rG(iBu) N2-Isobutyrylguanosine

Nucleosides are glycosylamines that can be thought of as nucleotides without a phosphate group. A nucleoside consists simply of a nucleobase (also termed a nitrogenous base) and a five-carbon sugar (either ribose or deoxyribose), whereas a nucleotide is composed of a nucleobase, a five-carbon sugar, and one or more phosphate groups. In a nucleoside, the anomeric carbon is linked through a glycosidic bond to the N9 of a purine or the N1 of a pyrimidine. Examples of nucleosides include cytidine, uridine, adenosine, guanosine, thymidine and inosine.

N2-Isobutyrylguanosine is a synthetic nucleoside analog. It is activated by the enzyme thymidine kinase and inhibits the synthesis of RNA and DNA, which leads to cell death. N2-Isobutyrylguanosine has been shown to be an effective inhibitor of epidermal growth factor receptor (EGFR) in mammalian cells. This drug has also been shown to inhibit insulin-like growth factor I and phosphorothioate monomers. N2-Isobutyrylguanosine inhibits the synthesis of fatty acids, leading to a decrease in lipid content in cells.