DNA Interactions of Monofunctional Organometallic Ruthenium(II) Antitumor Complexes in Cell-free Media

Modifications of natural DNA in a cell-free medium by antitumor monodentate Ru(II) arene compounds of the general formula [(eta 6-arene)Ru(en)Cl]+ (arene ) biphenyl, dihydroanthracene, tetrahydroanthracene, p-cymene, or benzene; en ) ethylenediamine) were studied by atomic absorption, melting behavior, transcription mapping, circular and linear dichroism, plasmid unwinding, competitive ethidium displacement, and differential pulse polarography. The results indicate that these complexes bind preferentially to guanine residues in double-helical DNA. The data are consistent with DNA binding of the complexes containing biphenyl, dihydroanthracene, or tetrahydroanthracene ligands that involves combined coordination to G N7 and noncovalent, hydrophobic interactions between the arene ligand and DNA, which may include arene intercalation and minor groove binding. In contrast, the single hydrocarbon rings in the p-cymene and benzene ruthenium complexes cannot interact with double-helical DNA by intercalation. Interestingly, the adducts of the complex containing p-cymene ligand, which has methyl and isopropyl substituents, distort the conformation and thermally destabilize double-helical DNA distinctly more than the adducts of the three multiring ruthenium arene compounds. It has been suggested that the different character of conformational alterations induced in DNA, and the resulting thermal destabilization, may affect differently further “downstream” effects of damaged DNA and consequently may result in different biological effects of this new class of metal-based antitumor compounds. The results point to a unique profile of DNA binding for Ru(II) arene compounds, suggesting that a search for new anticancer compounds based on this class of complexes may also lead to an altered profile of biological activity in comparison with that of metal-based antitumor drugs already used in the clinic or currently on clinical trials

On the field emulation techniques in over-the-air testing:experimental throughput comparison

Abstract In this letter, we compare two field emulation techniques, namely plane-wave synthesis (PWS) and prefading signal synthesis (PFS) for multiple-input-multiple-output over-the-air (MIMO OTA) testing of mobile terminals in an anechoic chamber equipped with multiple probes. The comparison is performed in terms of measured throughput. The measurements were performed under urban microcellular scenario of the spatial channel model extended and at Long Term Evolution lower band 20. A practical mobile terminal is used as a test device. The throughput of four different browsing positions of the mobile terminal utilizing both emulation techniques has been measured. Results shows that at a fixed median throughput, the differences of the downlink channel power between the PFS and PWS techniques are small and are in the range of 0.2–1.0 dB for different browsing positions of the mobile terminal. The PWS and PFS techniques are equally capable of emulating the target field inside the test zone and are suitable for the MIMO OTA antenna testing based on anechoic chambers equipped with multiple probes