Serum L-Ascorbic Acid Concentration And Its Potential For Scavenging Of Reactive Oxygen Species In Acute, Uncomplicated, Falciparum Malaria Infection
I Garba, U Abraham, U Shuaibu
acute, adults, antioxidants, children, falciparum, l-ascorbic acid
I Garba, U Abraham, U Shuaibu. Serum L-Ascorbic Acid Concentration And Its Potential For Scavenging Of Reactive Oxygen Species In Acute, Uncomplicated, Falciparum Malaria Infection. The Internet Journal of Infectious Diseases. 2005 Volume 5 Number 2.
The substance widely referred to as vitamin C is an equilibrium mixture containing L-ascorbic acid, semidehydroascorbic acid and L-dehydroascorbic acid with over 80 percent of the vitamin C activity accounted for by L-ascorbic acid at equilibrium 1. These three forms comprise a reversible redox system making the vitamin an effective quencher of free radicals such as the singlet O2 - species 2. Evidence abounds on the role of this vitamin in disease and maintenance of health 3,4,5. Vitamin C has been reported to be markedly decreased in patients at risk of developing multiple organ failure 6. In a study on the effect of vitamin C on plasma lipids, Howard and Meyers 7 were able to show some evidence of an inverse relationship between vitamin C intake and the development of atherosclerosis. The mediatory role of vitamin C in this instance may not only be due to its antioxidant activity, but also through a plasma lipid-modifying effect. The oxidative modification of low density lipoproteins (LDL) has been postulated to be one of the early steps in atherogenesis. In this respect ascorbate has been shown to reduce LDL oxidative susceptibility, even though it is not lipophilic 8. Vitamin C has also been shown to have a positive therapeutic effect in the treatment and control of autoimmune disorders, including diabetes mellitus and acquired Immune Deficiency Syndrome (AIDS), whose immunological background data are in favour of the participation of an autoimmune mechanism in the genesis of the disease 9.
Endothelium-dependent vasodilatation is an also known to be impaired in humans with diabetes mellitus via inactivation of endothelium-derived nitric oxide by oxygen-derived free radicals. Vitamin C has been reported to improve this condition, thus further supporting the hypothesis that nitric oxide inactivation by oxygen-derived free radicals contributes to abnormal vascular reactivity in diabetes 10. Paolisso et al. 11 have also been able to show that chronic vitamin C administration improves whole body glucose disposal and non-oxidative glucose metabolism in aged non-insulin dependent (type II) diabetic patients. Similarly, a high vitamin C intake has been documented to reduce the risk of cartilage loss and progression in people with osteoarthritis 12. Thus the specific objective of this work was to assess the serum concentration of L-ascorbic acid in patients presenting with acute, uncomplicated
Patients And Methods
The southern and northern limits of Bauchi State, Nigeria, where the study was conducted are demarcated by latitudes 9°30' North and 10°30' North respectively. Its Western and Eastern limits are bounded by longitudes 8°45' East and 11°0' East respectively. Two thirds of the land area is in the south of latitude 11°15'.
Patients and Study Design
Patient selection and pre-qualification was done by simple random sampling of individuals presenting at the Bauchi Specialist Hospital Outpatient Department with a history of fever and malaise within a period of 1-7 days, and who were confirmed to be infected with the
Serum Sample Collection and Preparation
Blood samples from each of the participants were collected between the hours of 9.00 a.m. and 11.00 a.m. by venepuncture of the antecubital vein into clean, sterile, plastic centrifuge tubes. The samples were centrifuged at 3000g for ten minutes after clotting. Sera was collected by aspiration using a Pasteur pipette and assayed within 24 hours.
Assay for serum L-ascorbic acid
Serum L-ascorbic acid concentration was measured using the 2,6-dichlorophenolindophenol method 13.
Data was analyzed using the MINITAB-10 Statistical Software. Results are expressed as mean ± SEM. Comparison of mean serum L-ascorbic acid concentration between the control group and patients were done using one-way analysis of variance (ANOVA). Where P values are < 0.05, the Duncan's Multiple Range Test was used to test the difference between pair of means. p values < 0.05 were considered significant.
This work was conducted in accordance with the CIOMS / WHO International Guidelines for the Conduct of Research Involving Human Subjects 14.
Results obtained showed a significantly higher serum L-ascorbic acid concentration in all categories of
Mean serum L-ascorbic acid in both adult male and female patients was over twice the control serum L-ascorbic acid concentration of 0.53 ± 0.03 mg/dl, p < 0.05, table 1. A similar pattern was obtained among children presenting with acute, uncomplicated
Potentially damaging free radicals or reactive oxygen species are produced in cells under normal conditions through either homolytic cleavage of a covalent bond, univalent oxidation or reduction 15. Such free radicals, particularly reactive oxygen species have been implicated in the pathogenesis of various diseases, including atherosclerosis, diabetes mellitus, cancer and Parkinson's disease 16,17,18,19. In particular, lipid peroxidation induced by free radicals is believed to be one of the major causes of cell membrane damage, leading to cell lysis and dysfunction 20. Free radical defenses in the body comprise of a complex antioxidant system including vitamins A, E and C, glutathione and enzymatic antioxidants such as glutathione reductase, glutathione peroxidase, superoxide dismutase and catalase 15, 21,22. Biologically, free radicals are known to exert some physiological functions in the body such as biosynthesis, detoxification and microorganism clearance 23,24. Therefore it is the duty of the antioxidant defenses to maintain normal homeostatic balance between free radical production and clearance. During acute