Preparation,crystal structure,and spectroscopic,chemical, and electrochemical properties of (2E,4E)-1,4-di(3-guaiazulenyl)-1,3-butadiene compared with those of (E)-1,2-di(3-guaiazulenyl)ethylene

Wittig reaction of (E)-3-(3-guaiazulenyl)propenal (11) with (3-guaiazulenylmethyl)triphenylphosphonium bromide (9) in ethanol containing NaOEt at 25 °C for 24 h under argon gives the title new (2E,4E)-1,3-butadiene derivative 4, in 33% isolated yield, which upon treatment with hexafluorophosphoric acid (i.e., 65% HPF₆ aqueous solution) in tetrahydrofuran (=THF) at 25 °C for 1 h under aerobic conditions affords a new air (two-electron) oxidation product (E)-ethylene-1,2-bis(3-guaiazulenylmethylium) bis(hexafluorophosphate) (14), quantitatively, and further, zinc-reduction of 14 in trifluoroacetic acid (=CF₃COOH) at 0 °C for 1 h under argon reverts 4, quantitatively. Along with the above interesting results, our discovered another preparation method, spectroscopic properties, crystal structure, and electrochemical behavior of 4, which serves as a strong two-electron donor and acceptor, compared with those of the previously reported (E)-1,2-di(3-guaiazulenyl)ethylene (3) are documented in detail.     

Peptidehelicenes in solution and gel: chiral discrimination through interactions between two types of helixes

Helical [5]thiaheterohelicene 5HM, which rapidly interconverts between P and M enantiomers in solution, was connected to helical l-phenylalanine oligomers with an ester linkage to give peptidehelicenes (5Fn, where n: number of bonded phenylalanines). The characteristics of 5F4 and 5F5 with two types of helixes in a molecule were investigated, particularly in comparison with those of 5F1–5F3 with an incomplete coil of a peptide moiety. l-Phenylalanine peptide chains induced a shift in the equilibrium between the P and M helixes of 5HM toward the P side for all the 5Fns examined. The enantiomeric excess (ee) of the P form increased with a decrease in temperature, together with an elongation of the peptide chains. 5F4 and 5F5 in hot solutions of some solvents formed a gel at room temperature, whereas 5F1–5F3 showed no such behavior. In this gel, the stable helical form of the 5HM moiety in 5F4 and 5F5 was observed to be the M form in contrast to that in their solutions.     

Synthesis of 2-[2-(8-hydroxyquinolyl)azo]-1-naphthol and its use in the spectrophotometric determination of calcium in potable water

The synthesis of a novel reagent, 2-[2-(8-hydroxyquinolyl)azo]-1-naphthol (HQAN), is described. The acidity constants of the reagent and its reactions with various metal ions are reported. The HQAN reagent forms a soluble calcium chelate in 50% (v/v) dioxane/ water at pH > 8.5 (? = 24 000 l mol^?1 cm ^t-1 at 570 nm). It also forms chelates with magnesium, other alkaline earth metals, and ivalent Mn, Fe, Ni, Cu, Zn, Cd and Pb. These interferences (except for Mn) can be avaoided by pH adjustment or by adding masking agents, and a very simple procedure for the determination of calcium in potable waters is obtained.     

Identification of Two Palmitoyl Groups in Octopus Rhodopsin

Abstract— We determined the structure and site of fatty acid incorporated in octopus rhodopsin using a combination of fluorescence label and enzymatic cleavage methods in conjunction with fast-atom bombardment (FAB) mass spectrometry. A single peptide containing two adjacent cysteines, Cys337 and Cys338, was successfully isolated using the fluorescence from a dye conjugated to Cys345. The FAB mass spectrometric analysis of the peptide (323phe-³⁴⁰phe) revealed that two palmitoyl groups are linked to Cys337 and Cys338 via thioester bonds in octopus rhodopsin as in bovine rhodopsin.     

2′,4′-BNA/LNA with 9-(2-Aminoethoxy)-1,3-diaza-2-oxophenoxazine Efficiently Forms Duplexes and Has Enhanced Enzymatic Resistance**

Artificial nucleic acids are widely used in various technologies, such as nucleic acid therapeutics and DNA nanotechnologies requiring excellent duplex-forming abilities and enhanced nuclease resistance. 2′-O,4′-C-Methylene-bridged nucleic acid/locked nucleic acid (2′,4′-BNA/LNA) with 1,3-diaza-2-oxophenoxazine (BNAP ( B^H )) was previously reported. Herein, a novel B^H analogue, 2′,4′-BNA/LNA with 9-(2-aminoethoxy)-1,3-diaza-2-oxophenoxazine (G-clamp), named BNAP-AEO ( B^AEO ), was designed. The B^AEO nucleoside was successfully synthesized and incorporated into oligodeoxynucleotides (ODNs). ODNs containing B^AEO possessed up to 10⁴-, 152-, and 11-fold higher binding affinities for complementary (c) RNA than those of ODNs containing 2′-deoxycytidine ( C ), 2′,4′-BNA/LNA with 5-methylcytosine ( L ), or 2′-deoxyribonucleoside with G-clamp ( P^AEO ), respectively. Moreover, duplexes formed by ODN bearing B^AEO with cDNA and cRNA were thermally stable, even under molecular crowding conditions induced by the addition of polyethylene glycol. Furthermore, ODN bearing B^AEO was more resistant to 3′-exonuclease than ODNs with phosphorothioate linkages.     

