Table 2. In vitro inhibitory activity and selectivity index (SI) of clorsulon and acetazolamide (AAZ) as a reference sulfonamide-based drug against human CAs (hCA I, hCA II, hCA IX and hCA XII), schistosomal CA (SmCA) and other CAs belonging to different families, as assessed by a stopped-flow CO₂-hydration assay (Khalifah, 1971 ▸).

		K i † (nM)
		Clorsulon	AAZ
α-CAs	hCA I	4516	250.0
	hCA II	59.1	12.1
	hCA IX	137.5	25.7
	hCA XII	78.0	5.7
	SmCA	224.7	42.5
	VhCAα	291.7	6.8
	SazCA	7.7	0.9
β-CAs	VhCAβ	906.1	6.8
	BpsCAβ	223.3	745.0
	mtCA 02	2.9	9.8
	mtCA 03	827.5	104.0
γ-CA	BpsCAγ	2500	149.0
δ-CA	TweCA	95.8	83.0
SI (hCA I/SmCA)		20.09	5.88

^†Mean from three different assays using a stopped-flow technique (errors were in the range ±5–10% of the reported values).