Seasonal variation in the chemical composition and antimicrobial activity of volatile oils of three species of Leptospermum (Myrtaceae) grown in Brazil

This study investigates the seasonal variation of three species of Leptospermum (Myrtaceae) grown in Brazil. The chemical composition of the volatile oils of L. flavescens and L. petersonii did not show any significant seasonal variation in the major components, while for Leptospermum madidum subsp. sativum the levels of major constituents of the volatile oils varied with the harvest season. Major fluctuations in the composition of L. madidum subsp. sativum oil included α-pinene (0-15.2%), β-pinene (0.3-18.5%), α-humulene (0.8-30%), 1,8-cineole (0.4-7.1%) and E-caryophyllene (0.4-11.9%). Levels of β-pinene (0.3-5.6%), terpinen-4-ol (4.7-7.2%) and nerolidol (55.1-67.6%) fluctuated seasonally in the L. flavescens oil. In L. petersonii, changes were noted for geranial (29.8-32.8%), citronellal (26.5-33.9%) and neral (22.7-23.5%). The activity of the volatile oils against the tested bacteria differed, depending on season the oils were obtained. In general, the volatile oils were more active against Gram-positive bacteria.     

GC/MS Analysis,Antioxidant Activity,and Antimicrobial Effect of Pelargonium peltatum (Geraniaceae)

In recent years, the increase in antibiotic resistance demands searching for new compounds with antimicrobial activity. Phytochemicals found in plants offer an alternative to this problem. The genus Pelargonium contains several species; some have commercial use in traditional medicine such as P. sinoides, and others such as P. peltatum are little studied but have promising potential for various applications such as phytopharmaceuticals. In this work, we characterized the freeze-dried extracts (FDEs) of five tissues (root, stem, leaf, and two types of flowers) and the ethyl acetate fractions from leaf (Lf-EtOAc) and flower (Fwr-EtOAc) of P. peltatum through the analysis by thin-layer chromatography (T.L.C.), gas chromatography coupled to mass spectrometry (GC-MS), phytochemicals quantification, antioxidant capacity, and antimicrobial activity. After the first round of analysis, it was observed that the FDE-Leaf and FDE-Flower showed higher antioxidant and antimicrobial activities compared to the other FDEs, for which FDE-Leaf and FDE-Flower were fractionated and analyzed in a second round. The antioxidant activity determined by ABTS showed that Lf-EtOAc and Fwr-EtOAc had the lowest IC₅₀ values with 27.15 ± 1.04 and 28.11 ± 1.3 µg/mL, respectively. The content of total polyphenols was 264.57 ± 7.73 for Lf-EtOAc and 105.39 ± 4.04 mg G.A./g FDE for Fwr-EtOAc. Regarding the content of flavonoid, Lf-EtOAc and Fw-EtOAc had the highest concentration with 34.4 ± 1.06 and 29.45 ± 1.09 mg Q.E./g FDE. In addition, the minimum inhibitory concentration (M.I.C.) of antimicrobial activity was evaluated: Lf-EtOAc and Fwr-EtOAc were effective at 31.2 µg/mL for Staphylococcus aureus and 62.5 µg/mL for Salmonella enterica, while for the Enterococcus feacalis strain, Fwr-EtOAc presented 31.2 µg/mL of M.I.C. According to the GC-MS analysis, the main compounds were 1,2,3-Benzenetriol (Pyrogallol), with 77.38% of relative abundance in the Lf-EtOAc and 71.24% in the Fwr-EtOAc, followed by ethyl gallate (13.10%) in the Fwr-EtOAc and (Z)-9-Octadecenamide (13.63% and 6.75%) in both Lf-EtOAc and Fwr-EtOAc, respectively.     

Analysis and antimicrobial activity of volatile constituents from Quercus leucotrichophora (Fagaceae) bark

The chemical composition of the volatile extract (yield ≈ 0.13%, v/w) from the bark of Quercus leucotrichophora (Fagaceae) was analysed for the first time by GC-MS. Twenty-three constituents, amounting to 93.0% of the total detected contents of the volatile extract, were identified. The volatile extract contained approximately 86.36% monoterpenoids, 6.53% sesquiterpenoids and 0.11% aliphatic aldehydes. 1,8-Cineol (40.359%) followed by γ-terpinene (16.369%) were the major monoterpene constituents of the volatile extract. The residue of volatile extract (0.00025-250 μg mL(-1)) exhibited a potent antimicrobial activity against Streptococcus pyogenes ATCC 19615. This study concludes that residues of the volatile extract of Q. leucotrichophora could serve as an important bioresource for the extraction and isolation of monoterpenoids exhibiting antimicrobial activity, and thus has good potential for use in the pharmaceutical industry.     

