Stability study of ptaquiloside biotoxin from P. esculentum var. Arachnoideum in bovine milk and artisanal dairy-food products.

The potential health risk of consuming dairy products made from milk processed in an artisanal manner was investigated due to possible contamination with Ptaquiloside (PTA), a carcinogenic compound found in the food chain of the bracken fern. The study aimed to assess the occurrence and stability of PTA across various processing stages, including pasteurization, cheese production, and yogurt production. Results indicated that pasteurization effectively converted all PTA to Pterosin (PTB), with PTB levels decreasing during refrigerated storage for up to two weeks. The stability and occurrence of initial PTA contamination remained unchanged in yogurt production. Biotoxin concentrations in soft cheeses decreased over time, independent of ionic strength; cheeses with low salt concentrations showed lower retention of the biotoxin within the cheese protein network. These findings offer valuable insights into the stability and occurrence of PTA, facilitating the monitoring and identification of potential adverse health effects.

The Norsesquiterpene Glycoside Ptaquiloside as a Poisonous, Carcinogenic Component of Certain Ferns.

Previous studies related to the ptaquiloside molecule, a carcinogenic secondary metabolite known from the world of ferns, are summarised. Ptaquiloside (PTA) belongs to the group of norsesquiterpenes of the illudane type. The name illudane refers to the fungal taxa from which the first representatives of the molecular group were identified. Ptaquiloside occurs mainly in Pteridium fern species, although it is also known in other fern taxa. The species of the genus Pteridium are common, frequent invasive species on all continents, and PTA is formed in smaller or larger amounts in all organs of the affected species. The effects of PTA and of their derivatives on animals and humans are of great toxicological significance. Its basic chemical property is that the molecule can be transformed. First, with the loss of sugar moiety, ptaquilosine is formed, and then, under certain conditions, a dienone derivative (pteridienone) may arise. The latter can alkylate (through its cyclopropane groups) certain molecules, including DNA, in animal or human organisms. In this case, DNA adducts are formed, which can later have a carcinogenic effect through point mutations. The scope of the PTA is interdisciplinary in nature since, for example, molecules from plant biomass can enter the body of animals or humans in several ways (directly and indirectly). Due to its physico-chemical properties (excellent water solubility), PTA can get from the plant into the soil and then into different water layers. PTA molecules that enter the soil, but mainly water, undergo degradation (hydrolytic) processes, so it is very important to clarify the toxicological conditions of a given ecosystem and to estimate the possible risks caused by PTA. The toxicoses and diseases of the animal world (mainly for ruminant farm animals) caused by PTA are briefly described. The intake of PTA-containing plants as a feed source causes not only various syndromes but can also enter the milk (and meat) of animals. In connection with the toxicological safety of the food chain, it is important to investigate the transport of carcinogenic PTA metabolites between organisms in a reassuring manner and in detail. This is a global, interdisciplinary task. The present review aims to contribute to this.

Ptaquiloside from bracken (Pteridium spp.) promotes oral carcinogenesis initiated by HPV16 in transgenic mice.

Bracken (Pteridium spp.) is a common weed that is consumed as food especially in Asia, and is suspected of promoting carcinogenesis induced by papillomaviruses in the digestive and urinary systems. This is particularly worrying because the incidence of head-and-neck cancers associated with the human papillomavirus (HPV) is rapidly increasing, and HPV co-carcinogens urgently need to be identified. This study tested the hypothesis that two bracken compounds, ptaquiloside and rutin, are able to promote head-and-neck and bladder carcinogenesis in HPV16-transgenic mice. Expression of HPV16 E6 and E7 in oral and bladder tissues was confirmed using quantitative real-time PCR. Mice were exposed orally to ptaquiloside (0.5 mg per animal per week for 10 weeks from 20 weeks-old) or rutin (413 mg kg-1 day-1 for 24 weeks from 6 weeks-old), sacrificed at 30 weeks-old and studied histologically. HPV16 E6 and E7 expression was higher in oral mucosa compared with the bladder (p 0.001). Importantly, ptaquiloside, but not rutin, increased the incidence of oral squamous cell carcinomas (p = 1.2 × 10-8) in HPV16-transgenic mice. Also, cancers of unexposed transgenic mice were restricted to the tongue base, while ptaquiloside-exposed mice showed multifocal lesions throughout the oral cavity. Wild-type controls showed no oral lesions. No bladder lesions were observed in any treated or untreated group. These results indicate that ptaquiloside from bracken is able to promote oral carcinogenesis initiated by HPV16. Rutin did not show any carcinogenic effects in this model. The absence of bladder lesions may reflect an insufficient incubation period or factors related to the specific viral oncogenes present in this model.

