Harderoporphyrin: a misnomer

More than 30 years ago it was reported that rodent Harderian glands contained a tricarboxylic acid porphyrin, which the authors named Harderoporphyrin. The recent finding in rat Harderian glands of the porphyrin glycoconjugate, protoporphyrin-1-O-acyl-beta-xyloside as a major component led to scrutiny of earlier publications. It became apparent that the results were flawed and that the conclusions were unsustainable. The procedural artefacts which led to the errors are discussed and their bases are demonstrated experimentally. Harderoporphyrin as originally defined never existed.     

Spectral study of a new dihydroisocoumarin

A novel dihydroisocoumarin, 3,4‐dihydro‐6,8‐dihydroxy‐3‐(2′‐acetyl‐3′‐hydroxy‐5′‐methoxy)methyl‐1H‐[2]benzopyran‐1‐one, was isolated from the chloroform extract of the sap of the traditional herb Aloe vera. Its structure was determined by high‐resolution negative fast atom bombardment mass spectrometry (MS), 2D NMR spectroscopy and x‐ray crystallography. The molecular structure was elucidated by 2D NMR analysis. The complete assignment of the ¹H and ¹³C NMR spectra of this compound was performed by using ¹H detected one‐bond heteronuclear multiple quantum correlation (HMQC) and long‐range (two and three bonds) heteronuclear multiple quantum bond correlation (HMBC) experiments. Detailed analyses of the one‐ and two‐dimensional NMR techniques are presented in additional to the spectral properties (MS, IR and UV). Copyright © 2003 John Wiley & Sons, Ltd.     

Fluoropolymer based on a polyaspartamide containing 1,2,4-oxadiazole units: a potential artificial oxygen (O2) carrier

In this preliminary work we have prepared a fluorinated polymer capable of solubilizing an appreciable amount of O(2) and, at the same time, maintaining a higher water solubility than perfluoroalkanes investigated as injectable O(2) carriers. In particular, we describe the synthesis and characterization of a new macromolecular conjugate obtained by derivatization of alpha,beta-poly(N-2-hydroxyethyl)-DL-aspartamide (PHEA) with 5-pentafluorophenyl-3-perfluoroheptyl-1,2,4-oxadiazole, called PHEA-F. This new water soluble fluoropolymer was prepared in high yield using a simple procedure. It was characterized by FT-IR and UV-vis spectrophotometry, (19)F-NMR and SEC measurements. O(2) solubility studies on PHEA-F aqueous solutions were carried out at 25 degrees C and 37 degrees C at atmospheric pressure and showed that PHEA-F conjugate, despite its low degree of derivatization in fluorine containing groups (2.60 mol-%), is capable of dissolving 13-15% more O(2) than non-fluorinated PHEA. Moreover, O(2) release in simulated physiological conditions is faster for PHEA-F than for PHEA. The biocompatibility of this conjugate has been evaluated by performing an in vitro viability assay on human chronic myelogenous leukaemia cells (K-562) chosen as a model cell line and in vitro haemolysis experiments on human RBCs. All these properties suggest the potential use of PHEA-F as an artificial O(2) carrier.     

Simulations of the active transport of a neutral solute based on a kinase-channel-phosphatase topology

Simulations of coupled interactions involving two opposite enzymatic reactions, solute diffusions, and electrostatic interactions between membrane charges and charged solutes were conducted under a fixed kinase-channel-phosphatase (KCP) topology oriented from the outside to the inside of a porous membrane structure. Depending on the kinase and phosphatase locations, we recently demonstrated that an active transport of a phosphorylated substrate may occur via the opposite topology, that is, a PCK topology. The present analysis demonstrates that, under a KCP membrane topology, which also behaves as a specific ATP-dependent transporter, the active transport of a neutral substrate may occur. This analogous active transport appears to be dependent on the phosphatase location and on the membrane surface potentials. A broad analysis of the role played by the main parameters taken into account in the model was conducted in order to define precisely the physico-chemical conditions and the membrane topology needed for the highest active transports within the shortest time.     

A Stereoselective Total Synthesis of Xyolide,a Natural Bioactive Nonenolide

A stereoselective total synthesis of xyolide, a naturally occurring bioactive nonenolide, has been accomplished. The acid fragment of the molecule has been prepared from D ‐mannitol and the alcohol fragment from (2Z)‐but‐2‐ene‐1,4‐diol. The synthesis involves the coupling of these two fragments using the Yamaguchi esterification protocol, followed by intramolecular ring‐closing methathesis. The diastereoisomeric alcohol fragment has also been utilized in this synthesis by employing the Mitsunobu esterification.     

