method were 85 ± 2 (PTA) and 91 ± 3 (PtB). The limits of detection (LOD) of the full method were 0.001 µg L−1 and 0.0001 µg L−1 for PTA and PtB, respectively. The method enables sensitive monitoring of PTA and PtB in groundwater. Carcinogenic PTA was detected in one groundwater well (0.35 µg L−1).

Medicinal dietary plants of the Yi in Mile, Yunnan, China

BACKGROUND

The Yi is the largest ethnic group in Yunnan Province (China), with a population of five million. The Yi people tend to live in mountainous areas, and their culture includes a unique dietary system for treating and protecting people against illnesses. Medicinal plants occupy an essential place in the Yi diet because they play a key role in health and the prevention and treatment of diseases. However, few studies have addressed these medicinal dietary plants and their importance in the Yi's daily lives. The aim of this study was to (1) investigate the medicinal dietary plants used by the Yi in Mile City, (2) document the traditional knowledge held about these plants, (3) identify species with important cultural significance to the Yi in Mile City, and (4) analyze the special preparation methods and consumption habits of these plants.

METHODS

Field investigations were performed in six villages in Mile City, Honghe Hani and Yi Autonomous Prefecture, Yunnan, from July 2017 to May 2018. Information was collected using direct observation, semi-structured interviews, key informant interviews, individual discussions, and focus group discussions. The use value (UV) and frequency of utilization index (FUI) of these plants were analyzed. Plant samples and voucher specimens were collected for taxonomic identification.

RESULTS

This study documented 124 species belonging to 62 families and 102 genera. These plants included angiosperms (117 spp.), gymnosperms (3), pteridophytes (2), lichen (1), and fungus (1). The 20 species with the highest UV were noted as being particularly important to the Yi people's daily life in Mile City. The primary medicinal preparation method for plants recorded in the study was decoction. The most commonly used plant parts were fruits and roots. The most frequently used edible parts were fruits, and the most frequently used medicinal parts were roots. The medicinal parts were used to treat diseases such as rheumatism, edemas, kidney deficiency, spleen deficiency, gastritis, parasites, and so on.

CONCLUSION

A wide variety of medicinal dietary plants are used by the Yi people in Mile City. Those plants, which have both rich nutritional and medicinal value, occupy an essential part of the Yi dietary and medicine culture. Ethnobotanical surveys of medicinal dietary plants provide a theoretical reference for the conservation and sustainable use of the plant resources and could contribute to the protection of the Yi food culture and traditional medicine in Mile City. In addition, this information provides a sound basis for developing and using Yi ethnic medicine and health products.

Fate of ptaquiloside-A bracken fern toxin-In cattle

Ptaquiloside is a natural toxin present in bracken ferns (Pteridium sp.). Cattle ingesting bracken may develop bladder tumours and excrete genotoxins in meat and milk. However, the fate of ptaquiloside in cattle and the link between ptaquiloside and cattle carcinogenesis is unresolved. Here, we present the toxicokinetic profile of ptaquiloside in plasma and urine after intravenous administration of ptaquiloside and after oral administration of bracken. Administered intravenously ptaquiloside, revealed a volume of distribution of 1.3 L kg-1 with a mean residence-time of 4 hours. A large fraction of ptaquiloside was converted to non-toxic pterosin B in the blood stream. Both ptaquiloside and pterosin B were excreted in urine (up to 41% of the dose). Oral administration of ptaquiloside via bracken extract or dried ferns did not result in observations of ptaquiloside in body fluids, indicating deglycosolidation in the rumen. Pterosin B was detected in both plasma and urine after oral administration. Hence, transport of carcinogenic ptaquiloside metabolites over the rumen membrane is indicated. Pterosin B recovered from urine counted for 7% of the dose given intravenously. Heifers exposed to bracken for 7 days (2 mg ptaquiloside kg-1) developed preneoplastic lesions in the urinary bladder most likely caused by genotoxic ptaquiloside metabolites.

The role of bracken fern illudanes in bracken fern-induced toxicities

Bracken fern is carcinogenic when fed to domestic and laboratory animals inducing bladder and ileal tumours and is currently classified as a possible human carcinogen by IARC. The carcinogenic illudane, ptaquiloside (PTQ) was isolated from bracken fern and is widely assumed to be the major bracken carcinogen. However, several other structurally similar illudanes are found in bracken fern, in some cases at higher levels than PTQ and so may contribute to the overall toxicity and carcinogenicity of bracken fern. In this review, we critically evaluate the role of illudanes in bracken fern induced toxicity and carcinogenicity, the mechanistic basis of these effects including the role of DNA damage, and the potential for human exposure in order to highlight deficiencies in the current literature. Critical gaps remain in our understanding of bracken fern induced carcinogenesis, a better understanding of these processes is essential to establish whether bracken fern is also a human carcinogen.

