Interactions of antitumor triazoloacridinones with DNA.

Abstract

Triazoloacridinones (TA) are a new group of potent antitumor compounds, from which the most active derivative, C-1305, has been selected for extended preclinical trials. This study investigated the mechanism of TA binding to DNA. Initially, for selected six TA derivatives differing in chemical structures as well as cytotoxicity and antitumor activity, the capability of noncovalent DNA binding was analyzed. We showed that all triazoloacridinones studied stabilized the DNA duplex at a low-concentration buffer but not at a salt concentration corresponding to that in cells. DNA viscometric studies suggested that intercalation to DNA did not play a major role in the mechanism of the cytotoxic action of TA. Studies involving cultured cells revealed that triazoloacridinone C-1305 after previous metabolic activation induced the formation of interstrand crosslinks in DNA of some tumor and fibroblast cells in a dose dependent manner. However, the detection of crosslink formation was possible only when the activity of topoisomerase II in cells was lowered. Furthermore, it was impossible to validate the relevance of the ability to crosslink DNA to biological activity of TA derivatives.

Limitation of usage of PicoGreen dye in quantitative assays of double-stranded DNA in the presence of intercalating compounds.

“…In our previous experiments in which Pico-Green dye was used to quantitate the level of crosslinked dsDNA, we showed the ability of the minorgroove-binding compound CC-1065 to form covalent interstrand DNA cross-links (Skladanowski et al, 2001). The approach employed was a variant of a method based on DNA denaturation-renaturation phenomena, in which the amount of renaturated ds-DNA serving as a measure of cross-linked dsDNA had been estimated either by S 1 nuclease assay using radiolabeled DNA (Skladanowski & Konopa, 1994;Koba & Konopa, 2007) or fluorimetrically with the ethidium homodimer dye (Skladanowski et al, 2001). Similar levels of interstrand cross-links in DNA of tumor cells treated with CC-1065 were observed independently whether measurement was performed with ethidium homodimer or PicoGreen.…”

A Review on Derivative Uv-Spectrophotometry Analysis of Drugs in Pharmaceutical Formulations and Biological Samples Review

“…In derivative spectroscopy, D 0 spectrum i.e. zeroth order is a representative feature of normal absorption spectrum [12]. The 1 st , 2 nd , 3 rd and 4 th order derivative spectra can be obtained directly from the zero th order spectrum.…”

“…Smoothing is an operation that is performed on spectra separately on each row of the data and acts on adjacent variables [14]. The noise can be lower significantly without loss of the signal of interest when variables are close to each other in the data matrix and contain similar information [12]. Derivative spectrum may be altered with a high degree of smoothing so, care must be taken [1,6].…”

Coupling of Angular Momenta

“…CHAKRABARTY If in order to separate out the motion of the centre of mass (non-relativistic) we apply, instead of the set (B. 7) [3], the set (B. 8) to the particle coordinates rl, -;2' r3, the two (complex) internal coordinates 3 (r1 + + 03C9*r3), 3 (ri + + corg)…”

“…3) and five for (A. 4)) can be written down directly by applying the proper permutation on both sides (i. e. the suffixes 1, 2, 3 and a, b, c are to be given the same permutation). It must be noted however that v undergoes a change of sign corresponding to each A. CHAKRABARTI…”