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By quantitative techniques it has been shown that the expected tumor frequency after x-irradiation of spores of the fern Pteridium aquilinum can be reduced by the addition of casein hydrolyzate or amino acids to the medium upon which the spores are germinated and grown into either prothalli or tumors.
The two major molting hormones of insects, alpha ecdysone and 20-hydroxyecdysone, were isolated in crystalline form from dry pinnae of the bracken fern, Pteridium aquilinum (L.) Kuhn. Three unidentified substances with molting hormone activity were also detected. Bracken is the first plant found to contain both of the major insect ecdysones, and it is the first known plant source of alpha ecdysone.
OBJECTIVE: To assess the risk to human health of the plant bracken (Pteridium sp). DESIGN: An evaluation of studies of human and animal populations exposed to bracken, together with a review of expert reports and advice to the public. MAIN RESULTS: Bracken induced disease has been demonstrated in animals in both laboratory and field studies. Depending on the species, diseases in animals associated with the plant have included; cancers of the alimentary and urogenital tract, lung and breast; haematuria; retinal degeneration; and, thiamine deficiency. Potential exposure of human populations is through: food either directly (people in some parts of the world eat bracken as a traditional dish) or indirectly by consuming animals fed on bracken; milk; water; inhalation and ingestion of spores; and insect vectors. Four studies of human populations (two analytical and two observational) failed to assess adequately confounding factors and other sources of bias, so that conclusions about a risk to human health from bracken cannot firmly be drawn. Establishing exposure is also extremely difficult in populations (such as the United Kingdom) where direct consumption of bracken is rare. CONCLUSION: Bracken is a common plant worldwide. It is toxic to many animal species and to several organ systems. There is no tumour (or other disease) that is pathognomic of exposure in animals, though cancers of the alimentary and urogenital tract seem to be the most commonly associated. It is not possible to extrapolate from animal models to humans. Studies of human populations, do not establish a clear risk of bracken to human health, largely because of methodological problems. Testing the evidence against traditional criteria of causality only fulfils the criterion of biological plausibility. Despite this, current public information implies a serious risk to human health from bracken, and increasing media coverage of the subject is likely to lead to greater public concern. Further epidemiological studies are required.
Polioencephalomalacia (PEM) was induced in sheep, with an overall incidence of 63 per cent, using local bracken fern (Pteridium esculentum) rhizomes as a source of thiaminase type 1 and pyridine as a basic cosubstrate. The condition was thiamin responsive and PEM was confirmed by histopathological examination. In a separate experiment to examine the effect of pyridine, it was shown that, for the duration of the experiment, pyridine had no toxic effect and caused no histologically detectable brain lesions.
The precise aetiology of enzootic haematuria in cattle remains unknown. The involvement of bracken fern (Pteridium aquilinium) appears certain because of the close association between bracken fern infested farms and enzootic haematuria. Several toxic principles have been identified but the main carcinogenic element remains to be conclusively demonstrated. More recently, bovine papilloma virus has been implicated in the aetiology of enzootic haematuria. Its possible interaction with bracken fern carcinogen is discussed.
Physiological parameters affecting reactivated ciliary beat in spermatozoids of braken fern (Pteridium aquilinum) were studied using a Triton/glycerol permeabilized cell model system. Reactivation frequencies of polylysine-tethered cells equalled in vivo rates at neutral pH. Frequency was dependent on ATP and Mg2+ concentration, and reactivation was inhibited by millimolar or greater free calcium. Reactivation was reversibly inhibited by micromolar concentrations of sodium ortho-vanadate, while intact cells were not affected by millimolar levels of the inhibitor. This is the first characterization of in vitro ciliary beat in a non-algal plant cell and demonstrates that the nucleotide and ionic requirements for reactivation of bracken cilia are similar to those of other systems.
Bovine urinary bladder tumors occur frequently in animals suffering from chronic enzootic hematuria because of prolonged ingestion of bracken fern (Pteridium spp.). Cyclooxygenase (COX) genes (COX-1 and COX-2) are known to be involved in the carcinogenesis of human and some animal urothelial tumors. The aim of the present study was to investigate COX-1 and COX-2 expression by immunohistochemical methods in 20 bovine urothelial carcinomas collected at public slaughterhouses from cows that had been suffering from chronic enzootic hematuria. COX-1 immunostaining was identified intracytoplasmically in normal urothelium and in 15 of 20 neoplastic specimens. COX-1 immunosignal in the tumor cells was either absent or weak. COX-2 was also expressed intracytoplasmically in 17 of 20 urothelial carcinomas. Moderate to intense COX-2 labeling was detected in both noninvasive and invasive urothelial carcinomas. Coexpression of both enzyme isoforms was also revealed by confocal laser scanning microscopic investigations. This study indicates that COX-2 is overexpressed in naturally occurring urothelial carcinomas of cows.
