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PubMed2006

Ruthenation of duplex and single-stranded d(CGGCCG) by organometallic anticancer complexes.

We have studied the interaction of the organometallic anticancer ruthenium(II) complexes [(eta(6)-p-cymene)Ru(en)Cl][PF(6)] (1) and [(eta(6)-biphenyl)Ru(en)Cl][PF(6)] (2) (en=ethylenediamine) with the single-stranded (ss) DNA hexamer d(CGGCCG) (I) and the duplex d(CGGCCG)(2) (II) by HPLC, ESI-MS, and one- and two-dimensional (1)H and (15)N NMR spectroscopy. For ss-DNA, all three G's are readily ruthenated with [(eta(6)-arene)Ru(en)](2+), but for duplex DNA there is preferential ruthenation of G3 and G6, and no binding to G2 was detected. For monoruthenated duplexes, N7 ruthenation of G is accompanied by strong hydrogen bonding between G-O6 and en-NH for the p-cymene adducts. Intercalation of the non-coordinated phenyl ring between G3 and C4 or G6 and C5 was detected in the biphenyl adducts of mono- and diruthenated duplexes, together with weakening of the G-O6NH-en hydrogen bonding. The arene ligand plays a major role in distorting the duplex either through steric interactions (p-cymene) or through intercalation (biphenyl).

Antineoplastic Agents↗
PubMed2004

Antioxidant activity of plant extracts on the inhibition of citral off-odor formation.

Grape seed, pomegranate seed, green tea, and black tea extracts were used to inhibit the off-odor from citral degradation. A 0.1 M citrate buffer (pH 3), containing 100 ppm citral and 200 ppm gallic acid equivalent plant extract, was incubated at 40 degrees C. The reaction mixtures were analyzed by high-performance liquid chromatography (HPLC) at days 0, 6, 10, 13, and 16 to monitor degradation of citral and formation of alpha, p-dimethylstyrene, p-cymene-8-ol, and p-methylacetophenone. The addition of plant phenolic extracts could not inhibit citral degradation, however, all four plant extracts significantly inhibited p-methylacetophenone formation. The samples, with the addition of plant extracts, exhibited higher concentrations of alpha, p-dimethylstyrene and p-cymene-8-ol than the control. This is presumed to be due to the oxygen-scavenging effect of plant extracts blocking the pathway from p-cymene-8-ol to p-methylacetophenone. Our results suggest that these plant extracts act as general antioxidants inhibiting the generation ofp-methylacetophenone regardless of the types of water-soluble phenolic compounds existing in the plant extracts.

Acyclic Monoterpenes↗
PubMed1979

Determination of halogenated organic compounds and mutagenicity testing of spent bleach liquors.

The content of organohalogenated compounds in spent bleach liquor from different bleaching stages in a sulphate and a sulphite plant has been determined by a combination of glass capillary gas chromatography, gas-liquid chromatography/mass spectrometry and neutron activation analysis. Several compounds which have not been reported before have been identified including halogenated derivatives of dimethyl-propylnaphthalenes and alkylated catechols. The unconcentrated effluents, non-polar and total extracts were tested for mutagenic activity with Ames' Salmonella test. Spent bleach liquors from most bleaching stages as well as the total effluents contained mutagenic compounds. Addition of liver microsomes for metabolic activation reduced the mutagenic activity in all stages except for the first chlorination stage in the sulphate plant. Two isomers of chloro-, bromo-, and dichloro-p-cymene previously determined in effluents from bleaching plants were synthesized from the parent molecule. Both bromo- and dichloro-p-cymene exhibited weak mutagenic activity in the Salmonella test system. Liver microsomes reduced the effect slightly. The chlorinated cymenes were found to account for up to 18% of the total organically-bound chlorine in the non-polar extracts.

Chemical Industry↗
PubMed2006

Estimation of aroma glycosides of nutmeg and their changes during radiation processing.

