Molecular mechanisms of toxicity of important food-borne phytotoxins

Abstract

At present, there is an increasing interest for plant ingredients and their use in drugs, for teas, or in food supplements. The present review describes the nature and mechanism of action of the phytochemicals presently receiving increased attention in the field of food toxicology. This relates to compounds including aristolochic acids, pyrrolizidine alkaloids, beta-carotene, coumarin, the alkenylbenzenes safrole, methyleugenol and estragole, ephedrine alkaloids and synephrine, kavalactones, anisatin, St. John's wort ingredients, cyanogenic glycosides, solanine and chaconine, thujone, and glycyrrhizinic acid. It can be concluded that several of these phytotoxins cause concern, because of their bioactivation to reactive alkylating intermediates that are able to react with cellular macromolecules causing cellular toxicity, and, upon their reaction with DNA, genotoxicity resulting in tumors. Another group of the phytotoxins presented is active without the requirement for bioactivation and, in most cases, these compounds appear to act as neurotoxins interacting with one of the neurotransmitter systems. Altogether, the examples presented illustrate that natural does not equal safe and that in modern society adverse health effects, upon either acute or chronic exposure to phytochemicals, can occur as a result of use of plant- or herb-based foods, teas, or other extracts.

Enforcement of the ban on aristolochic acids in Chinese traditional herbal preparations on the Dutch market

“…In Hong Kong cases of herb-induced aconitine poisonings are treated almost every year [34]. Also several herbs were sampled that are known to contain pyrrolizidine alkaloids (PAs), which are mutagenic and carcinogenic hepatotox-icants [12]. The pyrrolizidine alkaloid containing herbs are Zi Cao (Arnebia euchroma and Lithospermum erythrorhizon), Kuang Dong Hua (Tussilago farfara) and Pei Lan (Eupatorium fortunei) [35].…”

“…The resulting ultimate carcinogenic species is able to form adducts with DNA, which in turn can cause mutations and neoplastic changes [5,11]. We recently reviewed the toxic action of AA in some detail [12].…”

Coumarins — An Important Class of Phytochemicals

“…Venugopala et al (2013) presented several coumarins displaying activities such as antiinflammatory, anticoagulant, antibacterial, antifungal, antiviral, anticancer, anti-hypertensive, antitubercular, anticonvulsant, anti-adipogenic, Cytochrome P450 inhibiting, anti-hyperglycemic, antioxidant, and neuroprotective. Several recent reviews summarize and highlight advances in the application of coumarins, especially concerning their antioxidant and anticancer properties [62][63][64][65][66][67][68][69][70].From Calophyllum spp., it is remarkable the antiviral activity of calanolides and other related pyranocoumarins on Epstein-Barr virus and HIV [56]. As active compound of molluscicidal effects on Biomphalaria glabrata of C. brasiliense extracts were determined (-) mammea A/BB, also found in C. Verticillatum [71].…”

Scientific Opinion on the risks for human and animal health related to the presence of modified forms of certain mycotoxins in food and feed

“…Basically the same behaviour might be expected from acyl glucuronides and acyl glucosides of mycotoxins bearing carboxyl groups, such as ochratoxin A and citrinin, but acyl conjugates of mycotoxins have not been reported to date. Formation of sulphates is a well-known metabolic activation pathway of allylic alcohols (such as 1'-hydroxy-safrole, Figure 6), because the sulphate ion is a good leaving group and favors formation of electrophilic carbocations (Rietjens et al, 2005).…”