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.

Ex Input:
New oral anticoagulants: comparative pharmacology with vitamin K antagonists.

Ex Output:
vitamin K

Ex Input:
Ellagic acid attenuates bleomycin and cyclophosphamide-induced pulmonary toxicity in Wistar rats.

Ex Output:
bleomycin

Ex Input:
Isolation and function of the amino acid transporter PAT1 (slc36a1) from rabbit and discrimination between transport via PAT1 and system IMINO in renal brush-border membrane vesicles.

Ex Output:
amino acid