A new antifungal and antiprotozoal bibenzyl derivative from Gavilea lutea

A new bibenzyl derivative (4), together with two glycosylated flavonoids (1 and 2), batatasin III (3) and the phenanthrene isohircinol (5) were isolated from the aerial parts of Gavilea lutea. Their structures were elucidated on the basis of spectroscopic studies including 1D and 2D NMR, UV, IR and HRESIMS. All isolated compounds were evaluated for their antifungal activity towards Candida albicans. The new compound 4 showed inhibitory activity with a MIQ of 50 μg. In addition, compound 4 exhibited a selective activity (IC₅₀ = 2.3 μg/mL) against Leishmania donovani.     

A brief review of the computational modeling of CO2 electroreduction on Cu electrodes

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Structural Properties of Macrodontain I,a Cysteine Protease from <Emphasis Type="Italic">Pseudananas macrodontes</Emphasis> (Morr.) Harms (Bromeliaceae)

The primary structure of macrodontain I, a peptidase from Pseudananas macrodontes fruits, was determined using Edman’s degradation. The enzyme is a non-glycosylated peptidase composed by 213 amino acids with a calculated molecular weight of 23,486.18 Da, pI value 6.99, and a molar extinction coefficient at 280 nm of 61,685 M^?1 cm^?1. The alignment of the sequence of macrodontain I with those cysteine peptidases from species belonging to the family Bromeliaceae showed the highest identity degree (87.74%) against fruit bromelain. A remarkable fact is that all these peptidase sequences show two Met contiguous residues (Met121 and 122) and the nonapeptide VPQSIDWRD located in the mature N-terminal region. Residues Cys26 and His159, which constitute the catalytic dyad in all cysteine peptidases, as well as active site residues Gln20 and Asn176, characteristic of Clan C1A, are conserved in macrodontain I. The 3-D model suggests that the enzyme belongs to the α?+?β class of proteins, with two disulfide bridges (Cys23-Cys63 and Cys57-Cys96) in the α domain, while the β domain is stabilized by another disulfide bridge (Cys153-Cys201). Further, we were able to establish that the cysteine peptidases from P. macrodontes are involved in the anti-inflammatory activity.     

Nucleophilic addition to substituted 1H-4,5-dihydroimidazolium salts

1H-4,5-Dihydroimidazolium salts 1 react readily with nucleophilic reagents originating cyclic products which may be stable or become transformed into acyclic compounds maintaining the structural ethylenediamine unit. With methylmagnesium iodide compound 1e affords the expected imidazolidine, but in the case of substituted 1-aryl-3-methyl-2-phenyl salts 1b-d the N-aryl-N′-methylethylenediamines 3b-d and acetophenone ( 4 ) were isolated, the process representing the transfer of the C-2 unit to a nucleophilic carbon. With alkaline cyanides salts 1 react efficiently affording α,α-diaminonitriles 5 . In these compounds the cyano group may be readily substituted by nucleophiles (hydroxyl anion, species with nucleophilic carbon and reagents that act by hydride ion transfer), in a way similar to the salts but with better yields.     

Pentacyclic Triterpene Profile and Its Biosynthetic Pathway in Cecropia telenitida as a Prospective Dietary Supplement

Promising research over the past decades has shown that some types of pentacyclic triterpenes (PTs) are associated with the prevention of type 2 diabetes (T2D), especially those found in foods. The most abundant edible sources of PTs are those belonging to the ursane and oleanane scaffold. The principal finding is that Cecropia telenitida contains abundant oleanane and ursane PT types with similar oxygenation patterns to those found in food matrices. We studied the compositional profile of a rich PT fraction (DE16-R) and carried out a viability test over different cell lines. The biosynthetic pathway connected to the isolated PTs in C. telenitida offers a specific medicinal benefit related to the modulation of T2D. This current study suggests that this plant can assemble isobaric, positional isomers or epimeric PT. Ursane or oleanane scaffolds with the same oxygenation pattern are always shared by the PTs in C. telenitida, as demonstrated by its biosynthetic pathway. Local communities have long used this plant in traditional medicine, and humans have consumed ursane and oleanane PTs in fruits since ancient times, two key points we believe useful in considering the medicinal benefits of C. telenitida and explaining how a group of molecules sharing a closely related scaffold can express effectiveness.     

