Mansoura National University Faculty of Medicine Level 1 Semester 1 Lecture Notes on Lipids PDF

Mansoura National University Faculty of Medicine Level: 1 Semester: 1 2024-10-27 Mansoura National University 1  Lipids Chemistry Fatty Acids & Simple Lipids By Dr. Wesam Sameer El-Saeed...

Mansoura National University Faculty of Medicine Level: 1 Semester: 1 2024-10-27 Mansoura National University 1  Lipids Chemistry Fatty Acids & Simple Lipids By Dr. Wesam Sameer El-Saeed Email: [email protected] 2024-10-27 Mansoura National University 2  Contents Lipids: definition, biological importance and classification. Glycerol structure and importance. Fatty acids: definition, classifications. Essential fatty acids. Simple lipids: fats and oils – waxes. 2024-10-27 Mansoura National University 3  Learning Outcomes (LOs) At the end of this session, the students should be able to: Identify the general classification of lipids and its biological importance. Define and classify fatty acids. Understand the biological significance of essential fatty acids and recognize its sources. Describe the structure and function of different types of simple lipids. Correlate their knowledge to a clinical situation. 2024-10-27 Mansoura National University 4  Case scenario (Clinical correlate) A 54-year-old man with a history of hypertension and a family history of coronary artery disease (CAD) presented at night to the emergency department with intermittent squeezing chest pain, lasting for less than 5 minutes at a time. He had participated in a football match earlier in the same day. While in the ambulance, the patient had an episode of chest pain and was given a sublingual tablet by the ambulance crew, and 5 minutes later, the pain was relieved. What is your provisional diagnosis? What is the structure and mechanism of the given tablet ? 2024-10-27 Mansoura National University 5  LO 1 Identify the general classification of lipids and its biological importance. 2024-10-27 Mansoura National University 6  Lipids ❖ Lipids are organic compounds. ❖ They are esters of fatty acids or substances related to them. ❖ They are relatively insoluble in water (hydrophobic) but soluble in fat solvents (nonpolar organic solvents) e.g. benzene, chloroform, acetone and ether. 2024-10-27 Mansoura National University 8  Biological Importance of lipids Structure of cell membrane Metabolic regulators Source of energy (steroid hormones) Store of energy (TG in adipose tissue) LIPIDS Absorption of fat soluble vitamins (E,D,A,K) Thermal insulator (lipids under skin) Protection and Electrical insulator fixation of internal (lipids in myelin sheath) organs as kidneys 2024-10-27 Mansoura National University 29  Classification of lipids 2024-10-27 Mansoura National University 29  Classification of lipids 2024-10-27 Mansoura National University 29  Glycerol ❖ It is a polyhydric (trihydric) alcohol, containing 3 OH groups. ❖ Importance of glycerol: 1- It is used in pharmaceutical (e.g. glycerin suppositories) and cosmetic preparations. 2- It is used as vasodilator agent in coronary heart disease in form of nitro-glycerin. 2024-10-27 Mansoura National University 8  LO 2 Define and classify fatty acids LO 3 Understand the biological significance of essential fatty acids and recognize its sources 2024-10-27 Mansoura National University 6  Fatty acids (FAs) ❖ Fatty acids are organic acids, usually monocarboxylic chains with a methyl group (CH3) at one end → called the ω-carbon and a carboxyl group (COOH) at other end → called C1. ❖ The general formula of fatty acid is R-COOH CH3 2024-10-27 Mansoura National University 8  Fatty acids (FAs) Q What is the Omega-3 (ω-3) Fatty acid? → Fatty acid contains 1 st double bond position at C3-C4 (if we count from CH3:ω1). ω-6 represent 1 st double bond position at C6-C7 ω-9 represent 1 st double bond position at C9-C10 2024-10-27 Mansoura National University 8  Classifications of Fatty acids 2024-10-27 Mansoura National University 8  Classifications of Fatty acids ❑ Depending on length of hydrocarbon chain: a. Short chain: with 2 to 6 carbon atoms. b. Medium chain: with 8 to 14 carbon atoms. c. Long chain: with 16 to 22 carbon atoms. d. Very long chain fatty acids: ≥ 24 carbon. 2024-10-27 Mansoura National University 8  Classifications of Fatty acids ❑ Depending on length of hydrocarbon chain: Short chain FA Long chain FA Number of carbon Less than 10 More than 10 atoms carbons carbons Consistency at Liquid Solid room temperature Volatility Volatile Nonvolatile Solubility in water Soluble Insoluble Acetic (2 C) Palmetic (16 C) Examples Butyric (4 C) Stearic (18 C) 2024-10-27 Mansoura National University 8  Classifications of Fatty acids ❑ Depending on total number of carbon atoms: a. Even chain: ✓ They have carbon atoms 2, 4, 6 and similar series. ✓ Most of the naturally-occurring lipids contain even chain fatty acids. b. Odd chain: ✓ They have carbon atoms 3, 5, 7, etc. ✓ As propionic acid (3 C). 