Synthesis, crystal structure and physico-chemical properties of 3,3'-[(4-hydroxyphenyl)methyl] bis-(4-hydroxy-2H-chromen-2-one).

The compound 3,3'-[(4-Hydroxyphenyl)methyl]bis-(4-hydroxy-2H-chromen-2-one) was synthesized by the Knoevenagel reaction. Crystals, suitable for X-ray data collection, were grown by slow evaporation from an ethanol solution. The product 3,3'-[(4-Hydroxyphenyl)methyl]bis-(4-hydroxy-2H-chromen-2-one) · ethanol crystallizes in the monoclinic system, space group P2(1)/n. The ultraviolet/visible absorption spectra in different solvents were recorded. Sensitivity of the compound to solvent polarity and hydrogen bonding with protic (ethanol, H(2)O) and aprotic (dimethylsulfoxide, acetonitrile) solvents was detected. Based on (1)H-NMR spectroscopy as well as on potentiometric and UV/vis titration experiments the acid dissociation constants for 3,3'-[(4-Hydroxyphenyl)methyl]bis-(4-hydroxy-2H-chromen-2-one) were estimated.

Synthesis and Inhibiting Activity of Some 4-Hydroxycoumarin Derivatives on HIV-1 Protease.

Six novel 4-hydroxycoumarin derivatives were rationally synthesized, verified, and characterized by molecular docking using crystal HIV-1 protease. Molecular docking studies predicted antiprotease activity of (7) and (10). The most significant functional groups, responsible for the interaction with HIV-1 protease by hydrogen bonds formation are pyran oxygen, atom, lactone carbonyl oxygen and one of the hydroxyl groups. The newly synthesized compounds were biologically tested in MT-4 cells for inhibiting HIV-1 replication, exploring the protection of cells from the cytopathic effect of HIV measured by cell survival in MTT test. One derivative -7 showed 76-78% inhibition of virus infectivity with IC(50) = 0.01 nM, much less than the maximal nontoxic concentration (1 mM). Antiprotease activity of 7 in two different concentrations was detected to be 25%. Nevertheless, the results of study of (7) encourage using it as a pharmacophore for further synthesis and evaluation of anti-HIV activity.

Structure-activity relationships of new 4-hydroxy bis-coumarins as radical scavengers and chain-breaking antioxidants.

The main antioxidant properties of five new 4-hydroxy-bis-coumarins during bulk lipid autoxidation at 80 degrees C and 0.1 mM and 1.0 mM concentrations were studied and compared with 4-hydroxy-2H-chromen-2-one (1). These compounds are: 3,3'-((3,4-dihydroxy-phenyl) methylene) bis (4-hydroxy-2H-chromen-2-one) (2), 3,3'-((3,4-dimethoxyphenyl) methylene) bis (4-hydroxy-2H-chromen-2-one) (3), 3,3'-((4-hydroxy-3,5-dimethoxy-phenyl) methylene) bis(4-hydroxy-2H-chromen-2-one) (4) 3,3'-((3,4,5- trimethoxyphenyl) methylene) bis (4-hydroxy-2H-chromen-2-one) (5) 3,3'-((4-hydroxy-3-methoxy-5-nitrophenyl) methylene) bis (4-hydroxy-2H-chromen-2-one) (6), It was found that compound 2 with a catecholic structure in the aromatic nucleus showed the strongest antioxidant activity. Compound 4 showed a moderate antioxidant activity, and all the other compounds didn't show any capacity as chain-breaking antioxidants. Both 4-hydroxy-bis-coumarins (2 and 4) demonstrated also stronger radical scavenging activity towards DPPH radical by using TLC DPPH rapid test, than compound 1. The other compounds (3, 5, 6) didn't show any capacity as radical scavengers. The structure-activity relationship was discussed on the base of comparable kinetic analysis of studied 4-hydroxy-bis-coumarins with the known and standard antioxidants as alpha-tocopherol (TOH), caffeic acid (CA), sinapic acid (SA), ferulic acid (FA), and p-coumaric acid (p-CumA). In order to study the possible synergism between two phenolic antioxidants, the antioxidant efficiency and reactivity of two equimolar binary mixtures of coumarins and TOH (2+TOH and 4+TOH) and of corresponding cinnamic acid with TOH (CA+TOH and SA+TOH) were also tested and compared. The oxidation stability of the lipid substrate in presence of binary mixtures CA+TOH, SA+TOH and 2+TOH appeared to be higher than that of the individual antioxidants. However, no synergism was obtained for all tested binary mixtures.

