Pharmacological properties of fireweed (Epilobium angustifolium L.) and bioavailability of ellagitannins. A review

Abstract

SummaryFireweed (Epilobium angustifolium L.) is a well-known medicinal plant traditionally used in the treatment of urogenital diseases, stomach and liver disorders, skin problems, etc. E. angustifolium extracts show anti-androgenic, antiproliferative, cytotoxic, antioxidant, anti-inflammatory, immunomodulatory, and antimicrobial activities. The unique combination of biological properties demonstrated by the results of some studies indicates that fireweed has a positive effect in benign prostatic hyperplasia (BPH) and potentially in the prostate cancer chemoprevention. However, the efficacy of E. angustifolium phytotherapy is still poorly tested in clinical trials, while numerous beneficial effects of extracts have been documented in the in vitro and in vivo tests. Fireweed is rich in polyphenolic compounds, particularly ellagitannins. Currently, polyphenols are considered to be modulators of beneficial gut microbiota. The literature data support the use of ellagitannins in the prostate cancer chemoprevention, but caution is advised due to the highly variable production of urolithins by the individual microbiota. A better understanding of the microbiota’s role and the mechanisms of its action are crucial for an optimal therapeutic effect. This paper aims to summarize and discuss experimental data concerning pharmacological properties of E. angustifolium and bioavailability of ellagitannins – important bioactive compounds of this plant.

Bacterial Cellulose Membrane Containing Epilobium angustifolium L. Extract as a Promising Material for the Topical Delivery of Antioxidants to the Skin

“…E. angustifolium has been used for a long time in folk medicine as an herb supporting the treatment of skin infections [35]. This plant is characterized by high antioxidant activity and contains many valuable compounds, including phenolic acids [31,41]. It is worth mentioning that these compounds penetrated to human skin from the ethanolic extract of this plant, as we demonstrated in our previous study [42].…”

Treatment of Benign Prostatic Hyperplasia by Natural Drugs

“…Nevertheless, preclinical studies reported anti-inflammatory, antioxidative, anti-proliferative, antimicrobial, analgesic, and antiandrogenic activities of the extract [ 70 , 71 ]. Review articles summarized the biological activities of E. angustifolium, including the above-mentioned ones besides cytotoxic, immunomodulatory, photoprotective, anti-ulcer properties, and emphasizing its importance in BPH treatment and prostate cancer prevention [ 72 , 73 , 74 ]. A recent assessment was also made about the wound healing properties of Epilobium species due to its anti-hyaluronidase, anti-collagenase, and antioxidant activities [ 75 ].…”

“…In general, polyphenols are thought to be responsible for the effects of Epilobium extracts. Ellagitannins are metabolized by the gut microbiota resulting in anti-inflammatory urolithins [ 72 , 76 ]. Oenothein B, a macrocyclic ellagitannin, seems to be at least one of the major bioactive compounds of Epilobium species due to its antioxidant, anti-inflammatory, enzyme inhibitory, antitumor, antimicrobial, and immunomodulatory activity described in several preclinical studies [ 77 ].…”

“…Oenothein B, a macrocyclic ellagitannin, seems to be at least one of the major bioactive compounds of Epilobium species due to its antioxidant, anti-inflammatory, enzyme inhibitory, antitumor, antimicrobial, and immunomodulatory activity described in several preclinical studies [ 77 ]. Due to its large molecular size and relatively high polarity, the bioavailability of oenothein B is very poor, similarly to other ellagitannins, but in contrast to them, oenothein B is not metabolized by the human gut microbiota, and its metabolic pathway is still unknown [ 72 , 123 , 124 ]. In addition, recent studies suggest that catechin and epicatechin (flavonoids) can have a major role in prostatitis related effects of E. angustifolium due to their COX-2 inhibition [ 125 ], while quercetin, myricetin, and myricitrin, in the case of E. parviflorum in cancer therapy [ 126 ], based on molecular docking analysis.…”

“…Anti-inflammatory, antioxidative, anti-proliferative, antimicrobial, analgesic, anti-androgenic activities [ 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 ]…”