132 research outputs found
High-Resolution Inhibition Profiling Combined with HPLC-HRMS-SPE-NMR for Identification of PTP1B Inhibitors from Vietnamese Plants
No full textIsolation and structure elucidation of cyclopeptide alkaloids from **Ziziphus nummularia** and **Ziziphus spina-christi** by HPLC-DAD-MS and HPLC-PDA-(HRMS)-SPE-NMR
No full textAbstract: Seven cyclopeptide alkaloids were isolated from the stem bark of Ziziphus nummularia and Ziziphus spina-christi. Three previously undescribed compounds were identified: nummularine-U, spinanine-B and spinanine-C, together with the known compounds mauritine-F, nummularine-D, nummularine-E and amphibine-D. For their purification either semi-preparative HPLC with DAD and ESIMS detection or HPLC-PDA-(HRMS)-SPE-NMR was applied, together with conventional separation methods. Their structures were elucidated by spectroscopic means
NMR-based Metabolomics and Hyphenated NMR Techniques: A Perfect Match in Natural Products Research
No full textNew Resistance-Correlated Saponins from the Insect-Resistant Crucifer <i>Barbarea vulgaris</i>
No full textIsolation and characterization of plant constituents responsible for insect resistance are of the utmost importance for better understanding of insect−host plant interactions, for selection and breeding of resistant plant varieties, and for development of natural insecticides to be used in future sustainable agriculture and food production. In this study, 3-O-cellobiosyl-cochalic acid (1), 3-O-cellobiosyl-gypsogenin (3), and 3-O-cellobiosyl-4-epihederagenin (4) were isolated from the glabrous type of Barbarea vulgaris var. arcuata exhibiting resistance to the flea beetle Phyllotreta nemorum. In addition to the new constituents, 3-O-cellobiosyl-hederagenin (2), a known insect repellant, was identified. The structures were established by one- and/or two-dimensional homo- and heteronuclear NMR experiments acquired at 800 MHz and by fragmentation and high-resolution mass spectrometric analysis. Compounds 1, 3, and 4 are glycosides of cochalic acid, gypsogenin, and 4-epihederagenin, respectively, none of which have previously been identified in Brassicaceae. Compounds 3 and 4 have both recently been targeted as unidentified constituents exhibiting correlation with P. nemorum resistance, but this is the first report of their structures
Efficient and versatile COMU-mediated solid-phase submonomer synthesis of arylopeptoids (oligomeric N-substituted aminomethyl benzamides)
No full textInternational audienceThe development of a highly efficient methodology for solid-phase synthesis of para- and meta-arylopeptoids (oligomeric N-substituted aminomethyl benzamides) with free acids or free amides at the C-terminus is described. The arylopeptoids were synthesised by means of a convenient submonomer protocol in which the arylopeptoid residues were created in an iterative manner on the growing chain using an acylation-substitution cycle. The uronium salt COMU was found to be the most efficient reagent for ensuring fast and clean couplings of the benzoic acid building block
Expedient Solution-Phase Synthesis and NMR Studies of Arylopeptoids
No full textInternational audienceThe development of a highly convenient and efficient protocol for iterative solution-phase synthesis of shorter oligomers of para- and meta-arylopeptoids is described. Peptide coupling methods for accessing longer oligomers were studied: use of the new coupling reagent COMU was found to be the most efficient for creation of the tertiary benzamide bonds. The cis/trans isomerism of arylopeptoid backbones was studied by NMR and was found to be highly dependent on the nature of the side chains. Increasing bulkiness of theside chains favored the cis amide bond conformation; arylopeptoids possessing tert-butyl side chains contained exclusively cis amide bond
Coupling of a high-resolution monoamine oxidase-A inhibitor assay and HPLC-SPE-NMR for advanced bioactivity-profiling of plant extracts
No full textInhibition of α-glucosidase activity by selected edible seaweeds and fucoxanthin
No full textA 5 mg/mL solution of water, methanol and acetone extracts of seaweeds were used for α-glucosidase inhibition assay hyphenated with high performance liquid chromatography-mass spectrometry (HPLC-HRMS). The results showed acetone extracts of Undaria pinnatifida has the strongest inhibitory effect against α-glucosidase activity with IC50 0.08 ± 0.002 mg/mL. The active compound found in Undaria pinnatifida was identified as fucoxanthin. Analytical standard sample of fucoxanthin significantly inhibited α-glucosidase with IC50 value 0.047 ± 0.001 mg/mL. An inhibition kinetics study indicates that fucoxanthin is showing mixed-type inhibition. These results suggest that Undaria pinnatifida has a potential to inhibit α-glucosidase and may be used as a bioactive food ingredient for glycaemic control.</p
Data-dependent acquisition-mass spectrometry guided isolation of new benzoxazinoids from the roots of <i>Acanthus mollis</i> L.
No full textBenzoxazinoids (BXs) are phytochemicals that exert plant-protecting, allelopathic, and human-health-promoting effects. Here, we present a data-dependent acquisition-mass spectrometry based method to locate and annotate BX-conjugates in different fractions of a plant extract. This allows for isolation of compounds present in a much smaller percentage than common for natural products yet still sufficient for subsequent identification through nuclear magnetic resonance (NMR) spectroscopy. The presence of BXs has been extensively studied in monocotyledons, whereas only a limited number of studies have focused on dicotyledons. Here, the presence of hitherto unknown BXs in the roots of the dicotyledonous plant Acanthus mollis L. has been determined. Two acetylated glycosylated BXs, compound 1 2-(6-acetyl-β-D-glucopyranoside)-2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one) and compound 2 (-2-(6-acetyl-β-D-glucopyranoside)-2-hydroxy-2H-1,4-benzoxazin-3(4H)-one), and a BX-derived glucoside carbamate olide, compound 3 (2-hydroxy-6-(2-deoxy-β-D-glucopyranosyloxy)-phenyl) carbamic acid 2′-olide), were isolated and identified by NMR. These previously unknown BXs may contribute to the reported biological activities of A. mollis L
Application of rotated PCA models to facilitate interpretation of metabolite profiles:commercial preparations of St. John's wort
No full text- …