Synthesis, computational study and cytotoxic activity of new 4-hydroxycoumarin derivatives.

Six new 4-hydroxycoumarin derivatives have been synthesized. They were characterized by UV-vis, IR, (1)H NMR, (13)C NMR, mass spectral data, elemental analysis, TLC and melting point determination. The new 4-hydroxycoumarin derivatives are studied by computational methods--DFT (B3LYP) and force field methods (MM2 and OPLS), in order to optimize their geometry and calculate quantum-chemical properties and conformational analysis. Five new 4-hydroxycoumarin derivatives were tested for cytotoxic activity in two tumor cell lines--HL-60 and EJ. The obtained results are compared with the utilized anticancer drug melphalan. Two of these compounds--ethyl 2-[(3,4-dihydroxyphenyl)(4-hydroxy-2-oxo-2H-chromen-3-yl)methyl]-3-oxobutanoate (SS-16) and ethyl 2-[(4-hydroxy-2-oxo-2H-chromen-3-yl)(3-nitrophenyl)methyl]-3-oxobutanoate (SS-21) show comparatively good cytotoxic properties. Their activity is weaker than melphalan. SS-16 seems to be more active than SS-21.

Synthesis, structure, toxicological and pharmacological investigations of 4-hydroxycoumarin derivatives.

Twenty 4-hydroxycoumarin derivatives were synthesized. Five of them are described for the first time. The X-ray crystal structure analysis of 3,3'-(2,3,4-trimethoxyphenylmethylene)bis-(4-hydroxy-2H-1-benzopyran-2-one) (7) and 3,3'-(3,5-dimethoxy-4-hydroxyphenylmethylene)bis-(4-hydroxy-2H-1-benzopyran-2-one) (9) confirmed the structure of these compounds. A comparative pharmacological study of the anticoagulant effect with respect to Warfarin showed that the synthesized compounds have different anticoagulant activities. The most prospective compound is 3,3'-(4-chlorophenylmethylene)bis-(4-hydroxy-2H-1-benzopyran-2-one) (12) with low toxicity, very good index of absorption and dose dependent anticoagulant activity.

Synthesis and anticoagulant activities of substituted 2,4-diketochromans, biscoumarins, and chromanocoumarins.

Different substituted 2,4-diketochromans, biscoumarins, and chromanocoumarins are the final products when 4-hydroxycoumarin and aromatic aldehydes containing hydroxyl group in o-, m,- or p-position condense in boiling ethanol. We synthesized 14 compounds. Three of them are described for the first time. The X-ray crystal structure analysis of 3-[6-oxo-(6H, 7H)-benzopyrano[4,3-b]benzopyran-7-yl]-4-hydroxy-2H-1-benzopyran-2-one 1 confirmed the structure of this compound. Acute toxicity studies of the compounds were performed on mice by oral and intraperitoneal administration. A comparative pharmacological study of the in vivo anticoagulant effect of the derivatives with respect to warfarin showed that the synthesized compounds have different anticoagulant activities. The most prospective compounds are 3-(3'-hydroxybenzylidene)-2,4-diketochroman 4 and 3,3'-(2-pyridylmethylene)-bis-4-hydroxy-2H-1-benzopyran-2-one 11 with low toxicity and dose-dependent anticoagulant activity in vivo.

Antihuman Immunodeficiency Virus Type 1 (HIV-1) Activity of Rare Earth Metal Complexes of 4-Hydroxycoumarins in Cell Culture.

