Mechanistic studies on two dinuclear organogold(III) compounds showing appreciable antiproliferative properties and a high redox stability

Two dinuclear oxo-bridged organogold(III) compounds, namely [(N,N,C)(2)Au(2)(μ-O)][PF(6)](2) (with N,N,CH = 6-(1-methylbenzyl)-2,2'-bipyridine, Au(2)O1; or 6-(1,1-dimethylbenzyl)-2,2'-bipyridine, Au(2)O2), were previously prepared and characterised. Their solution chemistry under physiological-like conditions has been investigated here as well as their in vitro antiproliferative properties. Notably, these compounds reveal a marked redox stability even in the presence of effective biological reductants such as ascorbic acid and glutathione. The two dinuclear gold(iii) compounds were evaluated for cytotoxic actions against a representative panel of 12 human tumor cell lines, in comparison to respective mononuclear parent compounds [(N,N,C)AuOH][PF(6)], and appreciable biological activity could be highlighted. The reactions of Au(2)O1 and Au(2)O2 with a few model proteins were studied and the ability to form metallodrug-protein adducts monitored through ESI MS methods. Typical adducts were identified where the protein is associated to monometallic gold fragments; in these adducts gold remains in the oxidation state +3 and conserves its organic ligand. A direct comparison of the biological profiles of these binuclear organogold(III) compounds with those previously reported for a series of dinuclear oxo-bridged complexes [(N,N)(2)Au(2)(μ-O)(2)][PF(6)](2) (N,N = 6(6')-substituted 2,2'-bipyridines) named Auoxo's was carried out. It emerges that the greater cytotoxicity of the latter is mainly due to the greater oxidising power of their gold(III) centres and to propensity to generate gold(i) species; in contrast, the here described bimetallic organogold(III) complexes manifest a far higher redox stability in the biological milieu coupled to lower, but still significant, antiproliferative properties. Different molecular mechanisms are thus hypothesised for these two classes of dinuclear gold(III) agents.     

Structural models for the interaction of Cd(II) with DNA: trans-[Cd(9-RGH-N7)2(H2O)4]2+

Reactions of Cd(NO(3))(2) with the model nucleobases 9-alkylguanine in water at neutral pH, give the compounds trans-[Cd(9-RGH-N7)(2)(H(2)O)(4)](NO(3))(2)(R=Me, Et), with the 9-alkylguanine ligands bound to the metal cation at the N(7) position. The X-ray structures of both compounds are reported. The six-coordinate Cd(II) complexes consist of a highly regular octahedral geometry in which the two 9-alkylguanine ligands are in a trans position to each other and approximately collinear with the metal cation. In addition, the networks of both compounds show interesting features. Thus, intramolecular H-bonds between O(6) and a coordinated water molecule are present, and self-association of guanines via H-bonding of N(3)-H...N(2) take place, leading to a 1D supramolecular polymeric ribbon. Density functional theory calculations have been applied to both compounds in order to study the stability of N(7) metalated guanine-guanine associations by comparing experimental and theoretical results. The potential relevance with regard to possible Cd(II)-DNA cross-links is briefly discussed.     

Synthesis and anti-influenza activity of aminoalkyl rupestonates

A series of aminoalkyl rupestonates were designed and synthesized by reacting rupestonic acid with 1,ω-dibromoalkanes, followed by amination. All of the new compounds were bioassayed in vitro to determine their activities against influenza A (H3N2, H1N1) and B viruses. The results showed that compounds 5a-5g, which each contain a 1H-1,2,4-triazolyl moiety, were found to be the most potent set of compounds. Compound 5g was demonstrated to possess the highest inhibitory activity against influenza H3N2 and H1N1, with IC(50) values of 0.97 and 0.42 μM, respectively. Our results also indicated that compounds 2g, 3g, 4g and 5g, which contain ten-CH(2)-unit spacers between the rupestonic acid and amino functional groups, were the most potent inhibitors of influenza H1N1 among the synthesized compounds. Unfortunately, most of the synthesized compounds did not show an obvious activity against influenza B; the only exceptions were compounds 5d and 5f, which had IC(50) values of 17.3 and 3.2 μM, respectively. Compounds 4g and 5g were potent inhibitors of influenza H1N1, and they might be potentially developed as new lead anti-influenza virus compounds. Further studies of the mechanism of action are underway.     

