Biola's seminar presentation

BABCOCK UNIVERSITYCOLLEGE OF HEALTH AND MEDICAL SCIENCESBENJAMIN S. CARSON SCHOOL OF MEDICINE

DEPARTMENT OF BIOCHEMISTRY

2014/2015 ORAL SEMINAR PRESENTATION (BCHM 433)

IMPORTANCE OF VITAMIN C IN METABOLIC REACTIONS

BY

OYEWOLE ABIOLA OLATOMIDE(11/0879)

BIOCHEMISTRY400L

SUPERVISOR: PROF. O. OSILESI.

Introduction Vitamin C was first discovered during the search

for the cause of scurvy. Thus, the scientific name

‘ascorbic acid’ was coined out from the disease.

It was later isolated by Hungarian scientist Szent-

Gyorgyi in 1928.

Since then, various biomedical applications and

uses of vitamin c has been discovered with the

help of scientific research.

Biochemistry and Functions of Vitamin C

Vitamin C which is also known as Ascorbic

acid is an essential water soluble vitamin

that is very important to human health.

It has various important functions which it

performs in the metabolic reactions that

take place in living organisms.

Structure L-ascorbic acid.

(Iqbal et al., 2004)

Vitamin c Nutrition

The Required Daily Allowance of Vitamin C is a minimum of 90 milligrams and no more than 2000 milligrams (2 grams) per day (Enstrom, 2005).

Biochemistry and Function of Vitamin C (contd) Why is vitamin C essential to humans?

Vitamin C is considered essential to

humans because we lack the enzyme ‘L-

gulonolactone oxidase’ which is required

for the synthesis of L-ascorbic acid from D-

glucose. (Iqbal et al., 2004)

Dietary Sources of vitamin c Vitamin c can be obtained majorly from

a wide range of fruit and vegetables like; Rose hip, Citrus fruit, Green peppers,

Red pepper, Broccoli, Brussels sprouts, Turnips and other leafy vegetables.

Milk and Fish also contain a considerable amount of vitamin c (Proteggente, 2009)

Dietary sources of vitamin c

(Nutrient data Laboratory, 2010)

Functions of Ascorbic acid The functions of Ascorbic acid in the living system

includes:

Aiding in the formation of Collagen.

It serves as an antioxidant in the cells.

Defence Against Cancer

Plays key role in the metabolism of cholesterol to

bile acids which helps in defence against heart

disease (Olson et al.,2012)

Ascorbic acid as an Antioxidant

Ascorbic acid is useful in the cellular

environment because it helps to mop up free

radicals that can cause oxidative damage to

the cells.

Ascorbic acid does this by donating

electrons to the unstable specie (element) in

the cellular environment. (Thurnham, 2000).

Antioxidant Action of Ascorbic Acid Simple illustration of antioxidant mechanism

[Ascorbic acid]

Antioxidant Action of Ascorbic Acid

(www.qiagen.com, 2012)

Regeneration of vitamin E Another important function that Ascorbic acid

plays in human health is the ‘Regeneration of

Vitamin E’

Vitamin C helps to regenerate vitamin E from

vitamin E radical.

Vitamin E radical is formed as a result of vitamin

E antioxidant action on lipid peroxyl radical.

(Myllyla et al, 2001)

Defence Against Cancer Cancers occur when cellular DNA is

damaged, causing mutations. Sometimes this damage is caused by free-

radical attacks. Antioxidants may reduce cancer risk by

protecting DNA from oxidative damage. Many studies report lower cancer rates

among people who consume abundant fruits and vegetables rich in antioxidants

(Myllyla et al, 2001)

Defence Against Cancer Diets rich in vitamin C correlated with

lower cancer rates, especially cancer of the mouth, larynx, esophagus, and stomach.

Such correlations reflect the benefit of consuming a diet rich in fruits and vegetables and low in fat, but it does not necessarily support taking vitamin C supplements to treat or prevent cancer.

Defence Against Heart Disease

High LDL cholesterol is a major risk factor for cardiovascular disease.

One way LDL cholesterol increases the risk of cardiovascular disease is that free radicals in the arteries oxidize LDL cholesterol. (Rath, 2006).

Oxidized LDL cholesterol accelerates the formation of artery-clogging plaques.

Defence Against Heart Disease

Free radicals also oxidize polyunsaturated fatty acids in cell membranes, initiating additional changes in artery walls which decrease blood flow.

Oxidative damage in artery walls is increased by a diet high in saturated fat or cigarette smoke.

Defence Against Heart Disease

On the other hand, diets high in fruits and vegetables, especially in combination with unsaturated fat, increase antioxidant action against LDL cholesterol oxidation which can help decreases the development of atherosclerosis.

Deficiency of Vitamin C

The main disease condition that results as a result of vitamin C deficiency is “scurvy”

Due to the importance of ascorbic acid in collagen synthesis, deficiency of vitamin c results in poor tissue and bone formation thus leading to scurvy.

(Enstrom, 2005).

Deficiency of Vitamin C

An image depicting a severe case of scurvy.

Conclusion

In conclusion, we can see that vitamin c plays a very important role in the daily metabolic reactions that take place on the molecular level. Thus making it very essential for existence of life.

ReferencesEnstrom E.J, 2005. Vitamin c intake and mortality among a sample of the united

states population, Epidemology, Pp:194-202.

Khalid Iqbal, Alam Khan, and M. Muzaffar Ali Khan Khattak 2004. Dietary Sources and Metabolism, Biological Significance of Ascorbic Acid to Human Health.

Myllyla, R., Majamaa, K., Gunzler, V., Hanauske-Abal, H.M., Kivirikko, K.I, 2001.“Ascorbate is consumed stoichiometrically in the uncoupled reactions catalyzed by prolyl-4-hydroxylase and lysyl hydroxylase” Journal of Biological Chemistry, Pp:213-275

Nutrient data Laboratory 2010. National Nutrient Database for Standard Reference, Release 23. United States Department of Agriculture Research Service. Retreived on 24-10-2014

Olson J.A, and Hodges R.E, 2012. Recommended Dietary Intake of vitamin c. American Journal of Clinical Nutrition. Volume 53: 693-703

Platt B.S, Eddy T.P, and Pellet P.L, 1993. Nutritional Analysis of Food in Hospitals. Nuffield Provincial Hospitals Trust and Oxford University, London.

Thurnham D.I, 2000. Water Soluble vitamins (Vitamin C and B vitamins, Thiamin, Riboflavin, and Niacin), Journal of Nutrition and Dietetics. Pp:231-244

Proteggente, A.R., Rehman, A., Halliwell, B., Rice-Evans, C.A, 2009. “Potential problems of ascorbate and iron supplementation: pro-oxidant effect in vivo?” Journal of Biochemical Physiology. Pp:277-286

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