Effects of Epilobium sp. main constituents and ellagitannins metabolites, urolitins, on proliferation and prostate specific antigen (PSA) secretion in prostate cancer cells (lncap)
Taking into consideration the pathogenesis of hormone-dependent prostate cancer and application of Epilobium sp. extracts in traditional medicine in the treatment of prostate ailments, we have investigated and compared the activity of individual main Epilobium constituent (oenothein B, quercetin-3-O-glucuronide and myricetin-3-O-rhamnoside) on hormone-dependent prostate cancer cells (LNCaP) proliferation and prostate specific antigen (PSA) secretion. Due to high quantity of oenothein B in Epilobium sp. and the information from the literature about ellagitannins metabolites , we have examined the in vitro formation of urolithins from Epilobium hirsutum herb extract, rich in oenothein B, by human gut microbiota.
The impact of urolithins on LNCaP cells has been also determined. Cell proliferation was measured using MTT and bisbenzimide (Hoechst 33258). PSA secretion was quantified by ELISA assays. Flutamid was used as positive control.
Selected constituents were proven to be active in relation to LNCaP cells. However oenothein B was the strongest inhibitor of cells proliferation (IC50= 7.8 ± 0.8µM) and PSA secretion (IC50= 21.9 ± 3.2µM). Additionally, ellagitannins from E. hirustum extract was proven to be transformed by human gut microbiota into urolithins A-C. Urolithin C showed the strongest activity in the inhibition of cell proliferation (IC50= 35.2 ± 3.7µM), PSA secretion (reduced secretion from 325.6 ± 25.3 ng/ml to the level of 100.7 ± 31.0 ng/ml). Oenothein B content seems to be an important quality marker of Epilobium species but its active metabolites, urolithins, together with other extracts' constituents, may also determine the biological activity of these plant materials. Our results partly confirm the use of Epilobium sp. herbs in the treatment of prostate diseases.
 Seeram et al. 2006. J Nutr 136: 2481 – 2485.