Glycosidically bound volatile compounds of nutmeg were identified as glyco-conjugates of p-cymene-7-ol, eugenol, methoxyeugenol and alpha-terpineol. Using phenyl-beta-glucoside as external standard the contents of these glycosidic precursors were estimated based on the measurement of TLC spot density on a densitometer. p-Cymene-7-ol rutinoside was the major aroma glycoside (3.15 mg/100 g), followed by glucosides of methoxyeugenol (0.61 mg/100 g), eugenol (0.50 mg/100 g) and alpha-terpineol (0.51 mg/100 g). A dose-dependent breakdown of these glycosidic precursors was observed during gamma-radiation processing. Among the four glycosides, alpha-terpineol glucoside was the most sensitive to radiation while p-cymene-7-ol rutinoside was the least sensitive. A reduction in the content of total glycosides by almost 50% was noted at a dose of 5kGy. Partitioning of aroma glycoside into n-butanol from aqueous extracts was found to result in rapid isolation of aroma glycosides, avoiding time consuming pre-purification on Amberlite XAD-2 column. A routine method based on extraction into n-butanol and subsequent quantification of post-irradiation changes in aroma glycosides on a TLC plate using a densitometer is proposed.

Chromatography, Thin Layer↗
PubMed2000

Chemotaxonomic study on Thymus villosus from Portugal.

The composition of the essential oils of four populations of Thymus villosus subsp. lusitanicus (Boiss.) Coutinho from Portugal was investigated by GC and GC-MS. To study the chemical polymorphism the results obtained from GC analyses of the volatile oils from individual plants from four populations were submited to Principal Component and Cluster analyses. A comparision with the essential oil of T. villosus subsp. villosus, previously studied by us was done. Important differences with regard to the major constituents in these two taxa were found. Linalool, geranyl acetate, geraniol and terpinen-4-ol were the main components of the essential oils of T. villosus subsp. lusitanicus, whereas in the oil of T. villosus subsp. villosus p-cymene, myrcene and alpha-terpineol were the major ones. Although, both taxa showed chemical polymorphism, different types of essential oils were characterized in each one: linalool; linalool/ terpinen-4-ol/trans-sabinene hydrate; linalool/1,8-cineole; geranyl acetate/geraniol; geranyl acetate/geraniol/1,8-cineole in T. villosus subsp. lusitanicus and p-cymene/camphor/linalool; p-cymene/borneol; linalool/geraniol/geranyl acetate; alpha-terpineol/camphor/myrcene in T. villosus subsp. villosus. Thus, the two subspecies of T. villosus can be easely differenciated by the composition of their essential oils.

Journal Article↗
PubMed2003

DNA interactions of monofunctional organometallic ruthenium(II) antitumor complexes in cell-free media.

Modifications of natural DNA in a cell-free medium by antitumor monodentate Ru(II) arene compounds of the general formula [(eta(6)-arene)Ru(en)Cl](+) (arene = biphenyl, dihydroanthracene, tetrahydroanthracene, p-cymene, or benzene; en = ethylenediamine) were studied by atomic absorption, melting behavior, transcription mapping, circular and linear dichroism, plasmid unwinding, competitive ethidium displacement, and differential pulse polarography. The results indicate that these complexes bind preferentially to guanine residues in double-helical DNA. The data are consistent with DNA binding of the complexes containing biphenyl, dihydroanthracene, or tetrahydroanthracene ligands that involves combined coordination to G N7 and noncovalent, hydrophobic interactions between the arene ligand and DNA, which may include arene intercalation and minor groove binding. In contrast, the single hydrocarbon rings in the p-cymene and benzene ruthenium complexes cannot interact with double-helical DNA by intercalation. Interestingly, the adducts of the complex containing p-cymene ligand, which has methyl and isopropyl substituents, distort the conformation and thermally destabilize double-helical DNA distinctly more than the adducts of the three multiring ruthenium arene compounds. It has been suggested that the different character of conformational alterations induced in DNA, and the resulting thermal destabilization, may affect differently further "downstream" effects of damaged DNA and consequently may result in different biological effects of this new class of metal-based antitumor compounds. The results point to a unique profile of DNA binding for Ru(II) arene compounds, suggesting that a search for new anticancer compounds based on this class of complexes may also lead to an altered profile of biological activity in comparison with that of metal-based antitumor drugs already used in the clinic or currently on clinical trials.

