title: Acetylated Rhamnogalacturonans from Immature Fruits of Abelmoschus esculentus Inhibit the Adhesion of Helicobacter pylori to Human Gastric Cells by Interaction with Outer Membrane Proteins.
abstract: Polysaccharide containing extracts from immature fruits of okra (Abelmoschus esculentus) are known to exhibit antiadhesive effects against bacterial adhesion of Helicobacter pylori (H. pylori) to stomach tissue. The present study investigates structural and functional features of polymers responsible for this inhibition of bacterial attachment to host cells. Ammonium sulfate precipitation of an aqueous extract yielded two fractions at 60% and 90% saturation with significant antiadhesive effects against H. pylori, strain J99, (FE60% 68% ± 15%; FE90% 75% ± 11% inhibition rates) after preincubation of the bacteria at 1 mg/mL. Sequential extraction of okra fruits yielded hot buffer soluble solids (HBSS) with dose dependent antiadhesive effects against strain J99 and three clinical isolates. Preincubation of H. pylori with HBSS (1 mg/mL) led to reduced binding to 3'-sialyl lactose, sialylated Le(a) and Le(x). A reduction of bacterial binding to ligands complementary to BabA and SabA was observed when bacteria were pretreated with FE90%. Structural analysis of the antiadhesive polysaccharides (molecular weight, monomer composition, linkage analysis, stereochemistry, and acetylation) indicated the presence of acetylated rhamnogalacturonan-I polymers, decorated with short galactose side chains. Deacetylation of HBSS and FE90% resulted in loss of the antiadhesive activity, indicating esterification being a prerequisite for antiadhesive activity.
authors.affiliation: Institute of Pharmaceutical Biology and Phytochemistry, University of Münster, Münster 48149, Germany. c.thoele@uni-muenster.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Thöle
authors.affiliation: Institute of Pharmaceutical Biology and Phytochemistry, University of Münster, Münster 48149, Germany. simone.brandt@uni-muenster.de.
authors.forename: Simone
authors.initials: S
authors.lastname: Brandt
authors.affiliation: Pathogen Biology Laboratory, Department of Biotechnology and Bioinformatics, University of Hyderabad, Hyderabad, Telangana 500046, India. ahmed.nizi@gmail.com.
authors.forename: Niyaz
authors.initials: N
authors.lastname: Ahmed
authors.affiliation: Institute of Pharmaceutical Biology and Phytochemistry, University of Münster, Münster 48149, Germany. ahensel@uni-muenster.de.
authors.forename: Andreas
authors.initials: A
authors.lastname: Hensel
mesh_terms: D028483:Abelmoschus / Q000737:chemistry*; D000107:Acetylation; D000230:Adenocarcinoma / Q000188:drug therapy / Q000378:metabolism / Q000382:microbiology; D001422:Bacterial Adhesion / Q000187:drug effects*; D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D005638:Fruit / Q000737:chemistry*; D016481:Helicobacter Infections / Q000188:drug therapy / Q000378:metabolism* / Q000382:microbiology; D016480:Helicobacter pylori / Q000187:drug effects; D006801:Humans; D010368:Pectins / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology; D011134:Polysaccharides / Q000494:pharmacology; D013274:Stomach Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000382:microbiology; D014407:Tumor Cells, Cultured
chemical_list: D001425:Bacterial Outer Membrane Proteins; D010936:Plant Extracts; D011134:Polysaccharides; C042491:rhamnogalacturonan I; C078167:OMPA outer membrane proteins; D010368:Pectins
keywords: Abelmoschus esculentus; BabA; Helicobacter pylori; acetylation; adhesion; antiadhesion; okra; rhamnogalacturonan