10/11/2016
Vitamin dan Mineral dr. Syazili Mustofa, M. Biomed Lektor mata kuliah ilmu biomedik Departmen Biokimia dan Biologi Molekuler FK Unila
Klasifikasi vitamin
Vitamin
Larut air
Larut lemak: Vitamin A ( Retinol ,Betakaroten) Vitamin D (cholecalciferol)
Non B kompleks ( Vitamin C)
Pelepas Energi:
Vitamin K (phylloquinones, menaquinones) B kompleks
Vitamin E (tocopherols
Tiamin (Vitamin B1)
Pembentukan darah:
Riboflavin (vitamin B2)
Asam folat
Vit B6
Niacin (vitamin B3)
Vit B12
Pyridoxal
Biotin
Lain lain:
Pyridoxamine
Pantothenic acid
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Asam folat • Penting untuk biosintesis • Fungsi : Tetrahidrofolat (folat tereduksi) menerima satu bagian karbon dari donor (serine, glycine, and histidine) dan memindahkannya ke perantara dalam sintesis asam amino, purin, dan thymidine mono phosphate (TMP) • Kurang asam folat sering terjadi karena – Kebutuhan meningkat (ibu hamil dan menyusui) – Gangguan absorbsi ( alkoholik, penyakit usus halus, obat obatan)
• Dampak kekurangan folat: – Anemia megaloblastik : Gangguan pembentukan purin dan TMP gagal replikasi DNA sel gagal membelah – Kerusakan “ neural tube” pada janin ( spina bifida dan anensefali)
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KOBALAMIN (VITAMIN B12) • Fungsi : Koenzim reaksi degradasi asam amino dan asam lemak • Sumber : hati, susu, kerang, telur, daging, ayam • Kekurangan Vit B12: – gangguan syaraf : degradasi lemak terganggu akumulasi lemakmenempel di membran sel, termasuk sel syaraf – Anemia perniciosa
ASAM ASKORBAT (VITAMIN C) • Fungsi : • agen pereduksi beberapa reaksi • Koenzim hidroksilasi : hidroksilasi prolil dan lisil pada pembentukan kolagen • Mempertahankan jaringan ikat: perlu untuk penyembuhan luka • Membantu penyerapan besi • Antioksidan • Sumber : buah buahan, lemon, Jeruk, stroberi,jambu , dan sayur sayuran • Kekurangan Vit C: – Scurvy : gusi berongga dan gigi tanggal, mudah berdarah, sendi bengkak, anemia
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Vitamin A • Retinoid adalah molekul yang berhubungan dengan retinol (vitamin A), penting untuk pengelihatan, reproduksi, pertumbuhan, dan menjaga jaringan epitel. • Sumber : hati, ginjal, cream, butter, dan telur. Sayuran kuning dan hijau gelap sumber karoten • Kebutuhan : dewasa 900 retinol activity equivalents (RAE) (lk) dan 700 RAE (pr) (1 RAE = 1 mg retinol, 12 mg βcarotene, atau 24 mg carotenoid)
• Sumber : hewani dan nabati • Dibawa kilomikron dari usus dan disimpan dihati dan adiposa • Dibutuhkan di sel dan retina
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Kegunaan vitamin A
Vitamin D
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Vitamin D • Kelompok sterol, punya fungsi seperti hormon • Fungsi : – Pada usus : 1,25-diOH-D3 merangsang penyerapan kalsium dan phosphate. – Pada tulang : 1,25-diOH-D3 merangsang mobilisasi calcium dan phosphate mempertahankan kadar kalsium dan fosfat darah
• Sumber – Diet: Ergocalciferol (vitamin D2), nabati, dan cholecalciferol (vitamin D3), dari hewani – Prekursor vitamin Endogen: 7-Dehydrocholesterol (pada kulit, butuh sinar matahari)
• Kekurangan vit D kehilangan mineral tulang, ricketsia (anak), osteomalasia (dewasa)
Vitamin k • Berperan pada pembekuan darah (koenzim reaksi karboksilasi asam glutamat) • Fungsi – Pembetukan γcarboxyglutamate (Gla): untuk pembentukan prothrombin dan blood clotting factors II, VII, IX, and X. – Interaksi prothrombin dengan platelets:
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Bentuk paling aktif adalah α-tocopherol Fungsi utama vitamin E adalah sebagai antioksidan Sumber vitamin E Minyak sayur sayuran, , hati dan telur kebutuhan harian α-tocopherol 15 mg Defisiensi vitamin E Terjadi pada bayi prematur dan gangguan absorbsi lipid (pada dewasa). Menyebabkan Gangguan sel darah merah dan membran sel.
