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. 2021 Aug 5;26(16):4739. doi: 10.3390/molecules26164739

Table 1.

Structures and antiplasmodial activity of bisindolylcyclobutenediones 2a–ar and bisindolylmaleimide 8 a.

graphic file with name molecules-26-04739-i001.jpg
Entry R1 R2 IC50 [µM] b Inhibition at 3 µM [%] c
2a H H 8.33 17.9 ± 3.3
2b H 5-Br 3.02 65.9 ± 1.8
2c H 5-Cl 4.23 44.7 ± 0.5
2d H 5-OCH3 n.d. 18.3 ± 5.0
2e H 5-OCH2Ph n.d. −4.43 ± 10.6
2f H 5-CN 6.72 26.8 ± 1.56
2g H 2-CH3 >30 23.4 ± 5.4
2h H 2-Ph 6.38 65.0 ± 2.8
2i 1-CH3 1-CH3 n.d. 3.53 ± 1.7
2k H 1-[3-(dimethyl-amino)propyl] 0.376 98.1 ± 1.8
2l 2-CH3 2-CH3 n.d. 18.3 ± 6.3
2m 2-Ph 2-Ph 2.47 41.1 ± 0.6
2n 5-OCH3 5-OCH3 n.d. 19.7 ± 3.6
2o 5-Br 5-Br >30 n.d.
2p 5-CN 5-CN n.d. −3.10 ± 0.9
2q H 1-CH3 2.97 52.0 ± 1.8
2r H 5-I 0.915 31.3 ± 2.7
2s 2-Ph 5-Br n.d. 16.0 ± 0.7
2t 5-Br 1-CH3 n.d. 1.38 ± 3.3
2u 2-Ph 1-CH3 1.72 67.7 ± 0.7
2v 5-OCH3 2-CH3 10.0 34.2 ± 8.0
2w 2-Ph 2-CH3 9.26 41.1 ± 1.7
2x 5-Br 2-CH3 >30 45.6 ± 1.8
2y 1-CH3 2-CH3 2.67 59.6 ± 0.2
2z 5-Br, 1-CH3 2-CH3 n.d. 12.7 ± 2.8
2aa 2-Ph 5-OCH3 n.d. 22.4 ± 2.7
2ab 5-F 5-OCH3 n.d. 19.2 ± 3.1
2ac 5-Cl 5-OCH3 1.52 87.0 ± 0.5
2ad 5-Br 5-OCH3 0.47 98.8 ± 0.7
2ae 5-I 5-OCH3 0.64 99.1 ± 0.3
2af 1-CH3 5-OCH3 n.d. 13.6 ± 3.9 d
2ag 5-Br, 1-CH3 5-OCH3 n.d. −0.06 ± 2.43
2ah 5-CN 5-OCH3 6.92 26.8 ± 1.1
2ai 7-Cl 5-OCH3 0.691 84.5 ± 1.0
2aj 7-Br 5-OCH3 0.296 99.5 ± 0.4
2ak 7-I 5-OCH3 0.116 98.8 ± 1.2
2al 7-C2H5 5-OCH3 0.511 87.0 ± 0.5
2am 6-Br 5-OCH3 n.d. 9.55 ± 5.8
2an 4-Br 5-OCH3 n.d. 25.7 ± 2.7
2ao 5-Br 1-CH3, 5-OCH3 0.504 95.4 ± 1.1
2ap 5-Br 5-OH n.d. 2.52 ± 1.4
2aq 5-I 5-I n.d. 1.79 ± 1.8
2ar 5-OBz 5-OCH3 n.d. 21.7 ± 2.5
8 - - 4.0 34.6 ± 0.8
BSD e - - 0.288 97.6 ± 0.5

a n.d. = not determined. b Concentration [µM] for 50% inhibition of P. falciparum (NF54-luc strain) erythrocytic stages. c Inhibition of P. falciparum (NF54-luc strain) erythrocytic stages at 3 µM. d determined at 30 µM. e Blasticidin (BSD) was used as the positive control.