Fast LC-MS quantification of ptesculentoside, caudatoside, ptaquiloside and corresponding pterosins in bracken ferns.

Ptaquiloside (PTA) is an illudane glycoside partly responsible for the carcinogenicity of bracken ferns (Pteridium sp.). The PTA analogues ptesculentoside (PTE) and caudatoside (CAU) have similar biochemical reactivity. However, both compounds are highly under-investigated due to the lack of analytical standards and appropriate methods. This study presents a robust method for preparation of analytical standards of PTE, CAU, PTA, the corresponding hydrolysis products: pterosins G, A and B, and an LC-MS based method for simultaneous quantification of the six compounds in bracken. The chromatographic separation of analytes takes 5 min. The observed linear range of quantification was 20-500 µg/L for PTA and pterosin B, and 10-250 µg/L for the remaining compounds (r > 0.999). The limits of detection were 0.08-0.26 µg/L for PTE, CAU and PTA and 0.01-0.03 µg/L for the pterosins, equivalent to 2.0-6.5 µg/g and 0.25-0.75 µg/g in dry weight, respectively. The method was applied on 18 samples of dried fern leaves from 6 continents. Results demonstrated high variation in concentrations of PTE, CAU and PTA with levels prior to hydrolysis up to 3,900, 2,200 and 2,100 µg/g respectively. This is the first analytical method for simultaneous and direct measurement of all six compounds. Its application demonstrated that bracken ferns contain significant amounts of PTE and CAU relative to PTA.

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.

Structural characterization and immunomodulatory activity of a novel polysaccharide from Pteridium aquilinum.

PAP1-A, a novel heteropolysaccharide with an average molecular mass of 1.35×105Da, was isolated from Pteridium aquilinum using a combination of chromatography by DEAE Sepharose Fast Flow and Sepharose 4B. The monosaccharide component of PAP1-A was L-rhamnose, L-arabinose, L-fucose, D-xylose, D-mannose, D-glucose and D-galactose in the molar ration of 1.82: 1.53: 1.42: 1.31: 5.24: 1: 12.35. The predicted structure of PAP1-A was established to be a complex polysaccharide with a main chain consisted of α-(1→4)-linked galactose partially substituted at O-6 position, with the (1→2)-linked xylose, (1→3)-linked arabinose, (1→3)-linked rhamnose, (1→3,6)-linked mannose, and (1→6)-linked mannose, as branches. Fucose, glucose, mannose, and rhamnose were located at the termini of the branches. The immunomodulatory activity assay showed that PAP1-A could significantly promote the RAW264.7 cells proliferation and induce the production of NO from RAW264.7 cells. Therefore, PAP1-A shows as a potent immunomodulator with potential applications in the medical and food industries.

Dissipation of pterosin B in acid soils - Tracking the fate of the bracken fern carcinogen ptaquiloside.