Animals↗
PubMed2004

Encapsulation of cationic ruthenium complexes into a chiral self-assembled cage.

A chiral supramolecular assembly encapsulates the two cationic ruthenium sandwich complexes [CpRu(eta(6)-C(6)H(6))](+) and [CpRu(p-cymene)](+). The host-guest complexes K(11)[CpRu(eta(6)-C(6)H(6)) subset Ga(4)L(6)] (2) and K(11)[CpRu(p-cymene) subset Ga(4)L(6)] (3) were characterized by one- and two-dimensional NMR techniques as well as by electrospray mass spectrometry. Encapsulation of the prochiral complex [CpRu(p-cymene)](+) by the chiral host renders enantiotopic protons diastereotopic as evidenced by (1)H NMR spectroscopy.

Cations↗
PubMed2005

Synthesis, characterization, and photochemical behavior of {Ru(arene)}2+ derivatives of alpha-[PW11O39]7-: an organometallic way to ruthenium-substituted heteropolytungstates.

Reaction of [Ru(arene)Cl(2)](2) (arene = benzene, toluene, p-cymene, hexamethylbenzene) with K(7)[PW(11)O(39)].14H(2)O provided two series of organometallic derivatives of heteropolytungstates: type-1 and type-2 complexes of general formulas [PW(11)O(39){Ru(arene)(H(2)O)}](5-) and [{PW(11)O(39){Ru(arene)}}(2){WO(2)}](8-), respectively. All compounds were characterized by infrared and multinuclear NMR ((1)H, (31)P, (183)W) spectroscopies. The crystal structures of Na(4)K(4)[{PW(11)O(39){Ru(benzene)}}(2){WO(2)}].6H(2)O (NaK-2a.6H(2)O), K(7)H[{PW(11)O(39){Ru(toluene)}}(2){WO(2)}].4H(2)O (K-2b.4H(2)O), and Cs(3)K(2)[PW(11)O(39){Ru(p-cymene)(H(2)O)}].4H(2)O (CsK-1c.4H(2)O) were obtained and revealed that the {Ru(arene)} fragment is supported on the oxometallic framework. Photochemical reactivity of [PW(11)O(39){Ru(arene)(H(2)O)}](5-) (arene = toluene, p-cymene) in the presence of various ligands L (L = H(2)O, dimethyl sulfoxide, tetramethylene sulfoxide, and diphenyl sulfoxide) was investigated, and led to the formation of [PW(11)O(39){Ru(L)}](5-), in which the ruthenium is incorporated into the lacunary [PW(11)O(39)](7-) anion.

Journal Article↗
PubMed2006

Synthesis, characterization, and reactivity of [Ru(bpy)(CH3CN)3(NO2)]PF6, a synthon for [Ru(bpy)(L3)NO2] complexes.

We report a high yield, two-step synthesis of fac-[Ru(bpy)(CH3CN)3NO2]PF6 from the known complex [(p-cym)Ru(bpy)Cl]PF6 (p-cym = eta(6)-p-cymene). [(p-cym)Ru(bpy)NO2]PF6 is prepared by reacting [(p-cymene)Ru(bpy)Cl]PF6 with AgNO3/KNO2 or AgNO2. The 15NO2 analogue is prepared using K15NO2. Displacement of p-cymene from [(p-cym)Ru(bpy)NO2]PF6 by acetonitrile gives [Ru(bpy)(CH3CN)3NO2]PF6. The new complexes [(p-cym)Ru(bpy)NO2]PF6 and fac-[Ru(bpy)(CH3CN)3NO2]PF6 have been fully characterized by 1H and 15N NMR, IR, elemental analysis, and single-crystal structure determination. Reaction of [Ru(bpy)(CH3CN)3NO2]PF6 with the appropriate ligands gives the new complexes [Ru(bpy)(Tp)NO2] (Tp = HB(pz)3-, pz = 1-pyrazolyl), [Ru(bpy)(Tpm)NO2]PF6 (Tpm = HC(pz)3), and the previously prepared [Ru(bpy)(trpy)NO2]PF6 (trpy = 2,2',6',2' '-terpyridine). Reaction of the nitro complexes with HPF6 gives the new nitrosyl complexes [Ru(bpy)TpNO][PF6]2 and [Ru(bpy)(Tpm)NO][PF6]3. All complexes were prepared with 15N-labeled nitro or nitrosyl groups. The nitro and nitrosyl complexes were characterized by 1H and 15N NMR and IR spectroscopy, elemental analysis, cyclic voltammetry, and single-crystal structure determination for [Ru(bpy)TpNO][PF6]2. For the nitro complexes, a linear correlation is observed between the nitro 15N NMR chemical shift and 1/nu(asym), where nu(asym) is the asymmetric stretching frequency of the nitro group.

