Urszula Krajewska

Cytotoxic effects, alkylating properties and molecular modelling of coumarin derivatives and their phosphonic analogues.

The cytotoxic effects and alkylating activity of a series of 3-[1-(alkylamino)-ethylidene]-chroman-2,4-dione (4a-4c), 2-methoxy-3-[1-(alkylamino)-ethylidene]-2,3-dihydro-2,4-dioxo-2lambda(5)-benzo[e][1,2] oxaphosphinane (5a-5c) and [2-oxo-4-phenyl(alkyl)-2H-chromen-3-yl]-phosphonic acids dimethyl ester (6a-6c) on the two leukemia cell lines HL-60 and NALM-6 have been determined. The test compounds are much more toxic to NALM-6 cells than to HL-60 cells. IC(50) data are up to nine times lower for the NALM-6 than for the HL-60 cell lines. As determined in an in vitro Preussmann test phosphonic derivatives 6a-6c possess very high (+++) alkylating activity, phosphoric derivatives 5a-5c are less active (++) while the derivatives 4a-4c can be included in the group of low activity (+) alkylating agents. Using regression analysis QSAR we found a relationship between biological activity and the physicochemical properties of the test compounds. Their cytotoxic effect increases with an increase of the hydrophobic parameters in the region of the substituents at the 2-, 3- and 4-positions of the benzopyrone skeleton of 4-6.

Chemical Composition and Biological Activities of Essential Oil from Salvia sclarea Plants Regenerated in vitro

The essential oils obtained by hydrodistillation of dried aerial parts of Salvia sclarea L. plants, regenerated in vitro and reproduced from seeds, were analyzed by GC and GC-MS. The oils from in vitro and in vivo plants were compared in respect to their chemical composition as well as antimicrobial and cytotoxic activities. The chemical profiles of both oils were very similar, although the yield of essential oil from in vitro plants was lower (0.1%, v/w) than the oil yield isolated from in vivo S. sclarea plants (0.2%, v/w). Both oils showed antimicrobial and cytotoxic activity. The oil from in vitro regenerated plants of S. sclarea exhibited stronger cytotoxic action against NALM-6 cell lines in comparison with the essential oil from in vivo plants.

An unusual taxodione derivative from hairy roots of Salvia austriaca

From a root culture of Salvia austriaca, transformed with Agrobacterium rhizogenes, a new diterpenoid was isolated and its chemical structure was determined as 7-(2-oxohexyl)-11-hydroxy-6, 12-dioxo-7,9(11),13- abietatriene [= 7-(2-oxohexyl)-taxodione] on the basis of spectroscopic methods, especially 1D and 2D NMR, and by comparison with structurally related compounds. This compound represents a hitherto unknown 2-oxohexyl diterpenoid derivative. Cytotoxic studies revealed that the new compound exhibited high cytotoxic activity against three cancer cell lines with IC(50) values ranging from 0.63 to 0.72μM. Its cytotoxic effectiveness against the cancer cells was ten fold higher than that of taxodione.

Synthesis and biological evaluation of α-methylidene-δ-lactones with 3,4-dihydrocoumarin skeleton

A series of new 3-methylidenechroman-2-ones bearing various aromatic moieties and various substituents at position 4 were synthesized in a three step reaction sequence. Friedel-Crafts alkylation of phenols or naphthols using ethyl 3-methoxy-2-diethoxyphosphorylacrylate in the presence of trifluoromethanesulphonic acid gave 3-diethoxyphosphorylchromen-2-ones. These compounds were employed as Michael acceptors in the reaction with Grignard reagents to give adducts which were finally used as Horner-Wadsworth-Emmons reagents for the olefination of formaldehyde. All obtained 3-methylidenechroman-2-ones were tested against two human leukemia cell lines NALM-6 and HL-60 as well as MCF-7 breast cancer and HT-29 colon cancer adenocarcinomas. Several obtained methylidenechromanones displayed high cytotoxic activity with IC(50) values below 1 μM, mainly against leukemia and MCF-7 cell lines. Investigation of structure-activity relationships revealed that the presence of additional, ortho-fused benzene ring and n-butyl or i-propyl group in position 4 enhances the activity. Selected methylidenechromanones were also tested on normal human umbilical vein endothelial cells (HUVEC) and chromanone 14o was found to be eightfold more toxic against MCF-7 than normal cells. Furthermore, antimicrobial assays revealed that chromanone 14n is highly active and bactericidal at concentration equal to MIC or 2MIC against nosocomial and community-associated staphylococci (MRSA) which are resistant to most or all available therapeutic classes of antimicrobial drugs.