The cerium Ce(III), lanthanum La(III), and neodymium Nd(III) complexes with 4-hydroxy-3-(3-oxo-1-phenylbutyl)-2H-1-benzopyran-2-one (warfarin) (W) and 3,3'-benzylidenebis[4-hydroxycoumarin] (1) were synthesized and studied for the first time for cytotoxicity (on MT-2 cells) and as anti-HIV agents under acute and chronic infection. The complexes were characterized by different physicochemical methods: mass spectrometry, (1)H NMR, (13)C NMR, and IR spectroscopy. The spectra of the complexes were interpreted on the basis of comparison with the spectrum of the free ligands. Anti-HIV effect of the complexes/ligands was measured in MT-2 cells by microtiter infection assay. Detection of endogenous reverse transcriptase (RT) activity and RT processivity by PCR indicative for proviral DNA synthesis demonstrated that anti-HIV activity has not been linked to early stages of viral replication. No effect on late steps of viral replication has been found using cells chronically producing HIV-1(LAI) virus. La(W) demonstrated anti-HIV activity (IC50=21.4 muM) close to maximal nontoxic concentration. Nd(W), Ce(1), and Nd(1) demonstrated limited anti-HIV potency, so none of the complexes seems appropriate to be used in clinic. Further targeting of HIV-1 inhibition by La(W) is under progress.

Cytotoxic activity of new cerium (III) complexes of bis-coumarins.

Complexes of cerium (III) with bis-coumarins: 3,3'-benzylidene-bis(4-hydroxy-2H-1-benzopyran-2-one) and bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-(1H-pyrazol-3-yl)-methane were synthesized by reaction of cerium (III) salt and the ligands, in amounts equal to metal/ligand molar ratio of 1:2. The complexes were prepared by adding an aqueous solution of cerium (III) salt to an aqueous solution of the ligand subsequently raising the pH of the mixture gradually to ca. 5.0 by adding dilute solution of sodium hydroxide. The cerium (III) complexes with bis-coumarins were characterized by different physicochemical methods--elemental analysis, IR-, 1H- and 13C-NMR-spectroscopies and mass-spectral data. The spectral data of cerium (III) complexes were interpreted on the basis of comparison with the spectra of the free ligands. This analysis showed that in the Ce (III) complexes the ligands coordinated to the metal ion through both deprotonated hydroxyl groups. On the basis of the nu(C=O) red shift observed, participation of the carbonyl groups in the coordination to the metal ion was also suggested. Cytotoxic screening by MTT assay was carried out. In the present study we performed comparative evaluation of the cytotoxic effects of the two newly synthesized cerium complexes against the acute myeloid leukemia derived HL-60 and the chronic myeloid leukemia (CML)-derived BV-173. In addition the cytotoxic effects of Ce (III) complex with 3,3'-benzylidene-bis(4-hydroxy-2H-1-benzopyran-2-one) were evaluated on the CML-derived K-562 and LAMA-84 cells, characterized by relative low responsiveness to chemotherapy. The DNA isolated from the cytosolic fraction of BV-173 cells after 24 h treatment with the same complex (at 100 and 200 microM) demonstrated a laddering phenomenon that is indicative for apoptotic cell death.

Cytotoxic activity of new neodymium (III) complexes of bis-coumarins.

