Fatty Acids PDF

# Your Patient A 55 year old male was presented to the ER because he felt crushing chest pain which radiated to the left arm. He was a chain smoker for the last 25 years. He felt mild chest pain when climbing stairs. # Lecture Objectives At the end of the lecture students will be able to: - Expl...

# Your Patient A 55 year old male was presented to the ER because he felt crushing chest pain which radiated to the left arm. He was a chain smoker for the last 25 years. He felt mild chest pain when climbing stairs. # Lecture Objectives At the end of the lecture students will be able to: - Explain the chemical structure of fatty acids. - Classify fatty acids with examples. - Describe the properties and functions of fatty acids. - Explain clinical significance of fatty acids. # Lipids - Lipid: That is insoluble in water, but soluble in an organic solvent e.g. ether, benzene, acetone, chloroform. - "lipid" is synonymous with "fat", but also includes waxes, oils, steroids etc. # Lipids are present in both animals and plants The image shows different food items that contain lipids. # CALORIE Energy yield from Nutrients: | Nutrient | Calorie Yield | |---|---| | Fat | 9 Cal / gm | | Carbohydrates | 4 Cal / gm | | Protein | 4 Cal / gm | # Essential functions - Lipids act as a dietary vehicle for the lipid soluble vitamins. - Dietary lipids supplies essential polyunsaturated fatty acid. - These polyunsaturated fatty acid as well other Fatty acids formed from them are important in membrane phospholipids. # Fatty Acids They are basic building blocks of lipids. ## Saturated Fatty Acid The image shows the structure of a saturated fatty acid. # Fatty acid are Amphipathic nature The image shows that fatty acids have a polar head group and apolar hydrocarbon tails. ## Micelle The image shows the arrangement of fatty acids in a Micelle. # There are two types of fatty acids: ## Saturated & Unsaturated Fatty Acids The image shows the difference between saturated and unsaturated fatty acids. # TYPES OF FATTY ACIDS (according to the number of double bonds) - Saturated (No bond) - Monounsaturated (1 bond) - Polyunsaturated (>1 bond) # Saturated and Monounsaturated Fatty Acids - The double bond is normally in a cis configuration. - Each cis double bond causes a kink in the chain. ## Chemical Structure Of Fatty Acids The image shows the chemical structures of saturated and unsaturated fats. # Saturated and Unsaturated Fatty Acids - Saturated fatty acids - Unsaturated fatty acids The image shows the difference between saturated and unsaturated fatty acids. # Clinical Correlation - Saturated fats can be converted into cholesterol by the liver. - Role of saturated Fatty acids in Obesity, Cardiac diseases, Atherosclerosis, Diabetes Mellitus type 2, certain cancers, stroke. # Most commonly found Fatty acids in human body have 16- or 18-carbon chain - Saturated Fatty acids: - Palmitic acid (16) - Stearic acid (18) - Unsaturated Fatty acids: - Palmitoleic acid (16c) one double bonds - Oleic acid (18c) one double bonds - Linoleic acid (18c) two double bonds - Linolenic acid (18c) three double bonds - Arachidonic acid (20c) four double bonds. # The most abundant fatty acids are: - 18 carbon chain length 1 double bond $CH_3(CH_2)_7CH=CH(CH_2)_7COOH$ Oleic acid - 18 carbon chain length 2 double bonds $CH_3(CH_2)_4CH=CHCH_2CH=CH(CH_2)_7COOH$ Linoleic acid - 18 carbon chain length 3 double bonds $CH_3CH_2CH=CHCH_2CH=CHCH_2CH=CH(CH_2)_7COOH$ Linolenic acid # Nomenclature The image shows the nomenclature of fatty acids. - The carbon atom closest to the carboxyl group is the alpha carbon, the next carbon is the beta carbon and so on. # IMPORTANT FATTY ACIDS | NAME | STRUCTURE | |---|---| | PALMITIC ACID | 16:0 | | STEARIC ACID | 18:0 | | PALMITOLEIC ACID | 16:1^9 | | OLEIC ACID | 18:1^9 | | LINOLEIC ACID | 18:2^9,12 | | LINOLENIC