A comprehensive review on Nepalese wild vegetable food ferns

Ferns are used as traditional and fascinating foods in many countries. They are also considered to possess important ethnomedicinal values; however, ferns are one of the underutilized plant resources by both scientific and local communities. Pharmagonostical studies reveal that ferns and fern-allies possess several biological activities including antibacterial, antiviral, antifungal, antimalarial, antidiarrheal, anthelmintic, analgesic, anti-inflammatory, antidiabetic, anticancer, neuroprotective, nephroprotective, hepatoprotective, antifertility, etc. Flavonoids and terpenoids are major secondary metabolites present in ferns. Ugonins, particularly isolated from Helminthostachys zeylanica, have found diverse bioactivities. Ptaquiloside, a norsesquiterpene glucoside, found in Pteridium revolutum, Dryopteris cochleata and Polystichum squarrosum, is one of the hazardous metabolites of ferns which is responsible for the toxic effect. Alkaloids are reported to be present in the ferns; however, the qualitative data are uncertain. Some fern metabolites, such as cyanogenic glycosides and terpenoids, are considered to possess defensive activity against animal attacks. Some ferns are also used for manuring as biological alternative to pesticides. Nepalese have consumed at least 33 species of ferns and fern-allies belonging to 13 families, 20 genera as cooked vegetable foods. The aim of this review is compilation of information available on their distribution, ethnomecinal values, pharmcognosy, pharmacology and phytochemistry.