Ptaquiloside, the major carcinogen of bracken fern, in the pooled raw milk of healthy sheep and goats: an underestimated, global concern of food safety

Bracken fern (Pteridium aquilinum) is a worldwide plant containing toxic substances, which represent an important chemical hazard for animals, including humans. Ptaquiloside, 1, a norsesquiterpenoid glucoside, is the major carcinogen of bracken detected in the food chain, particularly in the milk from farm animals. To date, ptaquiloside has been shown in the milk of cows feeding on a diet containing bracken fern. This is the first study that shows the systematic detection of ptaquiloside, 1, and reports its direct quantitation in pooled raw milk of healthy sheep and goats grazing on bracken. Ptaquiloside, 1, was detected by a sensitive method based on the chemical conversion of ptaquiloside, 1, into bromopterosine, 4, following gas chromatography-mass spectrometry (GC-MS) analysis. The presence of ptaquiloside, 1, possibly carcinogenic to humans, in the milk of healthy animals is an unknown potential health risk, thus representing a harmful and potential global concern of food safety.

Perfil de propriedades rurais com pastos invadidos por Pteridium arachnoideum na região norte de Mato Grosso e prevalência de hematúria enzoótica bovina

Descreve-se o perfil de 40 propriedades rurais com pastagens invadidas por Pteridium arachnoideum na região norte de Mato Grosso, bem como a prevalência de hematúria enzoótica bovina (HEB) em bovinos de leite e corte nessa região. A HEB foi observada em 15/40 propriedades com prevalências variando entre 0,8 e 16,6%. Aspectos relacionados à implantação das pastagens e manejos utilizados foram discutidos. A maior parte das propriedades que apresentaram HEB possuíam pastagens altamente invadidas pela planta, enquanto que a maioria das propriedades que nunca apresentaram animais acometidos por HEB possuíam pastos com áreas invadidas abaixo de 10%. O desmatamento e a utilização de queimada foram fatores determinantes na invasão de piquetes por P. arachnoidem.

Ptaquiloside-induced cytotoxicity in Crandall feline kidney and HGC-27 cells

Ptaquiloside (PTA) is a potent genotoxic carcinogenic compound, which is found in bracken ferns and predominantly causes gastric tumors in humans, as well as bladder tumors and chronic enzootic hematuria in cattle. The underlying molecular mechanisms of PTA remain a topic for interdisciplinary investigation. The aim of the present study was to determine the possible cytotoxic effect of 24 h of PTA exposure in Crandall feline kidney (CrFK) and human gastric cells (the HGC-27 cell line) using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and lactose dehydrogenase (LDH) analysis. The cytotoxic effects of PTA (0.0005–500 μg/ml) were found to increase in a dose-dependent manner, whereby the half maximal inhibitory concentration values were 11.17 and 11.86 μg/ml in the CrFK cells, and 2.03 and 2.56 μg/ml in the HGC-27 cells, by LDH and MTT assay, respectively. The results of the present study are consistent with those of previous studies associated with the cytotoxicity of PTA; however, cytotoxicity was identified to occur at significantly lower doses. This cytotoxic effect in vitro at particularly high doses may be linked to the initiation of carcinogenesis as a result of oxidative stress.

Association between dairy intake and gastric cancer: a meta-analysis of observational studies

Purpose

Observational studies have given inconsistent findings on the relationship between intake of dairy products and gastric cancer. We therefore conducted a systematic review with a meta-analysis of observational studies to summarize available evidence on this point.

Methods

We searched the electronic literature databases of PubMed (Medline), EMBASE and the Chinese Biomedical Literature Database up until August 30, 2013. All studies were limited to the English language. Random-effects models were used to pool study results between dairy products consumption and the risk of gastric cancer. We also performed subgroup, publication bias and sensitivity analysis.

