concentration of compound 4 (μM)	absorbance at 450 nm		
90	0.8796	0.8772	0.8494
60		0.8652	0.8409
40	0.7949	0.8603	0.8343
20	0.8107	0.7243	0.8377
10	0.7969	0.8303	0.8035
3.33	0.7897	0.8186	0.8384
1.11	0.8134	0.8211	0.8343
positive control	0.808	0.8214	0.8449
negative control	0.1343	0.1201	0.127
