Resonant-Mie-scattering of aggregates of phosphomolybdate and papaverine for measuring activities and screening inhibitors of cyclic nucleotide phosphodiesterase isozymes

A resonant-light-scattering (RLS) method was proposed to quantify phosphate for screening inhibitors of isozymes of cyclic nucleotide phosphodiesterase (PDE). In acidified mixtures of phosphate, papaverine and molybdate, there were aggregates exhibiting micrometre sizes, no absorbance peaks over 360 nm but strong RLS peaks at 392 nm; Mie scattering thus accounted for the RLS signals. When papaverine was added before molybdate to acidified samples of phosphate, RLS signals at 392 nm were stable from 5 to 25 min since the addition of molybdate; after optimization, phosphate from 0.40 to 3.60 μM was quantifiable. This RLS method tolerated 60 mg L⁻¹ proteins besides common PDE inhibitors and dimethyl sulfoxide in acidified samples of phosphate; the integration of this RLS method with the coupled action of a phosphomonoesterase on PDE product was thus rational to measure PDE activities without the removal of proteins in samples. By quantifying activities of a truncated mutant of human PDE4B2 via this RLS method, Michaelis–Menten constant, inhibition constants of rolipram, papaverine and theophylline varied over three magnitudes and were consistent with those estimated by an improved malachite green assay of phosphate, respectively. Hence, this novel RLS method was promising for screening inhibitors of PDE isozymes.     

Study of Chiral Ionic Liquid as Stationary Phases for GC

Due to the synthetic flexibility and special enantioselectivity, chiral ionic liquids (CILs) have heightened interest and an increasing number of CILs has been designed and utilized. In this work, CIL named l-1-butyl-3-(2-propionic-1-ether) imidazolium bromide ([BAlaIM]Br) derived from natural amino acids was synthesized, with chiral center at cation moiety. Chiral stationary phases for gas chromatography were then prepared by mixing the CIL with polymeric ionic liquid ([PSOMIM][NTf₂], homemade) at different ratios (4:1, 2:1, and 1:1). The column efficiency was measured to be about 3,200 plates m^?1 (8 m × 0.25 mm i.d.) when the content of [BAlaIM]Br was 50 % (mass percent) in the mixed stationary phase. All columns were coated via the static coating method using 0.30 % (w/v) of stationary phases dissolved in methanol. The results showed that the CIL contributed to the selectivity of stationary phase toward positional isomers dichlorobenzenes, methylnaphthalenes and pinenes, etc. Meanwhile, [BAlaIM]Br showed better selectivity for enantiomers such as carvones, citronellals, limonenes and camphors. The interactions between chiral selector and enantiomers were also discussed.     

Development of a Sensitive Method for the Determination of 4‐(Methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanol in Human Urine Using Solid‐phase Extraction Combined with Ultrasound‐assisted Dispersive Liquid–liquid Microextraction and LC‐MS/MS Detection

An efficient and sensitive analytical method based on molecularly imprinted solid‐phase extraction (MISPE) and reverse‐phase ultrasound‐assisted dispersive liquid–liquid microextraction (USA‐DLLME) coupled with LC–MS/MS detection was developed and validated for the analysis of urinary 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanol (NNAL), a tobacco‐specific nitrosamine metabolite. The extraction performances of NNAL on three different solid‐phase extraction (SPE) sorbents including the hydrophilic‐lipophilic balanced sorbent HLB, the mixed mode cationic MCX sorbent and the molecularly imprinted polymers (MIP) sorbent were evaluated. Experimental results showed that the analyte was well retained with the highest extraction recovery and the optimum purification effect on MIP. Under the optimized conditions of MIP and USA‐DLLME, an enrichment factor of 23 was obtained. Good linearity relationship was obtained in the range of 5‐1200 pg/mL with a correlation coefficient of 0.9953. The limit of detection (LOD) was 0.35 pg/mL. The recoveries at three spiked levels ranged between 88.5% and 93.7%. Intra‐ and inter‐day relative standard deviations varied from 3.6% to 7.4% and from 5.4% to 9.7%, respectively. The developed method combing the advantages of MISPE and DLLME significantly improves the purification and enrichment of the analyte and can be used as an effective approach for the determination of ultra‐trace NNAL in complex biological matrices.     

