Isolation and identification of two new flavanones and a chalcone from Citrus kinokuni

Two new flavanones and one chalcone were isolated from the peel of Citrus kinokuni Hort. ex Tanaka and identified as (2S)-5,6,7,8,4'-pentamethoxyflavanone (1), (2S)-5,6,7,3',4'-pentamethoxyflavanone (2) and 2'-hydroxy-3,4,3',4',6'-pentamethoxychalcone (3). The structures of new compounds were elucidated by spectroscopic analysis.     

Isolation and structural elucidation of a novel homogenous polysaccharide from Tricholoma matsutake

A crude polysaccharide possessing antitumour, radiation-resistant and anti-ageing attributes was extracted from Tricholoma matsutake by water extraction and alcohol precipitation. From this crude polysaccharide, a homogeneous polysaccharide, TMP-5II, was successfully purified by Sephacryl S-300 column chromatography. The average molecular weight (M_w) of TMP-5II was 15.76 kDa. Monosaccharide analysis indicated that the homogeneous polysaccharide contained four different residues: d-glucose, d-galactose, d-mannose and d-fucose. Attenuated total reflectance infrared spectroscopy revealed characteristics typical of carbohydrate polymers and a peak typical of a β-type glycosidic bond. TMP-5II was selected for structural characterisation by nuclear magnetic resonance (NMR) analysis. According to ¹H NMR, ¹³C NMR and two-dimensional-NMR analysis, TMP-5II contains two kinds of linkages, β and α, at a ratio of 4:1. Preliminary results indicated that the polysaccharide had (1-4)-beta-pyran glucose as the main chain, and a branched chain in the O-6 location with fucose (1-2) mannose (1-3)-alpha-pyran galactose.     

Identification and structural elucidation of steroidal saponins from the root of Paris polyphylla by HPLC-ESI-QTOF-MS/MS

The root of Paris polyphylla (RPP) is widely used as a traditional Chinese medicine for a long time due to the good properties of heat-clearing and detoxicating, detumescence, sedation, acesodyne and haemostasis. To clarify on the bioactive substances and ensure the safety in clinical medication, a feasible and accurate strategy was developed by applying the high-performance liquid chromatography coupled to electrospray ionisation and quadrupole time-of-flight-mass spectrometry (HPLC-ESI-QTOF-MS/MS). Separation was performed an Agilent poroshell 120 EC-C18 column (2.7 × 100 mm, i.d., 2.7 μm) with 0.1% formic acid aqueous solution and acetonitrile as the mobile phase under gradient conditions. Based on the proposed strategy, 30 constituents, mainly including steroidal saponins, were characterised or tentatively identified, 2 of which were the first to be reported as the potential new steroidal saponins in RPP. In conclusion, the HPLC-ESI-QTOF-MS/MS is a feasible and credible technique to separate and identify steroidal saponins from botanical extracts.     

Polystyrene fractionation by liquid chromatography and identification of the compounds by spectroscopy

Summary The fractionation of polystyrene materials including NBS polystyrene standards 705 and 706 was investigated by liquid adsorption chromatography. Identification of some of the individual components was achieved by infrared spectroscopy using solid pellets, micro internal reflectance techniques and computer-based background substraction methods. Ultraviolet spectroscopy was used as an additional means of identification. The advantages and disadvantages of these techniques are discussed.     

Isolation and structural elucidation of a polysaccharide with radiation-protective activity from Spirulina platensis

The structure of a radiation-protective sulfated polysaccharide, SP-APS, isolated from Spirulina platensis, was investigated by methylation analysis, partial acetolysis and 1H-NMR spec-troscopy. The repeating-unit of SP-APS as branched structures was elucidated.     

