Table 6. hMAO Enzyme Inhibitory Activity of Donepezil–ASS234 Hybrids.

compound	n	R1	R2	IC50 for MAO-A (μM)	IC50 for MAO-B (μM)	SI valuea
40	0	–Ph	–Me	>100	>100	1
41	1	–Ph	–Me	>100	>100	1
42	2	–Ph	–Me	>100	>100	1
43	3	–Ph	–Me	>100	>100	1
44	0	–Ph	–H	14.1 ± 3.8	>100	0.141
45	2	–H	–Me	>100	>100	1
46	0	–H	–H	>100	>100	1
47	2	–H	–H	>100	>100	1
48	4	–Ph	–Me	5.7 ± 2.1	>100	0.057
49	2	–Ph	–H	>100	>100	1
50	3	–Ph	–H	>100	>100	1
51	4	–Ph	–H	>100	>100	1
52	3	–H	–Me	>100	6.11 ± 1.4	16.366
53	4	–H	–Me	>100	3.95 ± 0.94	25.316
54	3	–H	–H	>100	>100	1
55	4	–H	–H	>50	>50	1

^aSelectivity index for MAO-B (IC₅₀ for MAO-A/IC₅₀ for MAO-B).