Two new acylated iridoid glucosides from the aerial parts of Paederia scandens

Two new acylated iridoid glucosides were isolated from the aerial parts of Paederia scandens along with six known iridoid glucosides. The structures of two new compounds were elucidated as 6'-O-E-feruloylmonotropein (1) and 10-O-E-feruloylmonotropein (2) by spectroscopic methods.     

Simultaneous determination of trifolirhizin, (–)‐maackiain, (–)‐sophoranone,and 2‐(2,4‐dihydroxyphenyl)‐5,6‐methylenedioxybenzofuran from Sophora tonkinensis in rat plasma by liquid chromatography with tandem mass spectrometry and its application to a pharmacokinetic study

A new liquid chromatography with tandem mass spectrometry method was developed and validated for the simultaneous determination of trifolirhizin, (–)‐maackiain, (–)‐sophoranone, and 2‐(2,4‐dihydroxyphenyl)‐5,6‐methylenedioxybenzofuran from Sophora tonkinensis in rat plasma using chlorpropamide as an internal standard. Plasma samples (50 μL) were prepared using a simple deproteinization procedure with 150 μL of acetonitrile containing 100 ng/mL of chlorpropamide. Chromatographic separation was carried out on an Acclaim RSLC120 C₁₈ column (2.1 × 100 mm, 2.2 μm) using a gradient elution consisting of 7.5 mM ammonium acetate and acetonitrile containing 0.1% formic acid (0.4 mL/min flow rate, 7.0 min total run time). The detection and quantitation of all analytes were performed in selected reaction monitoring mode under both positive and negative electrospray ionization. This assay was linear over concentration ranges of 50–5000 ng/mL (trifolirhizin), 25–2500 ng/mL ((–)‐maackiain), 5–250 ng/mL ((–)‐sophoranone), and 1–250 ng/mL 2‐(2,4‐dihydroxyphenyl)‐5,6‐methylenedioxybenzofuran) with a lower limit of quantification of 50, 25, 5, and 1 ng/mL for trifolirhizin, (–)‐maackiain, (–)‐sophoranone, and 2‐(2,4‐dihydroxyphenyl)‐5,6‐methylenedioxybenzofuran, respectively. All the validation data, including the specificity, precision, accuracy, recovery, and stability conformed to the acceptance requirements. The results indicated that the developed method is sufficiently reliable for the pharmacokinetic study of the analytes following oral administration of Sophora tonkinensis extract in rats.     

New Pyrrole Alkaloids with Bulky N‐Alkyl Side Chains Containing Stereogenic Centers from Lycium chinense

Four new pyrrole alkaloids, methyl 2‐[2‐formyl‐5‐(methoxymethyl)‐1H‐pyrrol‐1‐yl]propanoate ( 1 ), methyl 2‐[2‐formyl‐5‐(methoxymethyl)‐1H‐pyrrol‐1‐yl]‐3‐(4‐hydroxyphenyl)propanoate ( 2 ), dimethyl 2‐[2‐formyl‐5‐(methoxymethyl)‐1H‐pyrrol‐1‐yl]butanedioate ( 3 ), and dimethyl 2‐[2‐formyl‐5‐(methoxymethyl)‐1H‐pyrrol‐1‐yl]pentanedioate ( 4 ), were isolated from the AcOEt extract of the fruits of Lycium chinense Miller (Solanaceae). The stereogenic center C(2) in the bulky N‐alkyl side chain in each of 1 – 4 seems to hold the H‐atoms of nearby CH₂ groups, CH₂(7′) and CH₂(3) (if R≠H), leading to two different chemical shifts in the ¹H‐NMR spectrum due to their diastereotopic characteristics. In the ¹H‐NMR data of each of 2 – 4 , the enhancement of H? C(2) signal was inhibited by the R group, probably due to steric hindrance, and its chemical shift was influenced by the anisotropy effect. The structures of 1 – 4 were elucidated by analysis of various spectroscopic data, including 1D‐ and 2D‐NMR.     

One step purification of flavanone glycosides from Poncirus trifoliata by centrifugal partition chromatography

Flavanone glycosides were successfully separated from the crude extract of Poncirus trifoliata by preparative centrifugal partition chromatography with a two-phase solvent system composed of ethyl acetate-acetonitrile-water (3:2:5, v/v/v). Naringin (50.0 mg), neoponcirin (16.8 mg), and poncirin (71.9 mg) were purified from the 524 mg crude extract in only one step. The purities of the isolated compounds were determined to be over 90% by HPLC analysis and their structures were elucidated by (1)H NMR, (13)C NMR, and ESI-MS.     

