Helichrysum gymnocephalum essential oil: chemical composition and cytotoxic, antimalarial and antioxidant activities, attribution of the activity origin by correlations

Helichrysum gymnocephalum essential oil (EO) was prepared by hydrodistillation of its leaves and characterized by GC-MS and quantified by GC-FID. Twenty three compounds were identified. 1,8-Cineole (47.4%), bicyclosesquiphellandrene (5.6%), γ-curcumene (5.6%), α-amorphene (5.1%) and bicyclogermacrene (5%) were the main components. Our results confirmed the important chemical variability of H. gymnocephalum. The essential oil was tested in vitro for cytotoxic (on human breast cancer cells MCF-7), antimalarial (Plasmodium falciparum: FcB1-Columbia strain, chloroquine-resistant) and antioxidant (ABTS and DPPH assays) activities. H. gymnocephalum EO was found to be active against MCF-7 cells, with an IC(50) of 16 ± 2 mg/L. The essential oil was active against P. falciparum (IC(50) = 25 ± 1 mg/L). However, the essential oil exhibited a poor antioxidant activity in the DPPH (IC(50) value > 1,000 mg/L) and ABTS (IC(50) value = 1,487.67 ± 47.70 mg/L) assays. We have reviewed the existing results on the anticancer activity of essential oils on MCF-7 cell line and on their antiplasmodial activity against the P. falciparum. The aim was to establish correlations between the identified compounds and their biological activities (antiplasmodial and anticancer). β-Selinene (R2 = 0.76), α-terpinolene (R2 = 0.88) and aromadendrene (R2 = 0.90) presented a higher relationship with the anti-cancer activity. However, only calamenene (R2 = 0.70) showed a significant correlation for the antiplasmodial activity.     

How linker's modification controls swelling properties of highly flexible iron(III) dicarboxylates MIL-88

A series of organically modified iron(III) terephthalate MIL-88B and iron(III) 4,4'-biphenyl dicarboxylate MIL-88D flexible solids have been synthesized and characterized through a combination of X-ray diffraction, IR spectroscopy, and thermal analysis (MIL stands for Material from Institut Lavoisier). The swelling amplitude of the highly flexible MOFs tuned by introducing functional groups onto the phenyl rings shows a clear dependence on the steric hindrance and on the number of groups per aromatic ring. For instance, while the introduction of four methyl groups per spacer in dried MIL-88B results in a large permanent porosity, introducing two or four methyl groups in MIL-88D allows an easier pore opening in the presence of liquids without drastically decreasing the swelling magnitude. The influence of the degree of saturation of the metal center and the nature of the solvent on the swelling is also discussed. Finally, a computationally assisted structure determination has led to a proposal of plausible structures for the closed (dried) and open forms of modified MIL-88B and MIL-88D and to evaluation of their framework energies subject to the nature of the functional groups.     

Capture of the complex [Ni(dto)2]2- (dto2- = dithiooxalato ligand) in a Mo12 ring: synthesis, characterizations, and application toward the reduction of protons

The encapsulation of the complex [Ni(dto)(2)](2-) within an oxothiododecamolybdic cyclic cluster has been investigated. The resulting molybdenum ring, [Mo(12)O(12)S(12)(OH)(12)(Ni(dto)(2))](2-), corresponds to the first example of the {Mo(2)O(2)S(2)}-based assembly arranged around a 3d transition-metal complex. It was unambiguously characterized in the solid state and in solution by FT-IR spectroscopy, single-crystal X-ray diffraction, NMR, UV-visible spectroscopy, and electrospray ionization-high-resolution mass spectrometry (ESI-HRMS). The latter technique revealed to be a powerful tool for the characterization of templated molybdenum ring systems in solution and gave excellent results in high resolution. The electronic spectrum of [Mo(12)O(12)S(12)(OH)(12)(Ni(dto)(2))](2-) evidenced a strong red shift of the LMCT bands attributed to the complex [Ni(dto)(2)](2-), suggesting significant variations of the electronic properties upon its encapsulation within the Mo(12) ring. These differences were demonstrated by electrochemical studies in CH(3)CN, which also revealed, for both compounds [Ni(dto)(2)](2-) and [Mo(12)O(12)S(12)(OH)(12)(Ni(dto)(2))](2-), electrocatalytic properties for the reduction of protons. These results evidence the ability of dithioxalato complexes to act as electrocatalysts for the hydrogen evolution reaction (HER) and confirm such a property for oxothiomolybdenum rings.     