Ptaquiloside (PTA) is a well-known toxin produced by the bracken fern (Pteridium aquilinum (L.) Kuhn). It is proposed that PTA from bracken stands can leach through soil and sediments into drinking-water reservoirs, thus representing a concern for human health. To predict the persistence of the toxin, a full understanding of the PTA degradation in aqueous environments is important. The kinetics of PTA hydrolysis was examined at 22 degrees C in aqueous buffered solutions (pH 2.88-8.93). The reaction was found to follow first-order kinetics with respect to PTA at all pH and temperature conditions. At pH lower than 4.43 (+/- 0.32), the reaction is acid-mediated, whereas the reaction is base-mediated at pH higher than 6.39 (+/- 0.28). The rate constants for the acid-catalyzed, base-catalyzed, and neutral hydrolysis are 25.70 (+/- 0.96), 4.83 (+/- 0.03) X 10(4), and 9.49 (+/- 6.02) x 10(-4) h(-1), respectively. The PTA hydrolysis at pH 4.46 is strongly dependent on temperature, with an activation energy of 74.4 (+/- 2.6) kJ mol(-1). Stoichiometric calculations, reaction kinetics, and ultraviolet-visible spectrophotometry strongly indicates the formation of an intermediary compound at pH 5.07 and 6.07 via a mechanism comprising two first-order consecutive reactions. Ptaquiloside has the lowest rate of hydrolysis at slightly acidic pH and low temperatures. Therefore, because PTA is not sorbed in soil, slightly acidic sandy soils in cold climates are most prone to PTA leaching to deeper soil layers and aquifers.
Two glucosides to enhance histamine release from rat peritoneal mast cells were isolated from rhizomes of bracken fern (Pteridium aquilinum (L.) Kuhn) by column chromatography on Sephadex LH-20 and droplet counter-current chromatography, and named braxin A1 and A2. They were beta-glucopyranosides with an aromatic structure in the aglycone moiety. They were appreciably unstable in activity and chemical structure, and were different from the active glucoside in the young fronds. Braxin A1 and A2 may well be identical with the toxic principles responsible for the bracken poisoning.
The complex taxon embraced in the Pteridium genus, popularly known as bracken fern and notorious weeds in many parts of the world, is one of the few vascular plants known to induce cancer naturally in animals. It has been known for long to be acutely toxic to livestock and sublethal chronic oral feeding of bracken fronds leads to cancerous lesions in the urinary bladder, or bovine enzootic haematuria (BEH) and ileum of cattle. Bracken poisoning has been attributed chiefly to ptaquiloside, a norsesqui-terpene which is also a potent carcinogen inducing various malignancies in laboratory animals. It is capable of alkylating uncoiled DNAbases at key proto-oncogenes of selected organs. Some human populations also eat young bracken shoots and epidemiological studies in Japan and Brazil have shown a close association between bracken consumption and cancers of the upper alimentary tract. In addition, other studies reveal that the mere presence of bracken swards represents a greater risk to die of gastric adenocarcinoma for people who live more than 20 years in such areas or are exposed in childhood. This work reviews the bracken-cancer connections established by in vitro and in vivo experiments and epidemiological studies in various parts of the world, and provides insights into the possible bridges for bracken carcinogens to reach the human diet. Also, specific points where more research is needed are highlighted.
The carcinogenicity of bracken fern, Pteridium aquilinum, was demonstrated most clearly by the experiment of Evans and Mason in 1965. We have performed fractionation of the aqueous extract by means of the assay based on carcinogenicity and isolated an unstable norsesquiterpene glucoside of illudane type named ptaquiloside (PT). It was proved that PT is the carcinogenic principle present in bracken fern, inducing mammary cancer and multiple ileal tumors in high incidences when given orally to female Sprague-Dawley rats. The present review article deals with the explanation of carcinogenicity of bracken fern, progress in separation of carcinogenic fraction, isolation of PT, and its carcinogenic activity in rats.
Diacylglyceryl-N,N,N-trimethylhomoserine (DGTS) belongs to a family of three known betaine lipids. It is synthesized by a number of bacteria, fungi, brown, red and green algae, in addition to lichens, and is also found in higher plants Bryophyta, Equisetophyta and Polydiophyta. It has been determined that DGTS plants can be DGTS-positive or DGTS-negative. The purpose of the present study was to examine the leaves of the ferns Drytopteris filix-mas (L.) Tod. and Pteridium aquilinum (L.) Kuhn, collected at different time periods during a single vegetation season for their DGTS contents. The results obtained show that amounts of DGTS in all of the species examined varies relative to the time periods in which they were collected.
