Plant growth inhibitory activity of azo- and azoxyformamides from Calvatia craniiformis and Lycoperdon hiemale

4-Methoxybenzene-1-ONN-azoxyformamide (1), 4-methoxybenzene-1-azoformamide (2), 4-hydroxyben-zene-1-azoformamide (3) and 4-hydroxybenzene-1-ONN-azoxyformamide (4) were isolated from the fruiting bodies of Calvatia craniiformis and Lycoperdon hiemale, respectively. Compounds 1 and 4 showed radicle growth inhibitory activities against the lettuce seedlings by more than 50% at 5.0 x 10(-1) mM, suggesting that the azoxy moiety contributes to the inhibitory activity. The plant growth inhibitory activities of 1, 2 and 4 against the barnyard millet seedlings were also measured.     

Molecular interactions between estrogen receptor and its ligand studied by the ab initio fragment molecular orbital method

The ab initio fragment molecular orbital calculations were performed for molecular interactions of the whole estrogen receptor (ER) ligand-binding domain with a natural ligand, 17beta-estradiol (EST). The interaction energies of the ligand at the residue level were calculated using HF and MP2 methods with several basis sets. The charge-transfer (CT) interactions were also analyzed based on configuration analysis for fragment interaction. Strong electrostatic interactions were observed between the EST and surrounding charged/polarized residues, Glu353, Arg394, His524, and Thr347. Weak electrostatic and significant van der Waals dispersion interactions were observed between the EST and the many surrounding hydrophobic residues. Together with the experimental interpretations, both interactions equally contributed to the total binding energies, and it was found that the inclusion of electron correlation was essential to obtain an appropriate picture of the interaction. The strongest interaction energy was observed between Glu353 and the EST, and the CT interactions from the lone-pair orbital of the carbonyl oxygen of Glu353 to the sigma(OmicronEta) orbital of the hydroxyl group of EST were found to be important. The CT interactions from the lone-pair orbital of EST to the sigma(NuEta) of Arg394 and from the lone-pair orbital of EST to the sigma(NuEta) of His524 were also observed. These CT interactions occurred through the hydrogen-bond networks between the ER and EST. Therefore, electron donations from the ER to the EST and electron back-donations from EST to the ER were characteristic of ER-ligand binding. Our approach provides a powerful tool to understanding detailed molecular interactions at the quantum mechanical level.     

Chemical constituents of Ligularia virgaurea and its diversity in southwestern Sichuan of China

Chemical constituents of root extract and the nucleotide sequences of the atpB-rbcL intergenic region and the internal transcribed spacers (ITSs) of the ribosomal RNA gene were studied for Ligularia virgaurea var. virgaurea collected in southwestern Sichuan Province of China. Eleven samples were collected. Four of them were found to contain four new furanoeremophilanes, virgaurenones A-D, as well as a new eremophilanolide, virgaurenolide A. The other samples contained different furanoeremophilanes and their derivatives including nor-type of compounds, two of which were new. Diversity was found to be present in the nucleotide sequences as well. The chemical composition was found to be correlated with the ITS variation but not with the geographic distribution of the samples.     

Micro-organic ion-associate phase extraction via in situ fresh phase formation for the preconcentration and determination of di(2-ethylhexyl)phthalate in river water by HPLC.

A high-enrichment method was proposed for the HPLC determination of trace di(2-ethylhexyl)phthalate (DEHP) in environmental water. A micro-organic ion-associate phase (IAP) was formed in situ from an aqueous sample by adding 4-trifluoromethylanilinium ion and dodecylbenzenesulfonate ions. Centrifugation of the solution led to the isolation of a liquid organic phase containing DEHP at the bottom of the centrifuge tube. The volume of the phase formed was less than 30 microL. DEHP was extracted into the IAP quantitatively during phase formation. After discarding the aqueous phase, the ion associate was dissolved with 50 microL of 2-methoxyethanol, and DEHP in the concentrate was determined by HPLC with an ultra-violet (UV) diode-array detector. DEHP in the concentrations range from 0.8 to 78 microg L(-1) was determined with good precision. The recovery tests for DEHP added to some river water were satisfactory. The detection limit of DEHP, defined as 3-times the standard deviation of the blank signals, was 0.07 microg L(-1) (n = 3). The present method is very simple, and was applied to the determination of DEHP in the river water samples collected around Toyama City, Japan.     

