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International audience; The rapid and preferential adsorption of a gastric lipase recombinant dog gastric lipase (rDGL) in heterogeneous films of phospholipids and triacylglycerols has previously been unveiled using Langmuir films analyzed by tensiometry, ellipsometry and Langmuir-Blodgett transfer coupled to atomic force microscopy. Here we invest the adsorption behavior of rDGL in heterogeneous galactolipid and mixed galactolipid-phospholipid or galactolipid-phospholipid-phytosterol films representative of plant membrane. Again rDGL, preferentially got adsorbed at the expanded lipid phases of the films underlining the genericity of such adsorption behavior. The addition of phytosterols to these mixtures resulted in the creation of defects, favoring the adsorption of rDGL at the fluid phases, but also improving the adsorption capacities of the lipase at the phase boundaries and towards the defects in the condensed phase. rDGL, like all gastric lipases, does not show any activity on galactolipids and phospholipids but its adsorption impacts their lateral organization and may change the adsorption and activity of other lipolytic enzymes in the course of digestion.

International audience; Pancreatic lipase related-protein 2 (PLRP2) exhibits remarkable galactolipase and phospholipase A1 activities, which depends greatly on the supramolecular organization of the substrates and the presence of surfactant molecules such as bile salts. It is responsible for the effective hydrolysis of the main lipids composing plant photosynthetic membranes, which represent an excellent source of omega-3 for human nutrition. The objective of the study was to understand the modulation of the adsorption mechanisms and enzymatic activity of Guinea pig PLRP2 (gPLRP2), by the physical environment of the enzyme and physical state of its substrate at the nanoscopic and microscopic scales. Langmuir monolayers were used to reproduce homogeneous and heterogeneous photosynthetic model membranes containing galactolipid, and/or phospholipid, and/or phytosterol, presenting uncharged or charged interfaces. The same lipid mixtures were also used to form micrometric liposomes, and their digestion kinetics by gPLRP2 were investigated in the presence or absence of bile salts (NaTDC) during static in vitro, so called “bulk”, digestion. The enzymatic activity of gPLRP2 onto mixed monolayer of galactolipids and/or phospholipids, and/or phytosterols was characterized with an optimum activity at 15 mN/m, in the absence of bile salts. Additionally, gPLRP2 showed enhanced adsorption onto biomimetic model monolayer containing negatively charged lipids, but the compositional complexity in these systems induced a lag phase before the initiation of lipolysis, and a slowdown in enzymatic activity. In bulk, no enzymatic activity could be demonstrated on GL-based liposomes in the absence of bile salts, probably due to the high lateral pressure of the lipid bilayers. In the presence of NaTDC (4 mM), however, gPLRP2 showed both high galactolipase and moderate phospholipase A1 activities on liposomes, probably due to a decrease in packing and lateral pressure upon NaTDC adsorption, and subsequent disruption of liposomes. The understanding of PLRP2 enzymatic activity at the level of natural plant-based assemblies open the way to new strategies to vectorize bioaccessible omega-3 and rebalance human and animal diets.; La lipase pancréatique apparentée à la protéine 2 (PLRP2) présente des activités galactolipase et phospholipase A1 remarquables, qui dépendent fortement de l'organisation supramoléculaire des substrats et de la présence de molécules tensioactives telles que les sels biliaires. Elle est responsable de l'hydrolyse efficace des principaux lipides composant les membranes photosynthétiques des plantes, qui représentent une excellente source d'oméga-3 pour la nutrition humaine. L'objectif de l'étude était de comprendre la modulation des mécanismes d'adsorption et de l'activité enzymatique de la PLRP2 de cobaye (gPLRP2), par l'environnement physique de l'enzyme et l'état physique de son substrat à l'échelle nanoscopique et microscopique. Des monocouches de Langmuir ont été utilisées pour reproduire des membranes modèles photosynthétiques homogènes et hétérogènes contenant des galactolipides, et/ou des phospholipides, et/ou des phytostérols, présentant des interfaces chargées ou non. Les mêmes mélanges lipidiques ont également été utilisés pour former des liposomes micrométriques, et leur cinétique de digestion par la gPLRP2 a été étudiée en présence ou en absence de sels biliaires (NaTDC) au cours d'une digestion statique in vitro, dite "bulk". L'activité enzymatique de la gPLRP2 sur une monocouche mixte de galactolipides et/ou phospholipides, et/ou phytostérols a été caractérisée avec une activité optimale à 15 mN/m, en l'absence de sels biliaires. De plus, la gPLRP2 a montré une meilleure adsorption sur des monocouches modèles biomimétiques contenant des lipides chargés négativement, mais la complexité de la composition de ces systèmes a induit une phase de latence avant l'initiation de la lipolyse, et un ralentissement de l'activité enzymatique. En bulk, aucune activité enzymatique n'a pu être démontrée sur les liposomes à base de GL en l'absence de sels biliaires, probablement en raison de la pression latérale élevée des bicouches lipidiques. En présence de NaTDC (4 mM), cependant, la gPLRP2 a montré des activités galactolipase élevées et phospholipase A1 modérées sur les liposomes, probablement en raison d'une diminution du packing et de la pression latérale lors de l'adsorption du NaTDC, et de la rupture ultérieure des liposomes. La compréhension de l'activité enzymatique de la PLRP2 au niveau des assemblages naturels à base de plantes ouvre la voie à de nouvelles stratégies pour vectoriser des oméga-3 bioaccessibles et rééquilibrer les régimes alimentaires humains et animaux.

