The Involvement of Epilobium parviflorum in Different Human Diseases, with Particular Attention to Its Antioxidant and Anti-Inflammatory Properties and Benefits to Vascular Health

Background/Objectives: Water and alcohol extracts of Epilobium have gained attention due to their high concentration of bioactive compounds and their associated health benefits. This review aimed to evaluate the effects of Epilobium parviflorum Schreb. (Onagraceae) preparations on vascular health in light of its medical applications in different human diseases over the last five years. Materials and Methods: A literature search was undertaken of databases such as PubMed/Medline, Scopus, and Google Scholar for original articles published between March 2000 and March 2025. The keywords used were “aortic rings”, “ellagitannins”, “Epilobium”, “hydrolyzable tannins”, “hypotension”, “oenothein B”, “Onagraceae”, “systolic blood pressure”, “vasorelaxation”, and “willow herb”. Results: The E. parviflorum Schreb. herb has been used as a remedy in folk medicine and has a variety of therapeutic properties. These include its preventive effects and ability to relieve symptoms in patients with benign prostate hyperplasia, prostatitis, and a variety of cancers. Other properties include effects on kidney and urinary tract diseases, lipid regulation, and skin infections. The herb also has antibacterial properties. E. parviflorum contains bioactive compounds such as oenothein B, quercetin-3-O-glucuronide, and myricetin-3-O-rhamnoside. At low doses, these compounds contribute to a reduction in oxidative stress due to their antioxidant and immunostimulatory effects, positively reducing inflammation, which can cause certain conditions. At higher concentrations, Epilobium generates reactive oxygen species that stimulate the body’s defense mechanisms against a variety of cancers. The presence of oenothein B in E. parviflorum may influence the production and storage of nitric oxide, which, in turn, promotes vasodilation and regulates blood pressure. Conclusions: Although the potential application of E. parviflorum in metabolic disorders has not been extensively studied before, its antioxidant and anti-inflammatory properties are well documented and suggest potential pathways for future research and the therapeutic development of preparations to benefit vascular health.