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BY: RASAQ, N. O
LECTURE CONTENTS INTRODUCTION TO VITAMINS COMPOSITION OF VITAMINS CLASSIFICATION OF VITAMINS FAT SOLUBLE VITAMINS: STRUCTURE ANDFUCTIONS WATER SOLUBLE VITAMINS AND FUNCTIONS COENZYMES AND FUNCTIONS MINERALS AND FUNCTIONS2
INTRODUCTION TO VITAMINS Vitamins are organic compounds required by the body in small amounts for metabolism, for protection, formaintenance of health and proper growthThey cannot be synthesized by the body. Must beobtained by outside sources like diet, rumen ofbacteria & sun.Vitamins also assist in the formation of hormones,blood vessels, nervous system chemicals and geneticmaterialsThey generally act as catalysts, combining withproteins to create metabolically active enzymes thatare essential for life reactionsWithout enzymes, many of the reactions essential tolife would slow down or cease3
COMPOSITION OF VITAMINS Vitamins are of different chemicalnature. These are alcohols, aldehydes,organic acids, their derivatives andnucleotide derivatives4
CLASSIFICATION OF VITAMINS Vitamins are classified according to their abilityto be absorbed in fat or water 1. Fat Soluble Vitamins: these are oily andhydrophobic compounds, they are stored in theliver and not excreted out of the body. Bile saltsand fats are needed for their absorption. VitaminsA,D,E and K are fat soluble 2. Water Soluble Vitamins: Vitamin B complex andVitamin C are water soluble. They are not storedin the body, therefore are required daily in smallamounts5
CLASSIFICATION OF VITAMINS CONT’DFat Soluble Vitamins:stored in tissuesExamplesADEKWater Soluble Vitamins:not stored in tissues,must have constantsupplyExamplesB, B1, B2, B6 & B12NiacinFolic AcidC6
FAT SOLUBLE VITAMINSVITAMIN AVitamin A is a paleyellow primary alcoholderived from carotene.It include Retinol(alcoholic form),Retinal (aldehydeform) and Retinoic acid( acidic form)Sources, physiologicalfunctions anddeficiency: refer tonotesSTRUCTURE OF VITAMIN A7
FAT SOLUBLE VITAMINSVITAMIN D(Calciferol)This comprises a group offat soluble sterol foundsnaturally in few foods.The two majorphysiolgically relevantforms of vitamin D are D2(ergocalciferol) and D3(cholecalciferol) Sources, physiologicalfunctions anddeficiency: refer tonotesSTRUCTURE OF VITAMIN D8
FAT SOLUBLE VITAMINSVITAMIN Ealso called Tocopherol orfertility hormoneVitamin E is required in thehuman diet but itsdeficiency is rare except inpregnancy and the newborn, where it is associatedwith hemolytic anaemia It exists in the diet as amixture of eight closelyrelated compoundscalled tocopherols Sources, physiologicalfunctions and deficiency:refer to notesSTRUCTURE OF VITAMIN E9
FAT SOLUBLE VITAMINSVITAMIN KAlso called phylloquinoneor anti-hemorragicvitamin or coagulationvitamin. Vitamin K is acomplex unsaturatedhydrocarbon found in twoforms, vitaminK1(phylloquinone) andvitaminK2(Menaquinone)Sources, physiologicalfunctions and deficiency:Refer to notesSTRUCTURE OF VITAMIN K10
WATER SOLUBLE VITAMINS These include the B-vitamins and vitaminC They are soluble in water and can therefore beexcreted in the urine They share few common properties besides theirsolubility characteristics Most of these vitamins act as coenzymes Examples include thiamine (Vit B1), Riboflavin(B2), Niacin, Pantothenic acid (Vit B5), Vitamin B6(Pyridoxine), Biotin, Vitamin B12 (Cobalamin)and folic acid11
WATER SOLUBLE VITAMINSVITAMIN B1(Thiamine) It is a colourless andcrystalline substance It is readily soluble inwater and slightly in ethylalcohol Addition of apyrophosphate(ppi) fromATP converts it tothiamine pyrophosphate(TPP), the coenzyme forall decarboxylation ofalpha keto acids Source, physiologicalfunctions and deficiency:refer to notesSTRUCTURE OF VITAMIN B112
WATER SOLUBLE VITAMINSVITAMIN B2 (Riboflavin) It is a component of theflavin coenzymes, FADand FMN. it is composed of anisoalloxazane ring systemlinked to ribitol It is mainly used inenergy metabolism ofsugars and lipids The activation of FMNand FAD is an ATPdependent reaction Source, physiologicalfunction and deficiency:refer to notesSTRUCURE OF VITAMIN B213
WATER SOLUBLE VITAMINSVITAMIN B3(NIACIN ORNICOTINIC ACID) Niacin can be synthesizedfrom tryptophan Niacin contains asubstituted pyridine ringand when NAD activatedforms NAD and itsphosphorylated derivativeNADP , which arecoenzymes of manydehydrogenases Sources, physiologicalfunctions and deficiency:refer to notesSTRUCTURE OF VITAMIN B314
WATER SOLUBLE VITAMINSPANTOTHENIC ACID (VIT.B5) STRUCTURE OF VIT .B5 Also called coenzyme,pantothenic acid is avitamin that forms anessential part of acyl groupsin general, including theacetyl group derived frompyruvate The coenzyme is derivedmetabolically from ATP, thevitamin pantothenic acidand β-mercaptoethylamine Sources, physiologicalfunctions and deficiency:refer to notes15