(Δ)[Fe(II)(phen)3]2+ Filled in the Chiral Cavitiy Constituted by {(Δ)[Fe(III)(C2O4)3](NH42+)(DMF)(H2O)32−}n

A chiral coordination compound {(Δ)[Fe(II)(phen)₃][(Δ)Fe(III)(C₂O₄)₃](NH₄)(H₂O)₃(DMF)}_n (phen = 1,10‐phenanthroline), (DMF = N,N'‐Dimethylformamide), has been synthesized, and the structure has been revealed by infrared spectroscopy and X‐ray single‐crystal diffraction. The framework consists of two chiral subunits. One subunit (Δ)[(Fe(III)(C₂O₄)₃]^3? which as host anion forms a chiral porous three‐dimensional supermolecular network with lattice water, lattice DMF and lattice ammonium cation through hydrogen bonds. And then the other is Δ[Fe(II)(phen)₃]²⁺ which as guest cation fills in the chiral cavity located in the previously mentioned host porous network.     

Design,Synthesis, and Antifungal Activities of New β‐Methoxyacrylate Analogues

Strobilurins have become one of the most important classes of agricultural fungicides. To search for new strobilurin derivatives with high activity against resistant pathogens, a series of new β‐methoxyacrylate analogues containing substituted pyrimidine in the side chain with strobilurin pharmacophore were synthesized and their biological activities were tested. The compounds were confirmed and characterized by ¹H‐NMR, elemental analysis and mass spectroscopy. The bioassays indicated that most of the compounds 1 exhibited potent antifungal activities against Colletotrichum orbiculare, Botrytis cinerea Pers and Phytophthora capsici Leonian at a concentration of 50 μg mL^?1. Notably, compound 1b (R = 2,5‐dimethylphenyl) showed better antifungal activity against all the tested fungi than the commercial strobilurin fungicide azoxystrobin.     

Prenylated Benzene Metabolites from Melicope pteleifolia

Chemical investigation on the stem and root of Melicope pteleifolia afforded three new prenylated benzene metabolites as racemic mixtures, named pteleifolins A–C ( 1 – 3 , resp.). Their gross structures were elucidated on the basis of spectroscopic analysis, especially 2D‐NMR experiments. An enantiomer resolution of (±)‐ 1 using chiral HPLC was performed, and the absolute configuration of the enantiomers were determined to be (+)‐(S)‐ 1 and (?)‐(R)‐ 1 by means of circular‐dichroism analysis.     

One-Pot Synthesis of 1-Alkynylphosphonates

1-Alkynylphosphonates 3 are prepared in a one-pot procedure from diethyl phosphorochloridates 2 and alkynyllithiums 1, which are readily generated by the reaction of 1-alkynes with n-BuLi.     

New Cytotoxic Triterpenoids from the Aerial Parts of Euphorbia sieboldiana

Phytochemical investigation of the EtOH extract of Euphorbia sieboldiana led to the isolation of four new oleanane‐type triterpenoids, (1β,2α,3β,19β)‐1,2,3,19‐tetrahydroxyolean‐12‐en‐28‐oic acid, (1β,3β,19β)‐1,3,19‐trihydroxyolean‐12‐en‐28‐oic acid, (1β,2α,3β,16β,19β)‐1,2,3,16,19‐pentahydroxyolean‐12‐en‐28‐oic acid, and (1β,2α,3β,19β,23)‐1,2,3,19,23‐pentahydroxyolean‐12‐en‐28‐oic acid, along with 16 known compounds. Their structures were established by extensive 1D‐ and 2D‐NMR, as well as other spectral analyses. Biological evaluation of the four new triterpenoids revealed potent cytotoxic activities against HeLa and Hep‐G2 cells.     

Three New C19‐Diterpenoid Alkaloids from Aconitum forrestii

A further study of the alkaloid constituents of Aconitum forrestii led to the isolation of three new C₁₉‐diterpenoid alkaloids, named 14‐acetoxy‐8‐O‐methylsachaconitine ( 1 ), 14‐acetoxyscaconine ( 2 ), and 8‐O‐ethylcammaconine ( 3 ). Their structures were determined by UV, IR, and MS, 1D‐ and 2D‐NMR analyses.