Lecture 3 Folic acid and Sulphonamides
Friday, 21 September 2012
Complex structure made of glutamic acid, p-aminobenzonic acid and pteridine derivative. The
pteridine contains a conjugated fused ring.
Sources include liver, spinach, citrus, fresh vegetables, not found in animal products such as
milk, meat and eggs.
You can get some folate from intestinal bacteria
Destroyed by cooking
Body reserves are 20mg
Daily intake is about 500-700 micrograms
Daily requirement is about 100-200 micrograms or 400+ micrograms is pregnant or
A structural component of purines, pyrimidines and the nucleotides derived from them.
Important in C1 transfer reactions.
Folic acid deficiency:
Folate levels are usually okay in a normal diet though poor dietary habits can lead to folate
deficiency eg alcoholism.
Folate deficiency in non alcoholics can be due to impaired absorption or metabolism or
increased need for the vitamin eg pregnancy
Causes anaemia in various forms, both white and red blood cells are affected because of the
failure to synthesis DNA when the blood cells are created.
Anaemia in megablastic and macrocytic form, as there is no DNA synthesis results in large RBC
with many nuclei due to no division.
Folic acid deficiency time line:
3 weeks: serum folic acid low
18 weeks: low RBC folic acid
19 weeks: megablastic bone marrow
20 weeks: Frank anaemia
Folic acid deficiency during pregnancy:
30-60% of pregnant women are deficient though only 2-5% in developed countries.
Dietary supplement recommended can prevent 50% or more neural tube defects (NTD) such
as spina bifida and anencephaly.
Recommended to increase folic acid intake to 800 microgram a day about 1 month before
contraception and continuing through the first trimester.
Effect of folate deficiency on metabolic processes:
Effects DNA synthesis as the nucleotides can not be formed, synthesis is inhibited by lack of
Impaired dTMP synthesis leads to the arrest of rapidly proliferating cells such as hematopoietic
cells, this is a serious and rapid effect the blood cells leading to severe anaemia.
Folic acid in metabolic reactions: Folic acid is used in 1Carbon transfers which are important in the biosynthesis of 2
deoxythymidylate (dTMP) and purines such as serine, glycine, his