CA4 and cancer: Compound 13 (Figure 6) (Table 1) showed the best cytotoxic activity in the HT-29 cell line in comparison to CA-4 (0.40 ± 0.05 μM vs 4.2 ± 0.5 μM); coefficient α calculated for this molecule was 80, which means significant selectivity towards cancer cells (coefficient α for CA-4–5.9).