5-Formylcytosine (5fC) is a pyrimidinenitrogen base derived from cytosine. In the context of nucleic acid chemistry and biology, it is regarded as an epigenetic marker. Discovered in 2011 in mammalian embryonic stem cells by Thomas Carell's research group[1] the modified nucleoside was more recently confirmed to be relevant both as an intermediate in the active demethylation pathway and as a standalone epigenetic marker.[2] In mammals, 5fC is formed by oxidation of 5-Hydroxymethylcytosine (5hmC) a reaction mediated by TET enzymes.[3] Its molecular formula is C5H5N3O2.[4]
^Pfaffeneder, Toni; Hackner, Benjamin; Truß, Matthias; Münzel, Martin; Müller, Markus; Deiml, Christian A.; Hagemeier, Christian; Carell, Thomas (2011). "The Discovery of 5-Formylcytosine in Embryonic Stem Cell DNA". Angewandte Chemie International Edition. 50 (31): 7008–7012. doi:10.1002/anie.201103899. ISSN1521-3773. PMID21721093.