Comparative Analysis of Ursolic and Oleanolic Acids in Eleven Epilobium Species

Abstract

A comparative analysis of pentacyclic triterpenoids (ursolic acid and oleanolic acid) in the aerial parts of eleven Epilobium species was performed using high-performance liquid chromatography (HPLC) results. Samples for the analysis were collected from various regions in Ukraine, Poland and Lithuania. Oleanolic acid and ursolic acid were identified and quantified in nine of the species (E. angustifolium, E. montanum, E. collinum, E. roseum, E. palustre, E. tetragonum, E. obscurum, E. nervosum, and E. nutans). However, neither compound was detected in E. parviflorum or E. hirsutum from any collection site, indicating notable chemotaxonomic divergence within the genus. The quantity of ursolic acid in the analysed samples ranged from 20.27 ± 0.49 to 74.84 ± 2.24 mg/100 g dry weight, consistently exceeding that of oleanolic acid (2.03 ± 0.05 to 32.09 ± 0.73 mg/100 g). The highest total triterpenoid content was observed in E. tetragonum. These findings emphasise the importance of oleanolic and ursolic acids as auxiliary chemotaxonomic markers for Epilobium species. Given the well-documented antiproliferative and antiviral activities of these triterpenoids, the present results also suggest that several under-explored Epilobium species could be a promising source of bioactive compounds for further pharmacological research, particularly regarding prostate cancer and viral infections.