Influence of Cu(II) on the interaction between sulfite and horseradish peroxidase in vitro

This paper discussed the quantitative influence of Cu(II) on the interaction between horseradish peroxidase (HRP) and sulfite (SO3(2-)), which is a derivate of sulfite dioxide in human bodies, by using fluorescence spectrum and ultraviolet (UV) absorption spectrometry in vitro. The results show that under the conditions of physiological pH and room-temperature, Cu(II) can bind strongly with both the protein part and the ferroporphyrin part in HRP at a low concentration (10(-4) mol L(-1)), and the combination constants are 2.047 x 10(3) and 7.66 x 10(2) L mol(-1), respectively. Under the same conditions, SO3(2-) at low concentrations (<0.15 mol L(-1)) has little quenching for the fluorescence of HRP at 330 nm, and the combination constant is 0.108 L mol(-1). While the fluorescence intensity at 440 nm enhance gradually with the increased concentration of SO3(2-) (<0.1 mol L(-1)), and the combination constant is 8.219 L mol(-1). These indicate that SO3(2-) at low concentration has little reaction with the enzyme protein part in HRP but obvious reaction with the ferroporphyrin part in HRP. After SO3(2-) at low concentrations is added into the HRP-Cu(II) binary system, the reaction constants between SO3(2-) and the enzyme protein part in HRP increase rapidly. Compared with the absence of Cu(II), the combination constant of SO3(2-) with the enzyme protein part in HRP increases nearly 70 times with a certain Cu(II) concentration (5.0 x 10(-4) mol L(-1)) in the system. However, the presence of Cu(II) in the system has little effect on the reaction constants between SO3(2-) and the ferroporphyrin part in HRP.     

Study of the interaction between ruthenium(II) complexes and CT-DNA: synthesis,characterisation, photocleavage and antimicrobial activity studies

Two polypyridyl ligands 6-fluro-3-(1H-imidazo [4,5-f] [1,10]-phenanthroline-2-yl)-4H-chromen-4-one (FIPC), 6-chloro-3-(1H-imidazo [4,5-f] [1,10]-phenanthroline-2-yl)-4H-chromen-4-one (ClIPC) polypyridyl ligands and their Ru(II) complexes [Ru(bipy)₂FIPC]²⁺(1), [Ru(dmb)₂FIPC]²⁺(2), [Ru(phen)₂FIPC]²⁺(3), [Ru(bipy)₂ClIPC]²⁺(4), [Ru(dmb)₂ClIPC]²⁺(5) and [Ru(phen)₂ClIPC]²⁺(6) ((bipy = 2,2′-bipyridine, dmb = 4,4′-dimethyl-2,2′-bipyridine and phen = 1,10-phenanthroline) have been synthesised and characterised by elemental analysis, Mass spectra, IR, ¹H and ¹³C-NMR. The DNA-binding of the six complexes to calf-thymus DNA (CT-DNA) has been investigated by different spectrophotometric, fluorescence and viscosity measurements. The results suggest that 1–6 complexes bind to CT-DNA through intercalation. The variation in binding affinities of these complexes is rationalised by a consideration of electrostatic, steric factors and nature of ancillary ligands. Under irradiation at 365 nm, the three complexes have also been found to promote the photocleavage of plasmid pBR 322 DNA. Inhibitor studies suggest that singlet oxygen (¹O₂) plays a significant role in the cleavage mechanism of Ru(II) complexes. Thereby, under comparable experimental conditions [Ru(phen)₂FIPC]²⁺(3), [Ru(phen)₂ClIPC]²⁺(6) cleaves DNA more effectively than 1, 2, 4 and 5 complexes do. The Ru(II) polypyridyl complexes (1–6) have been screened for antimicrobial activities.     

Identification of volatile components of liverwort (Porella cordaeana) extracts using GC/MS-SPME and their antimicrobial activity

