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.
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Question: Synthesis of quinoline derivatives: discovery of a potent and selective phosphodiesterase 5 inhibitor for the treatment of Alzheimer's disease.

Answer: quinoline


Question: Design, synthesis, and in-vivo evaluation of 4,5-diaryloxazole as novel nonsteroidal anti-inflammatory drug.

Answer: 4,5-diaryloxazole


Question: Design, Synthesis and biological evaluation of catecholamine vehicle for studying dopaminergic system.

Answer:
catecholamine