Methodological Aspects and Relevance of the Study of Vegetable Oil, Fat and Lipoprotein Oxidation Using Pancreatic Lipase and Arylesterase

Fats and oils as major dietary components are involved in the development of chronic diseases. In this paper the physiological relevance and some methodological aspects related to the determination of two enzymes enrolled in metabolism of fat – pancreatic lipase and arylesterase – are discussed. Pancreatic lipase has been extensively used to study the triacylglycerol fatty acid composition and the in vitro digestion of oils and fats. The action of this enzyme may be coupled to analytical methods as GC, HPLC, HPSEC, TLC-FID, etc. as a useful tool for understanding the composition and digestion of thermal oxidized oils. Pancreatic lipase hydrolysis occurs in the water/oil interface, and it presents a behaviour that seems to be Michaelian, in which the apparent Km and the apparent Vmax of the enzymatic process depend more on the type of oil tested than on the degree of alteration. The kinetic behaviour of pancreatic lipase towards thermally oxidized oils also depends on the presence of natural tensioactive compounds present in the oil and surfactants formed during the frying. Arylesterase is an HDL binding enzyme that inhibits LDL oxidation. Low serum concentration of this enzyme has been related to increased cardiovascular disease risk. In this paper the most widely used methods for the determination of arylesterase activity are commented on. The importance of intrinsic factors (e.g. substrates, cofactors) participating in the enzyme reaction is also discussed. Moreover, several suggestions about further researches on the influence of extrinsic factors (e.g. diet, oxidative stress) upon the enzyme activity are proposed.