Theoretical study on a chemosensor for fluoride anion‐based on a urea derivative

The sensing mechanism of the N‐Phenyl‐N′‐(3‐quinolinyl)urea (PQU) chemosensor for fluoride anion has been investigated by density functional theory/time‐dependent density function theory. The double intermolecular hydrogen bonds are formed between the three anions (X^??F^?, AcO^?, Cl^?) and the urea fragment of PQU. In the S₀ states, the H_b? X^? hydrogen bonds are slightly stronger than the H_a? X^? hydrogen bonds and the fluoride‐induced deprotonation occurs at the N? H_b position rather than at the N? H_a position. Consequently, the absorption peaks, including an intramolecular charge transfer transition and a ππ* transition, are significantly red‐shifted. Thermodynamic calculations confirm that the deprotonation in the ground state is favorable in energy only when excess fluoride anion exists. Along with the S₀ → S₁ transition, the H_a? X^? hydrogen bonds strengthen and the H_b? X^? hydrogen bonds weaken. However, the emission spectra of [PQU‐H_b]^?, instead of [PQU‐H_a]^?, are observed upon addition of fluoride anion. © 2013 Wiley Periodicals, Inc.     

Structure elucidation and antibacterial activity of a new coumarinolignoid from Daphne gnidium L.

Phytochemical investigation of the dichloromethane extract from the leaves of Daphne gnidium L. afforded 2‐(4‐hydroxy‐3,5‐dimethoxyphenyl)‐3‐hydroxymethyl‐2,3‐dihydro‐1,4,5‐trioxaphenanthren‐6‐one, and its structure was determined by a combination of spectral methods (1D and 2D ¹H, ¹³C NMR and HRMALDI and EI mass spectrometry). The new compound was found to possess moderate antibacterial activity against Staphylococcus aureus and Bacillus cereus. However, it showed no cytotoxic activity against KB cells. Copyright © 2002 John Wiley & Sons, Ltd.     

A Direct Route to a New Class of Acrylamide Thioglycosides

The preparation of a new class of acrylamide thioglycosides via one‐pot reaction of the potassium 2‐cyanoethylene‐1‐thiolate salts with 2,3,4,6‐tetra‐O‐acetyl‐α‐D‐gluco‐ and galactopyranosyl bromides has been studied. The E‐configuration of these thioglycosides was proven by their transformations to the corresponding 5‐aminopyrazoles.     

Thulium(III) Ions Monitoring by a Novel Thulium(III) Microelectrode Based on a S‐N Schiff Base

This study presents for the first time development of a highly selective and sensitive thulium(III) micro‐sensor. Theoretical calculations were conducted on a S‐N Schiff base [thiophene‐2‐carbaldehyde‐(7‐methyl‐1,3‐benzothiazol‐2‐yl) hydrazone] (TCMH) in order to obtain a clue about the tendency of TCMH to Tm(III) and some other metal ions. Then, TCMH was used as a membrane‐active component to prepare a Tm(III)‐selective polymeric membrane microelectrode. In line with the resulting data, the electrode exhibits a Nernstian response toward Tm(III) ions for a very wide concentration range (1.0×10^?11–4.0×10^?6 M) with a detection limit of 1.0×10^?11 (ca. 1.5 ppt) and a very fast response time in the whole concentration range (<5 s). In addition, the results showed that the certain microelectrode could be applied in the pH range of 4.0–11.0 with a usage of more than one month without any considerable potential divergence.     

Darstellung,Schwingungsspektren und Kristallstrukturen von [(Ph3P)2N]2[(W6Cl)I] · 2 Et2O · 2 CH2Cl2 und [(Ph3P)2N]2[(W6Cl)(NCS)] · 2 CH2Cl2