宁夏枸杞根和茎的化学成分及抗炎活性研究

研究宁夏枸杞(Lycium barbarum L.)根部和茎部的化学成分。采用硅胶柱、ODS开放柱、Sephadex LH-20葡聚糖凝胶柱及半制备反相高效液相等色谱手段,对宁夏枸杞根和茎部乙醇提取物的石油醚部位及乙酸乙酯部位化学成分进行分离纯化,根据其理化性质以及波谱数据鉴定得到12个化合物,分别为N-[2-(3,4-dihydroxyphenyl)-2-hydroxyethyl]-3-(4-methoxyphenyl)prop-2-enamide(1)、3-(4-hydroxy-3-methoxy phenyl)-N-2-(4-hydroxyphenyl)-2-methoxyethyl]acrylamide(2)、N-trans-coumaroyloctopamine(3)、(E)-2-(4,5-dihydroxy-2-{3-[(4-hydroxyphenethyl)amino]-3-oxopropyl}phenyl)-3-(4-hydroxy-3,5-dimethoxyphenyl)-N-(4-acetamidobutyl)acrylamide(4)、1,2-dihydro-6,8-dimethoxy-7-hydroxy-1-(3,4-dihydroxy-phenyl)-N1,N2-bis[2-(4-hydroxyphenyl)ethyl]-2,3-naphthalene dicarboxamide(5)、(+)-syringaresinol(6)、zhebeiresinol(7)、(±)-eriodictyol(8)、isovanilin(9)、5,5′-dimethoxybiphenyl-2,2′-diol(10)、p-hydroxyphenethyltrans-ferulate(11)、E-ferulic acid hexacosyl ester(12),所有化合物均为首次从该植物中分离得到。此外,采用MTT法和抑制一氧化氮(NO)生成实验,从细胞毒活性和抗炎活性两方面评估了化合物的生物活性。结果表明,化合物2具有显著的抗炎活性,其IC50值(17.00±1.11μmol/L)小于阳性对照药槲皮素的IC50值(17.21±0.50μmol/L)。     

A Yeast Bioassay for Androgenic and Anti-Androgenic Compounds Based on the NH2- and COOH-Terminal Interaction of Androgen Receptor

Androgenic compounds induce an interaction between the NH₂- and COOH-terminal regions (N–C interaction) of androgen receptor (AR). We describe a rapid yeast bioassay for androgenic and anti-androgenic compounds based on androgen-dependent β-catenin-enhanced N–C interaction. The bioassay was also effective at detecting compounds that inhibit the N–C interaction in ways that do not involve binding to the ligand-binding domain.     

Synthesis and cytotoxic activities of 1-benzylidine substituted beta-carboline derivatives

A series of new beta-carboline derivatives, bearing a benzylidine substituent at position-1, has been prepared and evaluated in vitro against a panel of human cell lines. The N(2)-benzylated beta-carbolinium bromates represented the most interesting cytotoxic activities. In particular, compounds 19 were found to be the most potent compounds with IC(50) values lower than 5 microM against 10 strains human tumor cell lines. These results confirmed that the N(2)-benzyl substituent on the beta-carboline ring played an important role in the modulation of the cytotoxic activities and suggested that further development of such compounds may be interest.     

Antikinetoplastid antimitotic activity and metabolic stability of dinitroaniline sulfonamides and benzamides

N(1)-Phenyl-3,5-dinitro-N(4),N(4)-di-n-propylsulfanilamide (1) and N(1)-phenyl-3,5-dinitro-N(4),N(4)-di-n-butylsulfanilamide (2) show potent in vitro antimitotic activity against kinetoplastid parasites but display poor in vivo activity. Seventeen new dinitroaniline sulfonamide and eleven new benzamide analogs of these leads are reported here. Nine of the sulfonamides display in vitro IC(50) values under 500 nM against African trypanosomes, and the most active antikinetoplastid compounds also inhibit the in vitro assembly of purified leishmanial tubulin with potencies similar to that of 2. While several of the potent compounds are rapidly degraded by rat liver S9 fractions in vitro, N(1)-(3-hydroxy)phenyl-3,5-dinitro-N(4),N(4)-di-n-butylsulfanilamide (21) displays an IC(50) value of 260 nM against African trypanosomes in vitro and is more stable than 2 in the in vitro metabolism assay.     

