Table 6.

Phthalazinone core hit series 6 SAR determined in the human sperm calcium influx assay.^[a]

Compd	R1	R2	IC50 [μM]
6 a			5.4±0.4
6 b			8.3±1.1
6 c			>100
6 d			>100
6 e			>100

[a] CatSper activated by 3 μM progesterone. IC₅₀ values are means±SEM of three independent experiments.