Vitamin B6 & Deficiency

Vitamin B6 & Deficiency


VITAMIN B6 (PYRIDOXINE)

Pyridine derivatives are-

  1. Pyridoxine
  2. Pyridoxial
  3. Pyridoxamine
  • Active form of pyridoxine is pyridoxial phosphate-PLP (for amino acid metabolism)

Important PLP reactions-

  1. Transamination
  2. Decarboxylation
  3. Non-oxidative deamination
  4. Condensation
  5. Transsulfuration
  6. Tryptophan Metabolism
  • Synthesis of niacin from tryptophan (can cause niacin deficiency)
  • xanthurenic acid (xanthurenate) excretion in urine is increased in pyridoxine deficiency. Thus pyridoxin may be used in xanturenic aciduria.

7. PLP is a cofactor for glycogen phosphorylase.

8. Pyridoxin can be used in oxaluria.

  • Daily recommended dose- 1-2mg/day

 Vitamin B6 Deficiency- Clinical Manifestations

  • Neural dysfunction
  • Anaemia
  • Convulsion
  • Pellagra
  • Kidney stones
  • Deterioration of parkinsonism
  • PPL dependent conditions are- Homocystinuria, oxaluria, cystathioninuria and xanthurenic acid.
  •  Drugs that interact with carbonyl group and causes PLP deficiencies are L -Dopa, Pencillamine, CycIoserine.

 Biochemical Assay of Vitamin B6-

  • Tryptophan load test

 Toxicity of Vitamin B6-

  • High doses of pyridoxine can cause neurotoxicity.
Exam Question
 

Pyridine derivatives are-

  1. Pyridoxine
  2. Pyridoxial
  3. Pyridoxamine
  • Active form of pyridoxine is pyridoxial phosphate-PLP (for amino acid metabolism)

Important PLP reactions-

  1. Transamination
  2. Decarboxylation
  3. Non-oxidative deamination
  4. Condensation
  5. Transsulfuration
  6. Tryptophan Metabolism
  • Synthesis of niacin from tryptophan (can cause niacin deficiency)
  • xanthurenic acid (xanthurenate) excretion in urine is increased in pyridoxine deficiency. Thus pyridoxin may be used in xanturenic aciduria.

7. PLP is a cofactor for glycogen phosphorylase.

8. Pyridoxin can be used in oxaluria.

  • Vitamin B6 Deficiency- Clinical Manifestations
  • Neural dysfunction
  • Anaemia
  • Convulsion
  • Pellagra
  • Kidney stones
  • Deterioration of parkinsonism
  • PPL dependent conditions are- Homocystinuria, oxaluria, cystathioninuria and xanthurenic acid.

Biochemical Assay of Vitamin B6-

  • Tryptophan load test

 Toxicity of Vitamin B6-

  • High doses of pyridoxine can cause neurotoxicity.
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