Catalytic intermolecular allyl-allyl cross-couplings between alcohols and boronates

We developed catalytic intermolecular C(sp(3))-C(sp(3)) cross-couplings between various allyl alcohols and allyl boronates, which proceeded smoothly in the presence of nickel(0) under mild conditions to form 1,5-dienes with excellent linear- and γ-selectivity; the use of boronates proved to be crucial in terms of reactivity.     

3D thermoplastic elastomer microfluidic devices for biological probe immobilization

Microfluidics has emerged as a valuable tool for the high-resolution patterning of biological probes on solid supports. Yet, its widespread adoption as a universal biological immobilization tool is still limited by several technical challenges, particularly for the patterning of isolated spots using three-dimensional (3D) channel networks. A key limitation arises from the difficulties to adapt the techniques and materials typically used in prototyping to low-cost mass-production. In this paper, we present the fabrication of thin thermoplastic elastomer membranes with microscopic through-holes using a hot-embossing process that is compatible with high-throughput manufacturing. The membranes provide the basis for the fabrication of highly integrated 3D microfluidic devices with a footprint of only 1 × 1 cm(2). When placed on a solid support, the device allows for the immobilization of up to 96 different probes in the form of a 10 × 10 array comprising isolated spots of 50 × 50 μm(2). The design of the channel network is optimized using 3D simulations based on the Lattice-Boltzmann method to promote capillary action as the sole force distributing the liquid in the device. Finally, we demonstrate the patterning of DNA and protein arrays on hard thermoplastic substrates yielding spots of excellent definition that prove to be highly specific in subsequent hybridization experiments.     

Electrochemical response of ascorbic and uric acids at organoclay film modified glassy carbon electrodes and sensing applications

A naturally occurring Cameroonian smectite clay has been grafted with trimethylpropylammonium groups and the resulting organoclay deposited as thin film onto a glassy carbon electrode (GCE) surface. It was then exploited as a suitable matrix for the accumulation and the electrochemical detection of ascorbic acid (AA) and uric acid (UA). Cyclic voltammetry revealed an increase in oxidation peak responses along with a negative shift of the corresponding anodic peak potential for both AA and UA species when using the organoclay coated GCE in comparison with the bare electrode. The electroanalytical response was improved by coating the electrode surface with a first layer of sublimed ferrocene (FC(s)), and then overcoating with the organoclay film to avoid the mediator leaching. The resulting bilayer film exhibited good characteristics such as extended linear range and high sensitivities for AA and UA, in cyclic voltammetry and amperometry. Interestingly, the redox mediator FC(s) was likely to lower overpotentials for AA oxidation (but not for UA), making possible the selective detection of these species in a mixture. The developed method could be used for the determination of AA in a pharmaceutical preparation and for UA in urine.     

Fast, ligand- and solvent-free copper-catalyzed click reactions in a ball mill

A new, ligand- and solvent-free method for the Huisgen 1,3-dipolar cycloaddition (click reaction) was developed using a planetary ball mill. Besides various alkynes and azides, a propargyl functionalized polymer was converted by mill clicking. Moreover, it was possible to carry out a click polymerization in a ball mill.     

4‐Benzoyl‐3,4‐dihydro‐2H‐1,4‐benzoxazine‐2‐carbonitrile: refinement using a multipolar atom model

The structural model for the title compound, C₁₆H₁₂N₂O₂, was refined using a multipolar atom model transferred from an experimental electron‐density database. The refinement showed some improvements of crystallographic statistical indices when compared with a conventional spherical neutral‐atom refinement. The title compound adopts a half‐chair conformation. The amide N atom lies almost in the plane defined by the three neighbouring C atoms. In the crystal structure, molecules are linked by weak intermolecular C—H...O and C—H...π hydrogen bonds.