Journal Article↗
PubMed1996

Synthesis and Characterization of Heterodinuclear IrCo, RuCo, IrNi, and RuNi Complexes Containing Pyrazolate and Pyrazolylborate Ligands.

Treatment of the metallo ligands [ML(pz)(2)(Hpz)] (pz = pyrazolate; L = C(5)Me(5), M = Ir (1); L = mesitylene, M = Ru (3)) with [M'Cl{HB(3-i-Pr-4-Br-pz)(3)}] (M' = Co (4), Ni (5)) yields heterodinuclear complexes of formula [LM(&mgr;-pz)(2)(&mgr;-Cl)M'{HB(3-i-Pr-4-Br-pz)(3)}] (L = C(5)Me(5); M = Ir; M' = Co (6), Ni (7). L = mesitylene; M = Ru; M' = Co (8)). The related complex [Ru(eta(6)-p-cymene)(pz)(2)(Hpz)] (2) reacts with equimolar amounts of 4 or 5 to give mixtures of the corresponding bis(&mgr;-pyrazolato) &mgr;-chloro complexes [(eta(6)-p-cymene)Ru(&mgr;-pz)(2)(&mgr;-Cl)M'{HB(3-i-Pr-4-Br-pz)(3)}] (M' = Co (9), Ni (10)) and the triply pyrazolato-bridged complexes [(eta(6)-p-cymene)Ru(&mgr;-pz)(3)M'{HB(3-i-Pr-4-Br-pz)(3)}] (M' = Co (11), Ni (12)). Complex 1 reacts with 5 in the presence of KOH to give the IrNi complex [(eta(5)-C(5)Me(5))Ir(&mgr;-pz)(3)Ni{HB(3-i-Pr-4-Br-pz)(3)}] (13) whereas its reaction with 4 and KOH rendered the bis(&mgr;-pyrazolato) &mgr;-hydroxo complex [(eta(5)-C(5)Me(5))Ir(&mgr;-pz)(2)(&mgr;-OH)Co{HB(3-i-Pr-4-Br-pz)(3)}] (14). The molecular structure of the heterobridged IrCo complex (6) and those of the homobridged RuNi (12) and IrNi (13) complexes have been determined by X-ray analyses. Compound 6 crystallizes in the monoclinic space group P2(1)/n, with a = 10.146(5) Å, b = 18.435(4) Å, c = 22.187(13) Å, beta = 97.28(4) degrees, and Z = 4. Complex 12 is monoclinic, space group P2(1), with a = 10.1169(7) Å, b = 21.692(2) Å, c = 11.419(1) Å, beta = 112.179(7) degrees, and Z = 2. Compound 13 crystallizes in the monoclinic space group Cc, with a = 13.695(2) Å, b = 27.929(6) Å, c = 13.329(2) Å, beta = 94.11(4) degrees, and Z = 4. All the neutral complexes 6, 12, and 13 consist of linear M.M'.B backbones with two (6) or three (12, 13) pyrazolate ligands bridging the dimetallic M.M' units and three substituted 3-i-Pr-4-Br-pz groups joining M' to the boron atoms. The presence in the proximity of the first-row metal M' of the three space-demanding isopropyl substituents of the pyrazolate groups induces a significant trigonal distortion of the octahedral symmetry, yielding clearly different M'-N bond distances on both sides of the ideal octahedral coordination sphere of these metals.

