Argemone Mexicana L. Root: A Comprehensive Review of Its Phytochemistry, Pharmacological Potential and Toxicological Aspects

Argemone mexicana L. (Papaveraceae), the Mexican prickly poppy, is a pantropical weed whose root features in Ayurvedic, African and Latin American folk medicine for infections, pain, worm infestation, poisoning and gynaecological complaints. This review gathers the published information on the root's phytochemistry, pharmacology and toxicology, and, where the literature allows, separates evidence that truly concerns the root from evidence generated with leaves, aerial parts, seeds or the whole plant. The root is dominated by benzylisoquinoline-derived alkaloids: protoberberines (berberine, coptisine), protopines (protopine, allocryptopine) and benzophenanthridines (sanguinarine, chelerythrine and their dihydro derivatives), with a total alkaloid fraction of roughly a quarter of one percent in dried root and stem material. Root extracts have shown antibacterial action that is strongest against Gram-positive organisms, growth-inhibitory effects on a human colon cancer cell line, and anti-inflammatory activity of the alkaloid fraction in rodents. The most advanced clinical work on the species, a Malian antimalarial decoction, was built on leaf material rather than root. The same alkaloids that underlie these activities, above all sanguinarine, are responsible for the severe poisoning (epidemic dropsy) that follows ingestion of edible oil adulterated with argemone seed oil, and they justify caution about unsupervised internal use of root preparations. Root-specific pharmacokinetic, dose-finding and safety data are almost absent. Standardised root extracts, validated marker compounds and well-designed toxicity studies are needed before therapeutic claims can be supported.