Advances in humeomics: Enhanced structural identification of humic molecules after size fractionation of a soil humic acid

We size fractionated a soil humic acid (HA) by preparative high performance size exclusion chromatography (HPSEC) and evaluated the analytical capacity of humeomics to isolate and identify humic molecular components in the separated size-fractions. HA and its three size-fractions were chemically fractionated to extract non-covalently bound organosoluble compounds (ORG1), weakly ester-bound organosoluble (ORG2) and hydrosoluble constituents (AQU2), strongly ester-bound organosoluble components (ORG3), and final unextractable residues (RES4). According to their solubility, the extracts were characterized by either GC–MS or on-line thermochemolysis/GC–MS techniques. The humeomic sequence showed that the analytical yields of identified compounds in either ORG or AQU extracts of size-fractions were invariably larger than for the unfractionated HA. This was attributed to a weaker conformational stability of humic suprastructures obtained by HPSEC fractionation, thereby enabling an improved separation and identification of single humic molecules. In line with the supramolecular understanding of humic substances, we found that hydrophobic compounds were mainly distributed in the largest size-fraction, while hydrophilic components were eluted in the smallest size-fraction. Furthermore, compounds with linear chains or stackable aromatic rings associated in regular structures were more abundant in the former fraction, whereas irregularly shaped compounds, that hindered association in larger size, were mostly found in the latter fraction. Thus the structural characteristics of single humic molecules determined their mutual association in humic suprastructures, as well as their conformational strength and shape. The lack of de novo synthesized macropolymers in the unfractionated soil humic matter was confirmed by the absence of RES4 fractions in the separated size-fractions. Our results indicate that humeomics capacity to reveal the complex molecular composition of humic suprastructures was significantly improved by subjecting humic matter to a preliminary HPSEC fractionation.     

Isolation and structural elucidation of a new sildenafil analogue from a functional coffee

A sildenafil analogue was detected in a functional coffee sample labelled to have male sexual performance enhancement effects. This analogue was isolated and purified by flash chromatography and preparative high-performance liquid chromatography. Its structure was elucidated using high-resolution mass spectrometry; electrospray ionization-tandem mass spectrometry; and nuclear magnetic resonance spectroscopy, ultraviolet spectroscopy, and infrared spectroscopy. Compared with sildenafil, instead of an N-methylpiperazinyl moiety, ring opening of the piperazine ring with the loss of a carbon atom resulted in a substituted benzenesulfonamide. The chemical name of this analogue is N-[2-(dimethylamino)ethyl]-4-ethoxy-3-(1-methyl-7-oxo-3-propyl-6,7-dihydro-1H-pyrazolo[4,3-d]pyrimidin-5-yl)benzenesulfonamide. It is named descarbonsildenafil because it has one less carbon atom when compared with sildenafil.     

The isolation and structural elucidation of three new biflavonoid glycosides from Lomatogonium carinthiacum

Three biflavonoid glycosides, named carinoside B, C and D (1, 2 and 3, respectively), were isolated from the n-BuOH crude extract of the aerial part of Lomatogonium carinthiacum (Wulfen) Rchb (L. carinthiacum). The structures of 1, 2 and 3 were elucidated by spectroscopic methods, including UV, IR, HR-ESI-MS and extensive 1D and 2D NMR techniques.     

Isolation and structural elucidation of novel antimicrobial compounds from maggots of Chrysomyis megacephala Fabricius

The excretions/secretions from the maggot of Chrysomyis megacephala Fabricius are traditionally used to treat serious infections in China. In this study, bioassay-guided fractionation led to the isolation of three novel antibacterial compounds (1–3), including important fluorinated compounds (3 and 5), together with other nine known compounds from 70% methanol extract of C. megacephala. The structures of the new compounds were elucidated by NMR spectroscopic analysis and high-resolution mass spectroscopy. The antibacterial activities of the isolated compounds were evaluated using agar disc diffusion method. New compounds 1 and 2 exhibited moderate activity against Bacillus subtilis with a minimum inhibitory concentration (MIC) of 250 μg mL^? 1. The most active compounds 3 and 5 displayed a broad spectrum of antimicrobial activity with an MIC of 125 μg mL^? 1 against G⁺ and G^?  bacteria. The structure of the above-mentioned novel compounds and their antimicrobial activities are herein reported for the first time from the natural product of insects.     

软珊瑚群柱虫中新的二萜化合物-群柱内酯萜的分离和结构测定

A new bicyclo[9.3.0]tetradecane diterpenoid (dolabellane) lactone named clavulactone (I) was isolated from soft coral qunzhuchong (Clavularia sp.). Its partial structure was determine by spectral anal. and hydrogenation reaction. X-ray anal. established the complete mol. structure of I and the relative configuration. Finally, according to the neg. Cotton effect of n畃* and CD band of a,b-unsatd. d-lactone at 252 nm, the absolute configuration was assigned.     