Bracken ferns (Pteridium spp.) are well-known for their carcinogenic properties, which are ascribed to the content of ptaquiloside and ptaquiloside-like substances. Ptaquiloside leach from the ferns and may cause contamination of drinking water. Pterosin B is formed by hydrolysis of ptaquiloside. In soil, Pterosin B is adsorbed more strongly and it is expected to have a slower turnover than ptaquiloside. We thus hypothesized that pterosin B may serve as an indicator for any past presence of ptaquiloside. Pterosin B degradation was studied in acid forest soils from bracken-covered and bracken-free areas. Soil samples were incubated with pterosin B at 3 and 8 µg g-1 for 10 days, whereas sterile (autoclaved) samples were incubated for 23 days. Pterosin B showed unexpected fast degradation in soils with full degradation in topsoils in 2-5 days. Pterosin B dissipation followed the sum of two-first order reactions. The initial fast reaction with half-lives of 0.7-3.5 h contributed 11-59% of the total pterosin B degradation, while the slow reaction was 20-100 times slower than the fast reaction. Total dissipation half-lives were shorter for loamy sand (4 h) than for sandy loam soils (28 h). No degradation of pterosin B took place under sterile conditions assuming observed dissipation during the first 3 h could be attributed to irreversible sorption. Our results demonstrate that pterosin B is microbially degraded and that pterosin B is as unstable as ptaquiloside and hence cannot be used as an indicator for former presence of ptaquiloside in soil.

Ptaquiloside from bracken (Pteridium spp.) inhibits tumour-infiltrating CD8+ T cells in HPV-16 transgenic mice.

Bracken is a fern with worldwide distribution. Exposure to bracken toxins such as ptaquiloside is hypothesized to increase the risk of papillomavirus-related cancers of the upper digestive tract. Ptaquiloside is thought to be an immunosupressor, thus allowing for the development of viral lesions. We have used a human papillomavirus type 16-transgenic (K14-HPV16) mouse model to study the effects of ptaquiloside on tumour-infiltrating CD8+ T lymphocytes, which are critical players in anti-tumour immunity. HPV16+/- mice received ptaquiloside (0.5 mg/mouse/week) for 10 weeks. These were then euthanized at 30 weeks of age, along with age-matched untreated controls. Skin samples were enzymatically digested and CD8+ T cells analysed for CD107a and CD44 surface expression. Ptaquiloside-exposed HPV16+/- mice showed a significantly decreased percentage (P < 0.05) of CD8+CD107a+ and CD8+CD44 + T cells when compared with untreated HPV16+/- animals. Histologically, 100% of ptaquilosidetreated mice showed diffuse epidermal dysplasia, compared with 50% of the untreated mice. These findings suggest that ptaquiloside exerts an immunosuppressive role by decreasing CD8+ T cell activation and degranulation in HPV-induced lesions. Given the key role of CD8+ T lymphocytes against HPV-induced lesions, this effect is likely to contribute for viral persistence, tumour progression and increased aggressiveness in patients with HPV-related malignancies.

Human gastric cancer, Helicobacter pylori and bracken carcinogens: A connecting hypothesis.

Long term infection of Helicobacter pylori (Hp) virulent strains is a key factor in the genesis of human gastric cancer, and so are certain dietary proinflammatory and genotoxic compounds. Carcinogenic bracken fern (Pteridium spp.) is one of these. Toxins from this plant are consumed as bracken culinary preparations, through milk and meat of bracken-exposed livestock, and drain waters from bracken swards. Bracken toxin ptaquiloside (PtQ), a suspected human carcinogen, elicits complex responses in animals leading to death. PtQ and Hp might cooperate in gastric pathologies. This paper presents an hypothesis on PtQ-Hp association leading to the enhancement of carcinogenesis in the human gastric environment that might explain the high gastric cancer incidence and death rates among Hp-infected people living in bracken zones at two levels: (1) The macroscopic scale comprising the flow of PtQ in the human diet. (2) the microscopic scale encompassing (A) gastric luminal medium; (B) gastric mucus structure and mucin degradation elicited by Hp; (C) bacterial pH gradient modification of the gastric mucosa that favors PtQ survival and its penetration into epithelial tissue; (D) combined PtQ/Hp effects on gastric immune and inflammatory responses; (E) PtQ-Hp complementary activity at selected cell signaling cascades and genome disturbance.

