Biochemistry Tutorial 7: Vitamins - Winter 2023/4 PDF

Biochemistry – Winter 2023/4 Tutorial 7: Vitamins Nourhan Elfar, PhD Nihal Moustafa Mansour, PhD Assistant Professor of Biochemistry Assistant Professor of Biochemistry [email protected] n.m...

Biochemistry – Winter 2023/4 Tutorial 7: Vitamins Nourhan Elfar, PhD Nihal Moustafa Mansour, PhD Assistant Professor of Biochemistry Assistant Professor of Biochemistry [email protected] [email protected] Mohamed Mohamed Naguib, PhD Assistant Professor of Biochemistry [email protected] December 20, 2024  Vitamins ✓ Vitamins are a group of organic nutrients that are chemically unrelated (no chemical grouping common to them all). ✓ They are required in the diet of human and animals in small amounts (because they are not synthesized by the body). ✓ They are needed for a variety of biochemical functions as for normal growth, maintenance of life, normal reproduction, and specific metabolic functions. ✓ They are not a source of calories (energy). 2 Lecture 9  Classification of Vitamins Vitamins are classified according to their solubility in water or fat into Water-soluble vitamins Fat-soluble vitamins ✓ They cannot be stored in the body (may ✓ They can be stored in the body (liver and be stored in limited amounts) so, regular fatty tissues) so, there is no need for supply is needed. regular supply. ✓ Excess of these vitamins in the body is ✓ They can be accumulated to toxic levels if excreted in the urine so; there is no large amounts ingested (hypervitaminosis) danger or toxicity levels of these because they are not readily excreted from vitamins. the body. ✓ They do not require bile for their ✓ They are found in fats and oils and require absorption and enter the blood directly. bile for intestinal absorption and enter the lymph then the blood with the dietary lipids. ✓ They include vitamin B-complex and vitamin C. ✓ They include vitamins D, E, K and A. 3 Classification of Vitamins 4 Lecture 9  I. Fat-Soluble Vitamins Vitamin Vit. A (Anti-Night blindness vit.) Vit. D (Anti-Ricket vit.) Chemistry Present in vegetables as pro-vitamin b It is a Steroid-derived vitamin that acts carotenes (yellow or orange pigment) as hormones. composed of 2 retinal. In human, vitamin D is the only fat-soluble vitamin that body can make in the presence of sunlight and cholesterol as precursor (non-essential vitamin). Functions 1. Responsible for visual process. 1. It plays an essential role in the 2. Maintenance of healthy epithelial regulation of the metabolism of calcium tissues as skin and mucous and phosphorus in the body. membranes. 2. It is necessary for the proper 3. b-carotene and other carotenoids formation of bones and teeth. are important antioxidants. Deficiency It Causes: It Causes: 1.Night blindness. 1. Rickets in children or Osteomalacia in 2. The skin, hair and nails become adults. extremely dry & rough. 5 BIOC 302 – Vitamins and Inorganic Metabolism Lecture 6 1: Homeostasis  I. Fat-Soluble Vitamins Vitamin Vit. E (Antioxidants) Vit. K (Anti-hemorrhagic vit.) Chemistry It has 3 types: 1) K1 type, phylloquinones of plant origin. 2) K2 type, menaquinones of bacterial origin (normal intestinal bacteria). 3) K3 type, menadione (synthetic). Functions Acts as Antioxidant that prevents It catalyzes the synthesis of several the cellular DNA alteration, the risk blood clotting factors including of Cancer development, Heart prothrombin in the liver. diseases and stroke. Deficiency 1) Anemia due to oxidative damage of It causes hemorrhagic diseases and RBCs. uncontrolled bleeding in various tissues. 2) Increased peroxide formation which is Carcinogenic. 