Isolation and structural elucidation of a novel rotenoid from the seeds of Clitoria fairchildiana

The seeds of Clitoria fairchildiana provided a new rotenoid, 6-hydroxy-2,3,9-trimethoxy-[1]benzopyrano[3,4-b][1]benzopyran-12(6H)-one. The structural elucidation was performed using detailed analyses of H- and 13C-NMR spectra including 2DNMR spectroscopic techniques (1H-13CHETCOR) and by comparison with spectrometric data from the literature. The anti-inflammatory activity was investigated using a capillary permeability assay.     

Isolation and structural elucidation of heliangolidin,a new sesquiterpene lactone from artemisia canariensis

A new heliangolide has been isolated from aerial parts of $\text{Artemisia canariensis}$, and identified as (6$\text{E}$,10$\text{Z}$)(3$\text{S}$,3a$\text{R}$,4$\text{S}$,lla$\text{R}$)-3a,5,8,11a--tetrahydro-4-acetoxy-3,6, 1O-trimethyl-2,9 (3$\text{H}$, 4$\text{H}$) -cyclodeca[b] furandione. The structural elucidation of the new compound, named heliangolidin, was carried out by spectral means (MS, IR, ¹H and ¹³C NMR, and two dimensional ¹H-¹³C chemical shift correlations) and X-ray diffraction analysis.     

Isolation and structural elucidation of 5-formyl-2,3-dihydroisocoumarin from Centaurium erythraea aerial parts

An isocoumarin was isolated from the aerial parts of Centauriwn erythraea Rafn. (Gentianaceae). Its structure was established by spectroscopic means as 5-formyl-2,3-dihydroisocoumarin.     

Electrochemical degradation of quercetin: Isolation and structural elucidation of the degradation products

This paper reports the first complete isolation, characterization and structural elucidation of 18 intermediates following the electrochemical oxidation of quercetin and provides a mechanism of reaction. Bulk electrolysis was employed to induce the oxidation of quercetin in ethanol–PBS buffered neutral solution (1:1, v/v, pH 7.40). Simultaneous UV–Vis, cyclic and differential pulse voltammetric studies indicated the formation of new products due to the induced electrochemical oxidation of quercetin. Preparative separation and the verification of the oxidized products were achieved using a combination of column chromatography, GC–MS and LC–MS–MS analyses. A possible mechanism for the degradation pathways of quercetin was proposed including an electrochemical step leading to the formation of semi-quinone, ortho-quinone and quinone methide, as well as a chemical step corresponding to the formation of complex degradation products of taxifolin, depside, small phenolic acids, quercetin–ethanol adduct, benzofuronone and dimer.     

Intracellular targets of cyclin-dependent kinase inhibitors: identification by affinity chromatography using immobilised inhibitors

BACKGROUND: Chemical inhibitors of cyclin-dependent kinases (CDKs) have great therapeutic potential against various proliferative and neurodegenerative disorders. Olomoucine, a 2,6,9-trisubstituted purine, has been optimized for activity against CDK1/cyclin B by combinatorial and medicinal chemistry efforts to yield the purvalanol inhibitors. Although many studies support the action of purvalanols against CDKs, the actual intracellular targets of 2,6, 9-trisubstituted purines remain unverified. RESULTS: To address this issue, purvalanol B (95. ) and an N6-methylated, CDK-inactive derivative (95M. ) were immobilized on an agarose matrix. Extracts from a diverse collection of cell types and organisms were screened for proteins binding purvalanol B. In addition to validating CDKs as intracellular targets, a variety of unexpected protein kinases were recovered from the 95. matrix. Casein kinase 1 (CK1) was identified as a principal 95. matrix binding protein in Plasmodium falciparum, Leishmania mexicana, Toxoplasma gondii and Trypanosoma cruzi. Purvalanol compounds also inhibit the proliferation of these parasites, suggesting that CK1 is a valuable target for further screening with 2,6,9-trisubstituted purine libraries. CONCLUSIONS: That a simple batchwise affinity chromatography approach using two purine derivatives facilitated isolation of a small set of highly purified kinases suggests that this could be a general method for identifying intracellular targets relevant to a particular class of ligands. This method allows a close correlation to be established between the pattern of proteins bound to a small family of related compounds and the pattern of cellular responses to these compounds.