Water Soluble Vitamins Flashcards
List the water soluble vitamins.
These are 2 types , the Vitamin B complex and Vitamin C.
VITAMIN B COMPLEX. These function as coenzymes in metabolic reactions and the following are the Vitamin B complex:
1. Thiamine.
2. Riboflavin
3. Niacin
4. Pyridoxine.
5. Cobalamin
6. Folic acid
7. Biotin
8. Panthothenic acid.
Describe the chemical structure of thiamine
It is made up of pyrimidine and a thiazole ring
Describe the metabolic role of thiamine
It is important in carbohydrate metabolism. It forms the coenzyme thiamine pyrophosphate( diphosphate) which is involved in decarboxylation reactions. It is a coenzyme in reactions catalyzed by the following enzymes:
- Pyruvate decarboxylase
It is also one of the 5 coenzymes involved in oxidative decarboxylation reactions catalysed by the following enzymes:
- Pyruvate dehydrogenase enzyme complex
- Alpha keto dehydrogenase enzyme complex.
- Branched chain amino acid dehydrogenase.
It is also involved in the Transketolase reaction in the pentose phosphate pathway
State the recommended daily requirements and the sources of thiamine
Recommended daily requirements:
1mg/day
Sources
I) Animal source: liver, meat eggs.
II)Plant source: cereals, whole grains and legumes
Describe the clinical feature due to deficiency of thiamine
Deficiency of thiamine causes beriberi characterized neuritis and heart failure. In chronic alcoholics thiamine deficiency causes Wernicke’s encephalopathy and Korsakoff psychosis
Describe the chemical structure of riboflavin
It is made up 3 fused rings called the isoalloxazine ring which is attaches to ribitol
Describe the metabolic role of riboflavin
It forms the Flavin nucleotides FMN and FAD which are coenzymes in oxidation reduction reactions. For example, FAD is a coenzyme for the reactions catalyzed by the following FAD dependent dehydrogenases:
- succinate dehydrogenase in the TCA cycle.
- Acyl dehydrogenase in the in beta oxidation
It is also one of the coenzyme in the pyruvate dehydrogenase enzyme complex and the alpha keto- glutarate dehydrogenase enzyme complex
State the recommended daily requirements and the sources of riboflavin
Recommended daily requirements
2mg/day
Sources. I)Animal source: liver and kidney( organ meat).
II)Plant source: cereals, whole grains and legumes
Describe the clinical feature due to deficiency of riboflavin
Riboflavin deficiency leads to angular stomatitis, dermatitis
Describe the chemical structures of niacin
It is a pyrimidine 3 carboxylic acid known as nicotinic acid. The active from is nicotinamide the amide from of nicotinic acid
Describe the metabolic role of niacin
It forms part of the structure NAD and NADP which are coenzymes carriers of electrons in oxidation reduction
reactions
State the recommended daily requirements and the sources of niacin
Recommended Daily Requirements.
12-20mg/day
Sources:
i) Animal source: liver kidney,meat and fish
ii) Plant source: legumes. Nuts, whole grain.
Niacin can be synthesized from tryptophan.
1mg of niacin is produced from 6mg of tryptophan
Describe the clinical feature due to deficiency of niacin
It causes pellagra characterized by the 3 Ds
- dermatitis
- diarrhea
- dementia
There is also the 4th D= death.
Pellagra is precipitated by a high maize diet and alcoholism
Describe the chemical structure and metabolic roles of pyridoxine
Chemical structure.
Pyridoxine, pyridoxal and pyridoxal phosphate.
Metabolic role.
It forms the coenzyme pyridoxal phosphate which is involved in amino acid metabolism such as transamination and decarboxylation reactions.
It is important in heme synthesis.
It is also a coenzyme for glycogen phosphrylase
State the recommended daily requirements and the sources of pyridoxine
Recommended Daily requirements
3mg/day
sources:
i). Animal source: liver kidney and muscle meat.
ii) Plant source: whole grain
Describe the clinical feature due to deficiency of pyridoxine
Microcytic hypochromic anemia
Patients on the antibiotic isoniazid(INH) which is used for treatment of tuberculosis requires pyridoxine supplements the prevent the patients from developing pyridoxine deficiency. The INH forms a complex with pyridoxine and makes it unavailable for metabolic processes
Describe the chemical structures of lipoc acid
Describe the metabolic role of lipoic acid
It is one of the coenzymes involved in enzyme complexes like pyruvate dehydrogenase and alpha keto glutarate dehydrogenase
Describe the chemical structures and metabolic role of panthothenic acid
Chemical structure.
It is made up of Beta alanine and pantoic acid
Metabolic role
It forms part of the structure of Coenzyme A which is a carrier of acyl groups . For example , acetate group, the fatty acyl group, succinyl group.
State the recommended daily requirements and the sources of panthothenic acid
Recommended Daily requirements
10 mg/day
Sources
Found in most foods both animal and plant
Describe the chemical structure of biotin
Describe the metabolic role of biotin
It is a coenzyme in carboxylation reactions. For example in the reactions catalysed by the following enzymes;
- acetyl CoA carboxylase- in fatty acid synthesis.
- pyruvate carboxylase- in gluconeogenesis
State the recommended daily requirements and the sources of biotin
Recommended Daily requirements.
25-50ug
Sources:
Animal source: live, kidney, milkand milk products
Plant source: vegetables, grains and legumes
Describe the clinical feature due to deficiency of biotin
It is commonly seen in people who ingest a lot of raw egg white. Egg white contains a protein called avidin which binds biotin and makes biotin to not be available in the body.
Deficiency causes dermatitis
