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. 2025 Jan 23;14(2):117.
doi: 10.3390/antibiotics14020117.

Efficacy of Willow Herb (Epilobium angustifolium L. and E. parviflorum Schreb.) Crude and Purified Extracts and Oenothein B Against Prostatic Pathogens

Alexia Barbarossa  1 , Antonio Rosato  1 , Alessia Carocci  1 , Sabrina Arpini  2 , Stefania Bosisio  2 , Luca Pagni  2 , Diletta Piatti  3 , Eleonora Spinozzi  3 , Simone Angeloni  3 , Gianni Sagratini  3 , Gokhan Zengin  4 , Marco Cespi  3 , Filippo Maggi  3 , Giovanni Caprioli  3
Affiliations

Efficacy of Willow Herb (Epilobium angustifolium L. and E. parviflorum Schreb.) Crude and Purified Extracts and Oenothein B Against Prostatic Pathogens

Alexia Barbarossa et al. Antibiotics (Basel). .

Abstract

Background/Objectives: Plants species of the Epilobium genus are traditionally used to treat prostatitis and other urinary tract disorders and are particularly rich in ellagitannins and flavonol 3-O-glycosides. The aim of this work was to evaluate the inhibitory activity of different extracts from E. angustifolium L. and E. parviflorum Schreb. and their major bioactive compound, oenothein B, against a panel of Gram-positive (Enterococcus faecalis ATCC 29212, Enterococcus faecalis BS, Staphylococcus aureus ATCC 25923, Staphylococcus aureus ATCC 29213, and Staphylococcus aureus ATCC 43300) and Gram-negative (Escherichia coli ATCC 25922, Escherichia coli ATCC 35218, Escherichia coli BS, Klebsiella pneumoniae ATCC 13883, Klebsiella pneumoniae ATCC 70063, Klebsiella pneumoniae BS, Proteus mirabilis BS, and Pseudomonas aeruginosa ATCC 27853) bacteria responsible for prostatitis. Methods: Aqueous and ethanolic raw extracts were prepared, and the latter were further purified using the resin AmberliteTM XAD7HP. Then, an HPLC-MS/MS method was developed for the quantification of the marker bioactives and their levels were correlated with the antimicrobial activity. Results: Purified extracts were richer in polyphenols (330.80 and 367.66 mg/g of dry extract for E. angustifolium and E. parvifolium, respectively) than the raw extracts. Oenothein B was the predominant compound in all the extracts (119.98 to 327.57 mg/g of dry extract). The minimum inhibitory concentrations (MICs) in the range of µg/mL indicated significant antibacterial activity, which was higher for the purified extracts and oenothein B (MIC values from 4 to 16 and 8 to 1024 µg/mL on Gram-positive and Gram-negative strains, respectively). Conclusions: These results outline the outstanding potential of E. angustifolium and E. parviflorum extracts and oenothein B as therapeutic alternatives or complementary agents to conventional antibiotic treatments of prostatitis and other urinary tract infections.

Keywords: Epilobium angustifolium; Epilobium parviflorum; HPLC-MS/MS; gram-positive; oenothein B; prostatic pathogens.

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Conflict of interest statement

Authors Sabrina Arpini, Stefania Bosisio and Luca Pagni were employed by the company Indena S.p.A. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Overlay of all the chromatograms obtained using the extraction of the quantitative transition (dynamic-MRM) of each analyte of the standard mixture.
See this image and copyright information in PMC

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