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.

Land management of bracken needs to account for bracken carcinogens--a case study from Britain.

Bracken ferns are some of the most widespread ferns in the World causing immense problems for land managers, foresters and rangers. Bracken is suspected of causing cancer in Humans due to its content of the carcinogen ptaquiloside. Ingestion of bracken, or food and drinking water contaminated with ptaquiloside may be the cause. The aim of this study was to monitor the content of ptaquiloside in 20 bracken stands from Britain to obtain a better understanding of the ptaquiloside dynamics and to evaluate the environmental implications of using different cutting regimes in bracken management. The ptaquiloside content in fronds ranged between 50 and 5790 µg/g corresponding to a ptaquiloside load in the standing biomass of up to 590 mg/m(2) in mature fronds. Ptaquiloside was also found in the underground rhizome system (11-657 µg/g) and in decaying litter (0.1-5.8 µg/g). The amount of ptaquiloside present in bracken stands at any given time is difficult to predict and did not show any correlations with edaphic growth factors. The content of ptaquiloside turned out to be higher in fronds emerging after cutting compared to uncut fronds. Environmental risk assessment and bracken management must therefore be based on actual and site specific determinations of the ptaquiloside content. Care must be taken to avoid leaching from cut ferns to aquifers and other recipients and appropriate precautionary measures must be taken to protect staff from exposure to bracken dust.

Chromium and nickel in Pteridium aquilinum from environments with various levels of these metals.

Pteridium aquilinum is a ubiquitous species considered to be one of the plants most resistant to metals. This fern meets the demands for a good bioindicator to improve environmental control. Therefore, it was of interest to survey the accumulation of Cr and Ni in the rhizome and fronds of this species collected in Lower Silesia (SW Poland) of serpentinite rich in Cr and Ni and granite poor in these metals. Additionally, concentrations of Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, and Zn were measured in granite and serpentinite parent rocks, soils, and in P. aquilinum (rhizome and fronds). The experiment was carried out with rhizomes of ferns from both types of soils placed in pots supplemented with 50, 100, and 250 mg kg(-1) of Cr or Ni or both elements together. At a concentration of 250 mg kg(-1) of Cr, Ni, or Cr + Ni, fronds (from granite or serpentinite origin) contained significantly higher Cr and Ni concentrations when both metals were supplied together. In the same concentration of 250 mg kg(-1) of Cr, Ni, or Cr + Ni, rhizomes (from granite or serpentinite origin) contained significantly higher Cr and Ni concentrations when both metals were supplied separately. The explanation of metal differences in the joint accumulation of Cr and Ni on the rhizome or frond level needs further investigation. The lack of difference in Cr and Ni concentration in the rhizome and fronds between experimental P. aquilinum collected from granite and serpentinite soils may probably indicate that the phenotypic plasticity of this species is very important in the adaptation to extreme environments.

Ptaquiloside-induced early-stage urothelial lesions show increased cell proliferation and intact ß-catenin and E-cadherin expression.

Bracken (Pteridium aquilinum) is a carcinogenic plant whose main toxin, ptaquiloside, causes cancer in farm and laboratory animals. Ptaquiloside contaminates underground waters as well as meat and milk from bracken-grazing animals and is a suspected human carcinogen. A better understanding of the underlying mechanisms of carcinogenesis can be achieved by studying the early stages of this process. Unfortunately, most research on ptaquiloside has focused on the late, malignant, lesions, so the early changes of ptaquiloside-induced carcinogenesis remain largely unknown. This study aims to characterize early-stage ptaquiloside-induced urinary bladder lesions both morphologically and immunohistochemically. 12 male CD-1 mice were administered 0.5 mg ptaquiloside intraperitoneally, weekly, for 15 weeks, followed by 15 weeks without treatment. 12 control animals were administered saline. Bladders were tested immunohistochemically for antibodies against a cell proliferation marker (Ki-67), and two cell adhesion markers (E-cadherin and ß-catenin). Two exposed animals died during the work. Six ptaquiloside-exposed mice developed low-grade and two developed high grade urothelial dysplasia. No lesions were detected on control animals. Significantly, increased (p < 0.05) Ki-67 labeling indices were found on dysplastic urothelium from ptaquiloside-exposed mice, compared with controls. No differences were found concerning E-cadherin and ß-catenin expression. Early-stage ptaquiloside-induced urothelial lesions show increased cell proliferation but there is no evidence for reduced intercellular adhesiveness, though this may be a later event in tumor progression.

