Trequinsin is a

phosphodiesterase inhibitor A phosphodiesterase inhibitor is a drug that blocks one or more of the five subtypes of the enzyme phosphodiesterase (PDE), thereby preventing the inactivation of the intracellular second messengers, cyclic adenosine monophosphate (cAMP) and cyc ...

. It has been shown to improve sperm motility ''in vitro''.McBrinn RC, Fraser J, Hope AG, Gray DW, Barratt CLR, Martins da Silva SJ, Brown SG. Novel pharmacological actions of trequinsin hydrochloride improve human sperm cell motility and function. ''Br J Pharmacol''. 2019 Dec;176(23):4521-4536.

References

Phosphodiesterase inhibitors {{organic-compound-stub