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

Abstract

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.

Health and Environmental Hazards of the Toxic Pteridium aquilinum (L.) Kuhn (Bracken Fern)

“…The norsesquiterpene glycoside ptaquiloside has been extensively investigated for its potential carcinogenic properties [ 1 , 102 , 103 , 104 , 105 ]. Ingesting large quantities or prolonged consumption of ptaquiloside can be toxic to humans, emphasizing the need for caution when considering the edibility of bracken fern.…”

“…Guinea pigs, unlike rats or mice, exhibit hemorrhagic cystitis and hematuria upon subcutaneous administration of ptaquiloside [ 110 ]. It has been suggested that ptaquiloside accounts for more than half of the mutagenic potency associated with bracken [ 1 , 102 , 105 ]. Although a comprehensive modern carcinogenicity bioassay of ptaquiloside is lacking, limited studies in rats have explored its carcinogenicity.…”

“…These pterosins enter the bloodstream and are transported to the liver, where a series of enzymatic reactions, involving glucosidases, cytochrome P450 enzymes, sulfotransferases, and glucuronosyltransferases, metabolize the breakdown products. This process enhances water solubility, facilitating excretion, typically through urine [ 102 , 127 , 128 , 129 ].…”

“…These alkylated DNA by-products play a crucial role in carcinogenesis, as they introduce mutations and aberrations, leading to the development of cancers. Importantly, if the ptaquiloside molecule degrades to pterosin B, these harmful consequences are averted [ 102 , 132 , 133 ].…”

Risk Assessment and Risk Reduction of Ptaquiloside in Bracken Fern

“…PTA is observed in the whole tissue of BF, low in roots and spores, and high in edible parts, crosiers [ 21 , 22 ]. Fortunately, PTA is degraded to a stable form by hydrothermal methods [ 23 , 24 , 25 ] and is expected to exhibit reduced toxicity.…”