Results

Eight prospective studies and 18 case-control studies were included in our analysis, with a total number of 7272 gastric cancer cases and 223,355 controls. Pooled relative risks of all studies showed no significant association between dairy intake and gastric cancer (odds ratio [OR]: 1.09, 95% confidence interval [CI]: 0.96–1.25). When study design was separately analyzed, population-based case-control studies showed a positive association between dairy intake and gastric cancer risk (OR: 1.36; 95% CI: 1.07–1.74), whereas no associations were shown by hospital-based case-control studies (OR: 0.86, 95% CI: 0.72–1.02) or cohort studies (OR = 1.01, 95% CI = 0.91–1.13).

Conclusions

The meta-analysis shows that no clear association apparently exists between consumption of dairy products and gastric cancer risk. Further well-designed cohort and intervention studies should be conducted to verify this lack of association.

Effects of copaene, a tricyclic sesquiterpene, on human lymphocytes cells in vitro

In this study, the cytotoxic, genotoxic/antigenotoxic and antioxidant/oxidant activity of copaene (COP), a plant-derived tricyclic sesquiterpene, on human lymphocyte cultures (n = 5) was investigated. COP was added into culture tubes at various concentrations (0, 10, 25, 50, 100, 200 and 400 mg/L). While the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays were used for viability and cytotoxic evaluations, the micronucleus (MN) and sister chromatid exchange (SCE) assays were used for genetic evaluations. Moreover, total antioxidant capacity (TAC) and total oxidative status analysis were used for biochemical evaluations. According to LDH and MTT assays COP significantly reduced cell proliferation at high concentrations (200 and 400 mg/L). In addition, there was no significant increase (P < 0.05) in both SCE and MN frequencies of cultures treated with COP as compared to controls. We have also concluded that concentrations of COP of 50 and 100 mg/L increased TAC level when compared to the controls. In conclusion, in this study it has been reported for the first time that copaene is not genotoxic and it increases the antioxidant capacity in human lymphocyte cultures.

Ferns and lycopods--a potential treasury of anticancer agents but also a carcinogenic hazard

Many species of seedless vascular plants-ferns and lycopods-have been used as food and folk medicine since ancient times. Some of them have become the focus of intensive research concerning their anticancer properties. Studies on the anticancer effect of crude extracts are being increasingly replaced by bioactivity-guided fractionation, as well as detailed assessment of the mechanism of action. Numerous compounds-especially flavonoids such as amentoflavone and protoapigenone, and also simpler phenolic compounds, steroids, alkaloids and terpenoids-were isolated and found to be cytotoxic, particularly pro-apoptotic, or to induce cell cycle arrest in cancer cell lines in vitro. In in vivo experiments, some fern-derived compounds inhibited tumour growth with little toxicity. On the other hand, many ferns-not only the well-known Bracken (Pteridium)-may pose a significant hazard to human health due to the fact that they contain carcinogenic sesquiterpenoids and their analogues. The objective of this review is to summarise the recent state of research on the anticancer properties of ferns and lycopods, with a focus on their characteristic bioactive constituents. The carcinogenic hazard posed by ferns is also mentioned.

Glycophenotypic alterations induced by Pteridium aquilinum in mice gastric mucosa: synergistic effect with Helicobacter pylori infection

The bracken fern Pteridium aquilinum is a plant known to be carcinogenic to animals. Epidemiological studies have shown an association between bracken fern exposure and gastric cancer development in humans. The biological effects of exposure to this plant within the gastric carcinogenesis process are not fully understood. In the present work, effects in the gastric mucosa of mice treated with Pteridium aquilinum were evaluated, as well as molecular mechanisms underlying the synergistic role with Helicobacter pylori infection. Our results showed that exposure to Pteridium aquilinum induces histomorphological modifications including increased expression of acidic glycoconjugates in the gastric mucosa. The transcriptome analysis of gastric mucosa showed that upon exposure to Pteridium aquilinum several glycosyltransferase genes were differently expressed, including Galntl4, C1galt1 and St3gal2, that are mainly involved in the biosynthesis of simple mucin-type carbohydrate antigens. Concomitant treatment with Pteridium aquilinum and infection with Helicobacter pylori also resulted in differently expressed glycosyltransferase genes underlying the biosynthesis of terminal sialylated Lewis antigens, including Sialyl-Lewis^x. These results disclose the molecular basis for the altered pattern of glycan structures observed in the mice gastric mucosa. The gene transcription alterations and the induced glycophenotypic changes observed in the gastric mucosa contribute for the understanding of the molecular mechanisms underlying the role of Pteridium aquilinum in the gastric carcinogenesis process.