Protein Protection by Antioxidants: Development of a Convenient Assay and Structure‐Activity Relationships of Natural Polyphenols

In this work, a convenient test of antioxidant activity was developed, with BChE‐contaminated HSA as the target of AAPH‐induced oxidation and its esterase activity as the marker of protein integrity or degradation. The method is relatively simple, of low cost, and convenient to use. Its application to natural polyphenols showed that quercetin ( 1 ), verbascoside ( 2 ), chlorogenic acid ( 3 ), caffeic acid ( 4 ), 1,3,6,7‐tetrahydroxyxanthone ( 5 ), and mangiferin ( 6 ), are good antioxidants (IC₅₀<9 μM ). 1,5‐Dihydroxy‐3‐methoxyxanthone ( 7 ), flemichin D ( 8 ), and cordigone ( 9 ) showed modest activities (ca. 50 μM <IC₅₀<350 μM ), whereas danthrone ( 10 ) was inactive. Complementary experiments with two of the more active antioxidants, namely quercetin ( 1 ) and chlorogenic acid ( 3 ) showed that both antioxidants were better radical scavengers than chain‐breaking antioxidants. The relative adiabatic oxidation potential (ΔH_ox), the relative H‐bond dissociation energy (ΔH_abs), and the first oxidation potential measured by cyclic voltammetry were found to be related to the radical‐scavenging activity of these antioxidants.     

Characterization of calcium phosphate coatings doped with Mg, deposited by pulsed laser deposition technique using ArF excimer laser

Calcium phosphate layers were deposited on Ti6Al4V substrates with TiN buffer layers by use of pulsed laser deposition method. With this technique three pressed pellets consisted of tricalcium phosphate (TCP, Ca(3)(PO(4))(2)), hydroxyapatite (HA, Ca(10)(PO(4))(6)(OH)(2)) and hydroxyapatite-doped with magnesium (HA with 4% of Mg and trace amount of (Ca,Mg)(3)(PO(4))(2)) were ablated using ArF excimer laser (lambda=193 nm). The using of different targets enabled to determine the influence of target composition on the nature of deposited layers. The obtained deposits were characterized by means of Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction method (XRD). The obtained Fourier spectras revealed differences in terms of intensity of spectral bands of different layers. The analysis from XRD showed that Mg-doped HA layer has crystalline structure and TCP and HA layers composition is characterized by amorphous nature.     

Structure–Function Relationships in Unsymmetrical Zinc Phthalocyanines for Dye‐Sensitized Solar Cells

Let it shine! The impact of the anchoring group on photovoltaic performance by a series of phthalocyanine sensitisers (see figure) has been demonstrated.

     

Influence of α- and γ- cyclodextrin lipophilic derivatives on curcumin-loaded SLN

Solid lipid nanoparticles (SLN) made of different triglycerides (TG) in the presence and in the absence of various modified α- and γ-cyclodextrins (CD) were prepared by the solvent injection technique. A new synthesis of lipophilic derivatives of γ- CD was developed in this work. Curcumin (CU), a natural polyphenol with antitumor, antioxidant and anti-inflammatory properties, was used as model drug. SLNs mean sizes were in the 250–800 nm range and afforded CU entrapment efficiency in the 12–85% range. The presence of CD derivatives with almost the same chain length of TG induced an improvement of nanoparticle characteristics decreasing mean size values and increasing CU entrapment efficiency. A significant reduction in CU photodegradation was noted only when the drug was vehicled in tristearin-SLN, which became less pronounced in the presence of CD-derivatives, determining a loss in photoprotection. The hydrolytic stability of curcumin was highly improved by drug loading in tristearin-SLN, and only slightly by loading it in tricaprin-SLN, and this seemed not to be influenced by the presence of CD derivatives. Skin uptake studies revealed an increase in CU skin accumulation when CU was loaded in SLN obtained with all CD derivatives, particularly with most lipophilic one.     

Inside Cover: A Spherical Molecule with a Carbon‐Free Ih‐C80 Topological Framework (Angew. Chem. Int. Ed. 27/2009)

Template‐controlled self‐assembly of discrete molecular pentaphosphaferrocene and CuCl units was used to form the first entirely carbon‐free molecule that has C₈₀ topology and encapsulates a carborane unit. In their Communication on page 5046 ff. , M. Scheer and co‐workers report the synthesis and characterization of this impressive supramolecular compound, which displays an electronic interaction between the carborane and the spherical host molecule. C blue, Fe olive, P pink, Cl green, C gray, B/C orange, H white.

     

Forces between mica surfaces, prepared in different ways, across aqueous and nonaqueous liquids confined to molecularly thin films

We have measured normal and lateral interactions across a range of different liquids between mica surfaces using a surface force balance (SFB). The mica surfaces were prepared either by melt cutting using Pt wire and standard procedures in our laboratories or by tearing sheets (that had not been exposed to Pt) off from a freshly cleaved sheet of mica. AFM micrographs revealed the substantial absence of Pt nanoparticles on the melt cut and torn-off mica surfaces. Normal-force versus surface-separation (D) profiles and shear force versus D measurements for purified water (no added salt), for concentrated aqueous NaCl solutions, and for cyclohexane revealed that in all cases the behavior of the highly confined liquids between melt-cut and between torn-off mica sheets was identical within experimental scatter. These results demonstrate directly that interactions measured between melt-cut mica surfaces as routinely prepared using established procedures in our laboratories and in other laboratories are free of the effect of any Pt contamination.     

Intramolecular [4+2] cycloaddition of furfurylsubstituted homoallylamines to allylhalides,acryloyl chloride and maleic anhydride

Acylation of 4‐(furyl‐2)‐4‐R‐aminobut‐1‐enes and 4‐R‐4‐furfurylaminobut‐1‐enes with maleic anhydride, acryloyl chloride or allylhalides provided 3‐aza‐10‐oxatricyclo[5.2.1.0^1,5]decenes. The tricycles are formed via an initial amide formation followed by a stereoselective exo‐IMDAF (Intramolecular Diels‐Alder of Furan). In case of competing cycloaddition (for compounds possessing two furan or two dienophilic moieties) the most substituted fivemembered cycle is preferably annulated. Refluxing of 4‐R‐4‐furfurylaminobut‐1‐enes in acetic anhydride led to exo‐3‐aza‐11‐oxatricyclo[6.2.1.0^1,6]undecenes with the pseudoequatorial substituent R‐4. Treatment of 3‐aza‐10‐oxatricyclo[5.2.1.0^1,5]decenes with PPA at 90?110°C promoted cyclic ether opening, aromatization and intramolecular cyclization reactions sequence to give the corresponding tetracyclic compounds — tetrahydroisoindolo[2,1‐a]quinolines and tetrahydroisoindolo[2,1‐b][2]benzazepines in good yields. Unusual products of ipso‐substitution in aromatic ring were obtained on cyclization of N‐p‐R‐substituted 2‐allyl‐4‐oxo‐3‐aza‐10‐oxatricyclo[5.2.1.0^1,5]dec‐8‐enes.