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 Q]: Expression and 1,4-dihydropyridine-binding properties of brain L-type calcium channel isoforms.
[EX A]: calcium

[EX Q]: Studies on an (S)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid (AMPA) receptor antagonist IKM-159: asymmetric synthesis, neuroactivity, and structural characterization.
[EX A]: (S)-2-amino-3-(3-hydroxy-5-methyl-4-isoxazolyl)propionic acid

[EX Q]: Tricycloalternarenes F-H: three new mixed terpenoids produced by an endolichenic fungus Ulocladium sp. using OSMAC method.
[EX A]:
terpenoids