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
XIG, 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