Guanosine is a kind of nucleoside, which is composed of guanine and ribofuran (ribofuran) ring β- N9 sugar bond. Guanosine can be phosphorylated into guanosine monophosphate (GMP), cyclic guanosine monophosphate (cGMP), guanosine diphosphate (GDP) or guanosine triphosphate (GTP). If guanosine is linked to deoxyribose, deoxyguanosine will be produced.