Fatty Acids

1. Fatty Acids

2. Fatty Acids • Long-chain carboxylic acids that have an even number (usually 12-18) of carbon atoms. • Insoluble in water. • Saturated or unsaturated.

3. Fatty acids

4. Fatty Acid Formulas • The formulas for fatty acids are written as condensed and line-bond formulas. • For example fatty acid with 8 carbon atoms can be written as:

5. CH3—(CH2)6—COOH CH3—CH2—CH2—CH2—CH2—CH2—CH2—COOH O || CH3—CH2—CH2—CH2—CH2—CH2—CH2—C—OH

6. General nomenclature • The carbon atoms of an acid are numbered (or lettered with Greek lettering system, such as α, β, γ) either from the carboxyl group or from the carbon farthest removed from the carboxyl group (n or omega numbering system) CH3-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-COOH 10 9 8 7 6 5 4 3 2 1 1 2 3 4 5 6 7 8 9 10 ωδγβα

7. Systematic names

9. Saturated F.As. Saturated fatty acids have single C–C bonds.

10. Saturated F.As. Saturated fatty acids have: • Molecules that fit closely together in a regular pattern. • Strong attractions between fatty acid chains. • High melting points that makes them solids at room temperature.

11. Unsaturated F.As. Unsaturated fatty acids have cis C=C bonds.

12. Unsaturated F.As. • Unsaturated fatty acids typically contain cis double bonds.

13. Unsaturated F.As. Unsaturated fatty acids: • Have nonlinear chains that do not allow molecules to pack closely. • Have low melting points. • Are liquids at room temperature.

14. Olive Oil • Olive oil contains a high percentage of oleic acid. • Oleic acid is a monounsaturated fatty acid with one cisdouble bond.

15. Triacylglycerols In a triacylglycerol, glycerol forms ester bonds with three fatty acids.

16. Hydrogenation of Oils Hydrogenation: • Adds hydrogen to double bonds in oils to form single bonds. • Produces solid shortening, margarine, and other products.

17. Omega-6 and Omega-3 F.As. The first double bond: • At carbon 6 (omega-6) (e.g. vegetable oils) • At carbon 3 (omega-3) (e.g. fish oils)

18. Essential fatty acids • Mammals cannot synthesize the two main types of polyunsaturated fatty acids: the linoleic (omega-6) and linolenic (omega-3) • Essential fatty acid deficiency is characterized by dermatitis and poor wound healing • Most prostaglandins are synthesized from arachidonic acid (a linoleic acid derivative) • Lack of these prostaglandins causes some aspects of the essential fatty acid deficiency syndrome

19. Essential fatty acids • A small daily intake of linolenic acid is recommended (this may be especially important when the nervous system is developing) • Docosahexaenoic acid (22:6 3,6,9,12,15,18) is needed for maximum development of the visual and central nervous systems during the neonatal period (it is present in large amounts in the retina and parts of the brain; it enhances the visual response and the function of certain domains in neural membranes)

20. Prostaglandins Prostaglandins have: • 20 carbon atoms in their fatty acid chains. • An OH on carbon 11 and 15. • A trans double bond at carbon 13.

21. Prostaglandins in the Body Prostaglandins are: • Produced by injured tissues. • Involved in pain, fever, and inflammation. • Not produced when anti-inflammatory drugs such as aspirin inhibit their synthesis.

22. Other eicosanoids • When a cell responds to a stimulus, bioactive mediators (prostaglandins, thromboxanes, leukotrienes, and others) often are formed from the lipids contained in its membranes. • Thromboxanes regulate blood coagulation. • Leukotrienes play a role in allergic and inflammation responses. They were isolated from leukocytes (white blood cells).