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.

[Q]: RDH12, a retinol dehydrogenase causing Leber's congenital amaurosis, is also involved in steroid metabolism.
[A]: retinol


[Q]: Synthesis of C17-OH-north unit of ritterazine G via "Red-Ox" modifications of hecogenin acetate.
[A]: ritterazine G


[Q]: Contribution of the Na+-K+-2Cl- cotransporter NKCC1 to Cl- secretion in rat OMCD.
[A]:
Cl-