Ptaquiloside

Ptaquiloside, 1, a norsesquiterpenoid glucoside, is the major carcinogen of bracken detected in the food chain, particularly in the milk from farm animals. Ptaquiloside has been shown in the milk of cows feeding on a diet containing bracken fern.

Bracken fern (Pteridium sp.) is a plant with invasive potential, and ingestion can cause chronic illness and cancers in farm animals. Bracken is a suspected human carcinogen, and exposures can result from ingestion of bracken-contaminated water, dairy products, or meat derived from livestock grazing on bracken fern. Bracken is also consumed in the diets of some communities. Ptaquiloside (PTQ) is a known bracken carcinogen. It is an illudane-type glycoside that forms a highly reactive electrophile, PTQ dienone, known to produce N7-guanine and N3-adenine adducts in DNA.

Bracken fern is a highly problematic plant worldwide due to its toxicity in combination with invasive properties on former farmland, in deforested areas and on disturbed natural habitats. The carcinogenic potential of bracken ferns has been of concern for several decades. Its genotoxic effects are linked to illudane-type glycosides (ITGs), their aglycons and derivatives. Ptaquiloside is considered the dominating ITG, but with significant contributions from other ITGs. The ITG content in bracken fern exhibits substantial spatial, temporal, and chemotaxonomic variation. Consumption of bracken fern as food is linked to human gastric cancer but it also causes urinary bladder cancers in bovines browsing on bracken. Genotoxic metabolites are found in milk and meat from bracken fed animals. ITG exposure may also take place via contaminated water with recent data pointing to concentrations at microgram/L-level following rain events. Airborne ITG-exposure from spores and dust has also been documented.

This study was conducted to determine the optimal boiling time to reduce ptaquiloside (PTA) and to carry out a risk assessment for PTA, a representative toxic substance found in bracken fern (BF; Pteridium aquilinum), which is frequently consumed as food in East Asian countries. High-performance liquid chromatography showed that the concentration of PTA in BF was reduced by up to 99% after boiling for 20 minutes. Risk assessment results showed that the cancer margin of exposure (MOE; greater than or equal to 25,000 = safe) to PTA for an average daily exposure scenario after boiling BF for 20 min was considered safe. In addition, the non-cancer MOE (≥ 300 = safe) to PTA under an average daily exposure scenario after BF boiling for 20 min was considered safe.

Substances that increase the risk of NEOPLASMS in humans or animals. Both genotoxic chemicals, which affect DNA directly, and nongenotoxic chemicals, which induce neoplasms by other mechanism, are included.

Chemical agents that increase the rate of genetic mutation by interfering with the function of nucleic acids. A clastogen is a specific mutagen that causes breaks in chromosomes.