Contribution of trans -aconitic acid to DPPH scavenging ability in different media

The antioxidant properties of trans-aconitic acid (TAA) alone or in the presence of usual antioxidants were assessed by DPPH assay. The IC50 value equal to 70mM was very high compared to usual antioxidants (vitamin C and trolox). A joint experimental/theoretical study suggested that hydrogen atom abstraction in TAA by DPPH was located on –CH2– methylene bridge because the corresponding radical was more stabilized than COO· and CC· radicals. In combination with antioxidants (vitamin C, gallic acid, caffeic acid, trolox), synergy or additivity effects were noticed. The magnitude of the synergistic effect varied between 1.06 and 1.24 depending on the type and concentration of antioxidant for a concentration of TAA equal to 22.3mM. Especially, the addition of TAA at a concentration below 32mM to a solution containing 20μM of vitamin C had a synergy effect. Beyond this concentration, TAA showed an additive effect

Correlations between molecular descriptors from various volatile organic compounds and photocatalytic oxidation kinetic constants

International audienceThe photocatalytic oxidation of seven typical indoor volatile organic compounds (VOCs) are experimentally investigated using novel nanocrystalline TiO2 dip-coated catalysts. Not only the role of hydrophilicity of the reactants but also other physico-chemical properties and molecular descriptors are studied and related to kinetic and equilibrium constants. The main objective of this work consists in establishing simple relationships that will be useful to deepen the understanding of gas phase heterogeneous photocatalytic mechanisms and for the prediction of degradation rates of these VOCs using an indoor air treatment process

Modified Clerodanes from the Essential Oil of Dodonea viscosa Leaves

Dodonea viscosa (L.) Jacq from Reunion Island (Indian Ocean) was investigated for its leaf essential oil composition. The plant was extracted by hydrodistillation and its essential oil analysed by gas chromatography coupled to mass spectrometry. This study revealed that oxygenated nor-diterpenes and diterpenes were one of the major chemical classes (> 50%) mainly consisting of three modified cyclopropylclerodanes containing a bicyclo[5.4.0]undecane ring system: one new furanoid norditerpene, dodovisate C, and two furanoid diterpenes, the known methyl dodovisate A and the new methyl iso-dodovisate A. These three compounds were isolated by liquid chromatography and their structures established on the basis of spectroscopic studies. The absolute configuration of dodovisate C was elucidated through a joint experimental and theoretical (B3LYP/6-311+G(d,p)) electronic circular dichroism study. The relative configurations of methyl dodovisate A and methyl iso-dodovisate A were determined using linear regressions of theoretical chemical shifts versus experimental values with the (B3LYP/6-311+G(d,p)) method

Chemical and biological investigation of Indigofera ammoxylum (DC.) Polhill. red and white phenotypes through feature-based molecular networking

International audienceChemical investigation of ethyl acetate bark extracts of Indigofera ammoxylum red and white phenotypes led to the bio-guided isolation of four previously undescribed flavonoids, named (2S,3R)-3′,7-dihydroxy-4′,6-dimethoxyflavanol (1), (2S,3R)-6-methoxy-7-hydroxyflavanol (2), 2′,3′,7-trihydroxy-4′,6-dimethoxyisoflavone (7) and 2′,5'-dimethoxy-4′,5,7-trihydroxyisoflavanone (8), along with 14 known compounds (3-6 and 9-18). The previously undescribed structures were characterized based on NMR, HRESIMS, UV and IR data. Published spectroscopic data were used to deduce the structure of the known compounds. Eleven of the 18 isolated metabolites were evaluated for anti-inflammatory activity and cytotoxic activity against human liver carcinoma cells and human colon and colorectal adenocarcinoma cells. All tested compounds showed an anti-inflammatory activity (IC 50 NO < 25 μg/mL), and compounds 2 and 3 were more selective than the positive control dexamethasone. Afromorsin (6) showed promising cytotoxic properties against both cancer cell lines (IC 50 18.9 and 11.4 μg/mL). Feature-based molecular networking approach applied to bark and leaves extracts of the two phenotypes allowed to detect bioactive analogues, belonging to the families of flavones, isoflavones, flavanones, flavanols and flavonols, and to explore the chemodiversity of the species. The red and white phenotypes have a similar composition, whereas bark and leaves contain specific chemical entities. Finally, this approach highlighted a cluster of potentially bioactive and undescribed metabolites