International audience; The microalgae Chlorella vulgaris represent a good model for the study of photosynthetic membranes and are rich in photosynthetic proteins, galactolipids, and pigments (Demarco et al., 2022). These photosynthetic organisms have been consumed in some parts of the world for centuries and their nutritional potential has been highlighted in many reports, explaining a growing interest in their use in new food applications (Torres-Tiji et al., 2020). However, their digestibility by gastrointestinal enzymes has not been extensively studied. So we used the Pancreatic lipase related-protein 2 (PLRP2) to get more information on the digestive mechanisms. Indeed, it has been shown to be responsible for the effective hydrolysis of galactolipids, the main lipids composing plant photosynthetic membranes. Guinea pig pancreatic lipase related-protein 2 (gPLRP2) is a model enzyme close to its human analogue, and that has been extensively studied for its ability to hydrolyze a wide range of acylglycerol substrates, exhibiting remarkable galactolipase and phospholipase A1 activity. In this study, Langmuir model monolayers were used to fellow the interfacial behavior of gPLRP2 at the level of natural plant lipid monolayers from Chlorella microalgae extracts, and to understand the impact of the chemical and physical heterogeneity of natural photosynthetic plant membranes on the enzymatic activity of gPLRP2. We compared also with data obtained on lipid extracts from nuts and almonds for which the composition is mainly composed of phospholipids. The results have shown that the enzymatic activity of gPLRP2 is with an optimum activity obtained at 15 mN/m. Interfacial studies showed enhanced adsorption of gPLRP2 onto natural monolayers containing negatively charged lipids, and that the compositional complexity in these systems induced a lag phase before the initiation of lipolysis, and a slowdown in enzymatic activity.; Les microalgues Chlorella vulgaris représentent un bon modèle pour l'étude des membranes photosynthétiques et sont riches en protéines photosynthétiques, galactolipides et pigments (Demarco et al., 2022). Ces organismes photosynthétiques sont consommés dans certaines régions du monde depuis des siècles et leur potentiel nutritionnel a été mis en évidence dans de nombreux rapports, expliquant un intérêt croissant pour leur utilisation dans de nouvelles applications alimentaires (Torres-Tiji et al., 2020). Cependant, leur digestibilité par les enzymes gastro-intestinales n'a pas été étudiée de manière approfondie. Nous avons donc utilisé la lipase pancréatique apparentée à la protéine de type 2 (PLRP2) pour obtenir plus d'informations sur les mécanismes digestifs. En effet, il a été démontré qu'elle est responsable de l'hydrolyse efficace des galactolipides, les principaux lipides composant les membranes photosynthétiques des plantes. La lipase pancréatique de cochon d'Inde (gPLRP2) est une enzyme modèle proche de son analogue humain, et qui a été largement étudiée pour sa capacité à hydrolyser une large gamme de substrats d'acylglycérol, présentant une remarquable activité galactolipase et phospholipase A1. Dans cette étude, des monocouches modèles de Langmuir ont été utilisées pour étudier le comportement interfacial de la gPLRP2 au niveau de monocouches lipidiques végétales naturelles provenant d'extraits de microalgues Chlorella, et pour comprendre l'impact de l'hétérogénéité chimique et physique des membranes végétales photosynthétiques naturelles sur l'activité enzymatique de la gPLRP2. Nous avons également comparé avec les données obtenues sur des extraits lipidiques de noix et d'amandes dont la composition est principalement composée de phospholipides. Les résultats ont montré que la gPLRP2 présente une activité optimale à 15 mN/m. Les études interfaciales ont montré une adsorption accrue de la gPLRP2 sur des monocouches naturelles contenant des lipides chargés négativement, mais également que la complexité de la composition de ces systèmes induisait une phase de latence avant l'initiation de la lipolyse, et un ralentissement de l'activité enzymatique.

