The main role of uric acid in metabolism is to serve as a byproduct of purine catabolism. It is produced when the body breaks down purines, which are common components of DNA and RNA. Uric acid is less toxic than ammonia, making it a safer product for nitrogen excretion in organisms like birds and reptiles that conserve water. Additionally, uric acid can function as an antioxidant, potentially protecting cells from oxidative stress. However, elevated levels can lead to health issues such as gout or kidney stones.