Table 2.

Chou–Talalay index for the various combinations of 5,6-ECs.

5,6 α-EC (µg/mL)	5,6 β-EC (µg/mL)	CI-24 h	CI-48 h	Effect
12 *	20 *	0.18 ± 0.03	0.22 ± 0.2	Synergistic
26 **	27 **	8.52−4 ± 0.13	9.09−4 ± 0.24	Synergistic

U266 cell lines were seeded in 24-well plates at the density of 2 × 10⁵ cells per well, then treated for 24 h or 48 h the with the indicated concentrations of 5,6 α-EC or 5,6 β-EC corresponding to the IC₂₅ * and IC₅₀ **. Cell viability was assessed using an MTT assay. The CI, presented as means ± SD, were calculated with the CompuSyn software (www.combosyn.com/, accessed on 21 July 2021).