Phenolic compounds in five Epilobium species collected from Estonia.

Epilobium species have been traditionally used as medicinal plants to treat benign prostate hyperplasia. The present study investigated the content of polyphenols, tannins, and flavonoids in Epilobium parviflorum Schreb., E. hirsutum L., E. adenocaulon Hausskn., E. montanum L., and E. palustre L. growing in Estonia. The total contents of polyphenols, tannins, and flavonoids were studied using UV spectroscopy with subsequent HPLC quantification of gallic acid, ellagic acid, and quercetin as marker compounds. All roots, stems, leaves, and flowers of the plants investigated contained comparable amounts of polyphenols, tannins, and flavonoids. There was a clear positive correlation between the contents of tannins and flavonoids in various plant parts. The content of these biologically active compounds suggests the use of E. parviflorum, E. hirsutum, E. adenocaulon, E. montanum, and E. palustre collected from Estonia as herbs both individually or as a blend.