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.

The atypical antidepressant mianserin exhibits agonist activity at kappa-opioid receptors.
mianserin

Manipulation of kinetic profiles in 2-aryl propionic acid cyclooxygenase inhibitors.
2-aryl propionic acid

Retigabine, a novel anti-convulsant, enhances activation of KCNQ2/Q3 potassium channels.

potassium