Visual light photoswitches derived from bindone: Toward stabilization of colored photo-isomers

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Interaction of styrylpyridinium compound with pathogenic Candida albicans yeasts and human embryonic kidney HEK-293 cells

Candida albicans-caused local and systemic diseases are a serious health issue worldwide, leading to high mycosis-associated morbidity and mortality. Efficient combinations of novel compounds with commonly used antifungals could be an important tool for fighting infections. The aim of this study was to evaluate the interaction of synthesized 4-(4-cyanostyryl)-1-dodecylpyridin-1-ium (CSDP+) bromide alone or in combination with fluconazole with yeast and mammalian cells. We investigated cytotoxicity of the tested agents to mammalian HEK-293 cells and the influence of CSDP+ on the ability of C. albicans wt and a clinical isolate to adhere to HEK-293. Accumulation of lipophilic cation ethidium (Et+) was used to monitor the activity of efflux pumps in HEK-293 cells. The effect of CSDP+ on the expression of the main efflux transporter genes and transcription factors in C.albicans cells as well as HEK-293 efflux pump gene ABCB1 was determined. The study showed that CSDP+ alone and in combination with fluconazole was nontoxic to HEK-293 cells and was able to reduce C.albicans adhesion. The treatment of C.albicans cells with CSDP+ in combination with fluconazole resulted in a considerable overexpression of the MDR1 and MRR1 genes. The findings suggest that these genes could be associated with efflux-related resistance to fluconazole. Measurements of Et+ fluorescence and analysis of ABCB1 gene expression demonstrated that mammalian cells were not sensitive to concentrations of CSDP+ affecting C. albicansBiochemijos katedraVytauto Didžiojo universiteta

Chromenes Involving A Two-Photon Absorbing Moiety: Photochromism Via Intramolecular Resonance Energy Transfer

New derivatives involving the photochromic 2H-benzo[h]chromene moieties covalently linked to the 2,7-bis(carbazolyl)fluorene-derived two-photon absorbing moiety were designed to enable the possibility of resonance energy transfer from the fluorene donor to the photochromic acceptor. The longest wavelength absorption of the photochromic acceptors overlaps with the fluorescence band of the two-photon absorbing donor and the distance between the both moieties is about 5-7 Å. Rapid coloration of colorless solutions was observed upon one- and two-photon absorption

Transient Ring Opening And Closing Of A Two-Photon Photochromic Molecule Utilizing Energy Transfer

We have developed an efficient two-photon photochromic molecule by coupling a chromene with a donating 2PA chromophore via resonance energy transfer. The essential parameters of ring opening and closing are determined from transient absorption measurements

Synthesis and spectroscopic properties of 4-amino-1,8-naphthalimide derivatives involving the carboxylic group: a new molecular probe for ZnO nanoparticles with unusual fluorescence features

Of a series of 4-substituted 1,8-naphthalimides, fluorescent 4-(6-piperidinyl-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl)benzoic acid (4) was found to be a sensitive molecular probe for ZnO nanoparticles. We investigated in detail one- and two-photon absorption properties of this fluorophore. In nonpolar solvents, the acid 4 absorbs at about 400 nm and fluoresces at 500 nm with a fluorescence lifetime of about 7 ns, similar to the ester 6 and typical of the lifetimes of other derivatives of this type. Although the anionic form of this acid is not fluorescent, partial ionization of 4 in polar solvents, such as ethanol and acetonitrile, is not only accompanied by the expected decrease in the fluorescence quantum yield, but also gives rise to bathochromic shifts of both absorption and fluorescence and dual fluorescence with lifetimes of 0.2–0.3 ns and 6 ns ascribed to the formation of anionic complexes. The interaction with the ZnO surface brings about further considerable changes in the fluorescence patterns

Transient Ring Opening And Closing Of A Two-Photon Photochromic Molecule Utilizing Energy Transfer

We have developed an efficient two-photon photochromic molecule by coupling a chromene with a donating 2PA chromophore via resonance energy transfer. The essential parameters of ring opening and closing are determined from transient absorption measurements

A new class of spirocyclic photochromes reacting with light of both UV and visible ranges

International audienceThe condensation of bindone with cinnamic aldehydes produces cyclic isomers instead of the expected colored merocyanine dyes. These compounds exhibit unprecedented photochromic behavior: the formation of the colored open forms is observed upon irradiation by light of any wavelength between 254 and 642 nm

Antifungal activity of styrylpyridinium compounds against Candida albicans

Accepted: 25 July 2020We synthesized a set of 13 new and earlier described styrylpyridinium compounds (N‐alkyl styrylpyridinium salts with bromide or tosylate anions) in order to evaluate antifungal activity against C. albicans cells, to assay the possible synergism with fluconazole, and to estimate cytotoxicity to mammalian cells. All compounds were synthesized according to a well‐known two‐step procedure involving alkylation of γ‐picoline with appropriate alkyl bromide and further condensation with substituted benzaldehyde. Compounds with long N‐alkyl chains (C18H37–C20H41) had no antifungal activity against the cells of all tested C. albicans strains. Other styrylpyridinium compounds were able to inhibit yeast growth at the concentrations of 0.06–16 μg/ml. At fungicidal concentrations, the compound with the CN‐ group was least toxic to mammalian cells, showed the most effective synergism with fluconazole, and only slightly inhibited the respiration of C. albicans. The compound with the 4′‐diethylamino group exhibited the strongest fungicidal properties and effectively blocked the respiration of C. albicans cells. However, toxicity to mammalian cells was also high. Summarizing, the results of our study indicate that styrylpyridinium compounds are promising candidates in the development of new antifungal drugsBiochemijos katedraVytauto Didžiojo universiteta