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.

Effects of selenium on Pteridium aquilinum and urethane-induced lung carcinogenesis.

The results of our previous study demonstrated that ptaquiloside, the main toxic agent found in Pteridium aquilinum, suppresses natural killer (NK) cell-mediated cytotoxicity. However, the ability of ptaquiloside to suppress the cytotoxicity of NK cells was prevented by selenium supplementation. NK cells play an important role in the innate immune response and have the ability to kill tumor cells. Therefore, we hypothesized that selenium may prevent the higher susceptibility to urethane-induced lung carcinogenesis that has been observed in mice treated with P. aquilinum. The immunosuppressive effects of ptaquiloside have been associated with a higher number of urethane-induced lung nodules in mice. Hence, we assessed the effects of P. aquilinum-induced immunosuppression on urethane-induced lung carcinogenesis in C57BL/6 mice that had been supplemented with selenium. For these experiments, mice were treated with both an aqueous extract of P. aquilinum (20 g/kg/day) and selenium (1.3 mg/kg) by gavage once daily for 14 days followed by a once-weekly intraperitoneal injection of urethane (1 g/kg) for 10 weeks that was accompanied by gavage 5 days a week. Lung adenomas in mice that had been treated with P. aquilinum plus urethane occurred with a frequency that was 44% higher than that in mice that had been treated with only urethane. In mice that had been supplemented with selenium and treated with P. aquilinum plus urethane, the occurrence of lung adenomas was reduced to 26%. These results suggest that selenium prevents the immunosuppressive effects of P. aquilinum on urethane-induced lung carcinogenesis.

Ptaquiloside reduces NK cell activities by enhancing metallothionein expression, which is prevented by selenium.

Pteridium aquilinum, one of the most important poisonous plants in the world, is known to be carcinogenic to animals and humans. Moreover, our previous studies showed that the immunosuppressive effects of ptaquiloside, its main toxic agent, were prevented by selenium in mouse natural killer (NK) cells. We also verified that this immunosuppression facilitated development of cancer. Here, we performed gene expression microarray analysis in splenic NK cells from mice treated for 14 days with ptaquiloside (5.3 mg/kg) and/or selenium (1.3 mg/kg) to identify gene transcripts altered by ptaquiloside that could be linked to the immunosuppression and that would be prevented by selenium. Transcriptome analysis of ptaquiloside samples revealed that 872 transcripts were expressed differentially (fold change>2 and p<0.05), including 77 up-regulated and 795 down-regulated transcripts. Gene ontology analysis mapped these up-regulated transcripts to three main biological processes (cellular ion homeostasis, negative regulation of apoptosis and regulation of transcription). Considering the immunosuppressive effect of ptaquiloside, we hypothesized that two genes involved in cellular ion homeostasis, metallothionein 1 (Mt1) and metallothionein 2 (Mt2), could be implicated because Mt1 and Mt2 are responsible for zinc homeostasis, and a reduction of free intracellular zinc impairs NK functions. We confirm these hypotheses and show increased expression of metallothionein in splenic NK cells and reduction in free intracellular zinc following treatment with ptaquiloside that were completely prevented by selenium co-treatment. These findings could help avoid the higher susceptibility to cancer that is induced by P. aquilinum-mediated immunosuppressive effects.