Chemical constituents of liverwort (Porella cordaeana) extracts have been identified using solid-phase microextraction-gas chromatography mass spectrometry (SPME-GC/MS). The methanol, ethanol and ethyl acetate extracts were rich in terpenoids such as sesquiterpene hydrocarbons (53.12%, 51.68%, 23.16%), and monoterpene hydrocarbons (22.83%, 18.90%, 23.36%), respectively. The dominant compounds in the extracts were β-phellandrene (15.54%, 13.66%, 12.10%) and β-caryophyllene (10.72%, 8.29%, 7.79%, respectively). The antimicrobial activity of the extracts was evaluated against eleven food microorganisms using the microdilution and disc diffusion methods. The minimum inhibitory concentration (MIC) varied from 0.50 to 2.00 mg/mL for yeast strains (Saccharomyces cerevisiae 635, Zygosacharomyces bailii 45, Aerobasidium pullulans L6F, Pichia membranaefaciens OC 71, Pichia membranaefaciens OC 70, Pichia anomala CBS 5759, Pichia anomala DBVPG 3003 and Yarrowia lipolytica RO13), and from 1.00 to 3.00 mg/mL for bacterial strains (Salmonella enteritidis 155, Escherichia coli 555 and Listeria monocytogenes 56Ly). Methanol extract showed better activity in comparison with ethanol and ethyl acetate extracts. High percentages of monoterpene and sesquiterpene hydrocarbons could be responsible for the better antimicrobial activity.     

Synthesis,spectroscopic characterization and in vitro studies of antimicrobial activity of bis(diorganodithiocarbamato)organodithiocarbonatobismuth (III) complexes

A brief account of the synthesis, spectroscopic characterization and the antimicrobial (bacterial and fungal) behaviour of bis(diorganodithiocarbamato)organodithiocarbonatobismuth(III) complexes is presented. The reaction of bis(diorganodithiocarbamato)bismuth(III) chloride with potassium organodithiocarbonate in equimolar ratio yielded the corresponding mixed derivatives of the type [R′₂NCS₂]₂BiS₂COR [where, R′ = CH₃ and C₂H₅; R = Et, Prⁿ, Prⁱ, Buⁿ and Buⁱ]. These have been characterized by molecular weight determinations, melting points (only solid complexes) and elemental (C, H, N, S and Bi) analysis as well as spectral IR and NMR [¹H and ¹³C] studies. The antibacterial and antifungal activities of the free ligands and their bismuth complexes were found in vitro by the disc diffusion method. The complexes showed good antibacterial and antifungal effect on some selected bacterial and fungal strains. The antimicrobial activities of two standard antibiotics (Chloroamphenicol and Terbinafin) were also measured and compared with these complexes. Copyright © 2005 John Wiley & Sons, Ltd.     

An in vitro evaluation of the antibacterial activity of the non-volatile phenolic fraction from rosemary leaves

In this study, the aim was to evaluate the antimicrobial action of the non-volatile phenols of rosemary leaves against two Gram-negative bacteria (Escherichia coli and Pseudomonas aeruginosa) and two Gram-positive bacteria (Staphylococcus aureus and Staphylococcus epidermidis). Three extracts with different phenolic compositions were tested. By the agar disc diffusion method, Gram-positive bacteria were more sensitive to the extracts, and S. epidermidis showed the highest inhibition zones. Overall, all the extracts tested by the broth dilution method showed higher activity than results from the agar disc diffusion method. The minimal bactericidal concentration values indicated that E. coli was the most susceptible strain. This study demonstrated that the flavonoidic fraction of rosemary leaves does not play a crucial role as antimicrobial agents against these microorganisms. The most active extract was characterised by the highest amount of non-volatile terpenoidic compounds.     

Chemical composition and antimicrobial activity of Erodium species: E. ciconium L., E. cicutarium L., and E. absinthoides Willd. (Geraniaceae)

The present study gives results of chemical composition analyses and antimicrobial activity testing of three Erodium species: E. ciconium L., E. cicutarium L., and E. absinthoides Willd. Essential oils were obtained by hydro-distillation from air-dried entire plants and analyzed by GC and GC-MS. A total of 209 different compounds were identified: 162 for E. cicutarium, 107 for E. ciconium, and 79 for E. absinthoides. Antimicrobial activity (broth microdilution method) of the oils was screened against a panel of Gram positive and Gram negative bacteria and a number of fungi. Moderate susceptibility of all tested strains was observed. Determined MIC values were 0.156–5 mg mL⁻¹ (bacterial strains) and 0.039–0.325 mg mL⁻¹ (fungal strains). Major component of the most active oil, palmitic acid, was also tested for activity together with stearic and myristic acids.     