Synthesis, X-ray structures and cytotoxic activity of platinum(II), palladium(II) and copper(II) complexes with chelating ligands

Here we present the synthesis of the new chelating ligands 1-benzothiazol-2-yl-5-(2-hydroxyphenyl)-3-methyl-1H-pyrazole-4-carboxylic acid methyl ester (2a) and 1-(6-chloropyridazin-3-yl)-5-(2-hydroxyphenyl)-3-methyl-1H-pyrazole-4-carboxylic acid methyl ester (2b), obtained in the reaction of 2-methyl-4-oxo-4H-chromene-3-carboxylic acid methyl ester (1) with hydrazine derivatives. These ligands 2a and 2b create solid complexes with Pt(II) (4a, 4b), Pd(II) (5a, 5b) and Cu(II) (6a, 7a, 8a, 8b and 9b) metal ions or can be cyclized to 1-benzothiazol-2-yl-3-methyl-1H-chromeno[4,3-c]pyrazol-4-one (3a) or 1-(6-chloropyridazin-3-yl)-3-methyl-1H-chromeno[4,3-c]pyrazol-4-one (3b). The crystal and molecular structures of ligand 2a, its Cu(II) complexes 6a and 7a were determined by X-ray diffraction method. Cytotoxic activity of the ligands 2a and 2b and their complexes 4a, 4b, 5a, 5a, 6a, 8a, 8b and 9b, and modulation of expression of BAX and P53 genes are also shown.

A convenient synthesis and cytotoxic evaluation of β-aryl-α-methylidene-γ-lactones and β-aryl-α-methylidene-γ-lactams

3-Aryl-2-diethoxyphosphoryl-4-nitrohexanoates 8, obtained by Michael addition of ethyl diethoxyphosphorylacetate 6 to 1-aryl-2-nitro-1-butenes 7, were utilized as convenient common intermediates in the synthesis of β-aryl-γ-ethyl-α-methylidene-γ-lactones 17 and β-aryl-γ-ethyl-α-methylidene-γ-lactams 21. Transformation of the nitro functionality in 8 into a hydroxyl or amino group and cyclization yielded lactones 16 or lactams 19, which were used in Horner–Wadsworth–Emmons olefination of formaldehyde to give target compounds in good yields. Cytotoxicity of these compounds was evaluated in vitro against mouse leukemia cell line L-1210 and two human leukemia cell lines, HL-60 and NALM-6. Two of the obtained compounds 17b,c with 4-bromophenyl and 4-methylphenyl substituents in the β position proved to be very potent against all three cell lines with IC50 values lower than 6 μM.

Synthesis and cytotoxic evaluation of β-alkyl or β-aryl-δ-methyl-α-methylene-δ-lactones. Comparison with the corresponding γ-lactones

We present a simple and general strategy for the synthesis of beta,delta-disubstituted-alpha-methylene-delta-lactones starting from easily available tert-butyl 2-(diethoxyphosphoryl)alk-2-enoates. The elaborated synthetic protocol includes pyrrolidine-catalyzed Michael addition of acetone, diastereoselective reduction of the carbonyl group, lactonization and finally the Horner-Wadsworth-Emmons reaction with formaldehyde. All alpha-methylene-delta-lactones were evaluated in vitro against mouse leukemia cell line L-1210 and two human leukemia cell lines HL-60 and NALM-6. Comparison of cytotoxic activity with corresponding alpha-methylene-gamma-lactones is also discussed.

