instruction:
In this task, you are given a sentence. You are expected to recognize the name of any form of chemical substances. Although there might be several correct answers, you need to write one of them.
question:
Molecular recognition of histidine tRNA by histidyl-tRNA synthetase from hyperthermophilic archaeon, Aeropyrum pernix K1.
answer:
histidine


question:
Synthesis and biological evaluation of novel pyrrolidine-2,5-dione derivatives as potential antidepressant agents. Part 1.
answer:
pyrrolidine-2,5-dione


question:
Sulfasalazine, a potent suppressor of lymphoma growth by inhibition of the x(c)- cystine transporter: a new action for an old drug.
answer:

cystine