ACID | 18:3^9,12,15 | | ARACHIDONIC ACID | 20:4^5,8,11,14 | # Fatty Acid Properties - Melting Temperature of saturated fatty acid increases with increasing chain length. - For unsaturated fatty acid melting temperature decreases with the increase in the number of double bonds. - Increase in the chain length of fatty acid decreases their solubility while increase in the double bond makes them more soluble. # FATTY ACIDS | | Saturated | Unsaturated | |---|---|---| | Formula | Common Name | Melting Point | Formula | Common Name | Melting Point | | $CH_3(CH_2)_10CO_2H$ | lauric acid | 45 °C | $CH_3(CH_2)_5CH=CH(CH_2)_7CO_2H$ | palmitoleic acid | 0 °C | | $CH_3(CH_2)_12CO_2H$ | myristic acid | 55 °C | $CH_3(CH_2)_7CH=CH(CH_2)_7CO_2H$ | oleic acid | 13 °C | | $CH_3(CH_2)_14CO_2H$ | palmitic acid | 63 °C | $CH_3(CH_2)_4CH=CHCH_2CH=CH(CH_2)_7CO_2H$ | linoleic acid | -5 °C | | $CH_3(CH_2)_16CO_2H$ | stearic acid | 69 °C | $CH_3CH_2CH=CHCH_2CH=CHCH_2CH=CH(CH_2)_7CO_2H$ | linolenic acid | -11 °C | | $CH_3(CH_2)_18CO_2H$ | arachidic acid | 76 °C | $CH_3(CH_2)_4(CH=CHCH_2)_4(CH_2)_2CO_2H$ | arachidonic acid | -49 °C | # Essential Fatty Acids - Essential Fatty acids must be obtained from the diet. - Two essential fatty acids are linoleic acid (omega 6, 18:2), and linolenic acid (omega 3, 18:3) - Arachidonic acid is formed from linoleic acid. Arachidonic acid is itself an important precursor for prostaglandins, thromboxanes, leukotrienes (which function as local hormones). # Omega Carbon In fatty acids the carbon atom of the methyl group at the end of the hydrocarbon chain is called the omega carbon. - Alpha-Linolenic acid (omega 3) - Linoleic acid (omega 6) # Cardioprotective Effects of Omega-3 Fattty acids - Omega-3 fatty acid are correlated with a decreased risk of cardiovascular disease. - A diet high in omega-3 fatty acids has also been associated with a decrease in serum triglycerides. - omega-3 fatty acids are found in cold-water fish, such as salmon, tuna and herring, as well as in walnuts and flax seeds. # Fatty Acids and Rancidity - Rancidity: spoiling of fats through oxidation. - The more double bonds there are, the more susceptible to oxidation and rancidity. - PUFA > MUFA > Saturated fatty acids. - Food exposure to oxygen, heat and light. # Hydrogenation of vegetable oils - At industrial level vegetable oils are saturated by the process of hydrogenation, which results in the saturation of fats. - Due to increase in melting point they are solidified i.e., converted to solid fats (banaspati ghee). # Hydrogenation Adding Hydrogen to an unsaturated fatty acid ## Hydrogenation of Oleic Acid $3(CH_2)_2CH=CH(CH_2)_2C-OH + H_2 \longrightarrow CH_3(CH_2)_7CHCH(CH_2)_7C-O$ Oleic Acid - Unsaturated $CH_3(CH_2)_7C-C-(CH_2)_7C-$ Stearic Acid - Saturated # TRANS FATS - Unsaturated FA but behave like Saturated FA. - synthetically made by partial hydrogenation of liquid vegetable oil→ Banaspati Ghee / Margarine. -> Used in baking / deep frying # Trans Fat Behave Like Saturated Fat - Stearic acid (saturated) - Elaidic acid (trans-unsaturated) - Oleic acid (cis-unsaturated) # Cis- Trans Fatty acid - Oleic Acid - Elaidic Acid The image shows the difference between cis and trans fatty acids. # BAD FATS Trans fats raise your bad (LDL) cholesterol levels and lower your good (HDL) cholesterol levels. Eating trans fats increases your risk of developing heart disease and stroke. # Trans fat in your food - Baked goods, such as cakes, cookies and pies. - Shortening. - Microwave popcorn. - Frozen pizza. - Refrigerated dough, such as biscuits and rolls. - Fried foods, including french fries, doughnuts and fried chicken. - Nondairy coffee creamer. - Stick margarine # Reference Books - Harper's Illustrated Biochemistry - Lippincott's Illustrated reviews of Biochemistry - Lehninger's Principles of Biochemistry - Biochemistry by Devlin