Analysis of the physical state of cholesteryl esters in arterial-smooth-muscle-derived foam cells by differential scanning calorimetry

The physical state of cholesteryl esters (CE) in the arterial-smooth-muscle-derived foam cells may contribute to the documented reduction in CE hydrolysis. The physical state of CE may also provide a potential enhancing mechanism for increased CE accumulation. To explore these concepts, we therefore examined the influence of alterations in CE and triacylglycerol (TG) content and their fatty acid composition on the thermotropic behaviour of these lipids by differential scanning calorimetry (d.s.c.). After exposure to cationized LDL (cLDL) or after infection with herpes simplex virus type I (HSV), smooth-muscle cells accumulated significant amounts of CE. The CE/TG ratio was significantly higher in cells treated with cLDL compared with HSV infection. TG content was unaffected by either treatment. However, the fatty acid profile of both CE and TG was significantly different between treatment groups, with the polyunsaturated fatty acid/saturated fatty acid (PUFA/SFA) ratio being significantly higher in cLDL-treated cells than in HSV-infected cells. The d.s.c.-generated thermograms of intact cells revealed that neutral lipids of both treatment groups were in the isotropic-liquid state, similar to the state of lipids derived from ‘fatty streak’ types of atherosclerotic lesions. Differences in the thermograms between HSV-infected and cLDL-treated cells can be ascribed to differences in the CE content and the fatty acid composition of CE and TG (PUFA/SFA ratio). Polarizing optical microscopy revealed the presence of isotropic lipids in both groups. Biochemical and physicochemical data confirm the lysosomal localization of engorged CE, and indicate that the cellular isotropic CE in these foam cells are in a physical state which favours enzymic hydrolysis.

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DIFFERENTIAL SCANNING CALORIMETRY OF LIQUID VEGETABLE

chemistry of plant raw material ◽

10.14258/jcprm.2020047603 ◽

2020 ◽

pp. 157-164

Author(s):

Igor' Aleksandrovich Saranov ◽

Oleg Borisovich Rudakov ◽

Konstantin Konstantinovich Polyansky ◽

Natal'ya Leonidovna Kleymenova ◽

Aleksey Valer'yevich Vetrov

Keyword(s):

Differential Scanning Calorimetry ◽

Fatty Acid Composition ◽

Fatty Acid ◽

Acid Composition ◽

Vegetable Oils ◽

Thermal Effects ◽

Scanning Calorimetry ◽

Total Proportion ◽

Dsc Thermograms

The thermophysical properties of vegetable oils were studied by differential scanning calorimetry method was used to study the fatty acid composition of vegetable oils liquid at room temperature, such as amaranth (Amaránthus), corn (Zea mays), flax (Línum usitatíssimum), sunflower (Helianthus), rape (Brusss napor), milk thistle (Sílybum mariánum), saffron milk cap (Camelina sativa) and pumpkin (Cucurbita pepo). The temperatures of the endothermic peak maxima and their area on the DSC thermograms of these oils were established as characteristic thermal effects. The interconnection between thermal effects and fatty acid composition are revealed. On the melting curves of liquid vegetable oils, up to 5 endothermic peaks of different intensities were selected in the ranges -80÷-55 °C, -40÷-15 °C, -25÷-8 °C, -19÷+6 °C and -10÷+4 °C. The coordinates of the maxima of these peaks (Ti) and their area (Si) significantly correlate with the content (Wi,%) in the oils, primarily oleic, linoleic and linolenic acids, the total proportion of which in oils is from 75 to 92%. Using the DSC thermograms of rapeseed oil as an example, it is shown that the program separation of DSC peaks allows a multiple increase in the number of analytical signals, an increase in the reliability of identification of the fat phase, and identification of the main fractions of triglycerides. DSC as a method for identifying vegetable oils using modern thermal analysis instruments is simple to sample, has good reproducibility and can be an independent method for identifying and controlling the quality of vegetable oils.

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