Journal Article↗
PubMed2003

Remarkably favorable hydration of carbonyl substituents in dicationic bis(arene) ruthenium complexes.

The addition of water and methanol to the carbonyl substituents in the dicationic bis(arene)ruthenium complexes [(p-cymene)Ru(C6H5CHO)][OTf]2 (1) and [(p-cymene)Ru(C6H5C(O)CH3)][OTf]2 (2) is remarkably favorable-the equilibrium constants for these reactions are 1 million times greater than those for uncomplexed benzaldehyde and acetophenone. The addition of methanol to the carbonyl group in the o-anisaldehyde complex, [(p-cymene)Ru(C6H4{OCH3}CHO)][OTf]2 (6), occurs with a high degree of kinetic selectivity (94% de).

Journal Article↗
PubMed2005

Identification of characteristic aroma-active compounds from water dropwort (Oenanthe javanica DC.).

Characteristic aroma components of water dropwort (Oenanthe javanica DC.) were evaluated by aroma extract dilution analysis and solid-phase microextraction-gas chromatography-olfactometry. Alpha-Terpinolene (plastic/cucumber-like) was the most intense aroma-active compound in water dropwort. Other potent aroma-active compounds included p-cymene (kerosene-like), alpha-terpinene (lemon), (E)-caryophyllene (woody), (Z,E)-alpha-farnesene (woody), hexanal (green), (Z)-3-hexenol (green), phenylacetaldehyde (honey), (E)-2-nonenal (cucumber), bornyl acetate (cooked vegetable), and gamma-terpinene (lemon). Of these, p-cymene was believed to be primarily responsible for the distinct kerosene-like aroma note of water dropwort. The aroma property of p-cymene was dependent on its concentration and was described as kerosene-like at relatively high concentrations but changed to citrus and green aroma notes at low concentrations.

Chromatography, Gas↗
PubMed2006

Lipolytic effects of citrus peel oils and their components.

This study was conducted to determine the lipolytic effects of eight kinds of citrus peel oils and their components. All of the citrus peel oils revealed lipolytic effects on olive oil model solution ranging from 10.9 to 73.8%. Hakyul (Citrus natsudaidai Hayata) showed the highest lipolytic effect (73.8%), followed by yuza (Citrus junos Sieb. ex Tanaka, 68.1%) and lemon (Citrus limonium, 63.4%), and their effects were comparable with or stronger than that of 5 mM raspberry ketone (p < 0.05). Among 17 authentic compounds relating to citrus peel oils, octanal (78.6%) showed the highest lipolytic effect, followed by gamma-terpinene (76.3%), limonene (75%), terpinen-4-ol (70.7%), nerol (69.9%), p-cymene (67.7%), and geranyl acetate (67.2%), and their effects were stronger than that of 5 mM raspberry ketone (p < 0.05). Ethyl acetate, alpha-pinene, myrcene, citronellal, linallyl acetate, and citronellol exhibited poor lipolytic effect in the model solution. Lipolytic effect was found to be high when the oils included a higher content of gamma-terpinene and p-cymene. Limonene showed potential lipolytic effect, and its effect is likely to be enhanced by the presence of gamma-terpinene and p-cymene. It is considered that monoterpene hydrocarbons consisting of one or two double bonds would have stronger lipolytic effect than those having three double bonds.

Citrus↗
PubMed2005

Uptake of organic gas phase species by 1-methylnaphthalene.

