Browsing by Author "Anichina K.K."

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    Fluorescent Probes as a Tool in Diagnostic and Drug Delivery Systems
    (2023-03-01) Georgiev N.I.; Bakov V.V.; Anichina K.K.; Bojinov V.B.
    Over the last few years, the development of fluorescent probes has received considerable attention. Fluorescence signaling allows noninvasive and harmless real-time imaging with great spectral resolution in living objects, which is extremely useful for modern biomedical applications. This review presents the basic photophysical principles and strategies for the rational design of fluorescent probes as visualization agents in medical diagnosis and drug delivery systems. Common photophysical phenomena, such as Intramolecular Charge Transfer (ICT), Twisted Intramolecular Charge Transfer (TICT), Photoinduced Electron Transfer (PET), Excited-State Intramolecular Proton Transfer (ESIPT), Fluorescent Resonance Energy Transfer (FRET), and Aggregation-Induced Emission (AIE), are described as platforms for fluorescence sensing and imaging in vivo and in vitro. The presented examples are focused on the visualization of pH, biologically important cations and anions, reactive oxygen species (ROS), viscosity, biomolecules, and enzymes that find application for diagnostic purposes. The general strategies regarding fluorescence probes as molecular logic devices and fluorescence–drug conjugates for theranostic and drug delivery systems are discussed. This work could be of help for researchers working in the field of fluorescence sensing compounds, molecular logic gates, and drug delivery.
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    New 1H-benzimidazole-2-yl hydrazones with combined antiparasitic and antioxidant activity
    (2021-12-14) Argirova M.A.; Georgieva M.K.; Hristova-Avakumova N.G.; Vuchev D.I.; Popova-Daskalova G.V.; Anichina K.K.; Yancheva D.Y.
    Parasitic infections, caused mainly by the speciesTrichinella spiralis(T. spiralis), are widespread around the world and lead to morbidity and mortality in the population. Meanwhile, some studies have showed that these parasites induce oxidative stress in the infected host. With the aim of developing a class of compounds combining anthelmintic with antioxidant properties, a series of new benzimidazolyl-2-hydrazones5a-l, bearing hydroxyl- and methoxy-groups, were synthesized. The anthelmintic activity on encapsulatedT. spiraliswas studiedin vitrothus indicating that all hydrazones were more active than the clinically used anthelmintic drugs albendazole and ivermectin.5band5dkilled the total parasitic larvae (100% effectiveness) after 24 hours incubation period at 37 °C in both concentrations (50 and 100 μg ml−1). The antioxidant activity of the target compounds was elucidatedin vitroagainst stable free radicals DPPH and ABTS as well as iron induced oxidative damage in model systems containing biologically relevant molecules lecithin and deoxyribose. The two 2,3- and 3,4-dihydroxy hydrazones5band5dwere the most effective radical scavengers in all studied systems. DFT calculations were applied to calculate the reaction enthalpies in polar and nonpolar medium and estimate the preferred mechanism of antioxidant activity. The relative radical scavenging ability of compounds5a-lshowed a good correlation to the experimentally observed trends. It was found that the studied compounds are capable to react with various free radicals - ˙OCH3, ˙OOH and ˙OOCH3, through several possible reaction pathways - HAT in nonpolar medium, SPLET in polar medium and RAF in both media.
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    Synthesis of 2-Substituted Benzimidazole Derivatives as a Platform for the Development of UV Filters and Radical Scavengers in Sunscreens
    (2023-12-01) Anichina K.K.; Georgiev N.I.
    The modern trend in sunscreen products is towards the development of UV filters with multi-functional properties, to provide a broad shielding against ultraviolet radiation, antioxidant activity, and the prevention of skin cancer. Additionally, they should also be safe for humans as well as the environment. The benzimidazole heterocycle is a suitable platform for the development of such multifunctional molecules with potential application in cosmetic formulations, due to their ability to act as both UV protectors and reactive pharmacophores. This review presents for the first time the progress in the synthesis and optimization of benzimidazole compounds as UV sunscreen filters. The modifications to the substitution pattern of the lead compound and structure–activity relationships are discussed, as well as the synthetic approaches for the preparation of 2-substituted benzimidazoles. These aggregated data will be useful in future in the development of modern benzimidazole-based sunscreen.