Ionic conduction properties of layer-type oxides NaxMx/2Ti1−x/2O2 (M=Ni, Co; 0.60≤x≤1.0)

Layer-type oxide Na_xM_x/2^IITi_1−x/2^IVO₂ (M=Co, Ni; 0.60≤x≤1.0) has been prepared by solid state reactions. In both series, two structural variants of type -NaFeO₂ (O3) and β-RbScO₂ (P2) have been obtained consecutively as x decreases with a borderline composition around x_c0.7. With the decrease of x, the ionic conductivity has been found to increase up to 8.4×10⁻² S cm⁻¹ at 770 K (Na_0.67Co_0.33Ti_0.67O₂). Compositions of P2 have been found to exhibit the conductivity values two to five times greater than those of O3, primarily due to the larger rectangular threshold available for the diffusion of Na⁺ ions. Such a structural effect has also been considered to depend on the polarizability of alkali ion. HT-XRD and ²³Na-NMR data of Na_0.67Co_0.33Ti_0.67O₂ strongly suggest that the diffusion of Na⁺ ion is deeply related with the local distortion of trigonal prismatic sites, leading to the change of activation energy around 430 K.     

High performance liquid chromatography-electrospray lonization MS-MS analysis ofForsythia koreana fruits, leaves, and stems. Enhancement of the efficiency of extraction of arctigenin by use of supercritical-fluid extraction

Summary A method involving high-performance liquid chromatography coupled with electrospray MS-MS has been developed for the analysis of the constituents of the fruits, leaves, and stems ofForsythia koreana. Ten compounds including caffeoyl glycosides and lignans could be separated and detected with good sensitivity. The MS-MS spectra obtained provided information about their structures, for example the sugar and aglycone moieties present. Supercritical-fluid extraction was also used to improve the efficiency of extraction of arctigenin, which has the highest anti-inflammatory activity of the compounds produced by this plant. Although carbon dioxide without any modifier extracted only 66% of that obtained by extraction with methanol, an 80:20 (v/v) carbon dioxide-methanol mixture greatly enhanced the extraction yield-to 110%.     

Preparative separation of dioscin derivatives from Dioscorea villosa by centrifugal partition chromatography coupled with evaporative light scattering detection

Dioscin derivatives from the Dioscorea villosa roots were isolated and purified by centrifugal partition chromatography coupled with evaporative light scattering detection. The two-phase solvent system composed of chloroform-methanol-isopropanol-water (7:6:1:4, v/v/v/v) was used to obtain prosapogenin A of dioscin (1, 11.1 mg), dioscin (2, 8.9 mg), deltonin (3, 29.2 mg) and diosgenin 3-O-[alpha-L-rhamnopyranosyl(1 --> 2)]-[beta-D-glucopyranosyl(1 --> 3)-beta-D-glucopyranosyl(1 --> 4)]-beta-D-glucopyranoside (4, 6.2 mg) from 300 mg of saponin-rich extract from the roots of D. villosa. The purities of 1, 2, 3 and 4 were determined to be 98.9, 97.4, 99.2 and 99.5%, respectively. Their chemical structures were determined by spectroscopic data of ESI-MS, 1H NMR and 13C NMR and comparing with those of previously reported values.     

Monolayer protected Au cluster (MPC)-bound Ru-carbene complex: synthesis and its catalytic activity in ring-closing olefin metathesis

Monolayer-protected gold cluster (Au-MPC)-bound Ru-carbene complex (MPC-7) has been synthesized and examined its catalytic activity in ring-closing olefin metathesis. The MPC-7 showed almost the same catalytic activity with that of simple molecules (Grubbs Ru-complex 1b and the thioacetate-functionalized Ru-complex 8) and reused several times.     

Trimethyl borate/magnesium halide complex-induced one-pot homologation reactions of isoquinoline with dialkyl-TMP-zincate

Novel one-pot homologation reactions of isoquinoline with lithium dialkyl-TMP-zincate⋅2MgBrCl/trimethyl borate are described. 1-Alkylisoquinolines (2, 3A, 4A, 5A, 6, and 7) and 1-alkyl-3,4-dihydroisoquinolines (3B, 4B, and 5B) are easily prepared under the presented reaction conditions. The role of the B(OMe)₃/MgBrCl complex is examined in these homologation reactions. The specific reaction mechanisms, including 1,2-migration of the alkyl ligands from 1-isoquinolylzincates, are proposed. The migratory aptitudes of ligands of 1-isoquinolylzincates are also discussed.