Table 1. The inhibitory activities of active bufadienolides on HGC-27 3D spheroids and 2D monolayer cells.

Compounds	3D						2D
	IC501 (μM)	IC502 (μM)	IC503 (μM)	IC504 (μM)	IC505 (μM)	IC506 (μM)	IC50(μM)
No.1	0.002 ± 0.001	0.001 ± 0.0006	0.001 ± 0.0005	0.001 ± 0.0004	0.002 ± 0.0008	0.002 ± 0.0008	0.034 ± 0.005
No.2	0.013 ± 0.011	0.012 ± 0.007	0.015 ± 0.006	0.014 ± 0.005	0.017 ± 0.006	0.019 ± 0.005	0.087 ± 0.017
No.3	0.067 ± 0.044	0.058 ± 0.024	0.053 ± 0.02	0.058 ± 0.019	0.067 ± 0.019	0.078 ± 0.026	0.152 ± 0.019
No.5	0.067 ± 0.046	0.091 ± 0.045	0.085 ± 0.04	0.086 ± 0.034	0.096 ± 0.036	0.112 ± 0.041	0.285 ± 0.057
No.6	–	0.002 ± 0.001	0.003 ± 0.002	0.003 ± 0.001	0.003 ± 0.001	0.004 ± 0.001	0.014 ± 0.002
No.7	0.019 ± 0.013	0.029 ± 0.007	0.034 ± 0.01	0.041 ± 0.014	0.058 ± 0.015	0.073 ± 0.018	0.018 ± 0.003
No.8	0.144 ± 0.104	0.15 ± 0.082	0.154 ± 0.076	0.152 ± 0.065	0.178 ± 0.078	0.199 ± 0.082	1.044 ± 0.274
No.9	0.051 ± 0.043	0.064 ± 0.038	0.069 ± 0.033	0.079 ± 0.031	0.099 ± 0.038	0.116 ± 0.04	0.279 ± 0.062
Taxol	1.683 ± 1.667	0.065 ± 0.044	0.069 ± 0.052	0.045 ± 0.031	0.064 ± 0.041	0.062 ± 0.031	0.275 ± 0.059
Epirubicin	1.488 ± 1.27	0.34 ± 0.217	0.104 ± 0.045	0.064 ± 0.028	0.048 ± 0.022	0.036 ± 0.015	1.041 ± 0.146

Notes: (1) IC₅₀¹, IC₅₀², IC₅₀³, IC₅₀⁴, IC₅₀⁵ and IC₅₀⁶ are the IC₅₀ values of bufadienolides on HGC-27 3D spheroids after treatment for 1, 2, 3, 4, 5 and 6 days, respectively. (2) “–” means that the inhibitory active is weak.