Exploring the Phytochemical Profile and Biological Insights of Epilobium angustifolium L. Herb

The aerial parts of Epilobium angustifolium L. (fireweed) (Onagraceae) are renowned for their use in the treatment of prostatic, kidney and urinary tract diseases, and skin infections. In this work, a comprehensive phytochemical profiling of the methanol-aqueous extract from E. anfustifolium aerial parts was performed by the means of liquid chromatography–Orbitrap high-resolution mass spectrometry. Annotation and dereplication of 121 secondary metabolites were achieved, including acylquinic acids, gallo- and ellagitannins, flavonoids, phenolic acids, and their glycosides. Forty-six compounds are reported for the first time in the species. Total phenolic and flavonoid content were 85.04 ± 0.18 mg GAE/g and 27.71 ± 0.74 mg QE/g, respectively. Antioxidant capacity assessment revealed that the extract actively scavenged DPPH and ABTS radicals (310.74 and 466.82 mg TE/g) along with a high reducing power in CUPRAC and FRAP assay (442.83 and 291.50 mg TE/g), respectively, and metal chelating (48.20 mg EDTA/g). The extract also had a distinct impact on α-glucosidase (3.48 mmol ACAE/g) and moderate activity towards α-amylase (0.44 mmol ACAE/g) and lipase (8.03 OE/g). It inhibited acetyl- and butyrylcholinesterase (2.05 and 1.67 mg GALE/g) and had a prominent anti-tyrosinase effect (61.91 mg KA/g). Our results contribute to establishing fireweed as a multifunctional agent for use in herbal preparations.