Organic compounds are a significant component of tropospheric aerosols. In the present study, 1-methylnaphthalene was selected as a surrogate for aromatic hydrocarbons (PAHs) found in tropospheric aerosols. Mass accommodation coefficients (alpha) on 1-methylnaphthalene were determined as a function of temperature (267 K to 298 K) for gas-phase m-xylene, ethylbenzene, butylbenzene, alpha-pinene, gamma-terpinene, p-cymene, and 2-methyl-2-hexanol. The gas uptake studies were performed with droplets maintained under liquid-vapor equilibrium conditions using a droplet train flow reactor. The mass accommodation coefficients for all of the molecules studied in these experiments exhibit negative temperature dependence. The upper and lower values of alpha at 267 and 298 K respectively are as follows: for m-xylene 0.44 +/- 0.05 and 0.26 +/- 0.03; for ethylbenzene 0.37 +/- 0.03 and 0.22 +/- 0.04; for butylbenzene 0.47 +/- 0.06 and 0.31 +/- 0.04; for alpha-pinene 0.47 +/- 0.07 and 0.10 +/- 0.05; for gamma-terpinene 0.37 +/- 0.04 and 0.12 +/- 0.06; for p-cymene 0.74 +/- 0.05 and 0.36 +/- 0.07; for 2-methyl-2-hexanol 0.44 +/- 0.06 and 0.29 +/- 0.06. The uptake measurements also yielded values for the product HD(l)(1/2) for most of the molecules studied (H = Henry's law constant, D(l) = liquid-phase diffusion coefficient). Using calculated values of D(l), the Henry's law constants (H) for these molecules were obtained as a function of temperature. The H values at 298 K in units 10(3) M atm(-1) are as follows: for m-xylene (0.48 +/- 0.05); for ethylbenzene (0.50 +/- 0.08); for butylbenzene (3.99 +/- 0.93); for alpha-pinene (0.53 +/- 0.07); for p-cymene (0.23 +/- 0.07); for 2-methyl-2-hexanol (1.85 +/- 0.29).

Journal Article↗
PubMed2004

Single and double metallic layer-containing ruthenium dendrimers. Synthesis and catalytic properties.

The reaction of a series of phosphanyl-terminated carbosilane dendrimers displaying only one phosphorus ligand per arm with [RuCl(2)(p-cymene)](2) resulted in the grafting of RuCl(p-cymene) moieties on the periphery of the dendrimer. In these species, the chloride ligand is easily displaced by the organic bases pyridine, 4-cyanopyridine and 4,4[prime or minute]-bipyridine to afford new cationic metallodendrimers. NMR studies have confirmed the chirality of the ruthenium centre. The species containing 4,4[prime or minute]-bipyridine reacts through the uncoordinated pyridyl nitrogen with a new equivalent of [RuCl(2)(p-cymene)](2) or [RhCl(CO)(2)](2) to lead to homo- or hetero-bimetallic layer-containing dendrimeric systems. The ruthenodendrimers were tested as catalysts in the transfer hydrogenation of cyclohexanone by propan-2-ol and their activity compared with that of some analogous mononuclear ruthenium(ii) complexes.

Journal Article↗
PubMed2005

The synthesis and characterisation of 4,1,2-MC2B10 metallacarboranes.

Reduction of the tethered carborane 1,2-(CH2)3-1,2-closo-C2B10H10 followed by treatment with CoCl2/NaCp, [(p-cymene)RuCl2]2(p-cymene=C6H4MeiPr-1,4), (PMe2Ph)2PtCl2 or (dppe)NiCl2(dppe=Ph2PCH2CH2PPh2) affords reasonable yields of the new 13-vertex metallacarboranes 1,2-(CH2)3-4-Cp-4,1,2-closo-CoC2B10H10 (1), 1,2-(CH2)3-4-(p-cymene)-4,1,2-closo-RuC2B10H10 (2), 1,2-(CH2)3-4,4-(PMe2Ph)2-4,1,2-closo-PtC2B10H10 (3) and 1,2-(CH2)3-4,4-(dppe)-4,1,2-closo-NiC2B10H10 (4), respectively. All compounds were characterised spectroscopically and crystallographically. The cobalt and ruthenium species 1 and 2 have Cs symmetry in both solution and the solid state, having henicosahedral cage structures featuring a trapezoidal C1C2B9B5 face. The platinum and nickel compounds 3 and 4 have asymmetric docosahedral cage structures in the crystal (the more so for 4 than for 3) although both appear, by 11B and 31P NMR spectroscopy, to have Cs symmetry in solution. Low-temperature experiments on the more soluble platinacarborane could not freeze out the diamond-trapezium-diamond fluctional process that we assume is operating in solution, and we therefore conclude that this process has a relatively low activation barrier, probably <35 kJ mol-1.

