Novel cytotoxic DNA sequence and minor groove targeted photosensitizers: Conjugates of pyrene and netropsin analogues
ACS Citation
Hartley, J. A.; Webber, J.; Wyatt, M. D.; Bordenick, N.; Lee, M. Novel cytotoxic DNA sequence and minor groove targeted photosensitizers: Conjugates of pyrene and netropsin analogues. Bioorg. Med. Chem. 1995, 3, 623-629.
Version of Record
Abstract
The design, syntheses, photochemical and biological properties of conjugates of pyrene with pyrrole- (1) and imidazole-containing (2) analogues of netropsin are reported. The results of an ethidium displacement assay and circular dichroism (CD) titration studies show both compounds bind with a higher affinity to poly(dA-dT) than to poly(dG-dC). In addition they bind as strongly to T4 coliphage DNA as to calf thymus DNA suggesting the binding occurs in the minor groove. The quenching rate constants of the singlet excited states of agents 1 and 2 by molecular oxygen were found to be 8.5 × 109 M-ˆ’1s-ˆ’1 and 7.7 × 109 M-ˆ’1s-ˆ’1, suggesting the involvement of singlet oxygen. Both compounds showed some cytotoxicity to human chronic myeloid leukemia K562 cells in the dark. Upon irradiation the activities were significantly enhanced resulting in photoinduced dose modifications of 8 and 14 for 1 and 2, respectively under the conditions employed. Both agents were markedly more phototoxic than 1-pyrenebutyric acid 8. To address the mechanism of action of compounds 1 and 2 their photoactivated abilities to produce DNA strand breaks were measured. Both agents caused increased single strand breakage with increasing UV exposure. The concentrations (EC50) of 1 and 2 needed to cause 50% single-strand cleavage of pBR322 DNA upon UV-A activation were found to be 40 μM and 45 μM, respectively. In contrast, no DNA strand breaks were observed in the dark with either conjugate or with 8 following irradiation. DNA strand breaks were measured in drug treated K562 cells using alkaline elution. Extensive strand breaks were observed following irradiation of the cells which were rapidly repaired.
Source Name
Bioorganic & Medicinal Chemistry
Publication Date
1-1-1995
Volume
3
Issue
6
Page(s)
497-497
Document Type
Citation
Citation Type
Article