Norsesquiterpene Glycosides in Bracken Ferns (Pteridium esculentum and Pteridium aquilinum subsp.wightianum) from Eastern Australia: Reassessed Poisoning Risk to Animals

Abstract

Austral bracken Pteridium esculentum contains three unstable norsesquiterpene glycosides: ptaquiloside, ptesculentoside, and caudatoside, in variable proportions. The concentration of each of the glycosides was determined in this study as their respective degradation products, pterosin B, pterosin G and pterosin A, by HPLC-UV analysis. Samples of P. esculentum collected from six sites in eastern Australia contained up to 17 mg of total glycoside/g DW, with both ptaquiloside and ptesculentoside present as major components accompanied by smaller amounts of caudatoside. Ratios of ptaquiloside to ptesculentoside varied from 1:3 to 4:3, but in all Australian samples ptesculentoside was a significant component. This profile differed substantially from that of P. esculentum from New Zealand, which contained only small amounts of both ptesculentoside and caudatoside, with ptaquiloside as the dominant component. A similar profile with ptaquiloside as the dominant glycoside was obtained for Pteridium aquilinum subsp. wightianum (previously P. revolutum ) from northern Queensland and also P. aquilinum from European sources. Ptesculentoside has chemical reactivity similar to that of ptaquiloside and presumably biological activity similar to that of this potent carcinogen. The presence of this additional reactive glycoside in Australian P. esculentum implies greater toxicity for consuming animals than previously estimated from ptaquiloside content alone.

Volatile organic compounds in the strongly fragrant fern genus Melpomene (Polypodiaceae)

“…Bearing these limitations in mind, the number of VOCs found in our six study species (22-33) was comparable to those recorded in other fern species analysed to date (Briggs & Sutherland 1947;Juliani et al 2004;Cheng & Mao 2005;Naseri et al 2006;Miyazawa et al 2007;Radulovi c et al 2008;Imbiscuso et al 2009;Fons et al 2010;Fletcher et al 2011). More direct comparisons are hampered by methodological differences in the extraction and analytical procedures in the different studies.…”

“…Chemically, these compounds belonged to fatty acid derivatives (FADs; 16 substances), aromatics (eight), Table 1. VOCs recorded in the six study species, with numbers representing percentage of amounts relative to all recorded VOCs, as well as indication of previous records of these substances among ferns (based on Briggs & Sutherland 1947;Juliani et al 2004;Cheng & Mao 2005;Naseri et al 2006;Miyazawa et al 2007;Radulovi c et al 2008;Imbiscuso et al 2009;Fons et al 2010;Fletcher et al 2011) and angiosperms (based mainly on Knudsen et al 2006). monoterpenes (ten), sesquiterpenes (one), sulphur-containing compounds (one), irregular terpenes (one) and heterocyclic aldehydes (one).…”

“…Although a number of fern species have long been known to be fragrant (already Linnaeus described the species Dryopteris fragrans (L.) Schott), there are few studies of VOCs in ferns, so far covering 26 species in the families Adiantaceae, Anemiaceae, Aspleniaceae, Athyriaceae, Blechnaceae, Dennstaedtiaceae, Dryopteridaceae, Equisetaceae, Lygodiaceae, Pteridaceae, Thelypteridaceae and Woodsiaceae (Briggs & Sutherland 1947;Juliani et al 2004;Cheng & Mao 2005;Naseri et al 2006;Miyazawa et al 2007;Radulovi c et al 2008;Imbiscuso et al 2009;Fons et al 2010Fons et al , 2013Fletcher et al 2011;Froissard et al 2011). In the only functional study to date, Imbiscuso et al (2009) showed that Pteris vittata L. reacts to herbivory by increasing the production of VOCs, in this case mostly consisting of mono-and sesquiterpenes, which are well known defence substances in plants (Par e & Tumlinson 1999;Cheng et al 2007;Mumm et al 2008).…”

A review of potential contaminants in Australian livestock feeds and proposed guidance levels for feed

“…Further detailed investigation concluded that the risk to health of persons consuming meat from livestock exposed to pyrrolizidine-containing plants in northern Australia was negligible (Fletcher et al 2011a). The risks from indospicine in meat and ptaquilosides in milk are not considered high, but are still under investigation (Fletcher et al 2011b). However, most exposure to the source plants is from grazing situations rather than from contaminated feedstuffs.…”

A DFT Study of the Conversion of Ptaquiloside, a Bracken Fern Carcinogen, to Pterosin B in Neutral and Acidic Aqueous Medium

“…In laboratory rodents, PtQ induces solid tumors in the ileum, the lung, mammary glands and the urinary bladder, in addition to severe or deadly acute intoxications in wild deer and cattle when ingesting bracken fern, an invasive plant worldwide . The transfer of PtQ and other similar illudanes from animal feed to meat and milk of exposed animals raises concerns about its impact on human health related to gastric malignancies . Brackens synthesise other closely related illudanes ( 1 b ‐ 1 g, Figure ) endowed with similar biological damaging potential.…”