Passage of the bracken fern carcinogen ptaquiloside into bovine milk

Abstract

Summary -Ptaquiloside has been discovered for the first time in milk samples 01 a bovine fed a dietary complement (6 kg fresh weighVday) of freshly-eut bracken fronds. This was equivalent to ca 216 mg/day pure ptaquiloside. The compound was found in a quantity of no less than 0.11 mg/I in milk. This was determined by the appearance of pterosin 6 -the decomposition product of ptaquiloside -in prepurified milk sampi es treated with milg 1I1kllii (pH 8.0 and 11.5). The lack of base treatment led to the absence of pterosin B. A mi!k j}rilpurlflcatlon protocol based on meth,anol-acetonitrile precipitations in succession, hexllne and dlchloromethane extractions, alkaline treatment, reextraction and silica gel microcolumn chromatography followed by reverse-phase HPLC was developed for the detection 01 ptaquiloside.bracken 1Pterldlum aqulllnum 1mllk 1ptaqulloslde 1human cancer 1HPLC

Excretion, through milk, of ptaquiloside in bracken-fed cows. A quantitative assessment

“…The passage of the evaporated organic phase through a microcolumn of silica gel secured the quantitative conversion of unstable ptaq and the dienone derived therefrom into pterosin B [2]. HPLC of this material with detection at 260 nm allowed the more sensitive quantitation ofpterosin Band therefore, of ptaq present in each milk sample by conversion of the molecular weight, as described earlier [4]. In no case was pterosin B detected as such in milk without previous treatment with alkali.…”

“…and higher [13]. Recently we discovered another plant xenobiotic in milk, namely ptaquiloside, from cows exposed to dietary complements of bracken Pteridium aquilinum [4,5].…”

“…It was hypothesized that ptaq was transferred through milk to calves and possibly humans from bracken-fed lactating cows [53,54]. The development of a method for detecting ptaq in milk by its quantitative transformation into pterosin B followed by HPLC separation [4], allowed for the first time the identification of moderate amounts of ptaq in milk from cows that had eaten bracken; however, these quantities could notjustify the dramatic effects reported earlier.…”

Naturally Occurring Toxicants of Plant Origin

“…Cattle eat bracken fern only in absence of alternatives (draught, overgrazed or heavily infested pastures). Bracken fern is carcinogenic in several animal species (Alonso-Amelot et al, 1993, 2002IARC, 1987). In cattle it causes bovine enzootic hematuria, an ultimately lethal disease with hemorrhage from the urinary tract and multiple bladder tumors.…”

Toxicidade da samambaia (Pteridium aquilinum (L.) Kuhn) para a saúde animal e humana

“…As samambaias são o maior grupo de pteridófitas existentes no mundo atualmente (PAGE, 1976). São consideradas uma das cinco plantas mais bem sucedidas do reino vegetal (ALONSO-AMELOT et al, 1993).…”