Comparative Study on the MDR Reversal Effects of Selected Chalcones.

Based on the structure of three previously established lead compounds, fifteen selected chalcones were synthesized and evaluated for their multidrug resistance (MDR) reversal activity on mouse lymphoma cells. The most active chalcones were stronger revertants than the positive control, verapamil. In the model of combination chemotherapy, the interactions between the anticancer drug doxorubicin and two of the most effective compounds were measured in vitro, on human MDR1 gene transfected mouse lymphoma cells, showing that the type of interaction for one of these compounds was indifferent while that for the other one was additive. Furthermore, two chalcones inhibited 50% of cell proliferation in concentration of around 0.4 µg/mL and were from 2- to 100-fold more active than the most chalcones. The structure-activity relationships were obtained and discussed in view of their usefulness for the design of chalcone-like P-gp modulators and drugs able to treat resistant cancers.

IR spectral and structural changes caused by the conversion of 3-methoxy-4-hydroxybenzaldehyde (vanillin) into the oxyanion.

The spectral and structural changes, caused by the conversion of the vanillin molecule into the corresponding oxyanion have been studied by IR spectra and normal coordinate calculations within the Onsager self-consistent reaction field (SCRF) model, using a density functional theory (DFT) method at the Becke3LYP/6-31+G** level. Structures of all conformational isomers of vanillin and of its anion have been located, as well as their total and relative energies have been determined. The conversion leads to geometry changes in the whole species, due to the strong O-/acceptor polar resonance through the para phenylene ring. The conversion causes a 41 cm(-1) decrease in the frequency of the carbonyl stretching band nu(C=O), strong intensity increases (1.6 - 7.2-fold) of the aromatic skeletal nu8 and nu19 as well as formyl nu(CH) bands. According to the calculations the oxyanionic charge is delocalized over aldehyde group (0.25 e-), phenylene ring (0.13 e-), methoxy group (0.07 e-) and oxyanyonic center (0.55 e-).

IR spectral and structural changes caused by the conversion of 3-hydroxybenzaldehyde into the oxyanion.

The spectral and structural changes, caused by the conversion of the 3-hydroxybenzaldehyde molecule into the corresponding oxyanion have been studied by IR spectra, and MP2 and DFT force field calculations. The conversion causes a 13 cm(-1) decrease in the frequency of the carbonyl stretching band nu(Cz=O), a 1.3-fold increase in its integrated intensity, strong intensity increases (2.1-5.3-fold) of the aromatic skeletal nu8 and nu19 as well as formyl nu(CH) bands. According to the calculations the oxyanionic charge is delocalized over aldehyde group (0.37 e-), phenylene ring (0.12 e-) and oxyanionic center (0.52 e-). The conversion into the oxyanion leads to geometry changes in the whole species, but it remains planar.

Experimental and ab initio MO studies on the IR spectra and structure of pyridinium dicyanomethylide and trimethylammonium dicyanomethylide.

The structures of the title ylides have been studied by both quantitative infrared (IR) spectra and ab initio HF and MP2 force field calculations. Good agreement has been found between theoretical and experimental data for their spectral and structural characteristics. According to both IR data and geometry parameters the dicyanomethide groups in the ylides studied have a pronounced carbanionic character. The analysis of the calculated net electric charges however shows only moderate (below 0.6 e-) intramolecular charge transfers between the pyridinium (trimethylammonium) and dicyanomethide fragments of the species studied.

Vibrational spectra and structure of benzophenone and its (18)O and d10 labelled derivatives: an ab initio and experimental study.

Infrared (4000-100 cm(-1)) and Raman (4000-10 cm(-1)) spectra of benzophenone, benzophenone-d10 and benzophenone-(18)O have been studied in the solid state and in solution and their fundamental frequencies have been assigned using isotopic frequency shifts and differential infrared linear dichroic spectra of oriented polycrystalline layers (4000-400 cm(-1)). Ab initio MO calculations have been carried out for the three benzophenone isotopomers at the HF/3-21G, 6-31G and 6-31G** levels and the computed vibrational frequencies have been compared with the experimental ones. Best agreement is achieved with the 6-31G data, the mean deviation being 25.4 cm(-1). The calculated isotopic frequency shifts induced by the (18)O and d10 labelling, are also in a good accordance with the measured ones. All geometry parameters calculated for the isolated molecule are in good agreement with the X-ray data for the benzophenone single crystal.