WATER SOLUBLE VITAMINSVITAMIN B6(PYRIDOXINE) Vit.B6 exists in three forms:Pyridoxine, Pyridoxal andPyridoxamine and theircorresponding phosphates Pyridoxal phosphateparticipates intransaminations,decarboxylations,racemizations and numerousmodification of amino acidsequence side chains Sources, physiologicalfunctions and deficiency:Refer to notesSTRUCTURE OF VIT.B616
WATER SOLUBLE VITAMINSVITAMIN B7 (BIOTIN) Biotin is a vitamin and acoenzyme commonlyassociated with enzymeperformingcarboxylation reactions Biotin is also known as“anti-egg white injuryfactor” or as H-factor Sources, physiologicalfunctions anddeficiency: refer to notesSTRUCTURE OF B717
WATER SOLUBLE VITAMINSVITAMIN B9 or M or Bc(folic acid) The active form acid istetrahydrofolate (THF) Coenzymes derived fromthe vitamin folic acidparticipates in thegeneration andutilization of single –carbon functionalgroups, methyl,methylene and formyl Sources, physiologicalfunctions anddeficiency:Refer to notesSTRUCTURE OF VIT.B918
WATER SOLUBLE VITAMINSVITAMIN B12(Cyanocobalamin) The metal cobalt invitamin B12 iscoordinated with atetrapyrole ring system,called a corin ring, whichis similar to the porphyrinringof heme compounds B12 requiring reactionsinvolve methyl grouptransfer andadenosylcobalamindependentisomerizations. Sources, physiologicalfunctions and deficiency: Refer to notesSTRUCTURE OF B1219
WATER SOLUBLE VITAMINSVITAMIN C (Ascorbicacid) It is a water solublevitamin It is essential for thehydroxylation ofproline and lysine inthe formation ofcollagen Collagen is a fibrousprotein with myriadconnective andsupportive functions Sources, physiologicalfunctions anddeficiency: Refer to notesSTRUCTURE OF VIT.C20
COENZYMES AND COFACTORS Cofactors essentially act as enzymes’ CHEMICALTEETHCofactorsEssential ionsActivator ionsMetal ions of(loosely bound) metalloenzymes(tightly bound)CoenzymesCosubstrates(loosely bound)Prostheticgroups(tightly bound)21
MANY VITAMINS ARE COENZYMEPRECURSORS22
MINERALS Minerals are inorganic elements needed for thefunctioning of the body They make up about 4%of body weight of adults,they cannot be changed or broken down Some which are needed in high quantities arereferred to as macro-elements, examples includeNa, K, Mg, Cl etc. Others are needed in smaller quantities and aretermed microelements, they include Fe, Cu, F, Ietc.23
MACRO-ELEMENTS The body requires relatively large amounts ofabout 7 minerals (macro-elements)1 Calcium (Ca)2 Phosphorus (P)3 Sulphur4 Magnesium5 potassium6 Chlorine7 Sodium24
MACRO-ELEMENTS Calcium ( Ca)Functions: Calcium plays myriad of functions thatincludesBones and teeth formation, membrane transport,nerve transmission, muscle contraction, hearthrhythm, blood clotting and enzyme cofactorSources: milk, milk products and leafy vegetablesDeficiencies : Osteoporosis and Bone fracturesExcesses: Nausea, vomiting, loss of appetite, kidneytoxicity, irregular heart beat, reduced absorption ofiron and zinc25
MACRO-ELEMENTS Phosphorus (P)Functions: in bone and teeth formation, ATPformation, creatine phosphate, DNA and RNA,phospholipids and active transportSource: Cheese, milk, nuts and eggsDeficiencies: hypophosphatemia with symptomssimilar to calcium deficiencyExcesses: Reduce body stores of calcium26
MACRO-ELEMENTS3. Sulphur (S): needed by most proteins4 Magnesium (Mg): it acts as coenzymes forenzymesSources: vegetables, cereals, beans, potatoes,cheese and animal tissuesDeficiencies: can result in poor calcium absorptionExcesses: Heart problems and difficulty inbreathing5 Potassium (K), 6 Chlorine (Cl) and 7 Sodium (Na)Functions: Osmotic Balance, Nerve impulse,Muscle contractions27
MICRO-ELEMENTS The body requires only trace amounts of others(micro-elements). These includes 1. Flouride (F)Functions: it strengthens bonesExcesses: Browning of teeth, brittle bones, fatigueand muscle weakness 2. Iodine (I)Functions: Synthesis of thyroid hormonesDeficiences: Goiter, mental and physicalretardation (cretinism)28
MICRO-ELEMENTS 3. Iron (Fe)Functions: Heamoglobin synthesisExcesses: has been linked to arthritis, heart disease,diabetes, infectious disease and cancer 4 Cobalt, 5 Chromium and 6 ManganeseFunctions: Cofactors for enzymes 7 CopperFunctions: Cofactors for enzymesDeficiency: Anemia, impaired immunity, alterediron metabolism29
MICRO-ELEMENTS 8 ZincFunctions: Cofactors for enzymes, synthesis oftestosterone and sperm developmentDeficiencies: Reduced immune functions, Vomiting,gastric upset and slow absorption of copper 9 Molybdenum: Functions: Cofactors for enzymes Excesses: Increased secretion of copper 10 SeleniumFunctions: Cofactors for enzymesDeficiencies: muscle pain or weakness and impairedimmunityExcesses: Fragile nails, hair loss, fatigue, abdominalpain, nausea and nerve damage30
CLASSIFICATION OF VITAMINS Vitamins are classified according to their ability to be absorbed in fat or water 1. Fat Soluble Vitamins: these are oily and hydrophobic compounds, they are stored in the liver and not excreted out of the body. Bile salts and fats are needed for their absorption. Vitamins A,D,E and K are fat soluble 2. Water Soluble .