Influence of bracken fern (Pteridium caudatum L. Maxon) pre-treatment on extraction yield of illudane glycosides and pterosins.

INTRODUCTION: Bracken (Pteridium spp) illudane glycosidess are labile biologically active terpenoids that undergo decomposition in mild alkali or acid, heat and enzymatic reactions. Hypothetically, quantitation of these weakly chromophoric carcinogens may be challenged by plant sample preparation procedures that may alter the yield of isolates. OBJECTIVE: To study the influence of common plant sample pre-treatments on the recovery of Pteridium caudatum illudane glycoside carcinogens, ptaquiloside (1a), caudatoside (1c) and ptaquiloside Z (1d), and associated pterosins A, B and Z (2a, b, c) using HPLC-DAD. METHOD: Bracken fronds were divided in equal left/right sections. One section was subjected to high vacuum desiccation (VD) and the other to freeze-drying (FD), air drying at room temperature (AD) for 7 days, air drying at 70 °C for 72 h (HD), or no treatment (fresh frond, FF). Quantitation was achieved by brief hot-water extraction, base-acid transformation of 1a, 1c and 1d to 2a, b, c and HPLC-DAD analysis against standards. RESULTS: Substantial differences in extraction yields were found for all illudane glycosides in the order FF > FD ≈ VD > AD > HD. Illudane instability to HD was 1c > 1d > 1a. Significant losses also were recorded in yields of Pterosins A, B and Z. CONCLUSION: Glycoside extraction suffers from substantial yield loss of all illudane glycosides and indigenous pterosins in all sample pre-treatments studied relative to fresh frond material.

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.

A new facile synthesis of d4-pterosin B and d4-bromopterosin, deuterated analogues of ptaquiloside.

Ptaquiloside (Pta) is a potent carcinogen present in bracken fern and in soil matrices, that can potentially leach to the aquatic environment. More recently its presence in the milk of different farm animals has been reported. Pterosin B (Ptb) and bromopterosin (BrPt) represent the most convenient analogues in the detection of ptaquiloside by mass spectrometry. Pterosin sesquiterpenes are also involved in many patented biomedical protocols. In this work we introduce a new and convenient approach to the synthesis in three steps and more than 80% yield of d4-pterosin B (d4-Ptb) and d4-bromopterosin (d4-BrPt), useful as internal standards in the quantification of ptaquiloside.

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

The multifactorial origin of gastric cancer encompasses environmental factors mainly associated with diet. Pteridium aquilinum-bracken fern-is the only higher plant known to cause cancer in animals. Its carcinogenic toxin, ptaquiloside, has been identified in milk of cows and groundwater. Humans can be directly exposed by consumption of the plant, contaminated water or milk, and spore inhalation. Epidemiological studies have shown an association between bracken exposure and gastric cancer. In the present work, the genotoxicity of P. aquilinum and ptaquiloside, including DNA damaging effects and DNA damage response, was characterized in human gastric epithelial cells and in a mouse model. In vitro, the highest doses of P. aquilinum extracts (40 mg/ml) and ptaquiloside (60 µg/ml) decreased cell viability and induced apoptosis. γH2AX and P53-binding protein 1 analysis indicated induction of DNA strand breaks in treated cells. P53 level also increased after exposure, associated with ATR-Chk1 signaling pathway activation. The involvement of ptaquiloside in the DNA damage activity of P. aquilinum was confirmed by deregulation of the expression of a panel of genes related to DNA damage signaling pathways and DNA repair, in response to purified ptaquiloside. Oral administration of P. aquilinum extracts to mice increased gastric cell proliferation and led to frameshift events in intron 2 of the P53 gene. Our data demonstrate the direct DNA damaging and mutagenic effects of P. aquilinum. These results are in agreement with the carcinogenic properties attributed to this fern and its ptaquiloside toxin and support their role in promoting gastric carcinogenesis.