Antioxidant activity of methimazole-copper(II) bioactive species and spectroscopic investigations on the mechanism of its interaction with Bovine Serum Albumin

Free radical-mediated oxidative stress has been implicated in numerous autoimmune disorders including Graves’ disease. Hyperthyroidism results in a marked increase in intracellular antioxidant enzymes including superoxide dismutase. The later activity is significantly increased in untreated Graves’ patients while treatment with methimazole results in normalization of the free radical and antioxidant activity indices. In this context, and considering the findings mentioned above, the aim of the present study was to evaluate unknown biological activities of methimazole and its methimazole-copper(II) complex investigating their superoxide scavenger power. Under the applied experimental conditions, methimazole did not show superoxide dismutase (SOD) activity while the copper complexes exhibited a strong superoxide radical scavenging capacity. Bearing in mind that the capacity of drugs to bind and/or interact with albumin is essential for their pharmacokinetic and pharmacodynamic properties, a complete investigation of the binding ability of both compounds by using Fourier transform infrared (FT-IR), Raman and Fluorescence spectroscopies, and UV-Vis spectrophotometry was included. Besides, in order to probe the copper ligand environment the EPR spectra of such compounds were analyzed.     

Inhibitory effect of lactone fractions and individual components from three species of the Achillea millefolium complex of Bulgarian origin on the human neutrophils respiratory burst activity

Achillea species are widely used in folk medicine for treatment of inflammatory diseases. The inhibitory effect on the human neutrophils respiratory burst activity of total extracts, their fractions and some main constituents of the flower heads from Achillea asplenifolia, A. collina and A. distans belonging to A. millefolium complex of Bulgarian origin, were tested by the modified method of Tan and Berridge. Seven from the investigated fractions showed activity similar or higher than that of indomethacine and might be evaluated as nonsteroidal anti-inflammatory agents.     

Synthesis and in vitro antimicrobial activity of new 3-(2-morpholinoquinolin-3-yl) substituted acrylonitrile and propanenitrile derivatives

A series of new 3-(2-morpholinoquinolin-3-yl)acrylonitrile derivatives (IVa-IVf) has been synthesised by the base-catalysed condensation reaction of 2-morpholinoqionoline-3-carboxaldehydes (IIa-IIc) and 2-cyanomethylbenzimidazoles (IIIa-IIIb). Subsequent regiospecific reduction of the C—C double bond in acrylonitrile moiety afforded 3-(2-morpholinoquinolin-3-yl)propanenitrile derivatives (Va-Vf). All the compounds synthesised were subjected to in vitro antimicrobial screening against some representatives of bacteria and fungi. The majority of the compounds were found to be active against Gram-positive bacteria Bacillus subtilis and Clostridium tetani as well as against the fungal pathogen Candida albicans.     

Study on the interaction between tetracene and Cu(110) surface

The electronic structure of tetracene on Cu (110) surface has been studied by using ultraviolet photoemission spectroscopy (UPS). The emission features from the organic molecule are located from 1 to 10 eV below the Fermi level, and they shift in binding energy with increasing the coverage of the organic material. For the surface with multilayer of tetracene, six well-resolved features were found at 1.90, 3.40, 4.70, 5.95, 6.95, and 9.15 eV below the Fermi level, respectively. On the surface with a lower coverage of tetracene, angle-resolved UPS measurements suggest that the molecular plane is parallel to the substrate. Density functional theory calculation confirms the flat-lying adsorption mode and shows that the tetracene molecule prefers to be adsorbed on the long bridge site with its long axis in the [110] azimuth.     

Recent methods for the determination of volatile and non-volatile organic compounds in natural and purified drinking water

Four analytical protocols for the extraction and preconcentration of organic residues in natural or purified drinking water were investigated and compared: closed loop stripping analysis; simultaneous extraction-distillation; purge and trap analysis; continuous liquid-liquid extraction. Organic extracts were submitted to a variety of separation and identification techniques. Volatiles were determined by conventional capillary column gas chromatography with tandem mass spectrometry, using triple-stage quadrupole instruments. Non-volatile and thermally labile molecules were investigated by several different techniques (high-temperature gas chromatography, capillary column supercritical fluid chromatography, pyrolysis gas chromatography-mass spectrometry, thermospray liquid chromatography with tandem mass spectrometry and conventional fast-atom bombardment with tandem mass spectrometry). Several samples recently examined in the laboratory provide examples of this multitechnique approach for a more complete knowledge of the organic carbon distribution in water-dissolved organic matter, taking into account organic substances with widely different volatilities, polarities and thermal stabilities.     

DNA/BSA interaction and in vitro antimicrobial studies of Mn(III) complexes bearing bidentate N,O donor Schiff bases

Journal of the Iranian Chemical Society - Eight new coordination compounds of Mn(III) with (E)-2-((3-(benzyloxypyridinylimino) methyl)-4-bromophenol (L1), (E)-2-((3-(benzyloxypyridinylimino)...     

