Isolation and structural analysis of the covalent adduct formed between a bis-amino mitoxantrone analogue and DNA: a pathway to major–minor groove cross-linked adducts

Abstract

The major covalent adduct formed between a C-labelled formaldehyde activated bis-amino mitoxantrone analogue (WEHI-150) and the hexanucleotide d(CGCGCG) has been isolated by HPLC chromatography and the structure determined by NMR spectroscopy. The results indicate that WEHI-150 forms one covalent bond through a primary amine to the N-2 of the G residue, with the polycyclic ring structure intercalated at the CpG/GpC site. Furthermore, the WEHI-150 aromatic ring system is oriented approximately parallel to the long axis of the base pairs, with one aliphatic side-chain in the major groove and the other side-chain in the minor groove. This study indicates that mitoxantrone derivatives like WEHI-150 should be capable of forming major-minor groove cross-linked adducts that will likely produce considerably different intracellular biological properties compared to known anthracycline and anthracenedione anticancer drugs.

Synthesis and DNA binding of 6-(alkylamino)indolo[1,2-b][2,7]naphthyridine-5,12-quinones

“…Infrared (IR) spectra were recorded on a Perkin-Elmer 599 spectrometer and are referenced to the 1601 cm -1 band of polystyrene. 1 H NMR (300 MHz) and 13 C NMR (75 MHz) were recorded on a Varian XL-300 multinuclear Fourier transform spectrometer. Unitary resolution mass spectra (MS) were obtained on a Finnigan 4023 GC/MS system.…”

“…We have previously synthesized and utilized the indolo [1,2-b] [2,7]naphthyridine-5,12-dione (6) ring system to forge several members of the 6H-pyrido [4,3-b]carbazole family of antitumor alkaloids, including ellipticine (7), 9-methoxyellipticine (8), olivacine (9), 13-oxoellipticine (10), 7,8,9,10-tetrafluoroellipticine (11), and ellipticine quinone (12) [15][16][17][18][19][20] (Figure 2). A variation of our method allowed for the synthesis of 10Hpyrido [2,3-b]carbazoles (13) 21 and 6,11-disubstituted-benzo[b]carbazoles (14).…”

“…We have previously synthesized and utilized the indolo [1,2-b] [2,7]naphthyridine-5,12-dione (6) ring system to forge several members of the 6H-pyrido [4,3-b]carbazole family of antitumor alkaloids, including ellipticine (7), 9-methoxyellipticine (8), olivacine (9), 13-oxoellipticine (10), 7,8,9,10-tetrafluoroellipticine (11), and ellipticine quinone (12) [15][16][17][18][19][20] (Figure 2). A variation of our method allowed for the synthesis of 10Hpyrido [2,3-b]carbazoles (13) 21 and 6,11-disubstituted-benzo[b]carbazoles (14). 22 The shape similarity of quinone (6) with that of ellipticine quinone (12) and calothrixin B (15), both of which display antitumor activity, [23][24][25] suggested that it would be fruitful to examine indoloquinone 6 and its amino-substituted derivatives for DNA binding, given the known enhancement of DNA binding and resulting biological activity imparted by the alkylamino side chains in antitumor quinones 2-5.…”

“…The antitumor activity and DNA affinity of amino-substituted quinones is well established, [1][2][3][4] and several drugs in this category have seen utility in the cancer clinic; for example, mitomycin (1), 5,6 ametantrone (2), 7 mitoxantrone (3), 8,9 pixantrone (4), [10][11][12] and WEHI-150 (5) 13,14 (Figure 1).…”