International audience; Pancreatic lipase related-protein 2 (PLRP2) exhibits remarkable galactolipase and phospholipase A1 activities, which depend greatly on the supramolecular organization of the substrates and the presence of surfactant molecules such as bile salts. The objective of the study was to understand the modulation of the adsorption mechanisms and enzymatic activity of Guinea pig PLRP2 (gPLRP2), by the physical environment of the enzyme and the physical state of its substrate. Langmuir monolayers were used to reproduce homogeneous and heterogeneous photosynthetic model membranes containing galactolipids (GL), and/or phospholipids (PL), and/or phytosterols (pS), presenting uncharged or charged interfaces. The same lipid mixtures were also used to form micrometric liposomes, and their gPLRP2 catalyzed digestion kinetics were investigated in presence or in absence of bile salts (NaTDC) during static in vitro, so called “bulk”, digestion.The enzymatic activity of gPLRP2 onto the galactolipid-based monolayers was characterized with an optimum activity at 15 mN/m, in the absence of bile salts. gPLRP2 showed enhanced adsorption onto biomimetic model monolayer containing negatively charged lipids. However, the compositional complexity in the heterogeneous uncharged model systems induced a lag phase before the initiation of lipolysis. In bulk, no enzymatic activity could be demonstrated on GL-based liposomes in the absence of bile salts, probably due to the high lateral pressure of the lipid bilayers. In the presence of NaTDC (4 mM), however, gPLRP2 showed both high galactolipase and moderate phospholipase A1 activities on liposomes, probably due to a decrease in packing and lateral pressure upon NaTDC adsorption, and subsequent disruption of liposomes.

International audience; Langmuir films and their analysis by tensiometry, ellipsometry and Langmuir-Blodgett transfer coupled to atomic force microscopy are suitable tools to study the interactions of various lipases with model membranes. The objective of our study was to characterize the adsorption and lipolysis behavior of different gastrointestinal enzymes onto biomimetic vegetal membranes. An heterogenous monolayer based on a mixture of unsaturated galactolipids (MGDG, DGDG), saturated phospholipids (DPPC), and phytosterols was used. Four enzymes were studied, i) gastric lipase (GL), which has no lipolytic activity on polar lipids but whose adsorption may modulate the subsequent adsorption and activity of other lipases, and three pancreatic enzymes: ii) pancreatic lipase 2 (PLRP2) presenting both galactolipase and phospholipase A1 activities, (iii) pancreatic triacylglycerol lipase and its cofactor, colipase (PTL/coPTL), and (iv) pancreatic secreted phospholipase A2 (sPLA2-IB). A strong surfactant property of GL and its preferential adsorption at both the expanded lipid phase and at the boundary phase were observed, in line with previous results obtained with biomimetic milk fat globule membrane. With PLRP2, changes in surface pressure indicated a lipolytic activity in addition to lipase adsorption, with a higher rate at surface pressure below 15 mN/m. A drastic decrease in film thickness was also observed by ellipsometry, suggesting the removal of some lipolysis products. Such variation was not observed upon PTL/coPTL adsorption, and may be related to the absence of activity of PTL on polar lipids. Finally, the evolution of adsorption kinetic after injection of sPLA2-IB did not indicate a clear trend of lipolysis on the lipid film. However, a change in the morphology of condensed domains was observed by AFM, suggesting a phase separation of lipids induced by binding of sPLA2-IB.This study is a step forward in the understanding of interaction of gastrointestinal lipases with plant lipid membranes, an overlooked aspect of lipid digestion.

International audience; The structural behavior of model assemblies composed of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG), the two main galactolipids found in plants, was investigated at the air/water interface and in aqueous dispersion. To approach the composition of the natural photosynthetic membranes, tunable Langmuir model membrane of galactolipids (GL) were used, and were complexified to form either heterogenous binary or ternary assemblies of GL, phospholipids (PL), and phytosterols (pS).The impact of pS, 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or both on the structural properties of GL membrane was studied. The nature of the interactions between the different molecules was investigated using biophysical characterizations (ellipsometry, tensiometry, atomic force microscopy). In addition, the phase behavior was determined by SAXS analysis on the model assemblies in aqueous dispersions.Results revealed the good interfacial stability of these specific plant membrane lipids. The morphology of the GL film was characteristic of a fluid phase, with an interfacial roughness induced by the intercalation of monogalactosyl and digalactosyl polar heads of MGDG and DGDG, respectively. A phase heterogeneity in the monolayer was induced by the addition of DPPC and/or pS, which resulted in the modification of galactolipid organization and headgroup interactions. These structural changes were confirmed by SAXS analysis, showing more favorable interactions between MGDG and DPPC than between DGDG and DPPC in aqueous dispersion. This phenomenon was exacerbated in the presence of pS.HIGHLIGHTS • Plant polar lipids formed stable monolayers at the air/water interface. • Phytosterols reduced the lateral elasticity of galactolipid and DPPC monolayer. • DPPC has affected MGDG-DGDG interactions. • Results highlighted preferential phase miscibility between DPPC and MGDG.