Synthesis, Crystal Structures, and Vibrational Spectra of [(Ph₃P)₂N]₂[(W₆Cl )I ] · 2 Et₂O · 2 CH₂Cl₂ and [(Ph₃P)₂N]₂[(W₆Cl )(NCS) ] · 2 CH₂Cl₂ By treatment of [(W₆Cl)I]^2– with (SCN)₂ in dichloromethane at –20 °C the hexaisothiocyanato cluster anion [(W₆Cl)(NCS)]^2– is formed. X‐ray structure determinations have been performed on single crystals of [(Ph₃P)₂N]₂[(W₆Cl)I] · 2 CH₂Cl₂ · 2 Et₂O ( 1 ) (triclinic, space group P1, a = 10.324(5), b = 14.908(3), c = 17.734(8) Å, α = 112.78(2)°, β = 99.13(3)°, γ = 92.02(3)°, Z = 1) and [(Ph₃P)₂N]₂[(W₆Cl)(NCS)] · 2 CH₂Cl₂ ( 2 ) (triclinic, space group P1, a = 11.115(2), b = 14.839(2), c = 17.036(3) Å, α = 104.46(1)°, β = 105.75(2)°, γ = 110.59(1)°, Z = 1). The thiocyanate ligands of 2 are bound exclusively via N atoms with W–N bond lengths of 2.091–2.107 Å, W–N–C angles of 173.1–176.9° and N–C–S angles of 178.1–179.3°. The vibrational spectra exhibit characteristic innerligand vibrations at 2067–2045 (ν_CN), 879–867 (ν_CS) and 490–482 (δ_NCS). Based on the molekular parameters of the X‐ray determination of 1 the vibrational spectra of the corresponding (n‐Bu₄N) salt of 1 are assigned by normal coordinate analysis. The valence force constants are f_d(WW) = 1.61, f_d(WI) = 1.23 and f_d(WCl) = 1.10 mdyn/Å.     

Sensitive determination of 4-(4-chlorophenyl)-4-hydroxypiperidine, a metabolite of haloperidol, in a rat biological sample by HPLC with fluorescence detection after pre-column derivatization using 4-fluoro-7-nitro-2,1,3-benzoxadiazole

4-(4-Chlorophenyl)-4-hydroxypiperidine (CPHP), one of the metabolites of haloperidol, is considered to exhibit brain toxicity. CPHP concentrations in plasma and tissue homogenates (each 200 microL) from rats were analyzed by HPLC fluorescence detection after pre-column derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F). After basic extraction of the samples with benzene, the derivatization with NBD-F was conducted in borate buffer (pH 8.0) at 60 degrees C for 3 min. Mexiletine was carried through the procedure as an internal standard. The regression equation for CPHP showed a good linearity in the range of 0.03-1 microg/mL with a detection limit of 0.008 microg/mL. The coefficient of variation was less than 11.6%. Plasma concentration-time courses of CPHP after intraperitoneal or per oral administration of CPHP, haloperidol or reduced haloperidol were examined, and the pharmacokinetic parameters were estimated. Additionally, CPHP levels in various tissues at 8 h after intraperitoneal administration of these compounds were compared. The method was simple and sensitive, useful for determination of CPHP in rat biological samples using as little as 200 microL of sample volume and could be applied for pharmacokinetic study.     

A New Megastigmane Palmitate and a New Oleanane Triterpenoid from Aster yomena Makino

A new megastigmane palmitate, 9‐oxomegastigm‐5(13)‐ene‐2β‐palmitate ( 1 ), and a new oleanane triterpenoid, (3β)‐3,23,28‐trihydroxyolean‐12‐en‐11‐one ( 2 ), together with three known oleanane‐type triterpenoids, β‐amyrin ( 3 ), erythrodiol ( 4 ), and (3β)‐olean‐12‐ene‐3,23,28‐triol ( 5 ), were isolated from the aerial parts of Aster yomena (Asteraceae). Their structures were identified based on 1D‐ and 2D‐NMR analysis, including ¹H,¹H‐COSY, HSQC, HMBC, and NOESY techniques.     

Selective Transformations of a Diprotected 2‐Oxobutanedial

The reactivity of 1,1‐diethoxy‐3‐(1,3‐dithian‐2‐yl)propan‐2‐one, a diacetal of oxobutanedial, and some of its derivatives toward selected reagents has been studied. As expected, hydride and Grignard‐type additions take place at the oxo moiety only and give the corresponding alcohols in good‐to‐excellent yields. Standard reductive amination occurs at the oxo moiety as well, but the reaction was in most cases not selective and furnished the expected amine mixed with 3‐(1,3‐dithian‐2‐yl)‐1,1‐diethoxypropan‐2‐ol. The conversion of the diethyl acetal moiety to an aldehyde group is generally an efficient transformation, but some aldehydes are unstable, making the deprotection useless. If the acetal contains a tertiary alcohol or a benzyloxy moiety, however, stable products are formed in good yields. Attempts to convert the 1,3‐dithiane substituent into an aldehyde group without concomitant decomposition of the product were totally unsuccessful. The chemical potential of this moiety, therefore, has to be utilized at an earlier stage and under different conditions.