5-Methylcytidine is a modified nucleoside derived from 5-methylcytosine and is a minor constituent of RNA as well as DNA for certain organisms.

5'-Deoxyadenosine is an oxidized nucleoside found in the urine of normal subjects. Oxidized nucleosides represent excellent biomarkers for determining the extent of damage in genetic material which has long been of interest in understanding the mechanism of aging neurodegenerative diseases and carcinogenesis.

5-aminovalerate (or 5-aminopentanoic acid) is a lysine degradation product. It can be produced both endogenously or through bacterial catabolism of lysine.