Fireweed (Epilobium angustifolium L.): botany, phytochemistry and traditional uses. A review

Fireweed (Epilobium angustifolium L., Onagraceae) is one of important medicinal plants used especially in the treatment of urogenital disorders, including benign prostatic hyperplasia (BPH) and prostatitis. The therapeutic effects of E. angustifolium extracts comprise antiproliferative, anti-inflammatory, immunomodulatory, antioxidant, and also antimicrobial activities. The aim of the present review was to provide the information on the botany, phytochemistry and traditional uses of E. angustifolium. This plant is a widespread circumboreal species of North America and Eurasia, tolerant in terms of habitat conditions, and often occupying man-made open habitats. Phytochemical studies on E. angustifolium resulted in the identification of about 250 different metabolites, including about 170 substances found for the first time in this plant in the last six years (2014–2019). Fireweed has an abundance of polyphenolic compounds, particularly ellagitannins. Oenothein B and quercetin-3-O-glucuronide are proposed as markers for the identification and standardization of the plant raw material. E. angustifolium exhibits significant phytochemical variability in relation to the geographical origin, plant part and time of harvest/vegetation phase. Survey of the ethnobotanical literature showed that the above-mentioned species has been widely used not only as a medicinal, but also as an edible, honey and decorative plant.