Molecular insights into the behaviour of bile salts at interfaces: a key to their role in lipid digestion

Olivia Pabois, Christian D. Lorenz, Richard D. Harvey, Isabelle Grillo, Myriam M-L Grundy, Peter J. Wilde, Yuri Gerelli, Cecile Dreiss

Research output: Contribution to journalArticlepeer-review

26 Citations (Scopus)
85 Downloads (Pure)

Abstract

Hypotheses
Understanding the mechanisms underlying lipolysis is crucial to address the ongoing obesity crisis and associated cardiometabolic disorders. Bile salts (BS), biosurfactants present in the small intestine, play key roles in lipid digestion and absorption. It is hypothesised that their contrasting functionalities – adsorption at oil/water interfaces and shuttling of lipolysis products away from these interfaces – are linked to their structural diversity. We investigate the interfacial films formed by two BS, sodium taurocholate (NaTC) and sodium taurodeoxycholate (NaTDC), differing by the presence or absence of a hydroxyl group on their steroid skeleton.

Experiments
Their adsorption behaviour at the air/water interface and interaction with a phospholipid monolayer – used to mimic a fat droplet interface – were assessed by surface pressure measurements and ellipsometry, while interfacial morphologies were characterised in the lateral and perpendicular directions by Brewster angle microscopy, X-ray and neutron reflectometry, and molecular dynamics simulations.

Findings
Our results provide a comprehensive molecular-level understanding of the mechanisms governing BS interfacial behaviour. NaTC shows a higher affinity for the air/water and lipid/water interfaces, and may therefore favour enzyme adsorption, whereas NaTDC exhibits a higher propensity for desorption from these interfaces, and may thus more effectively displace hydrolysis products from the interface, through dynamic exchange.
Original languageEnglish
Pages (from-to)266-277
Number of pages12
JournalJOURNAL OF COLLOID AND INTERFACE SCIENCE
Volume556
Issue number0
Early online date5 Aug 2019
DOIs
Publication statusPublished - 15 Nov 2019

Keywords

  • Bile salts
  • DPPC monolayer
  • Interfacial properties
  • Lipid digestion
  • Neutron reflectometry

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