Sequence‐Specific DNA Alkylation Targeting for Kras Codon 13 Mutation by Pyrrole–Imidazole Polyamide seco‐CBI Conjugates

Hairpin N‐methylpyrrole‐N‐methylimidazole polyamide seco‐CBI conjugates 2 – 6 were designed for synthesis by Fmoc solid‐phase synthesis, and their DNA‐alkylating activities against the Kras codon 13 mutation were compared by high‐resolution denaturing gel electrophoresis with 225 base pair (bp) DNA fragments. Conjugate 5 had high reactivity towards the Kras codon 13 mutation site, with alkylation occurring at the A of the sequence 5′‐ACGTCACC A ‐3′ (site 2), including minor 1 bp‐mismatch alkylation against wild type 5′‐ACG C CACC A ‐3′ (site 3). Conjugate 6 , which differs from conjugate 5 by exchanging one Py unit with a β unit, showed high selectivity but only weakly alkylated the A of 5′‐ACGTCACC A ‐3′ (site 2). The hairpin polyamide seco‐CBI conjugate 5 thus alkylates according to Dervan′s pairing rule with the pairing recognition which β/β pair targets T–A and A–T pairs. SPR and a computer‐minimized model suggest that 5 binds to the target sequence with high affinity in a hairpin conformation, allowing for efficient DNA alkylation.     

Highly hydrophilic and nonionic poly(2-vinyloxazoline)-grafted silica: a novel organic phase for high-selectivity hydrophilic interaction chromatography

A new hydrophilic and nonionic poly(2-vinyloxazoline)-grafted silica (Sil-VOX _n ) phase was synthesized and applied for the separation of nucleosides and nucleobases in hydrophilic interaction chromatography (HILIC). Polymerization and immobilization onto silica were confirmed by using characterization techniques including ¹H NMR spectroscopy, elemental analysis, and diffuse reflectance infrared Fourier transform spectroscopy. The hydrophilicity or wettability of Sil-VOX _n was observed by measuring the contact angle (59.9°). The chromatographic results were compared with those obtained with a conventional HILIC silica column. The Sil-VOX _n phase showed much better separation of polar test analytes than the silica column, and the elution order was different. Differences in selectivity between these two columns indicate that the stationary phase cannot function merely as an inert support for a water layer into which the solutes are partitioned from the bulk mobile phase. To elucidate the interaction mechanism, the separation of dihydroxybenzene isomers was performed on both columns in normal-phase liquid chromatography. Sil-VOX _n was very sensitive to the dipole moments of the positional isomers of polycyclic aromatic compounds in normal-phase liquid chromatography. The interaction mechanism for Sil-VOX _n in HILIC separation is also described.

Synthesis of (S,S)-1,2-Bis(3,5-DI-Tert-Butylphenyl)Ethane-1,2-Diol

The synthesis of (S,S)-1,2-bis(3,5-di-tert-butylphenyl)ethane-1,2-diol (98.6% ee), which should be useful as a chiral ligand of catalysts in asymmetric inductions, is described.     

Scandium Triflate–Promoted Addition of Organozinc Reagents to Benzaldiminetricarbonylchromium Derivatives

The reaction of benzaldiminetricarbonylchromium derivatives with organozinc reagents in the presence of scandium triflate afforded a single diastereomer of the corresponding amine complex exclusively. Even in the case of benzaldiminetricarbonylchromium having an m‐substituent of the aromatic ring, one diastereomer was obtained using the o‐TMS‐protected chromium complex. The TMS group and the chromium moiety were easily removed and the benzyl group was deprotected using HOOH and Pd to afford the corresponding amine.     

Fragmentation at sp2 carbon atoms in fragment molecular orbital method

In the fragment molecular orbital (FMO) method, a given molecular system is usually fragmented at sp³ carbon atoms. However, fragmentation at different sites sometimes becomes necessary. Hence, we propose fragmentation at sp² carbon atoms in the FMO method. Projection operators are constructed using sp² local orbitals. To maintain practical accuracy, it is essential to consider the three-body effect. In order to suppress the corresponding increase of computational cost, we propose approximate models considering local trimers. Numerical verification shows that the present models are as accurate as or better than the standard FMO2 method in total energy with fragmentation at sp³ carbon atoms.     

Retentivity and enantioselectivity of uniformly-sized molecularly imprinted polymers for (S)-nilvadipine in aqueous and non-aqueous mobile phases.

Uniformly-sized molecularly imprinted polymers (MIPs) for (S)-nilvadipine have been prepared by a multi-step swelling and polymerization method using methacrylic acid or 4-vinylpyridine (4-VPY) as a functional monomer, ethylene glycol dimethacrylate (EDMA) as a cross-linker, and toluene, chloroform, cyclohexanol or phenylacetonitrile as a porogen. The chiral recognition abilities of the MIPs for nilvadipine were evaluated using aqueous and non-aqueous mobile phases. Among the MIPs, the (S)-nilvadipine-imprinted 4-VPY-co-EDMA polymers prepared using toluene as a porogen showed the highest recognition ability for nilvadipine in both aqueous and non-aqueous mobile phases. In addition to molecular shape recognition, hydrogen-bonding interactions of the NH proton of nilvadipine with a pyridyl group of the (S)-nilvadipine-imprinted 4-VPY-co-EDMA polymers could play an important role in the retention and chiral recognition of nilvadipine in aqueous and non-aqueous mobile phases. Furthermore, the MIP for (S)-nilvadipine gave the highest molecular recognition ability when a porogenic solvent during polymerization was used as the mobile phase modifier.