Structurally Interesting Diarymethane Derivatives from Securidaca inappendiculata

Securines A—E, three dimeric diarymethane derivatives ( 1 — 3 ) and two enantiomeric diarymethane derivative monomers ( 4 and 5 ), were isolated and characterized from the medicinal plant Securidaca inappendiculata. Compounds 1 and 2 are a pair of enantiomeric diarymethane derivative dimers, and compound 3 is a mesomeric diarymethane derivative dimer. Their structures were determined by a combination of spectroscopic data, X‐ray crystallography, electronic circular dichroism (ECD) analysis, and computational ECD calculations. Dimeric compounds 1 — 3 showed moderate antiplasmodial activities with IC₅₀ values of 0.9, 1.4, and 1.5 μM, respectively.     

Reduced molybenum-oxide-based core-shell hybrids: "blue" electrons are delocalized on the shell

The present study refers to a variety of reduced metal-oxide core-shell hybrids, which are unique with regard to their electronic structure, their geometry, and their formation. They contain spherical {Mo72Fe30} Keplerate-type shells encapsulating Keggin-type polyoxomolybdates based on very weak interactions. Studies on the encapsulation of molybdosilicate as well as on the earlier reported molybdophosphate, coupled with the use of several physical methods for the characterization led to unprecedented results (see title). Upon standing in air at room temperature, acidified aqueous solutions obtained by dissolving sodium molybdate, iron(II) chloride, acetic acid, and molybdosilicic acid led to the precipitation of monoclinic greenish crystals (1). A rhombohedral variant (2) has also been observed. Upon drying at room temperature, compound 3 with a layer structure was obtained from 1 in a solid-state reaction based on cross-linking of the shells. The compounds 1, 2, and 3 have been characterized by a combination of methods including single-crystal X-ray crystallography, magnetic studies, as well as IR, M?ssbauer, (resonance) Raman, and electronic absorption spectroscopy. In connection with detailed studies of the guest-free two-electron-reduced {Mo72Fe30}-type Keplerate (4) and of the previously reported molybdophosphate-based hybrids (including 31P NMR spectroscopy results), it is unambiguously proved that 1, 2, and 3 contain non-reduced Keggin ion cores and reduced {Mo72Fe30}-type shells. The results are discussed in terms of redox considerations (the shell as well as the core can be reduced) including those related to the reduction of "molybdates" by FeII being of interdisciplinary including catalytic interest (the MoVI/MoV and FeIII/FeII couples have very close redox potentials!), while also referring to the special formation of the hybrids based on chemical Darwinism.     

The speciation of vanadium in human serum

A knowledge of the speciation of vanadium in human serum is essential for an understanding of the biotransformation of antidiabetic vanadium complexes in human blood and of how vanadium is transported to the target cells. Such information may be acquired by two completely different approaches: separation techniques and modeling calculations. This review focuses on the latter.The two major metal ion binders in human serum are apotransferrin (apoTf) and human serum albumin (HSA), the interactions of which with V^IVO and V^V are discussed in detail. A partially new model for HSA–V^IVO interactions is introduced, in which the two binding sites (one for two and one for one metal ion) compete not only with each other, but also with hydrolysis of the metal ion.Focus is also placed on the possibility and importance of ternary complex formation between V^IVO, serum proteins and drug candidate ligands (maltol (mal), 1,2-dimethyl-3-hydroxy-4(1H)-pyridinone (dhp), acetylacetone (acac) and picolinic acid, (pic)): the structures and formation constants of different ternary complexes reported by the different research groups are critically reviewed.The serum speciations for V^IVO and V^V are calculated through use of the most recent stability constants; at biologically relevant concentrations (～1 μM, but definitely <10 μM) the apoTf complexes predominate for both metal ions. This has the consequences that the primary role of the drug candidate ligands of the original complexes is a carrier function until the vanadium is taken up into the serum, and the vanadium ion itself is the active metabolite responsible for the antidiabetic effect.     

Corrigendum to “Absolute configurations of griseorhodins A and C” [Tetrahedron Lett. 58 (50) (2017) 4721–4723]

The known antibiotic and cytotoxic compounds griseorhodin A (1) and griseorhodin C (2) were produced in solid culture by Streptomyces puniceus AB10, which was isolated from the leaf-cutter ant Acromyrmex rugosus rugosus. Their absolute configurations were unambiguously established as 6S,6aS,7S,8S and 6R,6aS,7S,8R, respectively, using vibrational circular dichroism (VCD) and density functional theory (DFT) calculations.     