Oil bodies (OB) are the natural form of energy storage in oilseeds. They consist of a triacylglyceride core stabilized by proteins (mainly oleosins) embedded in a phospholipid membrane. In some tree nut species, OB contain an important amount of polyunsaturated fatty acids that make them interesting food ingredients but prone to oxidation. Due to the growing interest in minimally processed nut-based beverages, the understanding and the preservation of the physico-chemical properties of these lipoprotein assemblies are of great interest. In this context, previous inte rfacial studies have led to the proposition of a new model of adsorption for minimally processed OB that is useful to design functional emulsion or foam in which OB act as emulsifiers. The objective of the present study was to determine the impact of processing and fat content on the physico-chemical behavior of tree nut-based matrixes. The interfacial and oxidative behaviors of minimally processed isolated OB were compared with processed complex nut-based matrixes (i.e., beverages) of different fat content. Processing operations (heat-treatment, homogenization) affected OB interfacial properties and oxidative stability but fat content had even stronger impact on this last parameter, with more concentrated systems more stable to oxidation. The results underline the good physico-chemical stability of tree nut OB and raise the interest of their use in the minimally processed form to fully exploit their beneficial properties. (Texte integral)

International audience; Gastrointestinal lipases are crucial for lipid hydrolysis and must get adsorbed onto the substrate interface prior lipolysis. Such adsorption had not been deeply investigated on biomimetic vegetal membranes. Our objective was thus to characterize such adsorption and lipolysis using complementary biophysical tools (tensiometry, ellipsometry, atomic force microscopy) and in vitro digestion.Heterogenous monolayers based on galactolipids, phospholipids, and phytosterols were used. Four lipases were studied: i) gastric lipase (GL), ii) pancreatic lipase 2 (PLRP2), (iii) pancreatic triacylglycerol lipase and its cofactor, colipase (PTL/coPTL), and (iv) pancreatic secreted phospholipase A2 (sPLA2-IB).A strong surfactant property of GL and its preferential adsorption onto expanded lipid phase and at the phase boundary were observed, in line with previous results on milk fat globule membrane. With PLRP2, changes in surface pressure indicated a lipolytic activity. Such variation was not observed upon PTL/coPTL adsorption, and may be related to the absence of activity of PTL on polar lipids. The injection of sPLA2-IB did not indicate a clear trend of lipolysis on the lipid film but changed the morphology of condensed domains.This study is a step forward to understand the interactions of gastrointestinal lipases with plant lipid membranes, an overlooked aspect of lipid digestion

Oleoproteaginous and cereal seeds enclose a wide range of nutriments such as lipids, proteins, polysaccharides and various mineral and organic micronutrients. These nutrients are found under the form of natural assemblies such as oil or protein bodies or starch granules, that have interesting functionalities (micronic sizes, surface activity, high physicochemical stability, etc.). These assemblies are extracted by various processes using energy, organic solvents, steam, JOURNAL OF THE AMERICAN OIL CHEMISTS' SOCIETY 75 15589331, 2022, S1, Downloaded from https://aocs.onlinelibrary.wiley.com/doi/10.1002/aocs.12654 by CIRAD - DGDRS - DIST, Wiley Online Library on [01/06/2023]. See the Terms and Conditions (https://onlinelibrary.wiley.com/terms-and-conditions) on Wiley Online Library for rules of use; OA articles are governed by the applicable Creative Commons License alone or in combination. Thus, their natural structures are often strongly damaged, and some of their functionalities disappear. Storming through natural assemblies' biodiversity to address the societal demand for more natural and minimally processed food seems promising. Indeed, the soft extraction of such assemblies could be an alternative to traditional intensive fractionation methods of plant raw materials to isolate target ingredients (sucrose, starch, refined oils, etc.). This would allow energy savings and avoid solvent use but must be balanced with potential challenges of this new green refinery scheme. The purpose of the present work is to highlight the physicochemical properties of various oil bodies from diverse plant origins. A green refinery protocol is proposed for their extraction from various matrices. Then their size distribution, surface activity, resistance to oxidation and fatty acids and lipo- soluble vitamins bioaccessibility is also presented. Omega-3 rich sources (linseed, chia, hemp…) are of special interest to correct the low dietary intake of US and European population as well as the ω6/ω3 balance. Oil bodies from these plant species can thus constitute new dietary carriers of ω3 and other bioactive molecules. Moreover, the combination of oil bodies with specific features (fatty acid profiles, stabilities, vitamin contents) can help meeting the requirements of specific nutritional targets (infants, children, elderly, athletes, etc.). Altogether, we are convinced that the valorization of these diverse oil bodies can be a strategic route in the development of sustainable food systems. (Texte intégral)