Complex sentence: It is one of the products of the action of xanthine oxidase on xanthine, though more normally in purine degradation, hypoxanthine is formed from reduction of xanthine by xanthine oxidoreductase.
Split into simpler sentences: It is one of the products of the action of xanthine oxidase on xanthine. However, more frequently in purine degradation, hypoxanthine is formed from reduction of xanthine by xanthine oxidoreductase.