Table 2.

The K_i values for the inhibition of purified recombinant human MAO by isatin (1) and (E)-styrylisatin analogues (4–5)

		MAO-A wild- typea (μM)	MAO-B wild-typeb (μM)	MAO-B selectivityc	MAO-B I199A mutanta (μM)
1	Isatin	15d	3d	5.0	12 ± 2
4a	(E)-5-Styrylisatin	0.78 ± 0.10	0.31 ± 0.06	2.5	1.1 ± 0.2
4b	(E)-5-(3-Chlorostyryl)isatin	5.6 ± 0.3	1.4 ± 0.4	4.0	12.5 ± 0.7
4c	(E)-5-(3-Fluorostyryl)isatin	2.2 ± 0.2	0.60 ± 0.07	3.6	4.5 ± 0.2
5	(E)-6-Styrylisatin	22 ± 2	0.56 ± 0.02	39	2.2 ± 0.4

^aThe K_i values were determined spectrophotometrically using p-CF₃-benzylamine as substrate.

^bThe K_i values were determined spectrophotometrically using benzylamine as substrate.

^cSelectivity for the B isoform is given as the ratio of K_i(MAO-A) to K_i(MAO-B) of the wild-type enzymes.

^dValues obtained from reference.⁹