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Chapter 7 Vitamins

Introduction. Definition :Vitamins are organic nutrients that are required in small quantities for a variety of biochemical functions and which, generally, cannot be synthesized by the body and must therefore be supplied by the diet??.. history. The early history of vitamins can be traced to observ

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Chapter 7 Vitamins

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    1. Chapter 7 Vitamins ??? ??????????????????,?????????,???????

    2. Introduction Definition :Vitamins are organic nutrients that are required in small quantities for a variety of biochemical functions and which, generally, cannot be synthesized by the body and must therefore be supplied by the diet??.

    3. history The early history of vitamins can be traced to observations that certain disease could be cured by a supplement of another foodstuff. Eg: the ancient Arab physicians and their successors valued the use of liver to cure night blindness, the North America Indian knew that scurvy(???) could be treated by a tea made from cedar(?? ) leaves. In seventeenth century, it was standard procedure for the British Navy to provide lemon juice for its sailors to prevent scurvy.

    4. history Thiamine was discovered in 1912 & was thought to be a vital amine compound & thus the term vitamin was invented Vita=vital for life Min=amine

    5. Properties ??: 1. They are not used for energy supply, but have Important roles in regulating metabolism and maintaining physiological functions of the body. 2. They are low-molecular-weight organic compounds. 3. Generally, they cannot be synthesized in body and must be supplied by the diet in small amounts . 4. Absence or relative deficiency of vitamins leads to characteristic deficiency states and diseases. But if any vitamin is so much in excess of the body’s metabolic capacity, there maybe signs of toxicity.

    6. Classification?? lipid-soluble vitamin: soluble in non-polar organic solvents water-soluble vitamin: soluble in aqueous solvents

    7. Essential Vitamins For Human Being

    8. ????????? 1?????? 2????? 3?????? 4??????? 5????????

    9. Section I Water-soluble Vitamins?????? Common features: ?1.Water soluble ?2.Easy to be discharged through urine. Rarely accumulated to the toxic concentrations. ?3.Their storage is limit. Must be provided regularly. Vitamin B12 is the only water-soluble vitamin that can be stored in the liver for many years.

    10. (?)???C(???? ascorbic acid) Water soluble sour taste (acid) Six-carbon polyhydroxy compound Strong antioxidant ?????????.?? ?????

    11. 1535 Jacques Cartier and his sailors were cured by Newfoundland Indians by drinking the extract from spruce??tree needles. 1747, British naval surgeon prescribed lime?? to sailors to prevent scurvy. Thus the slang limey for British sailor.

    12. 1.Structure ??

    13. 2.??

    15. 3.????(Food Sources of Vitamin C)

    16. Food Sources of Vitamin C---- fresh fruit and vegetables???????

    17. 4.???? (1.) Hydroxylation ????????? Ascorbic acid is required for the activities of some hydroxylase???. ????????????biological oxidation???????Vit C???????????????????? ??collagen???:

    18. ????hydroxyproline?????hydroxylysine?????collagen???,????????????????????? ??????????????hydroxylase?????????????????proline????lysine?????Vit C??????????????Vit C????????????

    19. Collagen Synthesis

    20. Vitamin C deficiency???C???: scurvy ???: It's syptoms included swollen and bleeding gums and loose teeth, brittle?hair and nails, tiredness, problem in the joints ??????capillary fragility??; ???????; ???????menorrhagia; ???calcification??????????

    21. Vitamin C Deficiency Signs

    22. Pinpoint Bleeding in Scurvy 1

    23. Pinpoint Bleeding from Scurvy 2

    24. Hydroxylation ????????? ?????: ?????cholesterol???transformation: Cholesterol ? ? ? bile acid

    25. ????????aromatic amino acids ??: ?????phenylalanine??????tyrosine,???????????hydroxyphenylpyruvatate,??????????????????homogentisate ???Vit C??????Vit C??????????,?????? Vit C?????????biological transformation???????????

    26. (2)??????????? ? Vit C???????mercapto???:

    27. ?????antibody??? ?????? ----??????Fe3+???????Fe2+

    28. (3)?????? ???????? ???:?????

    29. THERAPEUTIC USES Cardiovascular diseases Cataracts ??? Diabetes Mellitus Cancer prevention Common cold Lead? toxicity

    30. ??Vitamin B1(???thiamine)

    31. Active form????: thiamin pyrophosphate ??????(TPP) Thiamin is rapidly converted to TPP in the brain and liver by a specific enzymes, thiamin diphosphotransferase ?????????.

