Table 10. In Vitro hMAO Enzyme Inhibitory Activity of Coumarin Conjugates.

compound	R1	R2	R3	R4	IC50 for MAO-A (μM)	IC50 for MAO-B (μM)	SI valuea
88	H	H	H		3.49	0.0038	930
89	H	CH3	H		2.62	0.0020	1310
90	H	CH3	Cl		2.13	0.0021	1024
91	H	CH3	CN		1.38	0.0019	700
92	p-Br	H	H		0.24	0.0005	480
93	p-Br	CH3	H		0.05	0.0009	56
94	p-Br	CH3	Cl		0.37	0.0008	463
95	p-Br	CH3	CN		0.05	0.0013	38
96	p-Br	H			>10	0.104	>96
97	p-F	CH3	CN		0.60	0.0022	273
98	p-Cl	CH3	CN		1.13	0.013	87
99	o-Br	CH3	CN		>10	0.073	>137
100	o,p-Br	CH3	CN		0.72	0.018	40
101	H	H	H		NA	9.21
102	H	CH3	H		NA	3.09
103	H	H	H	CH	>10	0.47	>21
104	H	CH3	H	CH	>10	0.53	>19
105	H	CH3	C	CH	>10	0.29	>34
106	H	CH3	CN	CH	>10	0.30	>33
107	H	CF3	H	CH	>10	5.33	>2
108	Br	H	H	N	>10	1.70	>6
109	Br	CH3	H	N	>10	3.60	>3
110	Br	CH3	Cl	N	>10	1.55	>7
111	Br	CH3	CN	N	>10	1.41	>7
112	Br	CF3	H	N	>10	5.64	>2

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