ABSTRACT
INTRODUCTION: Nuclear magnetic resonance (NMR) spectroscopy is increasingly employed in the quantitative analysis and quality control (QC) of natural products (NP) including botanical dietary supplements (BDS). The establishment of QC protocols based on quantitative (1) H NMR (qHNMR) requires method validation. OBJECTIVE: Develop and validate a generic qHNMR method. Optimize acquisition and processing parameters, with specific attention to the requirements for the analysis of complex NP samples, including botanicals and purity assessment of NP isolates. METHODS: In order to establish the validated qHNMR method, samples containing two highly pure reference materials were used. The influence of acquisition and processing parameters on the method validation was examined, and general aspects of method validation of qHNMR methods discussed. Subsequently, the method established was applied to the analysis of two NP samples: a purified reference compound and a crude mixture. RESULTS: The accuracy and precision of qHNMR using internal or external calibration were compared, using a validated method suitable for complex samples. The impact of post-acquisition processing on method validation was examined using three software packages: TopSpin, Mnova and NUTS. The dynamic range of the qHNMR method developed was 5000:1 with a limit of detection (LOD) of better than 10 µm. The limit of quantification (LOQ) depends on the desired level of accuracy and experiment time spent. CONCLUSION: This study revealed that acquisition parameters, processing parameters and processing software all contribute to qHNMR method validation. A validated method with a high dynamic range and general workflow for qHNMR analysis of NP is proposed.
Subject(s)
Biological Products/chemistry , Ginkgolides/analysis , Nuclear Magnetic Resonance, Biomolecular/methods , Ginkgolides/chemistry , Lactones , Limit of Detection , Nuclear Magnetic Resonance, Biomolecular/instrumentation , Reproducibility of ResultsABSTRACT
Botanical dietary supplements and herbal remedies are widely used for health promotion and disease prevention. Due to the high chemical complexity of these natural products, it is essential to develop new analytical strategies to guarantee their quality and consistency. In particular, the precise characterization of multiple botanical markers remains a challenge. This study demonstrates how a combination of computer-aided spectral analysis and 1D quantitative ¹H NMR spectroscopy (qHNMR) generates the analytical foundation for innovative means of simultaneously identifying and quantifying botanical markers in complex mixtures. First, comprehensive ¹H NMR profiles (fingerprints) of selected botanical markers were generated via ¹H iterative full spin analysis (HiFSA) with PERCH. Next, the ¹H fingerprints were used to assign specific ¹H resonances in the NMR spectra of reference materials, enriched fractions, and crude extracts of Ginkgo biloba leaves. These ¹H fingerprints were then used to verify the assignments by 2D NMR. Subsequently, a complete purity and composition assessment by means of 1D qHNMR was conducted. As its major strengths, this tandem approach enables the simultaneous quantification of multiple constituents without the need for identical reference materials, the semiquantitative determination of particular subclasses of components, and the detection of impurities and adulterants.
Subject(s)
Biological Products/chemistry , Ginkgo biloba/chemistry , Nuclear Magnetic Resonance, Biomolecular/methods , Humans , Molecular Structure , Plant Leaves/chemistry , Quality ControlABSTRACT
Seven new C-secosteroids were isolated from the gorgonian Tripalea clavaria collected from the South Atlantic. These compounds have a Delta(5), 9,11-secosteroid nucleus together with a 22S hydroxyl group. The absolute configuration of the 22-hydroxyl group was determined with the help of COSY spectra of the Mosher esters of the compounds.