    32. Food Sources of thiamin ??: Unrefined cereal grains and meat;seeds, nuts, legums?? Recommended Dietary Allowance(RDA): M:1.2mg/d, F:1.1mg/d

    33. (?)????: 1?Vit B1?TPP?a??????????????? eg: TPP???????pyruvate decarboxylase?a-???????a-ketoglutarate decarboxylase???,??a-???????? 2? TPP is necessary as a cofactor for the reactions of the pentose phosphate pathway ???????????????? 3???????choline esterase Vit B1?????????,????????????acetylcholine????,???????????

    34. DEFICIENCY & USES Severe thiamin deficiency can lead to: Beri-Beri Wernicke-Korsakoff syndrome??? ?????????????????????????? Thiamin is used for treatment of congestive???? heart failure???? & Alzheimer's disease as well as in cancer prevention.

    35. beriberi???,????? ???,??????????????? ??????????????: 1.?????:????????????????????????? 2.?????:?????????????????????????????????? 3.??????:??????????????,????????

    36. Wet Beri-Beri

    37. RISK OF THIAMIN DEFICIENCY Low intake & alcoholism???? Increased consumption: Malaria??& AIDS Excessive loss: hemodialysis???? and diuretics??? Anti-thiamin factors: tea & coffee. Thiaminases found in raw fish, raw shellfish & in silkworms.

    38. (1)?? ???ribitol,????isoalloxazine ring. ????????? ???? + ??,??? ?.Vitamin B2 (riboflavin???)

    39. Food Sources of riboflavin : Adequate amounts of B2 is present in eggs, milk, meat & cereals. ??,???,?????(??????) ???????????? ??yeast RDA:M: 1.4mg/d, F: 1.2mg/d

    40. Active form: FMN,FAD ????: Vit B2?FMN?FAD????????????????????????. ?????????????????,????????????????????????? ??????????? FMN:Flavin mononucleotide?????? FAD:Flavin adenine dinucleotide????????? ? ????FMN?FAD????,??????? ? FMN?FAD?????????,????????

    42. ???: Symptoms associated with riboflavin deficiency include, glossitis??, seborrhea?????, angular stomatitis???, cheilosis?? , scrotitis ??? and photophobia??

    43. glossitis

    44. ??VitPP/niacin,?????????) (?)??????? 1???: ??pyridine???derivative: ???(??, nicotinic acid) ????(???, nicotinamide ) 2???: ??,????????? ??:???tryptophan ? ???,???

    46. Food Sources of Vit PP ????: Niacin is available in both animal & plant food and is made in the body from tryptophane???. ????????????????????? ??????????: 60mg??? = 1mg??

    47. ????:Vit PP?NAD?NADP????????????????? ???:???(pellagra) ??dermatitis ??diarrhea ??dementia

    50. Pellagra

    51. Pellagra 2

    52. Hartnup disease(??????????????????????????? ), malignant carcinoid syndrome??????? & Isoniazid??? can lead to niacin deficiency . ?????????niacin deficiency? Niacin is toxic in excess.---liver damage

    53. ???????:???pyridoxol ,???pyridoxal ,???pyridoxamine . ??????,???? ??Vitamin B6( Pyridoxine ???)

    54. Active form: pyridoxal phosphate?????; pyridoxamine phosphate?????; pyridoxal phosphate is the major form transported in plasma?? ??:??

    55. ????: Pyridoxine functions as a cofactor in enzymes reactions required for the synthesis?? & catabolism????of the amino acids???as well as in glycogenolysis????. eg:Vit B6??????????????????????????????????????? ??,??????????????

    57. ???:?? ?????B6???????????? ??????d-???-???(ALA)??????,?ALA????????????????,Vit B6??????????????????????? Isoniazid therapy can induce vit B6 deficiency.

    58. ???????:???,?? ?.??( pantothenic acid,???)

    59. it is found in numerous foods and also is synthesized by intestinal bacteria. ????.?????,??????. Active form: Coenzyme A ??A ,acyl carrier protein(ACP)?????? ????:??? ??A ?????????,?????????????????????????? ???:CoA-SH

    62. ???:??? ???CoA??????????????,?????????????????

    63. ????? biotin .???B7 (1)???????

    65. ??:??,??????? ????:A Coenzyme of carboxylase???????CO2???????? ??? ???:?? Uncooked egg white???:Avidin??????

    66. ???????????????

    67. ??folic acid/folate?? (???B11) Obtained from yeasts and leafy vegetables as well as animal liver.

    68. ???????:????????????? ?????,??????? ??

    69. Active form: tetrahydro folate,THF ???? ????:????????????????One carbon unit,?????nucleotide???nucleic acid??? Thus, folate is needed for synthesis of nucleic acids ???: megaloblastic anemia ????????

