Selective modification of oleuropein,a multifunctional bioactive natural product

Oleuropein is the major phenolic compound extracted from olive leaves and it is also present in olive fruits and virgin olive oil. It has already demonstrated a wide range of pharmacological activities, but new derivatives have to be designed in order to obtain useful Structure–Activity Relationships for this family of products, as well as new analogs with improved and/or different biological properties. However, taking into account the multiple OH groups (catechol and sugar) present in oleuropein, the selective modification of this natural product is a challenging problem. In this paper, we present an efficient strategy allowing the selective modification at the primary alcohol position of this natural product. Using appropriate protection/deprotection sequences, we prepared by hemisynthesis several triazoles linked to the oleuropein core, as representative examples for the development of such an approach.     

Formation of an Ni7(μ3-OH)6(η-OOCBu t )6(μ3-OOCBu t )2(Hdmpz)6 cluster during the thermolysis of binuclear complex Ni2(μ-OOCBu t )4(Hdmpz)2 (Hdmpz = 3,5-dimethylpyrazole)

Cluster Ni₇(μ₃-OH)₆(OOCBu ^t )₈(Hdmpz)₆ was found to form as a result of the thermal destruction of complex Ni₂(μ-OOCBu ^t )₄(Hdmpz)₂ at 190°C. The cluster was characterized using X-ray crystallography.     

Structural,elastic, thermodynamic and electronic properties of LuX (X = N,Bi and Sb) compounds: first principles calculations

ABSTRACT

The structural, electronic, elastic and thermodynamic properties of LuX (X = N, Bi and Sb) based on rare earth into phases, Rocksalt (B1) and CsCl (B2) have been investigated using full-potential linearized muffin-tin orbital method (FP-LMTO) within density functional theory. Local density approximation (LDA) for exchange-correlation potential and local spin density approximation (LSDA) are employed. The structural parameters as lattice parameters a₀, bulk modulus B, its pressure derivate B’ and cut-off energy (E_c) within LDA and LSDA are presented. The elastic constants were derived from the stress–strain relation at 0 K. The thermodynamic properties for LuX using the quasi-harmonic Debye model are studied. The temperature and pressure variation of volume, bulk modulus, thermal expansion coefficient, heat capacities, Debye temperature and Gibbs free energy at different pressures (0–50 GPa) and temperatures (0–1600 K) are predicted. The calculated results are in accordance with other data.     

Bioassay-guided isolation and POM analyses of a new immunomodulatory polyphenolic constituent from Callistemon viridiflorus

Chromatographic separation of 80% EtOH extract of Callistemon viridiflorus leaves led to the isolation of six known constituents (1–6) along with a new polyphenolic compound 7 identified as apigenin 4′-O-β-d-glucopyranosyl-(1″′ → 4″)-O-β-d-glucopyranoside. The ethanolic extract of C. viridiflorus leaves and isolated compounds were evaluated for in vitro immunomodulatory activity by means of RAW 264.7 macrophages proliferation (MTT) assay. Ethanolic extract of leaves and compounds 1, 3, 4, 6 and 7 caused a significant increase in macrophage proliferation; these findings may suggest that this medicinal plant could be utilised as an excellent source of compounds for immunomodulatory activity.     

Fixed point theorems for the sum of ( ws)-compact and asymptotically $${\Phi}$$-nonexpansive mappings

In this paper, we introduce the concept of an asymptotically \({\Phi}\)-nonexpansive operator. In addition, we establish some Krasnoselskiitype fixed point theorems for the sum of two operators A and B, where the operator A is assumed to be (ws)-compact, and B is a (ws)-compact and asymptotically \({\Phi}\)-nonexpansive operator on an unbounded closed convex subset of a Banach space. Also we present Leray–Schauder alternatives and Furi–Pera-type fixed point theorems for the sum of two (ws)-compact mappings.     

Efficient synthesis of fluorophosphonylated alkyles by ring-opening reaction of cyclic sulfates

Ring-opening reactions of functionalized 1,2-cyclic sulfates and oxetanes with the phosphonodifluoromethyl carbanion are reported. This approach allows an easy access to fluorinated beta-hydroxyphosphonates that are building blocks in the synthesis of acyclic nucleosides. Synthesis of precursors of nucleoside phosphorylase inhibitors from these alcohols is described.     

Precession of the Orbit of Mercury

Doklady Physics - The influence of the planets of the Solar System on the precession of the orbit of Mercury is investigated in the framework of classical mechanics. The influence of each planet on...     

Nanometer-sized,rod-like,ligand-containing tryptophan complexes: Anion influence–structural geometry–antitumor activity correlations

Matrix metalloproteinases (MMPs) are metal-dependent endopeptidases that are related to the initiation and progression of diseases and are involved in physiological processes such as angiogenesis, wound healing, and embryonic development. Synthetic inhibitors of MMPs are amino acid–based ligands as analyzed by the interactions between the enzyme and its natural substrate. Low production cost and low environmental toxicity of α-amino acid complexes resulted in a wide pharmacological spectrum, including the anti-inflammatory and anticonvulsant properties in addition to cytotoxic activities. These facts directed our search for the development of selective inhibitors that contain chemical entity. l -Tryptophan is a main component of proteins and is essential in human nutrition for establishing and sustaining positive nitrogen balance. Nanomaterials exhibited clinical influence in terms of delivery approaches on bioactive molecules as therapeutic and imaging contrast agents. In this article, we report the synthesis of nanometer rod-like 2,2′-(1,3,5,7-tetraoxopyrrolo[3,4-f]isoindole-2,6(1H,3H,5H,7H)-diyl)bis(3-(1H-indol-3-yl)propanoic acid) and its metal complexes. The effect of different anions on the geometrical structures and properties of several complexes was studied. Studies indicated that most complexes exhibited dinuclear octahedral or tetrahedral topologies with M–M interaction being absent, whereas mononuclear square planar or square pyramidal topologies were obtained for copper complexes containing chloride or nitrate anions. The ligand exhibited its activity solely against Bacillus subtilis. [Co₂(L)Cl₂(H₂O)₂] complex exhibited potent activity against various species of pathogenic microorganisms. The cytotoxicity against MCF-7 cell line demonstrated that the inhibitory effect is dose dependent. [Cu(HL)Cl.H₂O] complex exhibited an interesting cytotoxic activity in addition to copper anticancer analogues, the alternatives to cis-platin because of their biocompatibility and important roles in biological systems.     

Proof of the Jacobian Conjecture in the Two-Dimensional Case and Global Isochronous Centers of Polynomial Hamiltonian Differential Systems

Differential Equations - It is proved that, up to a nonsingular linear transformation, the real Hamiltonian system $$\dot {x}=-y-P(x) $$ , $$\dot {y}=x+(y+P(x))P^{\prime }(x) $$ , where $$P(x) $$...