Vitamin E
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MINERAL Tubuh mengandung (dalam % berat) : • Oksigen 65% • Karbon 18% • Hidrogen 10% • Nitrogen 3 % • Kalsium 1, 5 % • Fosfor 1% • Elemen lain 1, 5 % (K,Na,Cl,dls)
Elemen/mineral yang penting untuk tubuh antara lain :
K,Na,Cl,Ca,P,Fe,I,F,Co. Berdasarkan atas kebutuhannya perhari,mineral dibagi atas : • MAKRO (major) MINERAL Dibutuhkan lebih dari 100mg/hari. Contoh : Ca,P,Na,K,Cl,Mg.
• MIKRO (trace) MINERAL Dibutuhkan kurang dari 100mg/hari. Contoh : Cr,Co,Cu,I,Fe,Mn,Mo,Se,Si,Zn,F.
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KALSIUM (Ca)
• Merupakan unsur pada tulang dan gigi. • Turut mengatur fungsi syaraf dan otot. • Penting pula untuk metabolisme sel • Absorpsinya membutuhkan “Calcium Binding Protein”,dikontrol oleh vit D, Parathormon, Calcitonin,dls.
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FOSFOR (P) : Merupakan unsur pada tulang, gigi, ATP, asam nukleat. Absorpsinya dikontrol Vit.D
Functions • Component of bones/teeth 80% in bone (hydroxyapatite) 20% in soft tissue Membrane phospholipids, DNA, RNA • Similar to calcium • Vitally important in energy metabolism ATP and creatine phosphate Sugar phosphates • Acid-base balance (HPO4–) • Regulation of metabolism Glucose-6-phosphate Phosphorylation activates or inactivates enzymes
NATRIUM : Kation utama dalam cairan ekstra sel. Mengatur volume plasma. Mengatur keseimbangan asam- basa Mengatur fungsi syaraf dan otot. Aktivator untuk enzim Na+ / K+ -ATP ASE.
KLORIDA • Mengatur balans cairan tubuh dan elektrolit. • Unsur cairan dan getah lambung.
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Sodium (Na) and Chloride (Cl)
Functions
Electrolytes Absorption of glucose and amino acids Transmission of nerve impulses
Osmotic pressure balance
Action potential
10% sodium and chloride intracellular, 90% extracellular Sodium is main extracellular cation
Chloride is main extracellular anion
Maintained by Na/K ATPase
HCl and chloride salts in gastric secretions
Sodium and Chloride
Blood concentrations highly regulated
Excess intake = increased excretion Little danger of toxicity if water available
NaCl added to diets to increase palatability Causes of deficiencies:
Lactation
Rapid growth
High temperatures or hard work
Sodium and chloride secreted in milk On a diet of cereals or forages Sweat
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Sodium, Serum Adults: 136-145 mEq/L Sodium is the major cation in extracellular space Intracellular sodium is approximately 5mEq/L…. Aldosterone and antidiuretic hormone help regulate sodium balance Symptoms of hypernatremia: Dehydration thirst, agitation, restlessness, hyper-reflexes and seizures. Symptoms of hyponatremia Muscle cramps, muscle twitching, headache, dizziness, lethargy, confusion, convulsions, stupor and coma. The changes in the central nervous system are due to fluid shifts from the extracellular spaces to the intracellular spaces, causing cells to swell. Elevated blood glucose levels give falsely low serum sodium values. Use this formula to correct serum sodium values. Na= glucose x 2 + Na
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Chloride, Cont’d Chloride Increased by
Decreased by
Dehydration Excessive infusion of saline Cushing’s syndrome Eclampsia Anemia Hypernatremia Multiple myeloma Metabolic acidosis Hyperventilation
Overhydration Congestive heart failure Vomiting Addison’s disease Hypokalemia Hyponatremia Diuretic therapy Metabolic alkalosis Burns Emphysema
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KALIUM/POTASSIUM Kation utama dalam cairan intra sel. Mengatur fungsi syaraf dan otot. Aktivator untuk enzim Na+ /K+ -ATP ASE.
