Alkaloids pyrrolizidine ingestion

Host plants play a key role in the production and use of sex pheromones by herbivorous insects through larval or adult sequestration of chemically active compounds and pheromone precursors [210]. One of the best examples of sequestration of plant chemicals by larvae and their subsequent use by adult males in sex attraction or courtship interactions is shown in Utetheisa ornatrix (Arctiidae), whose courtship pheromone derives from pyrrolizidine alkaloids (PAs) ingested at the larval stage from the host plant Crotalaria spectabilis [211]. U. omatrix larvae sequester PAs (e.g. monocrotaline) and retain the alkaloids through metamorphosis into the adult stage to provide egg protection for the next generation. 

A dietary supplement may be safe when taken in the recommended doses but may become dangerous in higher doses. However, patients may develop side effects even when ingesting recommended doses. Adverse reactions may be due to allergic reactions, dietary supplements containing toxic substances, mis-identification of plant, mislabeling of plant, natural toxic substances such as pyrrolizidine alkaloids in comfrey, unnatural toxic substances such as heavy metals, or pesticides. 

Coltsfoot Upper respiratory tract infections Pyrrolizidine alkaloids, hepatotoxicity Avoid ingestion of any parts of plant leaves may be used topically for anti-inflammatory effects for up to 4-6 weeks... 

Comfrey (Symphytum officinale) Uses Topical treatment of wounds, bruises, sprains, inflammation Action Multiple chemical components, allantoin promotes cell division, rosmarinic acid has anti-inflammatory effects, tannin possesses astringent effects, mucilage is a demulcent w/ anti-inflammatory properties, pyrrolizidine alkaloids cause hepatotox Available forms Topical application w/ 5—20% of herb applied on intact skin for up to 10 d Contra Do not take orally d/t hepatotox, do not use if PRG or w/ lactation Notes/SE N/V, exfoliative dermatitis w/ topical use Interactions T Risk of hepatotox W/ ingestion of borage, golden ragwort, hemp, Petasites EMS None... 

Two outbreaks of human liver disease in India have been attributed to the consumption of plants containing pyrrolizidine alkaloids. In the first instance, the disease was caused by eating cereals contaminated with seeds of a Crotalaria species.56 Haemodynamic studies were carried out on eight patients suffering from the characteristic veno-occlusive disease. In the second study, two cases of sudden liver failure that are believed to be due to the ingestion of herbal concoctions made from seeds and plants of Heliotropium species are reviewed.57... 

Comfrey Symphytum species Leaves and roots Internal digestive aid, topical for wound healing Pyrrolizidine alkaloids, hepatotoxicity Avoid internal ingestion topical use should be limited to 4-6 weeks... 

Alkaloids are generally bitter, which suggests that these compounds could be utilized as either animal deterrents or in intra- or interspecific competition of plant species. In some cases repellent alkaloids (e.g., pyrrolizidine alkaloids) are sequestered by herbivores and converted to compounds that function as sex pheromones while still possessing deterrent activities. The insect derivation of sex pheromones from known repellent alkaloids that accompany the ingested nutrients... 

An even higher level of specialization is realized by those insects that are attracted by alkaloid containing plants, not for feeding but to sequester them for defense purposes. Adults of some species of the Danaidae and Ihomiinae (butterflies, Lepidoptera) have evolved this special behavior and are attracted by pyrrolizidines and ingest them frequently from dead parts of pyrrolizidine alkaloid containing... 

EHMKE, A., PROKSCH, P., WITTE, L., HARTMANN, T., Fate of ingested pyrrolizidine alkaloid V-oxide in the grasshopper Melanoplus sanguinipes. Naturwissenschaften, 1989,76,27-29. 

Whilst the N-oxidation of pyrrolizidine alkaloids is a recognized detoxifying mechanism in mammals [26], it has also been shown that ingested N-oxides are indeed toxic, presumably via in vivo reduction to the parent pyrrolizidine alkaloids... 

Chemical-induced liver injury is encountered in a variety of circumstances. Some natural toxins such as the peptides of Amanita phalloides, the pyrrolizidine alkaloids, the toxin of the cycad nut, and other plant toxins are hazards posed by the environment. Some mycotoxins are ingested unknowingly because of feed contamination due to climatic conditions favorable to fungal growth. Other circumstances of exposure to hepatotoxins include contamination of water supply with cyanobacterial toxins, which led to the tragic death of 60 patients in a hemodialysis clinic in Brazil in 1996 (Jochimsen et al, 1998). 

There are no drugs based on the pyrrolizidine alkaloids of the Asteraceae (e.g., Senecio and Symphytum) and Boraginaceae (Crotolaria). However, these alkaloids pose a great threat to human and animal health because of their potential for inadvertent consumption. In the case of 1,2-dehydro derivatives, such as senecio-nine, ingestion leads to non-reversible hepatotoxicity. Pyrrolizidine nucleus formation from two units of ornithine is shown (Fig. 24). 

Crotalaria sagittalis-. The roots of this fabaceous plant were considered to be avery strong narcotic by the Delaware-Okl Indians (lantaquic eon 1942). Dangerous hepatotoxic pyrrolizidine alkaloids are known from Crotalaria species, and their ingestion should thus be avoided assiduously (Turner Szczawinski 1991). 

Ingestion of Pyrrolizidine Alkaloids A Health Hazard of Global Proportions... 

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