2024-10-27 Mansoura National University 8  Classifications of Fatty acids ❑ Depending on nature of hydrocarbon chain (presence of double bond =): a. Saturated fatty acids: ✓ No double bonds. ✓ They have the general formula : CH3 – (CH2)n – COOH. ✓ Ex. acetic, butyric, palmitic, stearic. ✓ Common sources: cream, cheese, butter, fatty meats, coconut oil and palm oil. 2024-10-27 Mansoura National University 8  Classifications of Fatty acids ❑ Depending on nature of hydrocarbon chain (presence of double bond =): b. Unsaturated fatty acids: ✓ having double bonds, sub-classified into: Mono-unsaturated (mono-enoic): having single double bond. Ex. Palmitoleic (16), Oleic (18). Common sources: vegetable oils (olive, corn, Sunflower), nuts and cod liver oil. Polyunsaturated (PUFA) (poly-enoic): having ≥ 2 double bonds. Essential Ex. Linoleic (ω6) – Linolenic (ω3) – arachidonic (ω6). FAs 2024-10-27 Mansoura National University 8 ❑ Essential fatty acids: They are Poly-Unsaturated Fatty Acids (PUFA). They must be taken in diet because the enzymes that are needed for their synthesis are absent in humans. They are essential for growth. They are important for phospholipids and eicosanoids (ex. prostaglandins) formation. Common sources: vegetable oils (corn, soybean, Sunflower seeds), fish, nuts and olives. 2024-10-27 Mansoura National University 8 ❑ Essential fatty acids: They have a cardio protective role →They are esterified with free cholesterol forming cholesterol esters (which are less liable to be deposited in the coronary arteries). → ↓ serum cholesterol, TG, LDL and ↑ HDL levels → Protect against atherosclerosis and cardiovascular diseases. 2024-10-27 Mansoura National University 8  For longer life, eat healthy fats 2024-10-27 Mansoura National University 8  LO 4 Describe the structure and function of different types of simple lipids 2024-10-27 Mansoura National University 21  Classification of lipids 2024-10-27 Mansoura National University 29  Simple lipids ❖ Esters of fatty acids with various alcohols. 1- Fats & oils (Triacylglycerol, TG): They are esters of 3 fatty acids with glycerol. TGs are the major dietary fat and the storage form of lipids in the adipose tissue. TGs are carried in blood by lipoproteins. 2024-10-27 Mansoura National University 8  Simple lipids 1- Fats & oils (Triacylglycerol, TG): According to fatty acids in TG: A) Simple TG: same FAs. B) Mixed TG: different FAs (more common). 2024-10-27 Mansoura National University 8  Simple lipids 2- Waxes: They are esters of one fatty acid with long chain alcohol higher than glycerol (ex. cholesterol). Examples of waxes: ✓ Bee’s wax: the most commonly known animal wax. ✓ Cholesterol esters (cholesterol wax): one of the most important waxes in plasma and tissues. 2024-10-27 Mansoura National University 8  Simple lipids 2024-10-27 Mansoura National University 8  MCQs s 2024-10-27 Mansoura National University 37 Q The major storage form of lipids in adipose tissue is___. a) Ceramide b) Sphingomyelin c) Phospholipids d) Steroids e) Triglycerides 2024-10-27 Mansoura National University 30 Q The number of double bonds in stearic acid is ___. a) None b) 1 c) 2 d) 3 e) 4 2024-10-27 Mansoura National University 31 Q The hydrolysis of cholesterol ester gives ___. a) Cholesterol and 3 fatty acids b) Cholesterol and 1 fatty acid c) Glycerol and 3 fatty acids d) Glycerol and 1 fatty acid e) Cholesterol and glycerol 2024-10-27 Mansoura National University 31 Q The fatty acid which must be taken in diet is called ___. a) Saturated fatty acid b) Unsaturated fatty acid c) Essential fatty acid d) Even chain number fatty acid e) Odd chain fatty acid 2024-10-27 Mansoura National University 31 Q ____ are examples of essential fatty acids. a) Linoleate and arachidonic b) Linoleate and oleic c) Stearic and arachidonic d) Stearic and palmitic e) Linoleic and oleic 2024-10-27 Mansoura National University 31 Q ____ is an example of monounsaturated fatty acid. a) Palmitic b) Arachidonic c) Stearic d) Oleic e) Linoleic 2024-10-27 Mansoura National University 31  References Chatterjea textbook of Medical Biochemistry, 8th edition, 2012. Vasudevan's Textbook of Biochemistry For Medical Students, 6th Edition. Mark′s essentials of Medical Biochemistry, a clinical approach, 2nd edition, 2015. Harper's Illustrated Biochemistry. 31e, Chapter 21, Botham & and Mayes, eds. 2024-10-27 Mansoura National University 37 2024-10-27 Mansoura National University 38