Interceptor potential of C60 fullerene aqueous solution: a comparative analysis using the example of the antitumor antibiotic mitoxantrone.

We performed a qualitative and quantitative analysis of intermolecular interactions in aqueous solution between the antitumor antibiotic mitoxantrone and C60 fullerene in comparison with interactions between the antibiotic and well-known aromatic molecules such as caffeine and flavin mononucleotide, commonly referred to as interceptor molecules. For these purposes, we obtained equilibrium hetero-association constants of these interactions using a UV/Vis titration experiment. Special attention was paid to the interaction of C60 fullerene with mitoxantrone, which has been quantified for the first time. Based on the theory of interceptor-protector action and using a set of measured equilibrium constants we managed to estimate the relative biological effect of these mixtures in a model living system, taking human buccal epithelium cells as an example. We demonstrated that C60 fullerene is able to restore the functional activity of the buccal epithelium cell nucleus after exposure to mitoxantrone, which makes it possible to use C60 fullerene as regulator of medico-biological activity of the antibiotic.

Nigellothionins from Black Cumin (Nigella sativa L.) Seeds Demonstrate Strong Antifungal and Cytotoxic Activity.

High-cationic biologically active peptides of the thionins family were isolated from black cumin (Nigella sativa L.) seeds. According to their physicochemical characteristics, they were classified as representatives of the class I thionin subfamily. Novel peptides were called "Nigellothionins", so-called because of their source plant. Thionins are described as components of plant innate immunity to environmental stress factors. Nine nigellothionins were identified in the plant in different amounts. Complete amino acid sequences were determined for three of them, and a high degree of similarity was detected. Three nigellothionins were examined for antifungal properties against collection strains. The dominant peptide, NsW2, was also examined for activity against clinical isolates of fungi. Cytotoxic activity was determined for NsW2. Nigellothionins activity against all collection strains and clinical isolates varied from absence to a value comparable to amphotericin B, which can be explained by the presence of amino acid substitutions in their sequences. Cytotoxic activity in vitro for NsW2 was detected at sub-micromolar concentrations. This has allowed us to propose an alteration of the molecular mechanism of action at different concentrations. The results obtained suggest that nigellothionins are natural compounds that can be used as antimycotic and anti-proliferative agents.

Study of the properties of doxorubicin-resistant cells affected by acute leucosis.

The stiffness of cell membrane was found to be one of the factors determining resistance of a cell in vitro to antibiotic doxorubicin action. Membranes of surviving cells are negatively charged (-35 - -30 mV) and have high values of stiffness (2.2-5.1 µÐ Ð°) at the doxorubicin concentrations in the medium of 1-500 µg/ml. If the drug concentration and exposure time are being increased, only cells with 'soft' membrane (0.25-1 µÐ Ð°) and positive surface potential (15-29 mV) survive. The data obtained have important prognostic value in studying drug resistance of tumour blood cells and can be used as objective markers of efficiency of the antitumor therapy.