Antioxidative and Anti-Inflammatory Phytochemicals and Related Stable Paramagnetic Species in Different Parts of Dragon Fruit

In this study, we investigated the antioxidant and anti-inflammatory phytochemicals and paramagnetic species in dragon fruit using high-performance liquid chromatography (HPLC) and electron paramagnetic resonance (EPR). HPLC analysis demonstrated that dragon fruit is enriched with bioactive phytochemicals, with significant variations between each part of the fruit. Anthocyanins namely, cyanidin 3-glucoside, delphinidin 3-glucoside, and pelargonidin 3-glucoside were detected in the dragon fruit peel and fresh red pulp. Epicatechin gallate, epigallocatechin, caffeine, and gallic acid were found in the dragon fruit seed. Additionally, 25–100 mg × L⁻¹ of dragon fruit pulp and peel extracts containing enrichment of cyanidin 3-glucoside were found to inhibit the production of reactive oxygen species (ROS), reactive nitrogen species (RNS), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) in cell-based studies without exerted cytotoxicity. EPR primarily detected two paramagnetic species in the red samples. These two different radical species were assigned as stable radicals and Mn²⁺ (paramagnetic species) based on the g-values and hyperfine components. In addition, the broad EPR line width of the white peel can be correlated to a unique moiety in dragon fruit. Our EPR and HPLC results provide new insight regarding the phytochemicals and related stable intermediates found in various parts of dragon fruit. Thus, we suggest here that there is the potential to use dragon fruit peel, which contains anthocyanins, as a natural active pharmaceutical ingredient.     

Optically stimulated luminescence (OSL) and thermoluminescence (TL) measurements on red TL (RTL) quartz samples using a new automated OSL/TL measuring system

A new automated OSL/TL measuring system, equipped with a small X-ray irradiator applicable to a single-aliquot method, has been developed. To ensure cross check between OSL and RTL, the naturally accumulated doses evaluated with OSL and RTL measurements were compared. The results nearly agreed with each other, although the ages estimated from the experimental data were different from the real ages of Shin-Yakushiji temple because of the uncertainty of the annual dose. Nevertheless, it was concluded that the application of this system to the dating could be performed owing to uses of the luminescence measurements.     

CO2 Conversion with Alcohols and Amines into Carbonates,Ureas, and Carbamates over CeO2 Catalyst in the Presence and Absence of 2‐Cyanopyridine

Recent progress on the CeO₂ catalyzed synthesis of organic carbonates, ureas, and carbamates from CO₂+alcohols, CO₂+amines, and CO₂+alcohols+amines, respectively, is reviewed. The reactions of CO₂ with alcohols and amines are reversible ones and the degree of the equilibrium limitation of the synthesis reactions is strongly dependent on the properties of alcohols and amines as the substrates. When the equilibrium limitation of the reaction is serious, the equilibrium conversion of the substrate and the yield of the target product is very low, therefore, the shift of the equilibrium reaction to the product side by the removal of H₂O is essential in order to get the target product in high yield. One of the effective method of the H₂O removal from the related reaction systems is the combination with the hydration of 2‐cyanopyridine to 2‐picolinamide, which is also catalyzed by CeO₂.     

Synthesis of 3,4‐Fused Tricyclic Indoles Using 3‐Alkylidene Indolines as Versatile Precursors

In this personal account, our recent studies of novel synthetic methods of 3,4‐fused tricyclic indole derivatives using 3‐alkylidene indoline derivatives as versatile precursors are discussed. Two types of cascade reactions producing 3,4‐fused tricyclic 3‐alkylidene indolines were developed based on a palladium‐catalyzed intramolecular Heck insertion to an allene‐allylic amination cascade and a platinum‐catalyzed intramolecular Friedel‐Crafts type C?H coupling‐allylic amination cascade. Furthermore, three types of 3,4‐fused tricyclic indoles were accessible from a single 3‐alkylidene indoline precursor via acid‐promoted olefin isomerization or oxidative treatments. The application of the developed methods to the synthesis of natural products bearing a 3,4‐fused tricyclic indole skeleton, (?)‐aurantioclavine, fargesine, and synthetic studies of dragmacidin E are also highlighted.