Journal Article↗
PubMed2006

Aggregation tendency and reactivity toward AgX of cationic half-sandwich ruthenium(II) complexes bearing neutral N,O-ligands.

The aggregation tendency of complexes [Ru(eta6-cymene)(N,O)Cl]X [N,O = 2-benzoylpyridine (2-bzpy), 1, and 2-acetylpyridine (2-acpy), 2, X- = BPh4- or PF6-] has been studied by means of PGSE NMR experiments. It was found that complexes with PF6- as counterion are mainly present in CD2Cl2 as ion pairs at low concentration, as a mixture of ion triples and free anions at medium concentration and as ion quadruples at elevated concentration. 19F, 1H-HOESY NMR experiments revealed that in ion triples and ion quadruples two cationic Ru-units pair up. Consistently, in the solid-state structure of 1PF6, determined through X-ray single-crystal investigation, two cationic Ru-units are held together by an intermolecular pi-pi stacking interaction between the pyridyl rings. Complexes having BPh4- as counterion are only present in solution as even aggregates, namely ion pairs at low concentration and ion quadruples at elevated concentration. In such a case a counteranion bridges two cationic Ru-units as observed in the solid-state structure of 1BPh4. The reactivity of complexes 1-2 toward AgX salts has been investigated in different solvents. Bicationic [Ru(eta6-cymene)(N,O)(MeCN)]X2 (N,O = 2-bzpy, 3, and 2-acpy, 4) and [Ru(MeCN)4(N,O)]X2 (N,O = 2-bzpy, 5, and 2-acpy, 6) complexes were obtained by the reaction of 1 and 2 with AgX in the presence of three equivalents of acetonitrile or in acetonitrile, respectively. The reaction of 1 with AgPF6 in acetone afforded complex [Ru(eta6-cymene)(N,O,O)]PF6 (7, where N,O,O = 4-alcoxide-4-phenyl-4-(pyridin-2-yl)butan-2-one) from the C-C coupling of a deprotonated methyl group of the coordinated acetone and the C=O moiety of 2-bzpy ligand.

Journal Article↗
PubMed2002

Inhibition of the microsomal metabolism of 1,8-cineole in the common brushtail possum (Trichosurus vulpecula) by terpenes and other chemicals.

1. Brushtail possums (Trichosurus vulpecula) ingest large amounts of terpenes in their diet of Eucalyptus leaf. Previously, we showed that dietary terpenes induce the cytochrome P450 enzymes (CYPs) responsible for their metabolism. The present study examined the effects of various CYP inhibitors on the metabolism of 1,8-cineole, the major dietary terpene, by liver microsomes from the possum and rat. 2. Ketoconazole inhibited the major reactions of terpene-induced microsomes in both species: 9-hydroxylation in the possum and 2-hydroxylation in the rat. This suggests the involvement of CYP3A enzymes, although in the possum there was a lack of the expected inhibition by troleandomycin or activation by alpha-naphthoflavone, highlighting the differences between species in CYP forms. Diethyldithiocarbamate also inhibited 9-hydroxylation in the possum, indicating that a CYP2E1-like enzyme contributes to this reaction. 3. Three other dietary terpenes were potent competitive inhibitors of 9-hydroxylation in the possum. K(i) ( micro M) (mean +/- SE, n = 4) were: alpha-pinene, 4.4 +/- 1.1; limonene, 7.8 +/- 2.1; p-cymene, 44.3 +/- 11.2; cuminyl alcohol (a p-cymene metabolite), 6.0 +/- 0.8. It appears likely that p-cymene acts via its metabolite to inhibit 1,8-cineole metabolism. 4. Inhibitory interactions between dietary terpenes, as well as other plant secondary compounds, may impose a significant constraint on foliage consumption in the common brushtail possum, therefore explaining the obligatory generalist nature of this browsing marsupial and other generalist herbivores.

Animals↗