2,5-Piperazinedione, 3-(1H-indol-3-ylmethyl)-, (S)- 2,5-Piperazinedione, 3-(indol-3-ylmethyl)-, L- 7451-73-2 Cyclic glycyl-L-tryptophan Cyclo(glycyl-L-tryptophan) Cyclo(glycyl-L-tryptophyl) NSC286599