Cordycepin (Cor)

Cordycepin, or 3'-deoxyadenosine, is a derivative of the nucleoside adenosine, differing from the latter by the absence of the hydroxy group in the 3' position of its ribose part. It was initially extracted from fungi of genus Cordyceps, but is now produced synthetically.
Because cordycepin is similar to adenosine, some enzymes cannot discriminate between the two. Therefore, it can participate in certain biochemical reactions (for example, be incorporated into an RNA molecule, thus causing the premature termination of its synthesis). Cordycepin has displayed cytotoxicity against some leukemic cell lines in vitro, and at least one clinical trial of cordycepin as a leukemia treatment is in progress.