- Extracts of fern species (family Polypodiaceae) have been used traditionally for numerous indications, most commonly in South America and Europe.
- The South American species Polypodium leucotomos L. is commonly known as "calaguala." Extracts of this species, called "anapsos," have been marketed and used as a treatment for multiple indications. Although laboratory and animal studies have reported anti-inflammatory, cytokine-suppressing, and leukotriene inhibitory properties, the small number of available human trials have not demonstrated efficacy for any specific indication