Biochemistry

Table 6.1 - Some natural Fatty Acids Carbon number Structure Systematic name Trivial name Temperature of melting point, °C Saturated Fatty Acids 12 CH 3 (CH 2 ) 10 COOH n-Dodecanova Lauric 44,2 14 CH 3 (CH 2 ) n COOH n-te tradecane Myristine 53.9 16 CH 3 (CHj) I4 COOH n-hexadecanoic Palmitic 63.1 18 CH 3 (CH 2 ) 16 COOH n-Octadecane Stearin 69.6 20 CH 3 (CH 2 ) 1S COOH n-eicosan Arachidonic 76.5 24 СН 3 (СН 2 ) И СООН n-tetracosan Lignoceric 86.0 Unsaturated fatty acids 18 CH 3 (CH 2 ) 7 CH=CH-(CH 2 ) 7 COOH Oleic 13,4 18 CH 3 (CH 2 ) 4 CH=CH-CH 2 CH-CH (CH 2 ), COOH Linoleic -5 18 CH 3 CH 2 CH<?H-CH 2 CH=CHCH 2 CH =CH(CH 2 ) 7 COOH Linolenic -11 20 CH 3 (CH 2 ) 4 CH=CH-CH 2 CH=CHCH 2 CH =CHCH 2 CH =CH(CH 2 ) 3 COOH Arachidonic -49.5 The easy oxidation of unsaturated fatty acids is one of the reasons for the accumulation of oxidation products in fats and their subsequent spoilage (rancidity). Of great importance is arachidonic acid that is part of some animal fats and is not found in vegetable oils. Currently, a complex of essential polyunsaturated fatty acids is considered as factor F, the biological significance of which is equated with vitamins. The biological role of PUFAs is very important: they participate as structural elements in phosphatides, lipoproteins of cell membranes. In addition, they are part of the membranes of nerve fibers, connective tissue, affect the exchange of cholesterol, increasing its oxidation and facilitating its transfer to a labile compound. PUFAs also have a normalizing effect on the walls of blood vessels. These acids are associated with the exchange of В vitamins (pyridoxine and thiamine), stimulate the body's defense mechanisms, increase its resistance to infectious diseases and the effects of radiation, and have a positive effect on the condition of the skin and hair. Arachidonic acid is a precursor to prostaglandins - modulators of hormonal activity. The daily human needfor PUFA is 5- lOg. Sources of PUFAs in food are vegetable oils, especially unrefined ones. 6.3 COMPLEX LIPIDS Glycerophospholipids (complex lipids) are esters of glycerol, fatty acids, phosphoric acid and nitrogen-containing compounds. A characteristic feature of their structure is the presence in the molecule of hydrophobic (radicals of fatty 128