Homocystiene

1. Homocysteine
&
Cardiovascular
Diseases
Homocysteine
&
Cardiovascular
Diseases
Prepared by:
Ardalan Ali Nabi
University of Soran
Faculty of Science
Chemistry Department

2. OutlineOutline
1) Homocysteine
2) Sources of Homocysteine
3) Level of Homocysteine
4) Metabolism of Homocysteine
5) Effect of Homocysteine on the Cardiovascular diseases
6) Reducing of Homocysteine Level
•

3. HomocystieneHomocystiene
• Homocystiene is an amino acid that contain sulfur and its non
proteinogenic amino acid.
•
• Homocystiene is formed from demethylation of essential
amino acid methionine.­

4. Sources of Homocystiene:Sources of Homocystiene:
Homocystiene is not possible to get in diet but is made from amino acid
methionine that can be found in food such as
1) Egg
2) Fish and meat
3) Dairy products ( milk, chess and yoghurt)
4) Nuts and seed (sesame seeds, sunflower seeds, cashews, and pistachio
and Brazil nuts)
5) Vegetables ( spinach, broccoli, red peppers, onions, garlic and squash)
6)

5. Level of HomocystieneLevel of Homocystiene
When the plasma concentration of homocysteine is increased in
the blood more than normal range is called
hyperhomocysteinemia. Increasing plasma concentration of
homocysteine in the blood has a great effect on the
cardiovascular diseases.

6. Metabolism of HomocystieneMetabolism of Homocystiene
The concentration of Homocystiene is regulated by kidneys and
liver by two different pathways.
1) Remethylation
If our body does not have sufficient methionine, the
Homocystiene is going to under remethylation pathway. Vitamin
B12 is required as a cofactor and methyl-THF as a co-substrate.
2) Transsulphuration
When methionine is in excess in our body, Homocystiene is
directed to transsulphuration pathway. Vitamin B6 is required as a
cofactor and serine co-substrate.

7. Metabolism of HomocystieneMetabolism of Homocystiene

8. Effect of Homocysteine on the
cardiovascular diseases:
Effect of Homocysteine on the
cardiovascular diseases:
Increasing serum concentration of homocysteine (hyperhomocysteinemia) is
affected to increase risk of the cardiovascular diseases by some multiple
mechanisms.
1) Homocysteine leads to arteriosclerotic disease due to have an effect on the
blood vessels wall as a result of the some chemical reactions between
homocysteine with some amino acids on the cells and tissues of blood
vessels wall. The cells and tissues are damaged by homocysteine.

9. Effect of Homocysteine on the
cardiovascular diseases:
Effect of Homocysteine on the
cardiovascular diseases:
2) Hyperhomocyteinemia relates with atherosclerosis disease (thickening of the
inner layer of arteries). High level of plasma homocysteine in blood leads to raise
the size of smooth muscles as a result of this growing the blood vessels wall
become narrow and obstruction blood supply.

10. Effect of Homocysteine on the
cardiovascular diseases:
Effect of Homocysteine on the
cardiovascular diseases:
3) Homocysteine causes of aggregation of cholesterol and Low density
lipoprotein (LDL). Homocysteine reacts with cholesterol and LDL as a
result of this reaction they are aggregating in the blood vessels. This
aggregation leads to form plaques which are the major risk factor for
increasing atherosclerosis disease.

11. Effect of Homocysteine on the
cardiovascular diseases:
Effect of Homocysteine on the
cardiovascular diseases:
4) Elevation of plasma homocysteine increases blood clotting
because it is reacted with apo lipoprotein as a result of this
reaction plasma modified fibrin is formed which is lead to
atherothrombosis.

12. Reducing of Homocystiene level:Reducing of Homocystiene level:
Folic acid, vitamin B6 and B12 are powerful vitamins for reducing
cardiovascular diseases because they decreased plasma homocysteine
level in blood.
a) Vitamin B12 with folic acid reduces homocysteine level in blood
by a process which is called remethylation.
b) Vitamin B6 converts dangerous amino acid homocysteine to a safe
amino acid cysteine in a process is called transsulphuration.
c)

13. References:References:
1) Combs, G.F. (2008).’The Vitamins Fundamental Aspects in Nutrition and Health’. Third edition.USA:
Elsevier Inc.
2) McCully, K., S. (2007). ‘Homocysteine, vitamins, and vascular disease prevention’, American Journal of
Clinical Nutrition, Vol.86 :( 1563S–1568S).
3) Malinow M, et al (1993).’ Carotid artery intimal-medial wall thickening and plasma homocysteine in
asymptomatic adults’ The Atherosclerosis Risk in Communities Study’. Circulation, Vol. 87 :( 1107-
1113).
4) Lim, U. and Cassano, P. A. (2002).’Homocysteine and Blood Pressure in the Third National Health and
Nutrition Examination Survey, 1988–1994’ American Journal of Epidemiology, Vol.156 :( 1105–
1113).
5) Foody, J. M., Milberg, J. A., Robinson, K., Pearce, G. L., Jacobsen, D. W. and Sprecher, D. L. (1998).
‘Homocysteine and Lipoprotein (a) Interact to Increase CAD Risk in Young Men and Women
‘American Thrombosis Vascular Biology, Vol. 18: (1895-1901).
6)