Pyrrolizidine and tropane alkaloids in teas and the herbal teas peppermint, rooibos and chamomile in the Israeli market

Abstract

Dehydro pyrrolizidine alkaloids (dehydro PAs) are carcinogenic phytotoxins prevalent in the Boraginaceae, Asteraceae and Fabaceae families. Dehydro PAs enter the food and feed chain by co-harvesting of crops intended for human and animal consumption as well as by carry-over into animal-based products such as milk, eggs and honey. Recently the occurrence of dehydro PAs in teas and herbal teas has gained increasing attention from the EU, due to the high levels of dehydro PAs found in commercially available teas and herbal teas in Germany and Switzerland. Furthermore, several tropane alkaloids (TAs, e.g. scopolamine and hyoscyamine) intoxications due to the consumption of contaminated herbal teas were reported in the literature. The aim of the present study was to determine the dehydro PAs and TAs levels in 70 pre-packed teabags of herbal and non-herbal tea types sold in supermarkets in Israel. Chamomile, peppermint and rooibos teas contained high dehydro PAs levels in almost all samples analysed. Lower amounts were detected in black and green teas, while no dehydro PAs were found in fennel and melissa herbal teas. Total dehydro PAs concentrations in chamomile, peppermint and rooibos teas ranged from 20 to 1729 μg/kg. Except for black tea containing only mono-ester retrorsine-type dehydro PAs, all other teas and herbal teas showed mixed patterns of dehydro PA ester types, indicating a contamination by various weed species during harvesting and/or production. The TA levels per teabag were below the recommended acute reference dose; however, the positive findings of TAs in all peppermint tea samples warrant a more extensive survey. The partially high levels of dehydro PAs found in teas and herbal teas present an urgent warning letter to the regulatory authorities to perform routine quality control analysis and implement maximum residual levels for dehydro PAs.

Alkaloid profiling of herbal drugs using high resolution mass spectrometry

“…In recent years, several studies have demonstrated that a real danger is posed by Pyz alks extracted from herbs in teas and infusions . In line with previous studies, our study confirmed the migration of Pyz alks from herbs to water infusions, albeit at a lower rate compared to the potential content.…”

“…Finally, it should be emphasised that in general, people consume no more than one/two cups of herb tea/infusions per day, and that several other foods may also contain alks. As regards Pyzs, the most widely studied alks, commodities such as honey, cereals, milk, and green salads could also definitely affect our daily intake …”

“…In particular, pyrrolizidine (Pyz) alks have hepatotoxic, mutagenic, and carcinogenic effects. Pyz alks and their N‐oxide forms, mainly found in the families of the Boraginaceae (all genera), Asteraceae (Senecioneae and Eupatorieae tribes), and Fabaceae (Crotalaria genus), are composed of a core necine base condensed with one or two necic acids, but only Pyz alks with double bonding in the 1,2‐position of the Pyz ring (dehydro Pyz alks), such as retronecine‐, heliotridine‐, otonecine‐, and supinidine‐types demonstrated these effects . Some Pyz alks are absorbed from the intestine and partly hydrolysed by esterases in non‐toxic compounds excreted by the kidneys, but most alks are transported to the liver, where monooxygenases metabolise them into pyrrole derivatives through hydrolysis, N‐oxidation, and dehydrogenation of the Pyz ring, inducing intoxication reactions .…”

“…Following these claims, several studies have focused their attention on the alkaloid content of various plant species used for infusions. Even restricting their research to Pyz alks and Trp alks, they observed that commercial preparations may contain high amounts of alks …”

“…Even restricting their research to Pyz alks and Trp alks, they observed that commercial preparations may contain high amounts of alks. 10,16,17 The toxicity of other groups such as quinolizidine (Qnz) alks and glycosteroid (Gst) alks has been demonstrated and evaluated in other food commodities, such as the lupin bean, potato, tomato, and eggplant, 18,19 but there have been no studies about infusion herbs. Qnz alk intoxication is characterised by trembling, shaking, excitation, and convulsions, and in more severe cases there can be acute oral toxicity due to neurological effects, leading to loss of motor co-ordination and muscular control.…”