Which purine compound is present in human saliva?

Explanation

Among the given choices, adenosine is a purine nucleoside found in saliva. Uric acid (urate) is a purine metabolite but not typically referred to as a purine compound in saliva. Thymine and thymidine are pyrimidines, and hypoxanthine is a purine derivative but less commonly noted in saliva compared to adenosine.