2- or 6-(1-azidoalkyl)-5,8-dimethoxy-1,4-naphthoquinone: Synthesis, evaluation of cytotoxic activity; Antitumor activity and inhibitory effect on DNA topoisomerase-I

6-(1-azidoalkyl)-DMNQ derivatives compared to 2-(1-azidoalkyl)-DMNQ isomers, exhibited higher cytotoxic activity against L1210 mouse leukemia cells and stronger inhibition of DNA topoisomerase-l (TOPO-I), suggesting involvement of steric hindrance. However, similar antitumor activity against mice bearing S-180 cell was shown by 2- and 6-(1-azidoalkyl)-DMNQ derivatives.