Fatty Acids and their derivatives

Lipid

Organic molecule which are not soluble I water but soluble in organic solvents

Functions of lipids

1. Insulation: fat deposited subcutaneasly acts as insulating material protecting bodies from extremes

2. Energy: major source

3. Creams: prevent water loss from skin

4. Birds: coats feathers preventing them from getting wet

5. Plants: coats leaves prevents abrasion and loss of moisture via evaporation

6. Hormones and vitamins

7. Plasma membrane

8. Blood

9. Organs

Classifications of lipids

1. Fatty acids and their derivatives

2. Glycerides (neutral esters of fatty acids and glycerols)

3. Phospholipids (ionic Ester of fatty acids glycerols and phosphoric acid)

4. Sphingolipids (lipids without glycerol)

5. Lipoproteins, glycoproteins (lipids combined with proteins)

Fatty acid

Have hydrophilic polar carboxyl group and hydrophobic non-polar hydrocarbon chain

1. Saturated: solid and easy at room tempreture. CnH2n+1COOH. Contain only single C-C bonds mostly esterified except free fatty acids

2. Unsaturated: C-C double bonds. Lower melting and boiling point as number of double bonds increase. More soluble in non-polar solvents. Liquid at room tempreture. Total number of double bonds determine degree on unsaturated

Unsaturated fatty acids

1. Monounsaturated (MUFA): contain only one C-C double bond

2. Polyunsatyrated (PUFA): -Dienoic series (contains 2 C-C double bonds (omega 6- linoleic acid C18:2 □9,12))

   -Trienoic series (3 C-C double bonds [omega 3 à-linoleic acid C18:3□8,12,15])

   -Tetranoic series (4 double bonds [arachidonic acid C20:4□5,8,11,14])

   -Pentatonic series (5 double bonds [eicosapentanoic acid C20:5□5,8,11,14,17)

   -Hexanoic series (6 double bonds [docosahexanoic acid C22:6□4,7,10,13,16,19])

Essential fatty acids

Cannot be produced in animal and human systems that they rely on plants to recieve. Omega 3 and 6. Plant desaturase enzymes are capable of providing double bonds at positions □12 and 15 which isn’t possible in animal and human systems. Saturated fatty acids biosynthesized 1st than double bonds are introduced later and various positions. Human and animal systems cannot introduce double bonds beyond the □9 position

Prostaglandin

Synthesized in all mammalian cells expect RBCs. Contain diverse groups such as keto (=C=O), carboxyl (-COOH) and hydroxyl (OH). Trans configuration

Functions: water retention, ion transport and BP regulation

Induce child birth and abortions

Prevent and treat peptic ulcers

Relief from pulmonary hypertension

Treat erectile dysfunction

Thromboxane

1st isolated from blood platelets. Has 6 membered ring with ether.

Functions: produced by platelets and act in formation of blood clots.

Reduction of blood flow to site of blood clot formation

Leukotrienes

Found in WBCs or leukocytes and contain 3 conjugated double bonds

Functions: results in contraction of smooth muscles, lungs

Inflammatory properties in rheumatoid arthritis

Asmatha attack result from contraction function of LTC4

Reaction of fatty acids

1. Esterification: one molecule of acid+ one molecule of alcohol react reversibly = H2O and ester

2. Hydrogenation: H2 may be added across the double bonds on unsaturated fatty acids in presence of Ni, Pt/d catalysts in cis

3. Ozonolysis: O3 can join with a double bond to form unstable ozonide with final product of 2 aldehydes

4. Oxidation by KMnO4: unsaturated

5. Peroxide formation causes rancidity

Isomerism

1. Geometrical: orientation of hydrocarbon around the double bond. Most cis but Trans more stable

2. Positional: number of isomers depend on the position of double bonds and number of carbon atom