Antimalarial Activities of Alkyl Cyclohexenone Derivatives Isolated from the Leaves of Poupartia borbonica

Bioactivity-guided fractionation of the ethyl acetate extract of the leaves of Poupartia borbonica led to the isolation of three new alkyl cyclohexenone derivatives 1−3, and named Poupartone A−C. The structures of the new compounds were elucidated by 1D and 2D NMR spectroscopic data analysis and MS, whereas calculated and experimental ECD spectra were used to define the absolute configurations. These compounds were active against 3D7 and W2 Plasmodium falciparum strains with IC50 values between 0.55 and 1.81 μM. In vitro cytotoxicity against WI38 human fibroblasts and the human cervical cancer cell line HeLa (WST-1 assay) showed that these compounds were also cytotoxic, but no hemolytic activity was observed for the extract and pure compounds. An in vivo antimalarial assay was performed on the major cyclohexenone using P. berghei-infected mice at a dose of 15 mg/kg/day ip. The assay revealed growth inhibition of 59.1 and 69.5% at days 5 and 7 postinfection, respectively, although some toxicity was observed. Zebrafish larvae were used as a model to determine the type of toxicity, and the results showed cardiac toxicity. The methanol extract was also studied, and it displayed moderate antiplasmodial properties in vitro. This extract contained the known flavonoids, quercetin, 3′-O-hydroxysulfonylquercetin, quercitrin, and isoquercitrin as well as ellagic acid, which showed high to low activity against the 3D7 P. falciparum strain

Cytotoxic Metabolites from Calophyllum tacamahaca Willd.: Isolation and Detection through Feature-Based Molecular Networking

peer reviewedIsocaloteysmannic acid (1), a new chromanone, was isolated from the leaf extract of the medicinal species Calophyllum tacamahaca Willd. along with 13 known metabolites belonging to the families of biflavonoids (2), xanthones (3–5, 10), coumarins (6–8) and triterpenes (9, 11–14). The structure of the new compound was characterized based on nuclear magnetic resonance (NMR), high-resolution electrospray mass spectrometry (HRESIMS), ultraviolet (UV) and infrared (IR) data. Its absolute configuration was assigned through electronic circular dichroism (ECD) measurements. Compound (1) showed a moderate cytotoxicity against HepG2 and HT29 cell lines, with IC50 values of 19.65 and 25.68 µg/mL, respectively, according to the Red Dye method. Compounds 7, 8 and 10–13 exhibited a potent cytotoxic activity, with IC50 values ranging from 2.44 to 15.38 µg/mL, against one or both cell lines. A feature-based molecular networking (FBMN) approach led to the detection of a large amount of xanthones in the leaves extract, and particularly analogues of the cytotoxic isolated xanthone pyranojacareubin (10)

Cyanide Compounds

Chapter 4, “Cyanide Compounds,” illustrates an explosively developing research theme in which the cyanide ligand is used as a linking agent for the designed assembly of polynuclear metal complexes. Syntheses of several basic building blocks, such as K3[Cr(CN)6],Cr(Me3tacn)(CN)3,K4[Mo(CN)8],Na[W(CO)5CN],K[CpFe(CO)(CN)2],[NEt4][Cp*Rh(CN)3],[Fe4(bpy)8(μ-CN)4][PF6]4,. are given here. These units may be used in several ways to construct polynuclear compounds. One approach involves a hexacyanometalate core decorated with peripheral metal centers, e.g., [{Cu(tpa)(CN)}6Fe][ClO4]8. or [Cr{CNNi(tetren)}6][ClO4]9. An octacyanometalate unit can lead to higher nuclearity condensed compounds, as in [Co{Co(MeOH)3}8(μ-CN)30{Mo(CN)3}6]. Alternatively, a cluster core may be substituted with cyano complexes as ligands, as in [PPh4]2[Fe4S4{NCW(CO)5}4]. If there are two cis cyano ligands on the building block, then quadrilateral or square structures often result, as in {CpFe(CO(μ-CN)2Cu(PCy3)}2 and [Fe2Cu2(bpy)6(μ-CN)4][PF6]4 However, if there are three adjacent cyano ligands, then cubic cages may be constructed as in [(CpCo)4(Cp*Rh)4(μ-CN)12][PF6]4