Evaluation of Anti Hyperuricemic Activity of Vitamin E on Potassim Oxonate Induced Hyperuricemic Rat Model

Background Hyperuricemia is often associated with oxidative stress and vitamin E alters uric acid level in hypertensive rats, consequently, vitamin E may have a significant role in non-hypertensive hyperuricemia. Therefore, we aimed to evaluate anti-hyperuricemic activity of vitamin E on potassium oxonate-induced hyperuricemic rats. Methods Eighteen adult Wistar Albino rats of similar weights were equally divided into group I (normal control), group II (disease control) and group III (treatment control). Group I received 0.5ml normal saline per oral while group II and group III received potassium oxonate (250 mg/kg-intraperitoneal) on day 1, 3, 6, 10, 13 and 15. Group III also received vitamin E (200 mg/kg-per oral) for 15 days. Blood samples were collected through retro orbital plexus from all the animals on day 15 to evaluate uric acid, creatinine, total cholesterol, triglycerides, albumin and blood urea nitrogen, as well joint diameter, and kidneys’ weight was also evaluated. Result We observed a statistically significant rise (p<0.05 or p<0.001) in all the parameters and a significant decline in serum albumin level (p<0.001) in group II as compared to group I, but no significant difference (p>0.05) in all the parameters between group I and III. In contrast to this, a significant reduction in all the parameters (p<0.05 or p<0.001) and significant increase in serum albumin level (p<0.001) were observed in group III as compared to group II. Conclusion Our findings suggest that vitamin E has an anti-hyperuricemic activity against hyperuricemia induced rats.


Introduction
Hyperuricemia is a common metabolic disorder with an elevated level of serum uric acid [1], more than 7.2 mg/dl in adult males, and 6.0 mg/dl in women and women. [2] Hyperuricemia can subsequently develop into gout, tophi formation, kidney stones and acute kidney failure [3] and is also associated with the risk of cardiovascular events, particularly chronic heart failure [4] and essential hypertension. [5] Uric acid is a potent antioxidant in the extracellular environment whereas intracellularly high level of uric acid can generate reactive oxygen species (ROS) causing oxidative stress in numerous kinds of cells that includes vascular smooth muscle cells, endothelium, renal tubular cells, islet cells and hepatocytes. [6][7][8] Oxidative stress occurs when cell cannot neutralise such ROS. [9] This stress can subsequently damage cellular components such as membranes, lipids, proteins, lipoproteins and DNA [10][11][12][13][14][15] as well as alter the intracellular activities including decline in the synthesis of protein, [16][17] increase in apoptotic activity. [18] Consequently, oxidative stress can induce several chronic diseases such as hypertension, congestive heart failure, COPD, renal failure, cancer, Parkinson disease, multiple sclerosis, rheumatoid arthritis and many more. [19] Serum uric acid level is a consequence of increased purine metabolism or decreased elimination. During purine metabolism, uric acid is formed from the final enzymatic oxidation of xanthine oxidase (XO) on xanthine, which is generated from the same process on hypoxanthine. Experimental Design [28][29] The rats were randomly divided into three groups consisting of each 6 rats each as follows: Group I: treated with normal saline only (Normal Saline po).
Groups I and III were orally administered once a day for 15 days. On day 1, 3, 6, 10, 13 and 15, potassium oxonate (250 mg/kg ip ) was injected one hour before the administration of vitamin E (200 mg/kg po) to all the groups except group I.

Statistical analysis
All the data were presented as mean±SEM (mean±standard error mean), the statistical difference were compared by using one-way analysis of variance (ANOVA) followed by Tukey's multiple comparison tests using SPSS (Version 20).

Results
The anti-hyperuricemia activity of vitamin E was determined in hyperuricemia-induced rats using potassium oxonate (250mg/kg ip) and treated with vitamin E (200 mg/kg po

Discussion
Our study evaluated the anti-hyperuricemic activity of vitamin E in potassium oxonateinduced hyperuricemic rats. The evaluation of physical and biochemical parameters suggested that administration of oral vitamin E at a dose of 200 mg/kg in potassium oxonate-induced hyperuricemic rat model show a significant anti-hyperuricemic activity.
The significant rise in serum uric acid, kidneys' weight, knee joint diameter, serum creatinine, TG, TC, BUN and the significant decline in serum albumin in rats that were administered with ip potassium oxonate (disease control group II) as compared to rats that were administered with normal saline (normal control group I) signify the induction of hyperuricemic activity of potassium oxonate. However, potassium oxonate-induced hyperuricemic rats that were simultaneously treated with 200 mg/kg oral vitamin E (treatment control group III) significantly reduced all the parameters but increased albumin level.
Hyperuricemia is a common metabolic disorder characterized by high levels of uric acid in the blood and one of the most important causative factors for gout. [30] It has also been associated with chronic kidney disease, [31]  subsequent failure of the cell to neutralise them can lead to oxidative stress in the cells [6][7][8][9] which can potentially lead to numerous chronic diseases. [19] Antioxidants such as vitamin E possesses potent in-vivo free-radical scavenging activity [24] which might be responsible for reducing ROS induced oxidative stress in our hyperuricemic rat models.
There is an evidence that suggest vitamin E has a protective role against oxidative stress in rats and humans. [25] The other reason for hyperuricemic activity might be due to possibility of increase in uric acid level in urine. Our study protocol did not take into account the measurement of urinary uric acid to support this mechanism, but evidence suggest that supplementation of vitamin E for 4 weeks in hypertension-induced rat models increases urinary uric acid level and decrease serum uric acid level. [26] We did not observe any apparent toxicity in the rats in the dose that was administered for the experiment, which suggests that the dose to be safer but its extrapolation in humans need further evidence and explanation. Vitamin E may be used in humans for the treatment and management of hyperuricemia and gout. However, the mechanism of action of vitamin E on hyperuricemia and its antioxidant property is yet to be thoroughly investigated.

Conclusions
Our study suggests that a repeated oral administration of 200mg/kg of vitamin E for 15 days has an anti-hyperuricemic effect in potassium oxonate-induced hyperuricemic rats.

Ethical approval and consent to participate
We obtained the ethical approval from Institutional Review Board of Nepal Health Research Council.

Consent for publication
I understand that the text and table for published in the article will be freely available on the internet and may be seen by the general public.

Availability of supporting data
The data used to support the finding of this study are included within the article.

Funding:-
No special funding were required as this experiment was conducted in college laboratory

Author contribution
Hari