7 BIOC 302 – Vitamins and Inorganic Metabolism Lecture 8 1: Homeostasis  II. Water-Soluble Vitamins A. Vitamin C (Non-B-Complex Vitamin) Vit. C (Ascorbic Acid or Anti-Scorbutus Vit.) It is a Reducing Agent in several reactions including formation of Collagen (Connective tissue protein) that is the cementing substance of Bone Matrix and Cartilage. It is an Antioxidant and prevents Scurvy. It helps the Absorption of iron. It promotes the Healing of Wounds and Healthy blood vessels. Symptoms of vitamin C deficiency (Scurvy): 1. Weakening of connective tissues. 2. Reduced resistance to colds and infections. 3. Incomplete iron absorption → causing anemia. 4. Delayed healing of wounds. 9 Lecture 9  Scurvy BIOC 302 – Vitamins and Inorganic Metabolism Lecture 10 1: Homeostasis  II. Water-Soluble Vitamins B. B-Complex Vitamins Biotin (Anti-raw egg white injury factor or vitamin H or B7) ✓ It acts as Coenzyme in the metabolism of carbohydrates, fats, and amino acids. ✓ Since biotin is synthesized by intestinal bacteria, naturally occurring deficiency disease is unknown, but a disease state can be produced by eating large amounts of raw egg in the diet contains a biotin antagonist avidin glycoprotein that inactivates biotin and inhibit its absorption. 11 Lecture 9  II. Water-Soluble Vitamins Continue B. B-Complex Vitamins Vitamin Vit. B2 (Riboflavin) greenish yellow Vit. B3 (Niacin, Nicotinic acid or Pellagra compound Preventing Factor PFF or Anti-Pellagra) Functions It is a component of 2 coenzymes It is a component of 2 coenzymes for for respiratory enzymes involved in respiratory enzymes involved in redox redox reactions: reactions: 1. FAD (flavin adenine dinucleotide). 1. NAD (nicotinamide adenine dinucleotide). 2. FMN (flavin mononucleotide). 2. NADP (nicotinamide adenine dinucleotide phosphate). Deficiency Deficiency of vitamin B2 leads to: - Causes Pellagra, its symptoms 3Ds 1. Fissures in the corner of the mouth. Dermatitis, Dementia & Diarrhea. 2. Inflammation of the tongue. 3. Skin disease. 4. Severe irritation of the eyes. 12 Fissures in the corner of the mouth Inflammation of the tongue Severe irritation of the eyes BIOC 302 – Vitamins and Inorganic Metabolism Lecture 13 1: Homeostasis  II. Water-Soluble Vitamins Vitamin Folic acid (vitamin B9 or folacin) Vit. B12 (Cobalamin or anti-pernicious anemia factor) Chemistry It contains cobalt atom at center. It is the most complex of all known vitamins. It is produced from bacteria. Higher plants are not able to make vitamin B12 forms. Functions Folic acid is directly involved in It acts as coenzyme in: the synthesis of nucleic acids 1) Synthesis of nucleic acids. and some amino acids. 2) It is involved in the synthesis of proteins Adequate folic acid reduces the and red blood cells (RBCs). risk of premature birth and heart diseases. Deficiency 1. Megaloblastic anemia. Inadequate absorption or deficiency of 2. Inadequate amounts of folic acids vitamin B12 causes pernicious and in the diet of pregnant women are megaloblastic anemia (decreased in RBCs) associated with neural tube and nervous system degeneration. defect in newborns. 14 Neural tube defect in newborns Megaloblastic anemia BIOC 302 – Vitamins and Inorganic Metabolism Lecture 15 1: Homeostasis  Important Notes On Vitamins 1. Vitamins that are recommended for Anemic patients → Vitamins E, C, B6, B9 & B12. 2. Vitamins that are recommended for Pregnant women → Vitamins B9 & B12. 3. Vitamins that act as Antioxidants (Anti-cancer) → Vitamins E, C & A. 4. Vitamins that are synthesized by Intestinal bacteria → Vitamins K2, B7 & B12. 5. Vitamins that are important for Redox reactions → Vitamins B2 & B3. 6. Vitamins that are involved in Energy release → Vitamins B1, B2, B3, B7 & B6. 16 Lecture 9 THE END