Antiadhesive Properties of Abelmoschus Esculentus (Okra) Immature Fruit Extract Against Helicobacter Pylori Adhesion

PLoS One. 2014 Jan 9;9(1):e84836. doi: 10.1371/journal.pone.0084836. eCollection 2014.

Abstract

Background: Traditional Asian and African medicine use immature okra fruits (Abelmoschus esculentus) as mucilaginous food to combat gastritis. Its effectiveness is due to polysaccharides that inhibit the adhesion of Helicobacter pylori to stomach tissue. The present study investigates the antiadhesive effect in mechanistic detail.

Methodology: A standardized aqueous fresh extract (Okra FE) from immature okra fruits was used for a quantitative in vitro adhesion assay with FITC-labled H. pylori J99, 2 clinical isolates, AGS cells, and fluorescence-activated cell sorting. Bacterial adhesins affected by FE were pinpointed using a dot-blot overlay assay with immobilized Lewis(b), sialyl-Lewis(a), H-1, laminin, and fibronectin. (125)I-radiolabeled Okra FE polymer served for binding studies to different H. pylori strains and interaction experiments with BabA and SabA. Iron nanoparticles with different coatings were used to investigate the influence of the charge-dependence of an interaction on the H. pylori surface.

Principal findings: Okra FE dose-dependently (0.2 to 2 mg/mL) inhibited H. pylori binding to AGS cells. FE inhibited the adhesive binding of membrane proteins BabA, SabA, and HpA to its specific ligands. Radiolabeled compounds from FE bound non-specifically to different strains of H. pylori, as well as to BabA/SabA deficient mutants, indicating an interaction with a still-unknown membrane structure in the vicinity of the adhesins. The binding depended on the charge of the inhibitors. Okra FE did not lead to subsequent feedback regulation or increased expression of adhesins or virulence factors.

Conclusion: Non-specific interactions between high molecular compounds from okra fruits and the H. pylori surface lead to strong antiadhesive effects.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Abelmoschus / chemistry*
  • Adhesins, Bacterial / metabolism*
  • Bacterial Adhesion / drug effects*
  • Binding, Competitive
  • Cell Line, Tumor
  • Fruit / chemistry*
  • Gene Expression Regulation, Bacterial / drug effects
  • Helicobacter pylori / drug effects*
  • Helicobacter pylori / metabolism*
  • Helicobacter pylori / physiology
  • Hemagglutination / drug effects
  • Humans
  • Plant Extracts / metabolism
  • Plant Extracts / pharmacology*
  • Polysaccharides / chemistry
  • Polysaccharides / metabolism
  • Polysaccharides / pharmacology
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Species Specificity

Substances

  • Adhesins, Bacterial
  • Plant Extracts
  • Polysaccharides
  • RNA, Messenger

Grant support

Financial support by the German Research Foundation, DFG (International Research Training Group 1549 Molecular and Cellular Glyco-Sciences MCGS, Münster Hyderabad), to AH, JM, and CT and from Vetenskapsrådet/VR(M), Cancerfonden to TB is acknowledged, and was in part performed within the Umeå Centre for Microbial Research. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.