Antiadhesive activity of traditionally used plants agaisnt urinary tract infections: An alternative strategy to combat uropathogenic Escherichia coli

The antiadhesive potential of a quantified aqueous extract from the leaves ofOrthosiphon stamineus Benth. (OWE) as well as the phenolic compounddepleted extract (OWEøPC) were investigated against uropathogenicEscherichia coli (UPEC). OWE was quantified by UHPLC for the content ofrosmarinic acid, cichoric acid and caffeic acid. 4- and 7-day pretreatment ofBalb/c mice with OWE (750 mg/kg) prior to the transurethral infection withUPEC NU14, reduced bacterial bladder colonization. Also, 3- and 5-dayposttreatment of Balb/c mice with OWE (750 mg/kg) after transurethralinfection with UPEC CFT073, reduced the bacterial load in bladder andkidney, similar to norfloxacin. In vitro investigations indicated that OWE (≤ 2mg/ml) has no proliferation-inhibiting activity against different UPEC strainsas well as against T24 bladder and A498 kidney cells. Under in vitroconditions, OWE and OWEøPC both exerted a dose dependent antiadhesiveactivity against UPEC strains NU14 and UTI89. OWE reduced the geneexpression of fimH, but significantly increased the expression of themotility/fitness gene fliC. Increase of bacterial motility on gene level wasconfirmed by a changed bacterial phenotype by an increased bacterial motilitywithin soft agar assay. OWE also inhibited the bacterial quorum sensing in aconcentration-dependent manner. Transcriptome analysis by next generationsequencing and cross-validation of data obtained by RT-PCR indicated thatOWEøPC down-regulated the genes responsible for chaperone-mediatedprotein folding/unfolding and pilus assembly process (leading to decrease ofporin activity) while flagellar assembly responsive genes were up-regulated asclaimed by mRNA-Seq analysis. Thus, it was concluded that OWE transformsthe sessile lifestyle of bacteria to a motile one and therefore disables thebacterial surface attachment.II) A hydroalcoholic extract (1:1) from Apium graveolens L. fruits, known ascelery seeds (CSE), was characterized by UHPLC/+ESI-QTOF-MS anddominated by the presence of different luteolin-glycosides and related flavonderivatives besides furocoumarins. CSE had no cytotoxic effects againstXIVUPEC strain NU14 and T24 bladder cells within the tested concentrationrange (0.1 to 1 mg/mL). CSE exerts a dose dependent antiadhesive activityagainst UPEC strains NU14 and UTI89 under in vitro conditions. CSEinhibited bacterial quorum sensing in a concentration dependent manner. 4-and 7-day pretreatment of Balb/c mice with CSE (200 and 500 mg/kg/day),transurethrally infected with UPEC NU14, significantly reduced the bacterialload in bladder tissue. Therefore, CSE is evaluated as a strong antiadhesiveplant extract for which the traditional use in phytotherapy for UTI might bejustified.III) The rhizomes from Agropyron repens (L.) Beauv. were extracted withsolvents of different polarities. The extracts did not show any cytotoxic effectsagainst different E. coli strains (2980 and NU14) and human T24 bladder cellsunder in vitro conditions. Significant antiadhesive activity against the bacterialattachment to human T24 bladder cells was found for the acetone extract(AAE) at concentrations > 250 μg/mL. Other hydrophilic extracts did notinfluence the bacterial attachment to the eukaryotic host cells. Bioassay guidedfractionation of AAE led to the identification of (E)-hexadecyl-3-(4-hydroxyphenyl)-acrylate (Compound A) as the responsible compound forinhibiting the bacterial adhesion to T24 bladder cells. A and two otherstructural analogs B (with shorter alkyl chain, C8) and C (with changed phenylring system) were synthetized. A, B and C were tested for their potentialantiadhesive activity but only A reduced the bacterial adhesion significantly,indicating that a shorter alkyl chain at the ester moiety as well as the lack ofhydroxylation of the phenyl moiety will abolish the antiadhesive activity. Aalso reduced the bacterial invasion into the T24 bladder cells as shown by aspecific gentamicin protection assay.