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Table 2 Electronegativities (χ, Pauling units) for added 7-position functional groups, and EC50 +/- K0143 in HCT116-SN50 cells

From: FL118, a novel camptothecin derivative, is insensitive to ABCG2 expression and shows improved efficacy in comparison with irinotecan in colon and lung cancer models with ABCG2-induced resistance

Compound χa χb χc EC50 (95% CI) EC50 + Ko143 (95% CI) P Ratio EC50/EC50 + Ko143
FL118 - - - 4.04 (2.79-5.86) 3.02 (2.08-4.49) 0.22 1.34
7-Methyl-FL118 2.27 2.47 2.40 1.49 (1.05-2.12) 1.11 (0.80-1.54) 0.20 1.34
7-Ethyl-FL118 2.28 2.48 2.43 2.43 (1.63-3.63) 1.85 (1.38-2.48) 0.22 1.31
7-Allyl-FL118 2.37 2.48 2.46 5.25 (2.71-10.2) 4.07 (2.93-5.65) 0.42 1.29
7-Bromomethyl-FL118 2.40 2.50 2.51 87.0 (53.0-142) 17.0 (13.2-23.8) < 0.0001 5.12
7-Chloromethyl-FL118 2.47 2.53 2.54 26.8 (14.0-51.2) 12.9 (9.92-16.7) 0.016 2.08
7-Hydroxymethyl-FL118 2.74 2.59 2.52 24.2 (16.8-34.7) 4.79 (3.87-5.92) < 0.0001 5.05
  1. a. Huheey 1965 [37], 1966 [38], b. Inamoto 1982 [39], c. Wu 1999 [40].
  2. 95% CI = 95% confidence interval.