[Caffeine clusters as transmitters of actinomycin antibiotics to DNA in solutions]

Biophysical Viscosity: Thermodynamic Principles of Per Capita Chemical Potentials in Human Populations

Dynamic viscosity has been used to describe molecular resistance to flow under an applied force. This study introduces the theory of biophysical viscosity, the resistance of a region to molecular flow under environmental force to define the rates of per capita anthropogenic chemical efflux into the environment. Biophysical viscosity is an important intermediate quantity, in that it can be used to calculate the chemical potentials of single molecules for individuals in a population. Nonhypothetical emission data was combined with chemical potentials of anthropogenic tracers, to demonstrate that thermodynamic quantities can be used as parameters to directly compare energies associated with individual chemical emissions across geographic regions. These results indicate that population density is not the only factor in the determination of population-level chemical efflux and that biophysical viscosity is a useful tool in determining the per capita chemical potentials of anthropogenic chemicals for environmental risk assessment.

[Energy of interaction in actinomycin-nucleotide complexes]

Variety of different compounds has been used for delivery of antibiotics to the tumor cells. In this work, using the highly sensitive spectrophotometry, the natural complexes of heterocyclic antibiotic actinomycin D (AMD) with such possible curriers like purine and pyrimidine nucleotides as well as fragmented DNA and phospholipid liposomes were studied. The antibiotic is not only adsorbed on the surface of purine clusters, but also is embedded in them. The antibiotic is especially well integrated into the unwound DNA regions. Embedding is accompanied by a long-wavelength shift in the absorption spectrum. The magnitude of the shift was used for calculation of the interaction energy. In the case of AMD with caffeine and adenosine, the value of energy is 2.4 and 2.7 kcal/mol and in the case of guanosine and fragmented DNA--considerably higher: 3.3 and 3.7 kcal/mol. It can be assumed that guanosine, adenosine, caffeine, and the fragmented DNA could serve as carriers of antibiotic.

Nucleotide carriers for anti-tumour actinomycin antibiotics

We have investigated a number of complexes of 7-aminoactinomycin D (7AAMD), with its potential carriers: caffeine, folic acid (FA), purine bases-guanine and adenine, pyrimidine base-thymine and with fragmented DNA to determine more stable and suitable complex. The process of binding of the fluorescent antibiotic with clusters of caffeine, guanine, adenine, thymine and with fragmented DNA was accompanied by a considerable long-wavelength shift in excitation spectrum. The energy of interaction between phenoxazine hetero-cycle of 7AAMD and chromophores of the carriers studied has been found. In the case of 7AAMD with guanine, adenine, thymine and caffeine, the energy is about of 7 kcal/mol, which is a little lower than in the case with DNA (7.7 kcal/mol). On the basis of emission spectra, in all examined compounds, with the exception DNA, the 7AAMD molecule emits photons from water phase, not from a cluster, since photo-excitation leads to desorption of the antibiotic from a cluster surface. We observed also the mutual fluorescence quenching of 7AAMD and FA in their complex. It may well be that this complex forms due to interaction of peptide-lactone rings of 7AAMD with system of FA. In the case of DNA, the complex with 7AAMD has very high stability that is determined not only by interaction between phenoxazine of 7AAMD and the DNA bases, but it is largely owing to the interaction between two peptide-lactone rings of 7AAMD and the DNA deoxyribose-phosphate chains.

[Fluorescence study of energetics in nucleotide-actinomycin complexes]

Variety of different compounds use for delivery of antibiotics to the tumor cells. In this work, using a highly sensitive fluorescence analysis, we have studied complexes of fluorescent analog of the natural heterocyclic antibiotic actinomycin D (7-aminoactinomycin D) with potential carriers: purine bases and fragmented DNA. The antibiotic is not only adsorbed on the surface ofpurine clusters, but also is embedded in them. The antibiotic is especially well integrated into the unwound DNA regions. Embedding is accompanied by a long-wavelength shift in the excitation spectrum. The magnitude of the shift was used for calculation of the interaction energy. In the case of AMD with guanine, caffeine and adenine, the value of energy was about of 7 kcal/mol and in the case of fragmented DNA it was only a bit higher: 7.7 kcal/mol. It can be assumed that guanine, adenine, caffeine, and the fragmented DNA could apply as carriers of antibiotic.

Actinomycins like anti-cancer photo-sensitizers

Spectroscopic and microscopic study on application of actinomycins as anti-tumor photo-sensitizing drugs was carried out in this work. It has been shown that 7-aminoactinomycin (7AAMD) and actinomycin D (AMD) inside cells of line HeLa bind not only with DNA, but also with proteins. Fluorescence of 7AAMD in HeLa cells and destruction of these cells by photosensitizing with actinomycin D were detected. When photo-destruction occurs, the antibiotic is released out from destroyed cells.