3 research outputs found
HPLC–NMR Revisited: Using Time-Slice High-Performance Liquid Chromatography–Solid-Phase Extraction–Nuclear Magnetic Resonance with Database-Assisted Dereplication
Time-based trapping of chromatographically
separated compounds
onto solid-phase extraction (SPE) cartridges and subsequent elution
to NMR tubes was done to emulate the function of HPLC–NMR for
dereplication purposes. Sufficient mass sensitivity was obtained by
use of a state-of-the-art HPLC–SPE–NMR system with a
cryogenically cooled probe head, designed for 1.7 mm NMR tubes. The
resulting <sup>1</sup>H NMR spectra (600 MHz) were evaluated against
a database of previously acquired and prepared spectra. The in-house-developed
matching algorithm, based on partitioning of the spectra and allowing
for changes in the chemical shifts, is described. Two mixtures of
natural products were used to test the approach: an extract of Carthamus oxyacantha (wild safflower), containing
an array of spiro compounds, and an extract of the endophytic fungus Penicillum namyslowski, containing griseofulvin and
analogues. The database matching of the resulting spectra positively
identified expected compounds, while the number of false positives
was few and easily recognized
Combined Use of High-Resolution α‑Glucosidase Inhibition Profiling and High-Performance Liquid Chromatography–High-Resolution Mass Spectrometry–Solid-Phase Extraction–Nuclear Magnetic Resonance Spectroscopy for Investigation of Antidiabetic Principles in Crude Plant Extracts
Type 2 diabetes is a metabolic disorder
affecting millions of people
worldwide, and new drug leads or functional foods containing selective
α-glucosidase inhibitors are needed. Crude extract of 24 plants
were assessed for α-glucosidase inhibitory activity. Methanol
extracts of Cinnamomum zeylanicum bark, Rheum rhabarbarum peel, and Rheum
palmatum root and ethyl acetate extracts of C. zeylanicum bark, Allium ascalonicum peel, and R. palmatum root showed
IC<sub>50</sub> values below 20 μg/mL. Subsequently, high-resolution
α-glucosidase profiling was used in combination with high-performance
liquid chromatography–high-resolution mass spectrometry–solid-phase
extraction–nuclear magnetic resonance spectroscopy for identification
of metabolites responsible for the α-glucosidase inhibitory
activity. Quercetin (<b>1</b>) and its dimer (<b>2</b>), trimer (<b>3</b>), and tetramer (<b>4</b>) were identified
as main α-glucosidase inhibitors in A. ascalonicum peel, whereas (<i>E</i>)-piceatannol 3′-<i>O</i>-β-d-glucopyranoside (<b>5</b>), (<i>E</i>)-rhapontigenin 3′-<i>O</i>-β-d-glucopyranoside (<b>6</b>), (<i>E</i>)-piceatannol
(<b>8</b>), and emodin (<b>12</b>) were identified as
main α-glucosidase inhibitors in R. palmatum root
High-Resolution Screening Combined with HPLC-HRMS-SPE-NMR for Identification of Fungal Plasma Membrane H<sup>+</sup>‑ATPase Inhibitors from Plants
Crude
extracts of 33 plant species were assessed for fungal plasma
membrane (PM) H<sup>+</sup>-ATPase inhibition. This led to identification
of 18 extracts showing more than 95% inhibition at a concentration
of 7.5 mg/mL and/or a concentration-dependent activity profile. These
extracts were selected for semi-high-resolution fungal PM H<sup>+</sup>-ATPase inhibition screening, and, on the basis of these results, Haplocoelum foliolosum (Hiern) Bullock and Sauvagesia erecta L. were selected for investigation
by high-resolution fungal PM H<sup>+</sup>-ATPase inhibition screening.
Structural analysis performed by high-performance liquid chromatography-high-resolution
mass spectrometry-solid-phase extraction-nuclear magnetic resonance
spectroscopy (HPLC-HRMS-SPE-NMR) led to identification of chebulagic
acid (<b>1</b>) and tellimagrandin II (<b>2</b>) from H. foliolosum. Preparative-scale isolation of the
two metabolites allowed determination of IC<sub>50</sub> values for
PM H<sup>+</sup>-ATPase, and growth inhibition of Saccharomyces
cerevisiae and Candida albicans. Chebulagic acid and tellimagrandin II are both potent inhibitors
of the PM H<sup>+</sup>-ATPase with inhibitory effect on the growth
of S. cerevisiae