2.7.7.60 | more |
inhibitor design and inhibition structure-activity relationships analysis, overview. In addition to (1R,3S)-configuration, potent growth inhibition requires 2',4'-disubstitution of the D-ring, featuring at least one electron-withdrawing substituent. Neither (1R,3S)-1-phenyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxylic acid (bearing an unsubstituted phenyl ring) nor (1R,3S)-1-[2,4-di(propan-2-yl)phenyl]-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxylic acid (bearing 2',4'-dimethyl substitution) inhibit Plasmodium falciparum growth at 0.01 mM. The 2'-chloro substituted analogue (1R,3S)-1-(2-chlorophenyl)-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxylic acid shows weak growth inhibition, and (1R,3S)-1-(2-chloro-4-methylphenyl)-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxylic acid (2'-chloro-4'-methyl substituted) nearly recapitulates the potency of (1R,3S)-MMV008138. The carboxy substituent at C3 of the C-ring also proves to be essential, replacement with CO2Me (3a) or H (11a) abrogates growth inhibition potency. But weak growth inhibition is restored with the first amide analogue (1R,3S)-1-(2,4-dichlorophenyl)-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxamide, and methyl amide derivative (1R,3S)-1-(2,4-dichlorophenyl)-N-methyl-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxamide proves equipotent to (1R,3S)-MMV008138. Not inhibitory: (1R,3S)-1-(3,4-dichlorophenyl)-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxylic acid, methyl (1R,3S)-1-(2,4-dichlorophenyl)-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxylate. |
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