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

: Plants species of the genus are traditionally used to treat prostatitis and other urinary tract disorders and are particularly rich in ellagitannins and flavonol 3--glycosides. The aim of this work was to evaluate the inhibitory activity of different extracts from L. and Schreb. and their major bioactive compound, oenothein B, against a panel of Gram-positive ( ATCC 29212, BS, ATCC 25923, ATCC 29213, and ATCC 43300) and Gram-negative ( ATCC 25922, ATCC 35218, BS, ATCC 13883, ATCC 70063, BS, BS, and ATCC 27853) bacteria responsible for prostatitis. : Aqueous and ethanolic raw extracts were prepared, and the latter were further purified using the resin Amberlite 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. : Purified extracts were richer in polyphenols (330.80 and 367.66 mg/g of dry extract for and , 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). : These results outline the outstanding potential of and extracts and oenothein B as therapeutic alternatives or complementary agents to conventional antibiotic treatments of prostatitis and other urinary tract infections.