Contribution of oenothein B in the anti-inflammatory activity of Epilobium sp. extracts

The Epilobium species (E. angustifolium, E. hirsutum and E. parviflorum) are traditionaly used in medicine for benign prostate hyperplasia (PBH) and related urination problems. Extracts from them exert anti-inflammatory, antiseptic and antioxidant activity [1, 2, 3]. Although, there are papers supporting those effects, there is no much informations about the phytochemical and biological comparison between the most often used species.

The aim of our studies was to investigate the anti-inflammatory activity of extracts of the three most popular species and to determine the main compounds present in the different extracts, in order to determine those responsible for the observed effects.

We used lipoxygenase and hyaluronidase in vitro models for the evaluation of the biological activity of hydrophilic extracts of E. angustifolium, E. hirsutum and E.parviflorum herbs. Then using chromatographic methods (HPLC-DAD and TLC) we separated and identified the main compounds from each extract.

All tested extracts, at concentration of 100–3.125µg/ml, showed significant inhibition of both enzymes activity in dose depend maner. The 50% inhibition of enzymes activity showed that hyaluronidase was affected to the greatest extent with IC₅₀ at the level of few µg/ml. Phytochemical analysis revealed that E. hirsutum is the richest in flavonoids and E. parviflorum in oenothein B. Quercetin glucuronide, myricetin rhamnoside and oenothein B were found to be responsible for lipoxygenase inhibition with IC₅₀ reaching 67µM, 54µM and 15µM respectively. The hyaluronidase activity was inhibited only by oenothein B with IC₅₀ as low as 1.1µM. The activity of the extracts partly correlated with the oenothein B content.

References: 1 Hiermann, A. et al. (1991) Planta Med. 57: 3573. 2. Battinelli, L. et al. (2001) Farmaco 56: 345. 3 Shikov, A.N. et al. (2006)J Agric. Food Chem. 54: 3617