Superoxide radical-scavenging effects from polymorphonuclear leukocytes and toxicity in human cell lines of newly synthesized organic selenium compounds

Synthetic organic selenium compounds such as 2-phenyl-1,2-benzisoselenazol-3(2H)-one may show glutathione peroxidase-like antioxidant activity. Recently, we synthesized new organic selenium compounds that are thought to be effective antioxidants. To study their possible applications as antioxidants, we evaluated two selenoureas, N,N-dimethylselenourea and 1-selenocarbamoylpyrrolidine, and two tertiary selenoamides, N-(phenylselenocarbonyl)-piperidine and N,N-diethyl-4-chloroselenobenzamide, for their superoxide radical (O2-)-scavenging effects and toxicity. We measured (O2-)-scavenging effects in polymorphonuclear leukocytes (PMNs) with a specific, sensitive and real-time kinetic chemiluminescence method. Furthermore, the toxicity of these compounds was measured in some human cell lines and PMNs using the tetrazolium method. Hydrogen peroxide was measured by a scopoletin method. Finally, translocation of an NADPH oxidase component, p47 phagocyte oxidase, to the cell membrane was investigated by confocal laser scanning microscopy. N,N-Dimethylselenourea and 1-selenocarbamoylpyrrolidine effectively scavenged (O2-) released from 4beta-phorbol 12-myristate 13-acetate-stimulated PMNs, and the 50% inhibitory concentrations were 6.8 +/- 2.2 and 6.5 +/- 2.5 microm, respectively. N-(Phenylselenocarbonyl)-piperidine and N,N-diethyl-4-chloroselenobenzamide also effectively scavenged (O2-) from PMNs, and the 50% inhibitory concentrations were 11.3 +/- 4.8 and 20.3 +/- 6.4 microm, respectively. Selenoureas showed very low toxicity in human cell lines and PMNs, even at high concentrations, whereas tertiary selenoamides were cytotoxic. These compounds did not produce significant amounts of hydrogen peroxide from 4beta-phorbol 12-myristate 13-acetate-stimulated PMNs. None of the compounds significantly affected the translocation of p47 phagocyte oxidase. Selenoureas acted as effective antioxidants and showed low toxicity in some human cells. Thus, these compounds might be new candidates as antioxidative substances.     

Insight into shock-induced chemical reaction from the perspective of ring strain and rotation of chemical bonds

Density functional theory BLYP/DNP and hyperhomodesmotic equations were employed to calculate ring strain energy, the bond dissociation energy of X–NO₂ (X=C, N) and the charges on the nitro groups of several four-membered and six-membered heterocycle compounds. BLYP/DNP and LST/QST + CG method were also applied to calculate bond rotational energy of X–NO₂ (X=C, N) of above mentioned compounds. It indicated that ring strain energy of four-membered heterocycle nitro compounds is apparently higher than that of six-membered heterocycle nitro compounds. Predictably, ring-opening reactions may preferentially occur for those compounds containing higher ring strain energy under shock. In addition, C–NO₂ bonds in these compounds may rotate easier than N–NO₂ bonds in response to the external shock. As for N–NO₂ bonds in these compounds, they also respond to the external shock by the rotation of N–NO₂ bonds, once to the saddle point of the rotational energy barrier, the whole molecule will become relaxed, N–NO₂ bond becomes weaker and eventually leads to the breakage. When one ?C=O, ?C=NH or ?NH₂ group is introduced to the six-membered heterocycle, the charges on the nitro groups of the new compound decrease drastically, and ring strains increase remarkably. It can be predicted that the new compounds will be more sensitive to shock, and the viewpoint is confirmed by the experimental results of shock sensitivity (small scale gap test) of several explosives.     

Substance P. New cyclic analogs

[Adpoc-Glu(N3)6, (Met-N3)11] substance P-(6-11)-peptide was reacted with diamines H2N(CH2) nNH2 (n = 3-10, 12) to give cyclopeptides. Subsequent careful cleavage of the Adpoc group leads to the formation of compounds of type cyclo-[H-Glu-Phe-Phe-Gly-Leu-Met-NH-(CH2) n-NH-] X HCl. The substances produce a specific two-phase myotropic effect in experiments on isolated guinea pig ileum. The compounds where n is 3, 7, 12 exhibit also a hypotensive activity when assayed on anaesthetized rats.     

Mutagenicity of various chemicals including nickel and cobalt compounds in cultured mouse FM3A cells

Employing a suspension culture of FM3A cells, we examined the cytotoxic and mutagenic effects of various chemical compounds. Mutagenicity of various types of mutagens (MNNG, ENNG, sterigmatocystin, mitomycin C, Trp-P-1, and X-rays) was sensitively detected by this assay. Mutagenicity of Trp-P-2 was detected in the presence of an activating enzyme system. Nickel(II) and cobalt(II) compounds (NiCl2, Ni(CH3COO)2, nickel complex [(C2H5)4N]2 [NiCl4], CoCl2, and a cobalt complex [(C2H5)4N]2-[CoCl4]) were cytotoxic to FM3A cells at concentrations of over 1 X 10(-4) M, and produced 2-6-fold increases of the control in the average number of 6-thioguanine-resistant (6TGr) colonies over a very narrow concentration range of 2-4 X 10(-4) M. Comparison of the mutagenicity of various chemical compounds suggested that some of the nickel(II) and cobalt(II) compounds were very weak mutagens.     