It is reported of botanical intoxications in 1379 ruminants (dairy cattle, beef cattle and ewes) in north-eastern Germany. The intoxications of these animals were caused by consumption of the following plants: meadow saffron (Colchicum autumnale L.), cowbane (Cicuta virosa L.), sweet clover (Melilotus alba MED.), sheep's sorrel (Rumex acetosella L.), bracken (Pteridium aquilinum KUHN) and St. John's wort (Hypericum perforatum L.). In all the five described cases animals died as a result of plant intoxications. The authors come to the conclusion that periodical inspections of the meadows are necessary, checking the plants in cooperation with veterinary surgeons.
During our investigations of the micro flora in NRW in the years of 1999 and 2000 we were able to collect and identify some new and rare species of micro fungi as parasites and saprophytes on wild and ornamental plants. Some of them are new for Germany: Podosphaera xanthii on Coreopsis verticillata; Cercospora traversiana on Trigonella foenum-graecum; Passalora dubia on Atriplex hortensis; Ophiobolus cirsii on Carduus spec.; Periconia britannica on Polemonium coeruleum; Ascochyta leptospora on Agropyron repens; Apomelasmia urticae on Urtica dioica; Cryptodiaporthe salicina on Salix caprea; Dasyscyphus nidulus on Anemone hupehensis; Rhopographus filicinus on Pteridium aquilinum; Sillia ferruginea on Corylus avellana; Sirococcus spiraeae on Spiraea spec. and Forsythia x intermedia. Examples of these findings are in the Herbarium ESS (Mycotheca Parva, Slg. Feige/Ale-Agha).
The present knowledge of the risks of exposure to bracken fern (Pteridium aquilinum) is presented. The history of research on bracken toxicity is reviewed, covering the animal observations and chemical analysis, and focusing on the carcinogenic effects in various animal species and on the nature and biological properties of the known carcinogens. The implications of human exposure to bracken are inferred, the possible ways of contamination are discussed, and the existing epidemiological studies are commented. Bracken contribution to digestive tract tumors is deduced, and the need of further research on the plant toxicity and detailed epidemiological investigations with the exposed population is stressed.
Various food products of plant origin were investigated for the occurrence of natural mutagens using the Salmonella/microsome assay. In general, food plants were freeze-dried and subsequently extracted with a number of solvents. Solvents were evaporated and the residues obtained were tested for mutagenicity. In addition to S9-mix, gut flora extracts were applied for metabolic activation. From bracken fern (Pteridium aquilinum) a novel mutagen, designated Aquilide A, was isolated and its chemical structure was identified. Aquilide A requires activation to become mutagenic. This activation occurs spontaneously at pH levels above 6-7. Activated Aquilide A was found to be genotoxic in cultured mammalian cells. Natural mutagens were detected in 4 out of 6 vegetables investigated. In addition, broad beans (Vicia faba) were found to be mutagenic after treatment with nitrite. All mutagenic vegetables showed marked intercultivar variations. From lettuce and string beans quercetin was isolated (after chemical hydrolysis) and in rhubarb emodin, an anthraquinon, was detected. The mutagenic activity of these two compounds was further investigated using cultured mammalian cells. Quercetin and emodin responded negative or weakly positive in the systems applied. The genotoxic properties of a number of pyrrolizidin alkaloids, which are reported to occur in various flowering plants and as a result occur in honey and some herbal preparations, were studied using a cocultivation system of V79 Chinese hamster cells and primary cultures of chick embryo hepatocytes (PCCEH/V79). All four pyrrolizidine alkaloids investigated were found to be potent inducers of SCEs in this test system. Anti-mutagenic effects of butylated hydroxyanisole (BHA) and indole-3-carbinol (I3C) were detected using the PCCEH/V79 cocultivation system. This indicates that the cocultivation system described can be a valuable tool for the screening of various products for potential anti-carcinogenic properties. Extracts of lettuce and string beans, and a number of natural chemicals were found to reduce the mutagenic activity of cigarette smoke condensate and benzo (a) pyrene (BaP) as detected in the Salmonella/microsome assay. Intercultivar variation with respect to the antimutagenic activity observed was less pronounced than the variation noted for the mutagenic activity of these vegetables. Measures which may result in a reduction of the exposure to a number of natural mutagens are discussed.
Tumours of the urinary bladder are uncommon in all domestic animals except cattle in certain regions. Where cattle eat bracken (Pteridium aquilinum) there is a high incidence of these tumours. Epithelial tumours are the most frequently encountered neoplasms in cattle and in dogs-the two species most studied. They are described under the following names: papilloma, adenoma, transitional cell carcinoma (with variants), squamous cell carcinoma, adenocarcinoma, and undifferentiated carcinoma.
The isolation and chemical characterisation of compounds not previously reported from bracken fern (Pteridium aquilinum L Kuhn) are described. They occurred in fractions derived from the plant which have been shown to be carcinogenic in mice. Known properties of structural analogues could have implications concerning initiation of tumour formation.