Kinga Ostrowska

Synthesis, structural studies and biological activity of new Cu(II) complexes with acetyl derivatives of 7-hydroxy-4-methylcoumarin.

The new Cu(II) complexes with 6-acetyl-7-hydroxy-4-methylcoumarin (HL1) and 8-acetyl-7-hydroxy-4-methylcoumarin (HL2) have been obtained by the electrochemical method. The density functional theory calculations and X-ray absorption spectroscopy techniques have been used to geometrically describe a series of new compounds. The studies have been focused on the coordination mode of the hydroxy ligands to the metallic centre. The complexes, Cu(HL1)2 and Cu(HL2)2⋅0.5H2O, have flat square geometry with oxygen atoms in the first coordination sphere. Two bidentate anionic coumarins are bonded to the metal cation via the acetyl and deprotonated hydroxyl O atoms. Biological activity, including microbiological and cytotoxic, has been evaluated and found to be enhanced in comparison with the parent ligands. Moreover, the Cu(II) complex with 8-acetyl-7-hydroxy-4-methylcoumarin shows similar antifungal activity as commercially used fluconazole.

Synthesis and Antifungal Activity of Derivatives of 2- and 3-Benzofurancarboxylic Acids

We found that amiodarone has potent antifungal activity against a broad range of fungi, potentially defining a new class of antimycotics. Investigations into its molecular mechanisms showed amiodarone mobilized intracellular Ca2+, which is thought to be an important antifungal characteristic of its fungicidal activity. Amiodarone is a synthetic drug based on the benzofuran ring system, which is contained in numerous compounds that are both synthetic and isolated from natural sources with antifungal activity. To define the structural components responsible for antifungal activity, we synthesized a series of benzofuran derivatives and tested them for the inhibition of growth of two pathogenic fungi, Cryptococcus neoformans and Aspergillus fumigatus, to find new compounds with antifungal activity. We found several derivatives that inhibited fungal growth, two of which had significant antifungal activity. We were surprised to find that calcium fluxes in cells treated with these derivatives did not correlate directly with their antifungal effects; however, the derivatives did augment the amiodarone-elicited calcium flux into the cytoplasm. We conclude that antifungal activity of these new compounds includes changes in cytoplasmic calcium concentration. Analyses of these benzofuran derivatives suggest that certain structural features are important for antifungal activity. Antifungal activity drastically increased on converting methyl 7-acetyl-6-hydroxy-3-methyl-2-benzofurancarboxylate (2b) into its dibromo derivative, methyl 7-acetyl-5-bromo-6-hydroxy-3-bromomethyl-2-benzofurancarboxylate (4).

Synthesis of new derivatives of 2,2-dimethyl-2,3-dihydro-7-benzo[b]furanol with potential antimicrobial activity

A series of 13 new ether-linked derivatives of 2,2-dimethyl-2,3-dihydro-7-benzo[b]furanol have been designed and synthesized. Ten of them were evaluated for their potential antimicrobial activity against some Gram-positive and Gram-Negative bacteria and fungi of the Candida species.

Anticancer effects of O-aminoalkyl derivatives of alloxanthoxyletin and seselin

Seselin and alloxanthoxyletin, naturally occurring pyranocoumarins, were recently isolated from a number of plant sources, such as family of Rutaceae. It was previously reported that their natural and synthetic derivatives show cytotoxic and antitumor activity. In the present study new series of O-aminoalkyl substituted alloxanthoxyletins and seselins were synthesized and evaluated for their anticancer toxicity. Microwave assisted synthesis was used, and the structures of the compounds were confirmed by 1H NMR, 13C NMR and MS spectroscopic data. The molecular and crystal structure of 3a was analyzed by single crystal X-ray diffraction. Alloxanthoxyletin derivatives 2a, 2b, and 2d showed the highest cytotoxic potential against HTB-140 cells with IC50 of 2.48, 2.80 and 2.98μM, respectively. In vitro drug sensitivity testing in HaCaT, A549 and HTB-140 cells were also performed. Tumor cells showed a higher sensitivity to tested compounds than normal cells. Compounds 2a, 2b and 2d inhibited cell migration and exerted stronger effect on A549 and HTB-140 cells than on HaCaT cells. In order to explain the basic mechanism of cell death induction we have investigated the effect of derivatives 2a, 2b and 2d on early and late apoptosis using annexin V-FITC/7-AAD flow cytometry analysis. Derivatives 2a and 2b were much more potent inducers of early apoptosis in HTB-140 cells compared to HaCaT and A549 cells.

Drug likeness prediction of 5-hydroxy-substituted coumarins with high affinity to 5-HT 1A and 5-HT 2A receptors

Abstract One of the latest trends is search for the new anti‐psychotic drugs among coumarin derivatives with piperazine moiety. Their therapeutic potential can be hampered by poor physico‐chemical parameters as low brain penetration or limited transport in the body fluid. Herein, we predicted the drug likeness of six coumarins with high affinity towards 5‐HT1A and 5‐HT2A receptors. Subsequent experimental determination of their binding constants to human serum albumin (HSA) revealed the binding with a moderate strength (logK = 4.8–5.8) at the Sudlows site 1, which represents a possibility of temporary storage of tested coumarins on HSA. Computational mapping of the binding of coumarins ‐ HSA complexes showed that the coumarin rings of all tested compounds were similarly located within the hydrophobic binding pocket of HSA, while the rest of molecules (composed with alkyl chains, piperazine and benzene rings) decided about the difference in binding modes by the hydrogen bonding interactions. The proton dissociation constants (pKa) of the compounds were also determined by UV–vis spectrophotometric titrations to obtain the distribution of the species in the different protonation states at physiological pH of 7.4. A good agreement of the computationally‐determined free enthalpy values of the ligand – HSA complexes with the values determined by experimental fluorescence quenching data could be a promising prospect for proposed theoretical strategy. Graphical abstract Figure. No caption available.

5-HT 1A and 5-HT 2A receptors affinity, docking studies and pharmacological evaluation of a series of 8-acetyl-7-hydroxy-4-methylcoumarin derivatives

In this work we describe the synthesis, docking studies and biological evaluation of a focused library of novel arylpiperazinyl derivatives of 8-acetyl-7-hydroxy-4-methylcoumarin. The new compounds were screened for their 5-HT1A and 5-HT2A receptor affinity. Among the evaluated compounds, six displayed high affinities to 5-HT1A receptors (4a-0.9 nM, 6a-0.5 nM, 10a-0.6 nM, 3b-0.9 nM, 6b-1.5 nM, 10b-1 nM). Compound 6a and 10a bearing a bromo- or methoxy- substituent in ortho position of the piperazine phenyl ring, were identified as potent antagonists of the 5-HT1A receptors. In the tail suspension test, mice injected with 6a showed a dose-dependent increase in depressive-like behavior that was related to a decrease in locomotor activity. Compound 10a did not decrease or prolong immobility time nor did it affect home cage activity. Molecular docking studies using 5-HT1A and 5-HT2A homology models revealed structural basis of the high affinity of ortho-substituted derivatives and subtle changes in amino acid interactions patterns depending on the length of the alkyl linker.