Tetrahydrobiopterin generate BH4 or BH3 radical and BH2, respectively. Research shows that ascorbic acid (also known as ascorbate or vitamin C) can reduce BH3 radical into BH4, preventing the BH3 radical from reacting with other free radicals (superoxide and peroxynitrite specifically). Without this recycling process, uncoupling of the endothelial nitric oxide synthase (eNOS) enzyme and reduced bioavailability of the vasodilator nitric oxide occur, creating a form of endothelial dysfunction. Ascorbic acid is oxidized to dehydroascorbic acid during this process, although it can be recycled back to ascorbic acid. Other than PKU studies, tetrahydrobiopterin has participated in clinical trials studying other approaches
Nucleic acid structure determination short lived in solution they need to be generated. This can be done using HO, ascorbic acid, and Fe(II)-EDTA complex which is attached to the backbone through EDTA. The Fe(II) along with ascorbic acid generates hydroxyl radicals which then can react with the nucleic acid molecules. Hydroxyl radical probing is often used in conjunction with chemical probing of nucleic acid molecules that are thought to associate with proteins, this is due to the modification done by hydroxyl radicals. Hydroxyl radicals attack the ribose/deoxyribose ring and this results in breaking of the phosphate backbone, which is independent of secondary structure, as