Presence of the carcinogen ptaquiloside in fern-based food products and traditional medicine: Four cases of human exposure.

Ptaquiloside (PTA) is a natural carcinogen present in many ferns. Brackens (Pteridium sp.) contain PTA and are classified by WHO/IARC as ' … possibly carcinogenic to humans', however, these ferns are used in food, traditional medicine and as food supplements around the world. This study aimed to outline the presence of PTA in different human exposure routes by using and validating an LC-MS based protocol to test the contents of PTA in commercial products, the degradation product Pterosin B (PtB) and wild specimens from Europe, Asia and North America. The Limit of Detection of the protocol was 0.024 µg g-1 for PTA and 0.028 µg g-1 for PtB. PTA and PtB were present in most wild specimens (PTA: BD - 6300 ± 520 µg g-1; PtB: BD - 449 ± 1 µg g-1) while commercial products made from fronds, as well as fronds prepared as traditional Chinese medicine, were in the range 44 ± 3 to 666 ± 33 µg g-1 for PTA and BD to 1653 ± 184 µg g-1 for PtB. This study did not find PTA/PtB in rhizomes and products made thereof nor in homoeopathic products based on bracken. Boiling or drying bracken showed to reduce PTA some degree but cannot remove it completely. Interestingly, crosiers with no PTA/PtB were found in the USA, indicating a potential for commercial production of PTA-free fronds.

A rapid GC-FID method for determination of sabinene, ß-pinene, α-thujone and ß-thujone in the essential oil of Kitchen Sage (Salvia officinalis L.).

Terpenes and terpenoids are dominant fragrances in the essential oils of many economically important fruits and vegetables. Hence, content and variation are important factors in the evaluation and common perception of food quality. Sabinene, ß-pinene, α-thujone and ß-thujone are examples of such compounds found in the different species of Sage. Sabinene and ß-pinene are spicy compounds much used by the fragrance industry while the two thujones are highly toxic. Here, we report a rapid method for quantification of these compounds in the essential oil of Sage. The total analytical time is approx. 7,5 min in contrast to approx. 30 min for similar gas chromatographic methods. The analytical method had a linear range of 28-342 mg L-1 for the different compounds, with an analytical precision of 0,6-0,9% for standards. Correlation coefficients were 0,9993-1,0000. The Limit of Detection of all compounds were 0,02-0,9 mg L-1 and the Limit of Quantification were 0,08-3,0 mg L-1. The technique was used for quantification of the compounds in seven commercial essential Sage oils and in a pilot study of the effect of ozone on the terpenes and terpenoids in fresh Sage leaves. Large variation was observed between the different commercial samples, of which some were thujone dominant and some did not have any content of thujone at all. Treatment of fresh Sage leaves with ozone caused degradation of the terpenes sabinene and ß-pinene whereas the terpenoids α/ß-thujone were more resistant to degradation.

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.

Sorption, degradation and mobility of ptaquiloside, a carcinogenic Bracken (Pteridium sp.) constituent, in the soil environment.

Ptaquiloside (PTA) is a carcinogenic norsesquiterpene glucoside produced by Bracken in amounts up to at least 500 mg m(-2). The toxin is transferred from Bracken to the underlying soil from where it may leach to surface and groundwater's impairing the quality of drinking water. The objectives of the present study were to characterize the solubility, degradation and retention of PTA in soils in order to evaluate the risk for groundwater contamination. PTA was isolated from Bracken. The logarithmic octanol-water and ethyl acetate-water partitioning coefficients for PTA were -0.63 and -0.88, respectively, in agreement with the high water solubility of the compound. PTA hydrolysed rapidly in aqueous solution at pH 4 or lower, but was stable above pH 4. Incubation of PTA with 10 different soils at 25 degrees C showed three different first order degradation patterns: (i) rapid degradation observed for acid sandy soils with half life's ranging between 8 and 30 h decreasing with the soil content of organic matter, (ii) slow degradation in less acid sandy soils with half-lives of several days, and (iii) fast initial degradation with a concurrent solid phase-water partitioning reaction observed for non-acid, mostly clayey soils. The presence of clay silicates appears to retard the degradation of PTA, possibly through sorption. Degradation at 4 degrees C was generally of type (iii) and degradation rates were up to 800 times lower than at 25 degrees C. Sorption isotherms for the same set of soils were almost linear and generally showed very low sorption affinity with distribution coefficients in the range 0.01-0.22 l kg(-1) at a solution concentration of 1 mg l(-1) except for the most acid soil; Freundlich affinity coefficients increased linearly with clay and organic matter contents. Negligible sorption was also observed in column studies where PTA and a non-sorbing tracer showed almost coincident break-through. Leaching of PTA to the aqueous environment will be most extensive on sandy soils, having pH >4 and poor in organic matter which are exposed to high precipitation rates during cold seasons.