Effects of isovaleraldehyde on cell-sized lipid bilayer vesicles

Assessment of beverage quality for ethyl caproate and procyanidin B2 utilizing binary liposomes

Procyanidins are bioactive compounds present in fruits like apples. These compounds can be extracted and studied for their functional properties. Within the class of procyanidins, procyanidin B2 (PB2) serves as a standard reference. Sake, a traditional Japanese alcoholic beverage, contains ethyl caproate (EC), which adds economic value to the drink. Analyzing PB2 in apple juice and EC in sake, particularly in simple prepared beverages without the use of organic solvents or in their original state, requires the application of binary liposomes composed of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). In this study, I investigated the size of liposomes and the ratio of solid ordered (So) to liquid disordered (Ld) liposomes. The results indicated that PB2 increased the size of liposomes, while EC decreased it. Additionally, EC influenced the ratio of So/Ld liposomes. These findings provide a foundational understanding for further research on the biophysical and physiological properties of EC and PB2.

Materials evaluation using cell-sized liposomes

Cell membranes play a vital role in delineating the internal cellular environment from the external surroundings, going beyond mere compartmentalization. Researchers have delved into the structural organization, properties, and functional roles of biological membranes, paving the way for their application in substance identification, detection, and quantification. This review introduces various studies and their implications for future research. It underscores the advantages of employing cell-sized liposomes, which enable real-time observation for rapid detection and analysis of diverse materials. The utility of cell-sized liposomes extends to their size, dynamic shape changes, and phase-separation, offering valuable insights into the evaluation of targeted materials.

Phase-Separated Structures of Sake Flavors-Containing Cell Model Membranes

Sake (a traditional Japanese alcoholic beverage) contains ethyl caproate (EC), which enhances its economic value. Isovaleraldehyde (IVA) is also a well-known flavoring agent in alcoholic beverages, which some people enjoy. Recently, studies revealed that EC decreased the size of homogenous 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC) liposomes whereas IVA increased their size. Cholesterol (Chol) and ergosterol were previously referred to as animal and fungus sterols. For the first time, this study demonstrated the phase behavior of the membrane in cell-sized liposomes containing EC and IVA. After adding EC, the solid ordered/liquid disordered (Ld) and liquid ordered (Lo)/Ld phase separation in DOPC/dipalmitoyl-sn-glycero-3-phosphocholine/cholesterol or ergosterol ternary membranes decreased, but the Lo/Ld phase separation decreased after adding IVA. Biophysics, physiological, and application aspects of EC and IVA evaluation were discussed. The findings of this study not only enhance our understanding of the function of flavors but also provide rapid and cost effective performance for the measurement.

Charged Lipids Influence Phase Separation in Cell-Sized Liposomes Containing Cholesterol or Ergosterol

Positively charged ion species and charged lipids play specific roles in biochemical processes, especially those involving cell membranes. The cell membrane and phase separation domains are attractive research targets to study signal transduction. The phase separation structure and functions of cell-sized liposomes containing charged lipids and cholesterol have been investigated earlier, and the domain structure has also been studied in a membrane model, containing the yeast sterol ergosterol. The present study investigates phase-separated domain structure alterations in membranes containing charged lipids when cholesterol is substituted with ergosterol. This study finds that ergosterol increases the homogeneity of membranes containing charged lipids. Cholesterol-containing membranes are more sensitive to a charged state, and ergosterol-containing liposomes show lower responses to charged lipids. These findings may improve our understanding of the differences in both yeast and mammalian cells, as well as the interactions of proteins with lipids during signal transduction.

Phase Separation in Liposomes Determined by Ergosterol and Classified Using Machine Learning

Recent studies indicated that ergosterol (Erg) helps form strongly ordered lipid domains in membranes that depend on their chemical characters. However, direct evidence of concentration-dependent interaction of Erg with lipid membranes has not been reported. We studied the Erg concentration-dependent changes in the phase behaviors of membranes using cell-sized liposomes containing 1,2-Dioleoyl-sn-glycero-3-phosphocholine (DOPC)/1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC). We observed the concentration range of phase separation in ternary membranes was significantly wider when Erg rather than cholesterol (Chol) was used as the sterol component. We used machine learning for the first time to analyze microscopic images of cell-sized liposomes and identify phase-separated structures. The automated method was successful in identifying homogeneous membranes but performance remained data-limited for the identification of phase separation domains characterized by more complex features.