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Biomedical subjects

I Kostova

Publications and source records attributed to I Kostova.

16 recordsLinked to original sources
PubMed2006

Chemical components of Fraxinus species.

A wide range of chemical components including coumarins, secoiridoids, phenylethanoids, flavonoids, and lignans has been isolated from Fraxinus species. Extracts and metabolites have been found to possess antiinflammatory, immunomodulatory, antimicrobial, antioxidative, skin regenerating, photodynamic damage prevention, liverprotecting, diuretic and antiallergic activities. Some species find application in contemporary medicine. In the present review the literature data on the phytochemical and biological investigations on the genus Fraxinus are summarized up to the middle of 2004.

Ethnopharmacology↗
PubMed2006

New zirconium (IV) complexes of coumarins with cytotoxic activity.

Complexes of zirconium (IV) with some bis-coumarin ligands have been synthesized. The zirconium (IV) complexes with bis-coumarins were characterized by different physicochemical methods-elemental analysis, IR-, and (1)H-NMR-spectroscopies and mass spectral data. The spectral data of zirconium (IV) complexes were interpreted on the basis of comparison with the spectra of the free ligands. The results of the ligands and their complexes, based on spectral data are informative and useful for suggestion of the metal-ligand binding mode. Cytotoxic screening by MTT assay was carried out. In the present study we performed comparative evaluation of the cytotoxic effects of the three newly synthesized zirconium complexes against the acute myeloid leukemia derived HL-60 and the chronic myeloid leukemia LAMA-84. The preliminary cytotoxicity screening program revealed that the investigated zirconium complexes induced 50% inhibition of the cell viability of HL-60 and LAMA-84 cells at micromolar concentrations and thus could be considered as biologically active. Independently of the tumor test system evaluated the complex of bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-(1H-pyrazol-3-yl)-methane proved superior to the remaining agents with respect to the IC(50) values obtained. The complexes of both the other coumarins evaluated proved to be less potent than the corresponding free ligands, as evidenced by the IC(50) values obtained. Thus the zirconium complexes with coumarin ligands represent a novel class of antiproliferative agents, which deserve further attention in search of anticancer lead compounds.

Antineoplastic Agents↗
PubMed2004

A novel furostanol saponin from Tribulus terrestris of Bulgarian origin.

The phytochemical investigation of the aerial parts of Tribulus terrestris of Bulgarian origin has resulted in the isolation of the novel furostanol saponin 1, named tribol, together with the known spirostanol saponins 2 and 3 and sitosterol glucoside. The structure of tribol was determined as (25R)-furost-5(6)-ene-3beta,16,26-triol-3-O-alpha-rhamnopyranosyl-(1-->2)-[alpha-rhamnopyranosyl-(1-->4)]-beta-glucopyranoside (1) by spectral analysis, including extensive 1D and 2D-NMR experiments.

Bulgaria↗
PubMed2001

Synthesis, physicochemical characterization, and cytotoxic screening of new zirconium complexes with coumarin derivatives.

Zirconium complexes of mendiaxon, warfarin, coumachlor, and niffcoumar have been synthesized by reaction of the ligands with zirconium chloride in stoichiometric ratio 1:2. The formation of the complexes has been proved on the basis of elemental analysis, IR-spectroscopy, 1H-NMR spectroscopy, and thermal studies. Differential thermal analyses and thermogravimetric analyses have been applied to study the compositions of the new complexes. It is concluded that the lactone- and the keto-carbonyl groups of warfarin, coumachlor, and niffcoumar are bonded to the metal ion as bidentate ligands, but mendiaxon is bonded as monodentate ligand. Cytotoxic screening by MTT-assay was carried out. Among these compounds the zirconium complex of mendiaxon showed highest cytotoxic activity against human promyelocytic leukemic HL-60 cells. The inorganic salt was found to be active against this cell line.

Antineoplastic Agents↗
PubMed2001

New lanthanide complexes of 4-methyl-7-hydroxycoumarin and their pharmacological activity.

Complexes of cerium(III), lanthanum(III) and neodymium(III) with 4-methyl-7-hydroxycoumarin (Mendiaxon, Hymecromone) were synthesized by the mixing of equimolar amounts of the respective metal nitrates and 4-methyl-7-hydroxycoumarin sodium salt in water. The complexes were characterized and identified by elemental analysis, conductivities, IR, (1)H and (13)C NMR spectroscopies and mass spectral data. DTA and TGA have been applied to study the compositions of the compounds. The newly synthesized compounds were assayed for acute intraperitoneal and per oral toxicity, influence on blood clotting time and the most active complex was investigated for spasmolytic activity. The complexes of cerium(III) and neodymium(III) showed marginal cytotoxic activity against transformed leukemic cell lines (P3HR1 and THP-1) as compared to the inorganic salts.

