Toxicological and medicinal aspects of the most frequent fern species, pteridium aquilinum (L.) kuhn

Abstract

Bracken fern, Pteridium aquilinum (L.) Kuhn, is not only a worldwide distributed aggressive weed species, but it has great toxicological-eco-toxicological importance in medicine and veterinary medicine, based on its characteristic chemical composition. The plant has different secondary plant metabolites of potentially high biological activities. Compounds of anti-thiamine character (thiaminase and thermostable other molecules) can cause vitamin B1 deficiencies (first of all in monogastric animals). Bracken fern has a cyanogenetic potential, through occurrence of cyanogen glycoside prunasin. This cyanogen compound has a protective role (against insects) in its life but found low contents do not indicate an actual possibility of poisoning in higher animals or in humans. Compounds of illudane skeleton (ptaquiloside and its derivatives) are the most problematic components. Ptaquiloside (=PT) belongs to glycosides of norsesquiterpene type and the plant organs (rhizome, roots, fronds and spores) contain it in greatly different concentrations. The ruminants (mainly the cattle) have distinct syndromes caused by PT: (a) The bovine enzootic haemature (BEH): a worldwide distributed syndrome (bleedings, later different epithelial and mesenchymal tumours / bladder /characteristic biochemical parameters in blood and urine) (b) Acute haemorrhagic disease: the bracken plants raise damages of bone marrow (as consequences: abnormal low number of platelets, haemorrhagic symptoms, etc. and finally fatal end are produced) (c) Bright blindness: a progressive retinal atrophy of sheep (extremely rare of cattle) Human problems: There is a significant correlation between the occurrence of different cancer forms (oesophageal, gastric and others) and bracken consumption. The milk of animals fed bracken containing forage (hay) can unfortunately transport PT to human organism, causing carcinogenesis. Carcinogen action of PT on animal or human organisms is based on production of an unstable dienon intermediate (via hydrolysis), which can form covalent adduct of DNA. The modified structures of certain bases can lead to different genetic mutations; these are the basis of the carcinogenesis. PT is measurable not only in bracken plant but in underlying litter and soil layers as well as in ground water. These new data call our attention to the importance of better understanding of possibly fate (transport, stability or instability) of carcinogen PT in our ecosystem. The bracken fern suggest authentic interdisciplinary problems.