Complexes of neodymium (III) with bis-coumarins: 3,3'-benzylidene-bis(4-hydroxy-2H-1-benzopyran-2-one); bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-piridin-2-yl-methane; bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-piridin-4-yl-methane; bis(4-hydroxy-2-oxo-2H-chromen-3-yl)-(1H-pyrazol-3-yl)-methane were synthesized by reaction of neodymium (III) salt and the ligands, in amounts equal to metal:ligand molar ratio of 1:2. The complexes were prepared by adding an aqueous solution of neodymium (III) salt to an aqueous solution of the ligand subsequently raising the pH of the mixture gradually to ca. 5.0 by adding dilute solution of sodium hydroxide. The neodymium (III) complexes with bis-coumarins were characterized by different physicochemical methods-elemental analysis, IR-, (1)H- and (13)C-NMR-spectroscopies and mass-spectral data. The spectral data of neodymium (III) complexes were interpreted on the basis of comparison with the spectra of the free ligands. This analysis showed that in the Nd (III) complexes the ligands coordinated to the metal ion through both deprotonated hydroxyl groups. On the basis of the nu(C=O) red shift observed, participation of the carbonyl groups in the coordination to the metal ion was also suggested. Cytotoxic screening by MTT assay was carried out. The complexes were tested on HL-60, HL-60/Dox and SKW-3 cell lines. The overall results from the preliminary screening program revealed that all of the new Nd (III) complexes reach 50% inhibition of the malignant cells proliferation and thus could be considered as biologically active. On the basis of the IC(50) values obtained compounds Nd(L(1))(OH).H(2)O and Nd(L(3))(OH).2H(2)O were found to exert superior activity in comparison to the remaining complexes.

Stability of the complexes of some lanthanides with coumarin derivatives. II. Neodymium(III)-acenocoumarol.

A complex of neodymium(III) with 4-hydroxy-3[1-(4-nitrophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one (acenocoumarol) was synthesized by mixing water solutions of neodymium(III) nitrate and the ligand (metal to ligand molar ratio of 1:3). The complex was characterized and identified by elemental analysis, conductivity, IR, 1H NMR and mass spectral data. DTA and TGA were applied to study the composition of the compound. Elemental and mass spectral analysis of the complex indicated the formation of a compound of the composition NdR3 x 6H2O, where R = C19H14NO6-) The reaction of neodymium(III) with acenocoumarol was studied in detail by the spectrophotometric method. The stepwise formation of three complexes, vis., NdR2+, NdR2+ and NdR3 was established in the pH region studied (pH 3.0-7.5). The equilibrium constants for 1:1, 1:2 and 1:3 complexes were determined to be log K1 = 6.20 +/- 0.06; log K2 = 3.46 +/- 0.07 and log K2) = 2.58 +/- 0.05, respectively.

Stability of the complexes of some lanthanides with coumarin derivatives. I. Cerium(III)-4-methyl-7-hydroxycoumarin.

A complex of cerium(III) with 4-methyl-7-hydroxycoumarin was synthesized by mixing water solutions of cerium(III) nitrate and 4-methyl-7-hydroxycoumarin sodium salt in a metal-to-ligand molar ratio of 1:2. The complex was characterized and identified by elemental analysis, conductometry, IR, 1H and 13C NMR-spectroscopy, mass spectral data, DTA and TGA. Thermal analysis of the complex indicated the formation of a compound of the composition CeR2(OH).5H2O, R standing for the ligand. The reaction of cerium(III) with 4-methyl-7-hydroxycoumarin was studied in detail by the spectrophotometric method. The stepwise formation of two complexes, vis., CeR2+ and CeR2+, was established in the pH region studied. The equilibrium constants for 1:1 and 1:2 complexes were determined to be 10.72 and 9.22, respectively.

Synthesis and pharmacological investigations of some 4-hydroxycoumarin derivatives.

The synthesis of ten coumarin derivatives of 4-hydroxycoumarin and various unsaturated ketones and aldehydes is described. The structures of the synthesized compounds were confirmed by IR, (1)H-NMR, and mass-spectral data. Acute toxicity studies of the compounds were performed on mice by oral and intraperitoneal administration. A comparative pharmacological study of the in vivo anticoagulant effects of the derivatives with respect to warfarin, showed that the compounds have anticoagulant activity. Compounds 4-hydroxy-3-[1-phenyl-2-(4'-chlorobenzoyl)ethyl]-2H-1-benzopyran-2-one 2b, 4-hydroxy-3-[1-(4-fluorophenyl)-3-oxobutyl]-2H-1-benzopyran-2-one 3a, and 3, 3'-p-bromobenzylidene-bis-(4-hydroxy-2H-1-benzopyran-2-one) 4b showed slight acute toxicity and a greater anticoagulant effect than warfarin.