Cordycepin

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 moiety. It was initially extracted from the fungus "Cordyceps militaris", but can now be produced synthetically. It is also found in other "Cordyceps" species as well as "Ophiocordyceps sinensis".
Because cordycepin is similar to adenosine, some enzymes cannot discriminate between the two. It can therefore participate in certain biochemical reactions (for example, incorporation into an mRNA molecule, resulting in premature termination of protein 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.
Cordycepin has been found to produce rapid, robust imipramine-like antidepressant effects in animal models of depression, and these effects, similarly to those of imipramine, are dependent on enhancement of AMPA receptor signaling.