¹H NMR screening of pharmacologically active substances in weight‐loss supplements being sold online

Abstract

Weight-loss or slimming food supplements may be adulterated with synthetic pharmaceuticals, such as anorectic, anxiolytic and antidepressant compounds, especially when sold over the internet. An NMR screening method to detect these pharmacologically active compounds in slimming products is introduced in this study. As a first step, we gathered NMR-related information ( chemical shifts, multiplicity ) both from the scientific literature and own theoretical spectra prediction for 53 substances, which are likely to be illegally present in weight-loss products. The experimental strategy consists of dissolving the samples in a proper solvent ( most commonly ethanol ) and manually comparing each observed chemical shift with table values and thus identifying possible adulteration. A compound is considered to be identified if all the compound's resonances were present with correct multiplicity ( finally confirmed by J-resolved 2D spectra ). The method has been introduced in routine practise in our institute and we have already detected sibutramine, caffeine and L-carnitine in slimming products. Furthermore, quantification can be conducted by simple integration of a target resonance in comparison with the internal reference standard ( e. g., TSP ), or by using standard solutions ( when available ). We believe that NMR is ideally suited to controlling dietary supplements as it provides qualitative and at least semi-quantitative information more rapidly ( measurement time of about 20 min ) than with any other currently available spectroscopic or chromatographic method. Future research regarding the automation of spectral processing and inclusion of non-targeted analysis is necessary.

Authentication of Garcinia fruits and food supplements using DNA barcoding and NMR spectroscopy

“…1 H NMR is useful for qualitative and quantitative analysis of constituents in medicinal plants and herbal products 24 . However, NMR has, so far, not received a wider application in the official food supplements testing and medicine control laboratories than other chromatographic methods, mostly because the NMR technique was judged to be complicated and instruments too expensive 25 . However, several improvements in instrumentation during the last decade have made NMR available for routine applications 25 .…”

“…However, NMR has, so far, not received a wider application in the official food supplements testing and medicine control laboratories than other chromatographic methods, mostly because the NMR technique was judged to be complicated and instruments too expensive 25 . However, several improvements in instrumentation during the last decade have made NMR available for routine applications 25 . In the future, a metabolomic approach using NMR would be useful for large-scale analysis of Garcinia food supplements and this study has shown that qNMR is a fast and sensitive enough method for the quantification of (−)-hydroxycitric acid content.…”

“…NMR spectroscopy is highly reproducible, robust and inherently quantitative without the need for prior chromatographic separation of multiple components. The technique has been used for detection, identification and quantitative determination of adulterants in weight loss food supplements 24 , 25 . Combining DNA barcoding with spectroscopic methods for authentication of herbal medicines increases the resolution in species identification and analysis of mixtures 19 .…”

The Use of Analytical Techniques to Detect Toxic Synthetic Drug, Sibutramine, Adulterated in Traditional Herbal Medicines

“…Figure 9: Mass fragmentation pattern and fragment compounds of the compound Sibutramine and its analogues. (Roh et al, 2011) Methods involving LC coupled with various detectors (usually MS), have the advantage of high sensitivity; however, they also have disadvantages of being laborious, time consuming and the fact that they are too selective and cannot provide global information in detecting a particular component, because compositions of drugs vary among different brands (Monakhova et al, 2012). These methods were also considered to have inadequate reliability for screening because herbal medicines contain a complex mixture of many components which may interfere with chromatographic and mass spectroscopic assays (Calahan et al, 2016).…”

Effect of Different Drying Methods on the Nutritional Value of Hibiscus sabdariffa Calyces as Revealed by NMR Metabolomics

“…NMR spectroscopy allows the simultaneous detection and quantification of compounds belonging to different chemical classes: sugars, organic and amino acids, flavonoids, alkaloids, terpenoids, and others. This method was applied to the classification and characterization of different medicinal plants, as well as to the detection of the adulteration of plant materials [ 16 , 17 , 18 , 19 ]. The objective of this study is to assess the differences in proximate and metabolic compositions of H. sabdariffa calyces using NMR metabolomics from plants collected in different locations in India and dried using the shade drying (SD) and tray drying (TD) techniques.…”