PUB - Publikationen an der Universität Bielefeld

Three new series of bis-indole derivatives were synthesized based on p-phenylenediamine (2-4, 5 and 6) and 4,4'-ethylenedianiline moieties (7-9) using facile and efficient condensation of three positional isomeric indole-carboxaldehyde derivatives (1a-c) with bifunctional amines upon microwave irradiation. The symmetric dimeric indole derivatives 2-4 as well as non-symmetric analogues 5 and 6 were obtained by in situ condensation of the respective positional 3-, 2- and 5-isomeric indole-carboxaldehydes with p-phenylenediamine, while compounds 7-9 resulted from respective condensation based on 4,4'-ethylenedianiline. Structures of the obtained compounds were deduced by advanced spectroscopic methods (H-1 NMR, C-13 NMR and MS). In agar diffusion assay, derivative 6 showed moderate antibacterial activity against various Gram positive and negative bacteria, while derivative 7 displayed moderate activity against several Gram positive bacteria. However, in Resazurin assay employing the human cervix carcinoma cell line (KB-3-1), derivatives 2-9 turned out to be inactive.