Synthesis and in vitro antimicrobial activity of some pyrazolyl-1-carboxamide derivatives

A series of 3,5-disubstituted pyrazole-1-carboxamides were obtained by treatment of chalcones with semicarbazide hydrochloride in dioxane containing sodium acetate/acetic acid as a buffer solution. N-acetyl derivatives of pyrazole-1-carboxamides were isolated in good yields either by treatment of the carboxamide derivatives with acetic anhydride or refluxing chalcones with semicarbazide in ethanol containing few drops of acetic acid to give the corresponding hydrazones. Subsequent treatment of hydrazones with acetic anhydride gave the desired N-acetyl pyrazole-1-carboxamides derivatives. When chalcones were refluxed with dioxane containing few drops of acetic acid, 4,5-dihydropyrazole-1-carboxamides were isolated, which were subsequently oxidized using 5% sodium hypochlorite in dioxane to afford pyrazole-1-carboxamides. The structures of isolated compounds were confirmed by elemental analyses and spectral methods. The isolated compounds were tested for their antimicrobial activities.     

Phytochemical composition and in vitro screening of the antimicrobial activity of essential oils on oral pathogenic bacteria

In this study, the activity of essential oils (EOs) against microorganisms involved in oral diseases was evaluated. Fourteen EOs were selected and subjected to gas chromatographic analysis, including Illicium verum, Eucaliptus globulus, Eugenia caryophyllata, Leptospermum scoparium, Mentha arvensis, Mentha piperita, Myrtus communis, Salvia officinalis, Melaleuca alternifolia, Rosmarinus officinalis, Lavandula x intermedia, Thymus capitatus and Thymus vulgaris. These EOs were tested for their antimicrobial activity on Streptococcus mutans and Lactobacillus species clinically isolated from dental surgery patients. The antibacterial activity was evaluated by means of the disc diffusion and the minimum inhibitory concentration (MIC). Five EOs, having shown an interesting antimicrobial activity, were selected for a second screening in combination between them and with chlorhexidine. From the second assays, two EO–EO and three EO-chlorhexidine associations gave interesting results as potential constituents of mouthwashes, especially for the contribution of oxygenated monoterpenes, including menthol, thymol and carvacrol.     

Synthesis and antimicrobial activity of aminomethoxy-substituted 1-(ethylthio)heptanes

The Mannich condensation of 1-(ethylthio)heptane-2-ol, formaldehyde and secondary amines taken in equimolar amounts gives rise to new aminomethoxy-substituted 1-(ethylthio)heptanes in a yield of 70–77%. The structure of the synthesized compounds was proved by the elemental analysis, IR and ¹H NMR spectroscopy, and mass spectrometry. The compounds were tested as antimicrobial additives to lubricating oils. They were found to suppress effectively the activity of microorganisms.     

J-聚集态下中位-四(对-磺酸基苯基)卟啉与ct-DNA相互作用的研究

采用紫外可见光谱法研究了中位-四(对-磺酸基苯基)卟啉(TPPS)在高酸度条件下的J-聚集行为,及该J-聚集体与ct-DNA的相互作用特点.TPPS形成J-聚集体不仅需要一定的临界聚集浓度,还需要一定的酸度范围.酸的阴离子种类也对TPPS的聚集有一定程度的影响.一定浓度的ct-DNA对TPPS的J-聚集体产生减色效应,而对TPPS的质子化型体却几乎没有任何影响.说明,在实验条件下,TPPS可以以J-聚集体的形式与ct-DNA发生相互作用.     

Cr（VI）与牛血清白蛋白的相互作用

采用荧光光谱、紫外光谱、CD光谱法研究了K2Cr2O7与牛血清白蛋白(BSA)的相互作用。实验结果表明, 铬(Ⅵ)使BSA的紫外吸收降低,峰位红移,表明铬(Ⅵ)与BSA发生较强的相互作用;铬(Ⅵ)酸根离子与BSA形成基态复合物导致BSA内源荧光猝灭,猝灭机理主要为静态猝灭。测定了不同温度下该反应的热力学参数,ΔGθ＜0,ΔHθ和ΔSθ分别为–12.60 kJ/mol 和 56.60 J/(mol·k), 表明上述作用过程是一个熵增加、自由能降低的自发分子间作用过程,铬(Ⅵ)酸根离子与BSA之间以静电作用力为主;非辐射能量转移机理确定了铬(Ⅵ)与牛血清白蛋白中色氨酸残基之间的距离 r＝2.85 nm;同步荧光和CD光谱研究表明,铬(Ⅵ)使BSA的二级结构发生改变,α–螺旋含量降低,色氨酸残基所处微环境的极性减小。