Adenine, cytosine, thymine and guanine are the four main nucleobases found in nucleic acids DNA and RNA. Guanine is a purine derivative. It is reported to assemble into square-planar groups that resemble macrocycles, in which the bases interact via hydrogen bonds. In DNA and RNA, stretches of guanine bases are reported to form stable four stranded helices in the presence of sodium or potassium ions. The electrochemical oxidation of guanine has been studied in aqueous media at various carbon electrodes. It reacts with peroxynitrite under physiological conditions to afford 8-nitroguanine.