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vitamins B1 and B2
This document provides information on B-complex vitamins, including their classification and properties. It then focuses on thiamine (B1) and riboflavin (B2), discussing their history, structures, roles as coenzymes, dietary sources, deficiencies, investigations and treatments. For thiamine and riboflavin, key details are provided on their specific coenzymes, metabolic reactions they participate in, risk factors for deficiency, clinical signs, recommended intake levels, and management approaches. The document synthesizes information from various biochemistry textbooks and references.
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vitamins B1 and B2
- 1. B-COMPLEX VITAMINS Dr. M.Siva Kumar Reddy MBBS.,MD Post graduate Department of biochemistry
- 2. CLASSIFICATION • A • D •E • K FAT SOLUBLE VITAMINS • B-COMPLEX • C WATER SOLUBLE VITAMINS
- 3. WSV vs FSV Watersoluble vitamins Fat soluble vitamins Function as Precursor for co-enzymes & anti oxidants Function as co-enzymes , harmones, and anti-oxidants Excess amounts non toxic Excess amounts are toxic These vitamins are not stored except B12 These vitamins are stored Body requires them frequently They are not required frequently
- 4. B- COMPLEX VITAMINS B1-THIAMINE B2-RIBOFLAVIN B3-NIACIN B5-PANTOTHENIC ACID B6-PYRIDOXINE BIOTIN FOLIC ACID B12-CYANOCOBALAMINE
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- 6. You should atleast know these……. Specific co-enzyme of thiamine? Dietary sources of thiamine? Antimetabolites of thiamine? RDA of thiamine Types of beri beri & most complicated form of beri beri Metabolic reactions where TPP is involved Most commonly effected people? Investigations and treatment?
- 7. OTHER NAMES OF THIAMINE Anuerine Thiamin Thio-vitamine Anti beriberi factor Sulphur containing vitamine
- 8. HISTORY OF THIAMINE KANEHIROTAKAKI SURGEON GENERAL IN JAPANESE NAVY found seamen and crew were effected
- 9. CHRISTIAN EIJKMAN Dutch physician and professorof physiology nobel prize winner accidentally found the cause in fowls fed with cooked rice
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- 12. Glucose Glucose –6 P Pyruvate Acetyl CoA TPP PDH TCA TPP Citrate Oxaloacetate α- Ketoglutarate α- Ketoglutarate dehydrogenase Succinyl CoA Ribose - 5P Transketolase TPP Seduheptulose - 7P Xylulose - 5P Glyceraldehyde - 3P
- 13. Pyruvat e Acetyl - CoA NAD+ NADH+H+ CO2 Oxidativedecarboxylation TPP PD H
- 14. α ketoglutarate Succinyl - CoA NAD+NADH+H+ CO2 Oxidative decarboxylation TPP
- 15. Xylose-5 phosphate Ribose-5phosphate Glyceraldehyde-3 phosphate Sedoheptulose-7 phosphate Transketolase TPP
- 16. And also….. Essentialfor transmission of nerve impulse TPP is required for synthesis of Acetylcholine.
- 17. DUE TO LACKOF TPP……………… Increased plasma levels of pyruvate & lactate due to low activity of PDH complex Accumilation of pentose sugars in erythrocytes is due to decreased activity of transketolase Measurement of Transketolase activity is common test used for the diagnosis of B1 deficiency
- 18. Sources of thiamine Rich Sources Good sources Fair sources •Outer coatings of food grains like rice, wheat and yeast. • Whole cereals, pulses, oilseeds and nuts. • Meat, liver and egg and fish.
- 19. Thiaminase Itis present in raw fish & seafood Thiaminase destroys thiamine if it is present in the diet ANTIMETABOLITES
- 20. ABSORBTION: Thiamine iscarried by the portal blood to the liver, present as free thiamine STORAGE: Usually stored as thiamine pyrophosphate Mainly stored in skeletal muscle and also present in significant amounts in liver, heart, kidneys, erythrocytes and nervous system
- 21. RDA Adults -1-1.5 mg/day Children - 0.7-1.2 mg/day Pregnancy & lactation - 2 mg/day REQUIREMENT INCREASES WITH- increased carbohydrate intake Pregnancy Lactation Smoking Alcoholism Prolonged antibiotic intake Serious or prolonged illness
- 22. Food containing ahigh level of thiaminase, including milled rice, raw freshwater fish, raw shellfish, and ferns Lack of thiamine intake Food high in anti-thiamine factor, such as tea, coffee, and betel nuts Processed food with a content high in sulfite, which destroys thiamine Alcoholic state Starvation state Causes of thiamine deficiency
- 23. Increased depletion Diarrhea Diuretic therapies Peritonealdialysis Hemodialysis Hyperemesis gravidarum
- 24. Decreased absorption Chronic intestinaldisease Alcoholism Malnutrition Gastric bypass surgery Mal absorption syndrome - Celiac and tropical sprue
- 25. Increased consumption states Dietshigh in carbohydrate or saturated fat intake Pregnancy Hyperthyroidism Lactation Fever - severe infection Increased physical exercise
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- 27. BERI BERI CLASSIFICATION Dry Beriberi Wet Beriberi Infantile Beriberi Shoshin Beriberi Wernicke-Korsakoff syndrome
- 29. INVESTIGATIONS erythrocyte Transketolaseactivity and 24-h urinary thiamine excretion may be measured. Need to rule out other causes.
