Pteridium aquilinum (L.) Kuhn—A Review of Its Toxicology, Pharmacology, and Phytochemistry

<i>Pteridium aquilinum</i> (L.) Kuhn, known as bracken fern, is considered a poisonous plant due to its toxic substances. This species contains toxic substances and enzymes: thiaminase and an anti-thiamine substance, which cause thiamine deficiency syndrome. Prunasin induces acute cyanide poisoning. Ptaquiloside causes haematuria, retinal atrophy, immunodeficiency, and lymphoproliferative disorders. It also induces carcinogenesis in livestock, and in animals and human cell lines. Ptaquiloside has been found in the milk of cattle, goats, and sheep that grazed on <i>P. aquilinum</i> in pastures. Ptaquiloside is water-soluble and washes away from the plants into the soil with rainwater. It has been found in streams and groundwater wells. The International Agency for Research on Cancer has classified bracken fern as a Group 2B carcinogen. However, <i>P. aquilinum</i> has long been used as a folk remedy in various regions. Several studies have identified its medicinal value and bioactive compounds with potential pharmacological activity. Pterosin B and its analogues exhibit anti-osteoarthritis, anti-Alzheimer's disease, neuroprotective, anti-cardiomyocyte hypertrophy, anti-diabetic, and smooth muscle relaxant properties. Ptaquiloside also induces apoptosis in certain human cancer cell lines and acts as an anticancer agent. Therefore, pterosins and ptaquiloside have therapeutic properties. Other compounds, including some flavonoids and polysaccharides, act as antimicrobial, antifungal, and immunomodulatory agents. Based on their structures, it is possible to develop medicines with these therapeutic properties, particularly those containing pterosins and ptaquiloside. However, more research is needed on their use in medicinal treatments.