Tetrachlorocarbonyliridates: water-soluble carbon monoxide releasing molecules rate-modulated by the sixth ligand

A new family of compounds is presented as potential carbon monoxide releasing molecules (CORMs). These compounds, based on tetrachlorocarbonyliridate(III) derivatives, were synthesized and fully characterized by X-ray diffraction, electrospray mass spectrometry, IR, NMR, and density functional theory calculations. The rate of CO release was studied via the myoglobin assay. The results showed that the rate depends on the nature of the sixth ligand, trans to CO, and that a significant modulation on the release rate can be produced by changing the ligand. The reported compounds are soluble in aqueous media, and the rates of CO release are comparable with those for known CORMs, releasing CO at a rate of 0.03-0.58 μM min(-1) in a 10 μM solution of myoglobin and 10 μM of the complexes.     

Investigation on the Interaction of Bendazac with β-, Hydroxypropyl-β-, and γ-, yclodextrins

The interactions of Bendazac, a topical non-steroidal anti-inflammatory drug, with-cyclodextrin, hydroxypropyl--cyclodextrin and -cyclodextrinwere investigated to evaluate possibilities to improve the drug's poor water solubilityand eventually to enhance the topical delivery of Bendazac. Phase solubility studiesdemonstrated the ability of the selected cyclodextrins to complex with Bendazac andincrease drug solubility. The amount of solubilized Bendazac increased linearly withthe addition of each cyclodextrin according toA_L type plots. ¹³C-NMR studiesshowed that the Bendazac A-ring was included in the cavity of the three cyclodextrins.The -cyclodextrin was also able to include the B-ring of Bendazac, forminga complex where one drug molecule fitted into two cyclodextrin molecules. Equimolarsolid systems of the drug with each cyclodextrin carrier were prepared using varioustechniques (physical mixing, spray-drying and freeze-drying). The results of differential scanning calorimetry and Fourier transform infrared analysis, performed on the solid systems, demonstrated that freeze-dried and spray-dried products had a high degree of amorphization and agreed with the hypothesis of the existence of drug–cyclodextrin interaction in the solid state. The cyclodextrins tested were able to improve the dissolution of Bendazac. The dissolution profile of the drug was also affected by the physico-chemical properties of each solid system, the freeze-dried products being the most rapidly dissolving forms.     

Study of the bromide oxidation by bromate in zwitterionic micellar solutions

The redox reaction Br⁻ + BrO₃⁻ has been studied in aqueous zwitterionic micellar solutions of N‐tetradecyl‐N, N‐dimethyl‐3‐ammonio‐1‐propanesulfonate, SB3‐14, and N‐hexadecyl‐N,N‐dimethyl‐3‐ammonio‐1‐propanesulfonate, SB3‐16. A simple expression for the observed rate constant, k_obs, based on the pseudophase model, could explain the influences of changes in the surfactant concentration on k_obs. The kinetic effect of added NaClO₄ on the reaction rate in SB3‐14 micellar solutions has also been studied. They were rationalized by considering the binding of the perchlorate anions to the sulfobetaine micelles and their competition with the reactive bromide ions for the micellar surface. © 2000 John Wiley & Sons, Inc. Int J Chem Kinet 32: 388–394, 2000     

Triaquatris(μ‐oxydiacetato)dipraseodymium(III) pentahydrate and hexaaquatris(μ‐oxydiacetato)dineodymium(III) oxydiacetic acid solvate dihydrate

Two new complexes of the Ln₂(oda)₃·nH₂O (oda =–O₂CCH₂OCH₂CO₂–) series are reported, i.e. {[Pr₂(C₄H₄O₅)₃(H₂O)₃]·5H₂O}_n and {[Nd₂(C₄H₄O₅)₃(H₂O)₆]·C₄H₆O₅·‐2H₂O}_n. The former is isostructural with the reported La analogue, while the latter is a new structural variety within the series. Each compound exhibits two independent nine‐coordinated Ln centres showing a variety of coordination geometries.     

catena‐Poly­[fac‐tri­chloro­methyl­tin(IV)‐μ‐[meso‐1,2‐bis­(phenyl­sulfinyl)­ethane‐O:O′]]

In the title compound, [SnCl₃(CH₃)(C₆H₅SOCH₂)₂]_n, the octahedral Sn^IV centres are bridged by meso‐1,2‐bis­(phenyl­sulfinyl)­ethane ligands forming infinite chains along the [100] direction.