    70. ???5?6?7?8??????,??????(FH4),????????????,???????

    71. ??VitB12/ cobalamin??? (1)?? ???????: ???????????????,???

    74. active form: methylcobalamine(????) 5 ?-deoxyadenosylcobalamin(5 ?-???????) ??:????,?????????intrinsic factor(???) Biochemical function :methyl transfer? ????:????????????????????????????????????????? Deficiency:Megaloblastic anemia , nerve disease , High blood level of homocysteine?????? ???:????‘pernicious anemia ????????.

    75. ??Lipoic acid??? ???????:????? ??:????? ????:a-????????????? ???? ????????? ???:???

    77. Section II Lipid-soluble Vitamins ?????? Common features??: 1?????? 2??????(A?D?K)??????(E) 3????? 4???????

    78. ??Vitamin A Vitamin A is a generic term for many related compounds. 1???:?-??????????? Natural form: A1: retinol??? A2: 3-dehydro-retinol 3-????? Active form :retinol[ 'ret?n?l] ?retinal[ 'ret?n?l]???? retinoic acid??? 2???:???????????,????. ?????? ????????——?????

    79. ???(Stability) ?O2,120?,??12h???? ??O2?,??4h??? ???,????,O2??????? ????????? ?VE,??????? ????

    82. 3?Food source??: ?????:??????? ?????:?????carotinoid (???A?) Body can convert b-carotene to retinol, thus called provitamin A. ???A?: ?????VitA??,????????VitA????

    84. Biochemical function and deficiency ?????????? 1?Has a function in vision.--formation of rodopsin necessary for dark adaptation. . ??????????? Rhodopsin???? = Opsin??? + 11-cis retinal 11-???? Rod cell????:????,???,??? cone cell????:????,???,??

    86. Synthesis and decomposition of Rhodopsin

    87. ??????????

    88. ?????: ???????????????? ???nyctalopia/night blindness

    89. 2? Involved in glycoprotein synthesis.Important for the maintainance of integrity of epithelial tissue. ????????????,??????????????? VitA??:????,??? 3???????????????????? 4?Anticancer activity???? ?????????? 5. Regulates gene expression : vital to cell differentiation?? & physiologic processes

    93. Excess of vit A is toxic ???A?? ??:> 50?IU/d ??:????,???……

    94. ??Vitamin D 1???: Derivatives of steroid?????? D2(ergocalciferol?????):????( pro-VitD2 D2?) D3(cholecalciferol????):????? 7-dehydrocholesterol 7-?????( pro-VitD3 D3?) 2???:????? 3?Avtive form ????:1,25-(OH)2-D3

    96. ???D???

    97. ??

    99. 4???:

    100. 5.?????????? Calcium/phosphate metabolism: vitamin D enhances Ca++ absorption in the gut & renal tubules. ??Ca?P??:??Ca??P?,???????? ???:??:???rickets ??:???Osteomalacia ???:???? Osteoporosis Functions in Cell differentiation, Immunity

    101. ????

    105. Who is at Risk? Dark skinned

    107. ???D??Hypervitaminosis D causes hypercalcemia, which manifest as: Nausea & vomiting Excessive thirst & polyuria Severe itching Joint & muscle pains Disorientation & coma. ??:????,???????? ?????

    108. ??Vitamin E(???) The term vitamin E describes 2 family of antioxidants, 4 tocopherols (???a,b, g, & d) and 4 tocotrienols.????? a-tocopherol is the active form of vitamin E in the human body (?)??????? 1???:????????? 2???:?????? ????:????: ???? 3???:???:???????

    110. 3???: Vegetable oils???:???wheat germ oil? ???corn oil

    112. ????: 1.?????????:??????,??????; 2. The main function of vitamin E is anti oxidant. It intercepts free radicals & prevents destruction of cell membrane. ???????:?????????????,????????? 3???????? 4? ????????????? ???????? ??????? ??????? ?????????? ????????????

    114. VE???(Vitamin E Toxicity) 65x RDA = interferes with Vitamin K Interferes with clotting and causes hemorrhage??

    115. ??Vitamin K (?)??????? 1???:2-??-1,4????? 2???: K1:green leafy vegetables?????liver? K2:Bacterial flora of intestine??? K3:????,?? K4:?? 3???:?????(????????)

    119. (?)?????????? 1???: ????????????????? ??:????????????????????? Vit K:????? ?-?????? ??:???Ca++?? 2????: Is uncommon in adults????. ??:??????,??????????. ??????Hemorrhagic disease of the newborn ? ??:????,?????

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