15N natural abundance in fruit bodies of different functional groups of fungi in relation to substrate utilization

Natural abundances of ¹⁵N and N concentrations of 34 fruit bodies from 24 species of ectomycorrhizal and saprophytic fungi were measured in a temperate Central European mixed forest stand. The fungi of the two life forms are known to be capable of utilizing different types of N sources (organic N compounds from the humus, inorganic N from the soil and N from litter or wood) differing by their ¹⁵N natural abundance values. Based on the two life forms and the three different N sources, four functional groups of fungi were distinguished: (1) ectomycorrhizal fungi capable of utilizing organic N from the humus; (2) ectomycorrhizal fungi known to depend on inorganic N compounds in the soil; (3) saprophytes capable of utilizing organic N from the humus; and (4) saprophytes utilizing N from dead wood or litter. Large differences were found between species in the δ¹⁵N values (−3.0 to 3.3‰) and in the N concentrations (0.84 to 6.61 mmol eq N g dw⁻¹) of the fruit bodies. In most cases fungi were more enriched in ¹⁵N than their respective bulk N source was. Fungi living in humus, and presumably having access to organic N compounds (groups 1 and 3), were significantly more enriched in ¹⁵N than fungi which are known to depend on inorganic N (e.g. Laccaria , group 2), or fungi living on litter or wood (group 4), irrespective of whether they were ectomycorrhizal or saprophytic species. Fungi living in humus had significantly higher N concentrations than fungi living on litter or wood.     

Model investigations for vanadium-protein interactions: vanadium(III) compounds with dipeptides and their oxovanadium(IV) analogues

The reaction of VCl(3) with 1,10-phenanthroline and a series of dipeptides (H(2)dip), having aliphatic as well as aromatic side chains, in methyl alcohol and in the presence of triethylamine affords vanadium(III) compounds of the general formula [V(III)(dip)(MeOH)(phen)]Cl. Aerial oxidation/hydrolysis of the vanadium(III) species gives their oxovanadium(IV) analogues of the general formula [V(IV)O(dip)(phen)]. X-ray crystallographic characterization of the [V(IV)O(dip)(phen)] compounds (where dip(2-)=Gly- L-Ala, Gly- L-Val and Gly- L-Phe) revealed that the vanadium atom possesses a severely distorted octahedral coordination and is ligated to a tridentate dip(2-) ligand at the N(amine) atom, the deprotonated N(peptide) atom and one of the O(carboxylate) atoms, as well as an oxo group and two phenanthroline nitrogen atoms. Circular dichroism characterization of the V(III)/V(IV)O(2+)-dipeptide compounds revealed a strong signal for the V(IV)O(2+) species in the visible range of the spectrum, with a characteristic pattern which may be exploited to identify the N(am), N(pep) and O(car) ligation of a peptide or a protein to V(IV)O(2+) center, and a weak Cotton effect of opposite sign to their vanadium(III) analogues. The visible spectra of the V(III)-dipeptide compounds revealed two d-d bands with high intensity, thus indicating that the covalency of the metal-donor atoms is significant, i.e. the vanadium d orbitals are significantly mixed with the ligand orbitals, and this is confirmed by the low values of their Racah B parameters. The high-intensity band of the V(IV)O(2+)-dipeptide compounds at approximately 460 nm implies also a strong covalency of the metal with the equatorial donor atoms and this was supported by the EPR spectra of these compounds. Moreover, the V(III)/V(IV)O(2+)-dipeptide complexes were characterized by EPR and IR spectroscopies as well as conductivity and magnetic susceptibility measurements.     

Does the combination of optimal substitutions at the C²-, N⁵- and N⁸-positions of the pyrazolo-triazolo-pyrimidine scaffold guarantee selective modulation of the human A₃ adenosine receptors?

In an attempt to study the optimal combination of a phenyl ring at the C(2)-position and different substituents at the N(5)- and N(8)-positions towards the selective modulation of human A(3) adenosine receptors (hA(3)AR), we synthesized a new series of 2-para-(un)substituted-phenyl-pyrazolo-triazolo-pyrimidines bearing either a methyl or phenylethyl at N(8) and chains of variable length at N(5). Through biological evaluation, it was found that the majority of the compounds had good affinities towards the hA(3)AR in the low nanomolar range. Compound 16 possessed the best hA(3)AR affinity and selectivity profile (K(i)hA(3)=1.33 nM; hA(1)/hA(3)=4880; hA(2A)/hA(3)=1100) in the present series of 2-(substituted)phenyl-pyrazolo-triazolo-pyrimidine derivatives. In addition to pharmacological characterization, a molecular modeling investigation on these compounds further elucidated the effect of different substituents at the pyrazolo-triazolo-pyrimidine scaffold on affinity and selectivity to hA(3)AR.     