Effects of FeCl3 as oxidizing agent on the conduction mechanisms in polypyrrole (PPy)/pc–ZnO hybrid heterojunctions grown by oxidative chemical vapor deposition

P‐type polypyrrole (PPy) films are deposited on glass and on n‐type polycrystalline ZnO (pc–ZnO) substrates by oxidative chemical vapor deposition under three different amounts of FeCl₃ used as oxidizing agents to form hybrid heterojunctions. Their microstructure, morphology, and electrical characteristics are studied. Particularly, current–voltage characteristics of the PPy/pc–ZnO heterojunctions are analyzed by defining an electrical equivalent circuit. The extracted parameters, together with the estimated heterojunction barrier height and the HOMO energy level of the PPy, indicate that a thermionic emission of holes at the heterojunction determines the saturation current of the diode at low voltage. For larger FeCl₃ amounts, the diode ideality factor increases indicating an increment of recombination by tunneling of charge carriers occurring at the heterojunction. This is attributed to a narrowing of the space charge region due to an increment of the number of charge carriers with a growing amount of FeCl₃. At high voltages, the PPy thickness influences the ohmic and space–charge limited current mechanisms at the bulk region. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1537–1544     

Composites of Anthraquinone Dyes@HKUST-1 with Tunable Microstructuring: Experimental and Theoretical Interaction Studies

The metal–organic framework (MOF) HKUST-1 was employed as an interaction matrix for fundamental loading studies of anthraquinone dyes. Chosen dyes were alizarin (A), alizarin S (AS), disperse blue 1 (B1), disperse blue 3 (B3), disperse blue 56 (B56) and purpurin (P). All materials were characterized by XRD, FTIR, TGA and SEM. Hence the interaction of dyes with the framework was characterized by theoretical–experimental differential analysis. One-pot loading strategy resulted in more efficient scavenging of dyes, and reached 100 % for B56 using 50 mg L⁻¹. SEM revealed important microstructural changes, the smaller crystals ranged 0.8–3 μm in size and almost all composite sizes were from this to higher values, reaching 70 μm, with varying shapes. Two composites were larger in size range (about 2500–1000 μm), and were shaped as rods, octahedrons and coffin lids. Indeed, the microstructure could be modulated depending on preparation conditions and type of loaded dye. For the higher loading series, N₂ adsorption and XPS experiments were carried on to further evidence dye–MOF interactions. Ab initio prediction of structural properties for A@HKUST-1 and P@HKUST-1 were obtained by means of solid-state CRYSTAL14 code at the PBE0 level of theory. Computed findings evidenced two O→Cu coordinative bonds, one from O-ketone and the other from O-phenolate moiety as main interactions towards CuNET centers.     

Synthesis,structural and larvicidal studies of a series of triorganotin chrysanthemumates

A series of triorganotin chrysanthemumates (2,2‐dimethyl‐3‐(2‐methyl‐1‐propenyl)cyclopropanecarboxylates) (R₃SnO₂CC₉H₁₅) where R = methyl, ethyl, n‐butyl and phenyl was synthesized. The solid state structures were deduced using infrared (IR) and Mössbauer spectroscopies. The spectroscopic results indicated that all the compounds were found to be five‐coordinated in the solid state. Based on the NMR results, all the compounds are tetrahedral in solution. Larvicidal activities of the compounds were evaluated against the second instar stage of Aedes aegypti, Anopheles stephensi and Culex pipiens quinquefasciatus mosquitoes. The toxicity results indicated that these compounds of triorganotins were effective larvicides against all three species of larvae. Copyright © 2011 John Wiley & Sons, Ltd.