Table 1.

Inhibition of Tubulin Polymerization and Colchicine Binding

compound	inhibition of tubulin polymerizationa IC50	inhibition of colchicine bindingb % inhibition ± SD
	(μM)±SD	1 μM	5 μM
29 (CA1)c	1.9	NDd	99.6±0.7
42 (CA4)	0.64±0.01	84±2	97±0.7
20	0.84±0.1	50±5	84±1
21	0.82±0.04	72±4	94± 0.7
22	>20
23	>20
24	12±1
25	>20
26	9.5±0.9
35	1.7±0.2		25±3
36	>20
37	1.7±0.01	53±3	92±0.5
38	0.84±0.1	34±3	90±0.7
39	4.3±0.4		58±4
40	6.2±0.3		72±3
41	1.3±0.08		43±4
43	>20		26±1
44	>20		15±5
45	>20		33±3

^aAverage of n ≥ 2 independent determinations.

^bOnly compounds showing significant activity as inhibitors of tubulin polymerization (defined as having IC₅₀ values below 5 μM) were evaluated for inhibitory effects on colchicine binding.

^cData from refs. 44, 26, and 48.

^dND= not determined.