Administration, Oral↗
PubMed2001

Fraxinus ornus L.

The literature on the chemical constituents and the biological activity of Fraxinus ornus bark, leaves and flowers has been reviewed. Chemical studies show the presence of many compounds belonging mainly to the groups of hydroxycoumarins, secoiridoid glucosides, phenylethanoids and flavonoids. Biological studies reveal significant antimicrobial, antioxidative, photodynamic damage prevention, wound healing, anti-inflammatory, immunomodulatory and antiviral activities, and support the use of the bark in the folk medicine.

Anti-Infective Agents↗
PubMed2000

Cytotoxic activity of cerium complexes with coumarin derivatives. Molecular modeling of the ligands.

Cerium complexes of Umbellipherone, Mendiaxon, Warfarin, Coumachlor, and Niffcoumar have been synthesized by reaction of the ligands with cerium nitrate in a stoichiometric ratio of 1:2. The formation of the complexes has been proved on the basis of elemental analysis, conductivities, IR spectroscopy, and 1H-NMR spectroscopy. The molecules of the ligands were optimized by means of the semiempirical quantum mechanical method PM3 to the energetically most stable conformers. All the ligands were characterized by molecular and submolecular electronic indices and the putative donor centers are proposed. It is concluded that the lactone- and the keto-carbonyl groups of Warfarin, Coumachlor, and Niffcoumar are bonded to the metal ion as bidentate ligands. The other two coumarins are bonded as monodentate ligands. Conductivity measurements show the non-electrolytic nature of the complexes. Cytotoxic screening by MTT assay was carried out. The cerium complexes were found to be more active than the inorganic salts.

4-Hydroxycoumarins↗
PubMed1995

Effect of a total extract from Fraxinus ornus stem bark and esculin on zymosan- and carrageenan-induced paw oedema in mice.

This study investigates the total ethanol extract (TE) of the stem bark of Fraxinus ornus and its constituent esculin (EN). They inhibited classical pathway (CP) and alternative pathway (AP) of complement activation in mouse serum. After intraperitoneal administration the total extract displayed antiinflammatory activity in both zymosan- and carrageenan-induced paw oedema in mice. The results suggest that the traditional use of Fraxinus ornus stem bark extracts in the treatment of inflammatory disorders is at least partially due to its coumarin constituents.

Animals↗
PubMed1994

Effect of some hydroxycoumarins on complement-mediated hemolysis in human serum.

Coumarin derivatives are known to possess antiinflammatory and antimetastatic properties due to their direct action on cells, predominantly on macrophages. In the present study the interactions between esculin, esculetin, fraxin, fraxetin, as well as their acetylated and methylated derivatives and non-cell system participating in inflammatory processes, comprised of serum complement proteins, were investigated in vitro. 7-Methylesculin, esculin 5Ac and esculetin 2Ac exhibited good inhibition on classical pathway (CP) activity and scoparone strongly reduced alternative pathway (AP) activity in normal human serum (NHS). Some of the hydroxycoumarins were able to enhance hemolysis. Seven derivatives were tested in C1 and C3 functional assays, as 7-methylesculin appeared to be the strongest inhibitor of both activities. Esculin (En) and scopoletin (St) altered the effect of other complement activators (heat aggregated IgG, suramin, and zymosan) when applied with them simultaneously in vitro.

Buffers↗
PubMedDate not supplied

Lignan and coumarin glycosides from Haplophyllum suaveolens.

Two new lignan glycosides of dibenzylbutyrolactol type (haplomarin) and arylnaphthalene type (haploborin) were isolated from the aerial parts of Haplophyllumn suaveolens together with the known arylnaphthalene lignan glycoside arabelline and hydroxycoumarin glycoside xeroboside. So far arabelline is found only in H. buxbaunii. This is the first report of the isolation of xeroboside from Haplophyllum.

Carbohydrate Conformation↗
PubMedDate not supplied

Antiviral activity of some hydroxycoumarin derivatives.

Esculetin (6,7-dihydroxycoumarin) and its diacetate exhibited a marked inhibitory effect on Newcastle disease virus replication in cell cultures at concentrations of 36 microM and 62 microM, respectively. These compounds were selected from ten hydroxycoumarin derivatives through an in vitro antiviral screen involving viruses of the picorna-, orthomyxo-, paramyxo-, and herpes virus families.

Animals↗