- 30. TREATMENT Supplement thiamine, withdose based on clinical manifestations For mild polyneuropathy, thiamine 10 to 20 mg once/day is given for 2 wk. For moderate or advanced neuropathy, the dose is 20 to 30 mg/day; it should be continued for several weeks after symptoms disappear. For edema and congestion due to cardiovascular beriberi, thiamine 100 mg IV once/day is given for several days.
- 31. The prognosis forberiberi is usually good, unless patients have established Korsakoff syndrome. When patients have progressed to this stage, the degree of damage is only minimally reversible. PROGNOSIS OF BERIBERI
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- 33. You should atleast know these……. Specific co-enzyme of Riboflavin? Dietary sources of Riboflavin? RDA of Riboflavin? Riboflavin deficiency clinical features? Metabolic reactions where FAD and FMN are involved? Most commonly effected people? Investigations and treatment?
- 34. OTTO HEINRICH WARBURG Isolatedthe "yellow enzyme” of cellular respiration. He was nominated 47 times for Nobel prize Known for his works in cancers
- 35. AXEL THEORELL Isolatedriboflavin Won Nobel prize in 1955 for his discovery of oxidation enzymes and its effects
- 36. PAUL KARRER Determinedthe structure of riboflavin Best known for his research in vitamins Won Nobel prize in 1937
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- 39. Absorbed in small intestineand distributed to all tissues by circulation.
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- 43. RIBOFLAVIN – ACTIVE FORMS Activeforms of this vitamins(FMN & FAD) are involved in… Carbohydrate metabolism(PDH &TCA) Lipid metabolism Protein metabolism Purine metabolism
- 44. Active forms of riboflavin are FMN andFAD. They act as prosthetic groups of several enzymes. Catalyzes oxidation- reduction reactions. Growth, repair, development of body tissues - healthy skin, eyes and tongue
- 45. VITAMIN B2 -RIBOFLAVIN Co-enzyme activity FMN- dependent enzymes FAD - dependent enzymes
- 46. coenzymes for oxidoreductase enzymes(FADand FMN) Flavoprotien enzyme Pathway/ reaction Amino acid oxidase Deamination of amino acids Xanthine oxidase Purine degradation Succinate dehydrogenase Citric acid cycle Acyl-coA dehydrogenase Fatty acid oxidation NADH dehydrogenase Respiratory chain in mitochondria Pyruvate dehydrogenase and Alpha keto glutarate Oxidative decarboxylation of pyruvate and alpha ketoglutarate
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- 51. INVESTIGATIONS Urinary riboflavin determination RBCriboflavin load test
- 52. TREATMENT Riboflavin 2-5 mgPO daily with incresed intake of B-complex vitamins Parenteral riboflavin administered if relief not obtained with oral intake.
- 53. References Harper’s Biochemistry25th Edition. Fundamentals of Clinical Chemistry by Tietz. Text Book of Medical Biochemistry-A R Aroor. Text Book of Biochemistry- DM Vasudevan Text Book of Biochemistry-MN Chatterjea Text Book of Biochemistry-Dr.U.Satyanarana
Editor's Notes
- #39 In the United States today, the most significant dietary sources of riboflavin are meat and meat products, including poultry and fish, and milk and dairy products, such as eggs and cheese. In developing countries, plant sources contribute most of the dietary riboflavin intake. Green vegetables, such as broccoli, collard greens, and turnip greens, are reasonably good sources of riboflavin. Natural grain products tend to be relatively low in riboflavin, but fortification and enrichment of grains and cereals has led to a great increase in riboflavin intake from these food items. The food sources of riboflavin are similar to those of other B vitamins. Therefore, it is not surprising that if a given individual’s diet has inadequate amounts of riboflavin, it will very likely be inadequate in other vitamins as well. A primary deficiency of dietary riboflavin has wide implications for other vitamins, as flavin coenzymes are involved in the metabolism of folic acid, pyridoxine, vitamin K, niacin, and vitamin D (27). from dietary sources. Appreciable amounts of riboflavin may be lost with exposure to UV light, particularly during cooking and processing. Prolonged storage of milk in clear bottles or containers may result in flavin degradation (28). Fortunately, most milk is no longer sold in clear bottles. There has been some controversy as to whether opaque plastic containers provide greater protection than do cartons, particularly when milk is stored on a grocery shelf exposed to continuous fluorescent lighting.
- #42 FMN is formed in intestine FAD is formed in Liver Flavin dependent enzymes (flavoproteins)
- #45 The major function of riboflavin, as noted above, is to serve as the precursor of the flavin coenzymes, FMN and FAD, and of covalently bound flavins. These coenzymes are widely distributed in intermediary metabolism and catalyze numerous oxidation–reduction reactions. Because FAD is part of the respiratory chain, riboflavin is central to energy production. Other major functions of riboflavin include drug and steroid metabolism, in conjunction with the cytochrome P450 enzymes, and lipid metabolism. The redox functions of flavin coenzymes include both one-electron transfers and two-electron transfers from substrate to the flavin coenzyme (10). Flavoproteins catalyze dehydrogenation reactions as well as hydroxylations, oxidative decarboxylations, dioxygenations, and reductions of oxygen to hydrogen peroxide. Thus, many different kinds of oxidative and reductive reactions are catalyzed by flavoproteins.
- #46 FMN Dependent enzymes: FMN is a cofactor for L- amino acid oxidase. NADH dehydrogenase of respiratory chain contains FMN FAD Dependent enzymes: D-amino oxidase Succinate dehydrogenase Aceyl coA dehydrogenase Xanthine oxidase Pyruvate dehydrogenase A ketoglutarate dehydrogenase Complex II of R chain