Reactions of plant copper/topaquinone amine oxidases with N6-aminoalkyl derivatives of adenine

Plant copper/topaquinone-containing amine oxidases (CAOs, EC 1.4.3.6) are enzymes oxidising various amines. Here we report a study on the reactions of CAOs from grass pea (Lathyrus sativus), lentil (Lens esculenta) and Euphorbia characias, a Mediterranean shrub, with N6-aminoalkyl adenines representing combined analogues of cytokinins and polyamines. The following compounds were synthesised: N6-(3-aminopropyl)adenine, N6-(4-aminobutyl)adenine, N6-(4-amino-trans-but-2-enyl) adenine, N6-(4-amino-cis-but-2-enyl) adenine and N6-(4-aminobut-2-ynyl) adenine. From these, N6-(4-aminobutyl) adenine and N6-(4-amino-trans-but-2-enyl)adenine were found to be substrates for all three enzymes (Km approximately 10(-4)M). Absorption spectroscopy demonstrated such an interaction with the cofactor topaquinone, which is typical for common diamine substrates. However, only the former compound provided a regular reaction stoichiometry. Anaerobic absorption spectra of N6-(3-aminopropyl)adenine, N6-(4-amino-cis-but-2-enyl)adenine and N6-(4-aminobut-2-ynyl)adenine reactions revealed a similar kind of initial interaction, although the compounds finally inhibited the enzymes. Kinetic measurements allowed the determination of both inhibition type and strength; N6-(3-aminopropyl)adenine and N6-(4-amino-cis-but-2-enyl)adenine produced reversible inhibition (Ki approximately 10(-5) - 10(-4) M) whereas, N6-(4-aminobut-2-ynyl)adenine could be considered a powerful inactivator.     

N1,N5,N10-Tris(4-hydroxycinnamoyl)spermidines from Microdesmis keayana roots

Three new N1,N5,N10-tris(4-hydroxycinnamoyl)spermidines were isolated from a methanolic root extract of Microdesmis keayana. They were identified as N5,N10-di(p-coumaroyl)-N1-feruloylspermidine,N5-(p-coumaroyl)-N1,N10-diferuloylspermidine, and N1,N5,N10-triferuloylspermidine, and were named keayanidines A, B, and C (1-3), respectively. Their structures were established by spectral techniques(electrospray mass spectrometry, one- and two-dimensional NMR). A 4',4',4'-trimethylated derivative was prepared by methylation of keayanidine C, and the same compound was synthesized fromspermidine and 3,4-dimethoxycinnamic acid to confirm the spectral attributions of the NMR data of the natural compounds. Radical-scavenging properties of all compounds were evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical spectrophotometric assay.     

Synthesis of N-propargylphenelzine and analogues as neuroprotective agents

A series of N(1)- and N(2)-propargylphenelzine derivatives and analogues (1-7) was synthesized. In addition to their activity as monoamine oxidase inhibitors, two of the compounds, N(1)- and N(2)-propargylphenelzines (3 and 6), were found to be potent at preventing DSP-4-induced noradrenaline (NA) depletion in mouse hippocampus, suggesting that they have neuroprotective properties.     

The importance of molecular parameters of quaternary ammonium salts in their antigibberellin (retardant) activity

The importance of six theoretically calculated molecular parameters in the antigibberellin (retardant) activity of quaternary ammonium salts is studied using regression analysis. A bioassay system based on cell culture of fungus Gibberella fujikuroi is used to determine the activity. In the case of N,N,N-trimethyl-N-(2-hydroxyethyl)ammonium chloride (choline) and N,N,N-triethyl-N-(2-hydroxyethyl)ammonium chloride (N,N,N-triethylcholine) derivatives with linear structure, the polarizability, proton acceptor activity, and lipophilicity of these compounds exert the largest effect on the antigibberellin activity. The antigibberellin activity of more sterically hindered N,N-dialkylpiperidinium salts was mainly defined by the steric parameter, while the polarizability, proton acceptor activity, and (through them) lipophilicity exert a lesser effect. Other parameters are of minor importance for the three groups of compounds studied. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 6; see also http://www.maik.ru.