Potassium
Functions:
Third-most abundant mineral in the body
2/3 of whole-body potassium content in skin and muscles >95% of potassium intracellular (major intracellular cation)
Maintained by Na/K ATPase
Regulation of osmotic and acid-base balance Transmission of nerve impulses Potassium is the major determinant of the resting membrane potential of all cells
Cofactor for several reactions in carbohydrate metabolism
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Potassium, serum Adults: 3.5 - 5.0 mEq/L Potassium is the principle intracellular cation. The normal potassium levels within cells is approximately 150 mEq/L compared to 3.5 - 5.0 mEq/L in serum The serum potassium concentration is related to reninaldosterone mechanism, sodium reabsorption and acid-base balance. When acid-base balance is altered the serum potassium also changes. As the pH of the blood increases (becomes more alkalotic) the potassium shifts from the serum to the cells. As the pH of the blood decreases (becomes more acidic) the intracellular potassium shifts to the serum.
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Potassium, serum cont’d Symptoms of hypokalemia: Muscle weakness, cramps, hyporeflexia, paresthesias, decreased bowel motility, hypotension, cardiac arrhythmia, drowsiness, lethargy and coma. Serum potassium below 3.5 mEq/L is often seen with a serum pH above 7.45, decreased serum bicarbonate level and possibly elevated blood glucose. Symptoms of hyperkalemia: include confusion, irritability, nausea, vomiting, intestinal colic, paresthesia abdominal cramps and muscle paralysis. 23
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Magnesium (Mg)
Unsur pada tulang dan gigi. Kofaktor untuk enzim kinase Bone formation
Functions
~60% in bone
Enzyme activation
Carbohydrate, lipid metabolism
7 enzymes in glycolysis require magnesium as a cofactor
Urea cycle
Binds mRNA to ribosomes Associated with ATP metabolism
ATP–Mg2+ complex
Magnesium and Muscle Function
Magnesium required for energy releasing enzyme activity in skeletal muscle
ATP needed for detachment and calcium uptake
Calcium is the link between excitation and contraction
Lack of ATP to return calcium to storage results in tetany
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Magnesium
Deficiency
Vasodilation
Results in reduced blood pressure
Hyperirritability, convulsions Anorexia, reduced weight gain Hyperemia Hypomagnesemic tetany (grass tetany) Early lactating cows on grass Poor nervous and muscular control
Usually not an issue, adequate levels present in most diets
Magnesium Deficiency – Grass Tetany
Also called grass staggers, hypomagnesemia
Symptoms
Low blood magnesium Nervousness Tremors, twitching of face muscles Staggering gait or convulsions
Etiology not completely understood
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KOBALT Unsur pada vitamin B12 TEMBAGA (Cu) Unsur pada enzim oksidase. Berperan pada absorpsi Fe.
JODIUM Unsur pada hormon T3 dan T4
BESI Unsur pada enzim-enzim yang mengandung Heme (misal : hemoglobin, Sitokrom,dls.)
MOLIBDENUM (Mo) Unsur pada enzim-enzim oksidase
MANGAN (Mn) Kofaktor untuk enzim Hidrolase, Dekarboksilase,Transferase. Berperan pada sintesis Glikoprotein & Proteoglikan.
SELENIUM (Se) Unsur pada Glutathion Peroksidase.
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SILIKON (Si) Berperan pada kalsifikasi tulang.
SENG (Zn) Kofaktor untuk enzim LDH, Alkalifosfatase,Karbonik anhidrase, dls.
FLUORIDA (F) Meningkatkan pengerasan tulang dan gigi.
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