Traditionally used medicinal plants against uncomplicated urinary tract infections: Are unusual, flavan-4-ol- and derhamnosylmaysin derivatives responsible for the antiadhesive activity of extracts obtained from stigmata of Zea mays L. against uropathogenic E. coli and Benzethonium chloride as frequent contaminant faking potential antibacterial activities?

Fitoterapia

Volume 105, September 2015, Pages 246–253

• Nasli Rafsanjany,
• Jandirk Sendker,
• Matthias Lechtenberg,
• Frank Petereit,
• Birte Scharf,
• Andreas Hensel^,

doi:10.1016/j.fitote.2015.07.014

Get rights and content

---

Abstract

The dried stigmata from Zea mays L. are used traditionally for the treatment of uncomplicated urinary tract infections. A recent screening has indicated that hydroalcoholic extract of the herbal material inhibits the adhesion of uropathogenic Escherichia coli (UPEC) to T24 bladder cells. For verification of these data EtOH-water (1:1) extracts from 4 different batches of Maydis stigmata were investigated. Within an in vitro adhesion assay (UPEC strain 2980 and human T24 bladder cells) a dose-dependent antiadhesive activity against UPEC was verified (IC₅₀ 1040 μg/mL). Bioassay guided fractionation of M. stigmata, batch S1, by EtOH-water extraction, followed by chromatography on Sephadex LH20 revealed two active fractions (I and XI). Further purification of fraction I and structure elucidation of the isolated compound revealed the presence of significant amounts of the biocide benzethonium chloride as contaminant. Benzethonium chloride was also identified in subsequent investigations in 2 different batches of M. stigmata. The presence of such nondeclared and illegal contaminants in the herbal raw material market has to be discussed intensively. From benzethonium-free raw material (batch S2) as well as from batch S1 fraction XI was further fractionated by MPLC and preparative HPLC, leading to a still complex subfraction XI_G, which was analyzed by UHPLC/+ ESI-QTOF-MS analysis. Advanced data processing and species-metabolite relationship database revealed the tentatively existence of the unusual C-glycosidic flavones derhamnosylmaysin (6), 3′-deoxyrhamnosylmaysin (4), 3′-O-methylderhamnosylmaysin (3), apiferol (2) and alternanthin (8) which might be related to the antiadhesive activity of this subfraction against UPEC.

---

Graphical abstract

Abbreviations

• BCR, Bacteria-cell ratio;
• CFU, colony forming units;
• FACS, fluorescence activated cell sorting, flow cytometry;
• fimH, mannose sensitive fimbriae of UPEC;
• FITC, fluorescein isothiocyanate;
• MeOH, methanol;
• MPLC, Medium pressure liquid chromatography;
• UPEC, uropathogenic E. coli;
• UTI, uncomplicated urinary tract infections;
• TLC, thin layer chromatography;
• HPLC, high performance liquid chromatography

Keywords

• Zea mays;
• Adhesion;
• Bladder cells;
• Benzethoniumchloride;
• Maysin;
• Uropathogenic E. coli

Corresponding author.

Copyright © 2015 Elsevier B.V. All rights reserved.