Interactions of bile salts with a dietary fibre, methylcellulose, and impact on lipolysis

Methylcellulose (MC) has a demonstrated capacity to reduce fat absorption, hypothetically through bile salt (BS) activity inhibition. We investigated MC cholesterol-lowering mechanism, and compared the influence of two BS, sodium taurocholate (NaTC) and sodium taurodeoxycholate (NaTDC), which differ slightly by their architecture and exhibit contrasting functions during lipolysis. BS/MC bulk interactions were investigated by rheology, and BS behaviour at the MC/water interface studied with surface pressure and ellipsometry measurements. In vitro lipolysis studies were performed to evaluate the effect of BS on MC-stabilised emulsion droplets microstructure, with confocal microscopy, and free fatty acids release, with the pH-stat method. Our results demonstrate that BS structure dictates their interactions with MC, which, in turn, impact lipolysis. Compared to NaTC, NaTDC alters MC viscoelasticity more significantly, which may correlate with its weaker ability to promote lipolysis, and desorbs from the interface at lower concentrations, which may explain its higher propensity to destabilise emulsions

Etude de la réactivité et de la nature des espèces actives dans l'oxydation en milieu aqueux du phénol par le peroxyde d'hydrogène, en présence de catalyseurs à base de fer déposé sur support carboné

POITIERS-BU Sciences (861942102) / SudocSudocFranceF

The oil-drop tensiometer: Potential applications for studying the kinetics of (phospho)lipase action

In 1987, Nury et al. adapted the well-known oil-drop technique for measuring interfacial tension for the purpose of monitoring the lipase hydrolysis of natural long-chain triacylglycerols. On the basis of this initial study, we developed an automated, digitised, computer-driven device with which we further prospected for applications of the oil-drop tensiometer in studies on lipolytic enzyme kinetics. In the present study, we first established that the new device provided reliable interfacial tension measurements, similar to those previously published. Furthermore, by keeping the oil-water interfacial tension at a fixed end-point value, the enzyme kinetics can be monitored using the change with time in the area of the oil drop. We then describe specific applications involving: (i) the measurement of lipase kinetics using minute amounts of enzyme; we checked the existence of a linear relationship between the initial decrease in the interfacial tension and the lipase concentration and found that the initial rates did not vary significantly between several successive drops formed within a 20-min period in the same lipase solution; (ii) the kinetic assay of phospholipase A 2 and (iii) studying the effects of high-pressure conditions upon lipase activity.link_to_subscribed_fulltex