Cytotoxic and proapoptotic activity of diterpenoids from in vitro cultivated Salvia sclarea roots. Studies on the leukemia cell lines.

Four diterpenoids, ferruginol, salvipisone, aethiopinone and 1-oxoaethiopinone, were isolated from transformed roots of Salvia sclarea. Salvipisone and aethiopinone showed relatively high cytotoxicity against HL-60 and NALM-6 leukemia cells (IC50 range 0.6-7.7 μg/ mL which is equal to 2.0-24.7 μᴍ), whereas 1-oxoaethiopinone and ferruginol were less active in this regard. Moreover, we have found that all four diterpenoids of S. sclarea had equal cytotoxic activity against parental HL-60 and multidrug-resistant HL-60 ADR cells, what indicates that they are poor substrates for transport by multidrug resistance-associated protein (MRP1). Caspase-3 activity determinations showed that salvipisone and aethiopinone were able to induce apoptosis in a time- and concentration-dependent manner. The results obtained in this study show that S. sclarea diterpenoids aethiopinone and salvipisone may be useful in the treatment of human cancers, especially in the case of drug resistance.

Synthesis, X-ray structure and cytotoxic effect of nickel(II) complexes with pyrazole ligands.

Here we present the synthesis of the new Ni(II) complexes with chelating ligands 1-benzothiazol-2-yl-3,5-dimethyl-1H-pyrazole (a), 5-(2-hydroxyphenyl)-3-methyl-1-(2-pyridylo)-1H-pyrazole-4-carboxylic acid methyl ester (b) and 1-benzothiazol-2-yl-5-(2-hydroxyphenyl)-3-methyl-1H-pyrazole-4-carboxylic acid methyl ester (c). These ligands a-c create solid complexes with Ni(II). The crystal and molecular structures of two complexes were determined by X-ray diffraction method. Thermal stability of two complexes with ligand c by TG/DTG and DSC methods were also shown. Cytotoxic activity of all the complexes against three tumour cell lines and to normal endothelial cells (HUVEC) was also estimated. Complexes with ligand c exhibited relatively high cytotoxic activity towards HL-60 and NALM-6 leukaemia cells and WM-115 melanoma cells. Cytotoxic effectiveness of one of these complexes against melanoma WM-115 cells was two times higher than that of cisplatin. The protonation constant log K=9.63 of ligand b corresponding to the phenol 2-hydroxy group has been determined in 10% (v/v) DMSO/water solution (25°C). The coordination modes (formation of two monomeric species: NiL and NiL(2)) in the complexes with Ni(II) are discussed for b on the basis of the potentiometric and UV/Vis data.

Co(II), Ni(II) and Cu(II) complexes with phenylthiazole and thiosemicarbazone-derived ligands: synthesis, structure and cytotoxic effects

Complexes of Co(II), Ni(II) and Cu(II) with 2-(3,5-dimethyl-1H-pyrazole-1-yl)-4-phenyl-1,3-thiazole (a) and 3,5-dimethyl-1H-pyrazole-1-carbothioamide (b) ligands were synthesized. The crystal and molecular structures of four of them were determined by the X-ray diffraction method. In the complexes with ligand a the metal atom was bound via two nitrogen atoms, whereas ligand b interacted through the nitrogen and sulfur atoms. Comparing the coordination modes observed for both studied ligands, the thiocarbamoyl sulfur atom can participate in metal binding and in bridge formation, whereas the thiazole (aromatic) sulfur atom is not involved in the coordination. This effect seems to enhance (at least partially) conformational flexibility. Hydrogen bonds played a principal role in the crystal network formation of the analyzed compounds. The cytotoxic activity of the complexes against HL-60 and NALM-6 leukemia cells and the WM-115 melanoma cell line was also measured. The copper(II) complex with the thiosemicarbazone ligand (7b) exhibited relatively high cytotoxicity towards all tested tumor cells. The cytotoxicity of copper(II) complexes 7b and 9b against the melanoma WM-115 cells was over three times higher than that of cisplatin.