Identification of Major and Minor Constituents of Harpagophytum procumbens (Devil's Claw) Using HPLC-SPE-NMR and HPLC-ESIMS/APCIMS

Abstract

The HPLC-SPE-NMR technique, supported by HPLC-MS measurements, was used to determine structures of major as well as some minor constituents of ethanol and petroleum ether extracts of Harpagophytum procumbens (Devil's claw) roots. This method was also shown to be applicable for rapid and precise on-line identification of secondary metabolites present in commercial herbal products of H. procumbens. A total of 15 compounds (1-14 and 17) were identified from the ethanol and petroleum ether extracts, including a novel Diels-Alder dimer 14. Optimization of the HPLC-SPE-NMR experiments included quantitative (1)H NMR measurements, determination of trapping and elution efficiency, effect of multiple trapping of analytes, use of various deuterated solvents for SPE cartridge elution, and effect of post-column dilution ratio of eluent with water. Linear accumulation of apolar and relatively polar analytes was demonstrated for at least 8-10 repeated trappings, resulting in greatly improved signal-to-noise ratios in NMR spectra and reduced acquisition times. Thus, the HPLC-SPE-NMR technique provides an efficient means of identification of multiple components of crude extracts. By allowing on-line generation of high-quality 2D NMR data without traditional purification of extract components, the HPLC-SPE-NMR methodology represents a paradigm shift in natural products research with respect to structure elucidation.

Evaluation of the phytochemical content, antioxidant activity and antimicrobial properties of mountain tea (Sideritis syriaca) decoction

“…In this study, acetonitrile-d 3 and methanol-d 4 were used to elute seven phenolic acids and seven flavonoids from GP cartridges, whereas only four compounds have been tested so far (Clarkson, Strk, Hansen, Smith, & Jaroszewski, 2006). The results showed that acetonitrile-d 3 was more suitable for the elution of phenolic acids than methanol-d 4 .…”

“…The effect of the multiple trapping processes. One of the main advantages of HPLC-SPE-NMR technique is its ability to accumulate analytes onto SPE cartridges, using the multiple trapping procedure, which allows structure elucidation of major peaks in shorter acquisition time (Clarkson et al, 2006;Miliauskas et al, 2006). In addition, the multiple trapping provides adequate amount of analytes to perform 2D NMR experiments, including relatively low sensitive experiments, e.g., NOESY and HMBC, as approximately 1-1.5 mg of analyte can be accumulated in a cartridge (Jaroszewski, 2005).…”

Perspectives of the Metabolic Engineering of Terpenoid Indole Alkaloids in Catharanthus roseus Hairy Roots

“…Recently, a new technology, highperformance liquid chromatography combined with solid-phase extraction and NMR spectroscopy (HPLC-SPE-NMR), has been applied to rapidly identify secondary metabolites in some plants. For example, the structures of a total of 15 compounds, some major as well as some minor constituents, of Harpagophytum procumbens (Devil's claw) extracts, have been determined by using this technique [81]. Although there are limits to the sensitivity of the HPLC-SPE-NMR technique, it still provides a rapid strategy to identify the metabolites in a complex plant extract.…”

Important roles of the hyphenated HPLC‐DAD‐MS‐SPE‐NMR technique in metabonomics

“…Clarkson and colleagues have optimized the HPLC-SPE-NMR experimental conditions and identified a total of 15 compounds from the ethanol and petroleum ether extracts of Harpagophytum procumbens (Devil's claw) roots. [36] Seger et al also found (E/Z) pairs of 6 -O-(p-coumaroyl)harpagide (6 -PCHG) and 8-O-(pcoumaroyl)-harpagide (8-PCHG) in the extracts of Harpagophytum procumbens, of which, 8-(Z)-PCHG, 6 -(Z)-and 6 -(E)-PCHG are newly discovered natural products. [37] The generation of structural information by the on-line HPLC-DAD-MS-SPE-NMR technique also facilitated the identification of unstable metabolites that might have been lost during traditional purification of extract components.…”