Fellutanine
Fellutanine A , B , C and D are bio-active diketopiperazine alkaloids isolated from the cultures of "Penicillium fellutanum" , that belongs to a class of naturally occurring 2 , 5-diketopiperazines . 
<triplet> 2,5-diketopiperazines <subj> diketopiperazine <obj> subclass of