( Heterocyclic ( ring ( compound ; ) ) )
(ROOT (NP (NNP Heterocyclic) (NNP ring) (NN compound) (: ;)))
Heterocyclic ring compound;
(ROOT (S (NP (DT A) (JJ heterocyclic) (NN compound)) (VP (VBZ contains) (NP (NP (NNS atoms)) (PP (IN of) (NP (NP (QP (CD two) (CC or) (JJR more)) (JJ different) (NNS elements)) (PP (IN in) (NP (PRP$ its) (NN ring) (NN structure))))))) (. .)))