Herbal medicine products have been used for health-related purposes since ancient times, and their application is firmly anchored in all societies worldwide. Many people use herbal products for improvements in overall health, enhancement of cognitive or physical performance, increase in energy, weight loss, and reduction of pain. The US Food and Drug Administration categorizes herbal products as dietary supplements. For the past several years, many herbal products have been found to contain synthetic prescription drugs. Many methods have been reported to detect different substances, like phosphodiesterase type 5 enzyme (PDE-5) inhibitors, glucocorticoids, and sibutramine analogs. Most of them were developed to identify the analytes by searching the local library or online and were difficult to detect the unreported analogs. The blog titled “Which Compounds Are Really in Your Dietary Supplements,” mentioned the method developed and validated by Dr. Mastovska and colleagues, which help to identify the unknown. The strategy used by Dr. Mastovska was characteristic fragment filtering.
Using characteristic fragment filtering to ‘fish’ the unknown synthetic compound in herbal products is an available method for non-target screening, because the synthetic drugs and their analogs always have similar chemical structure and may have similar fragment ions. Fragment filtering has been used in identification of metabolites, the screening of unknown psychoactive drugs and the identification of the minor compounds in herbal products. This strategy can apply to different kinds of synthetic drugs and analogs that may be added into herbal products.
To establish characteristic fragment filtering, the following two steps must be taken. For each step, Thermo Fisher Scientific offers powerful tools to help to overcome the difficulties.
1) Acquire the MS/MS spectrum of representative standards and dig characteristic fragment ions.
Q Exactive Focus hybrid Quadrupole-Orbitrap Mass Spectrometer is developed for small molecule analysis. The advanced ability of Orbitrap was presented in this blog post. With excellent mass resolution, high sensitivity, outstanding instrument robustness, and consistent mass accuracy, confident quantitative and qualitative results can be achieved in a single platform. You can use full MS/data-dependent MS/MS scan mode or parallel reaction monitoring scan mode to get the precursors and fragments information of representative standards. MzVault software was designed for building local library. Customers can easily create and manage specialized accurate-mass based library with MS/MS information acquired using Q Exactive series products. With the specialized library, ions statistics can be processed to dig characteristic fragment ions. Even though reference standards are not available, you can get reliable MSn fragmentation spectrum from mzCloud mass spectral library, the world’s largest and most curated mass spectral library. The library includes particularly high-resolution and accurate-mass MSn fragmentation spectrum of more than ten thousands compounds, covering most of the reported synthetic drugs.
2) Use characteristic fragment filtering to find the suspected compound.
Structural elucidation via LC/MS is a time-consuming process of manual interpretation and requires a strong background in fragmentation pathways. Thermo Fisher Scientific offers Compound Discoverer software, and Mass Frontier software for the unknown screening. They can search mzCloud library online for free and can create automated software workflows for metabolite identification or structural elucidation. It can simplify your work considerably. Mass Frontier software features an enhanced fragment ion search (FISh) screening tool, which is a powerful tool for the screening of structurally similar compounds based on the characteristic fragment filtering. Mass Frontier software is enhanced with chemically intelligent tools that accelerate the interpretation of mass spectral data. The predictive fragmentation capabilities of the HighChem Fragmentation Library contain fragmentation mechanisms for small molecules collated from published literature, allowing users to quickly search thousands of entries. Containing an inclusion list of characteristic fragment ions, an automated workflow will be created by using the Fragments and Mechanisms, FISh, FISh Explanation, and Compare Spectra processing tools. The high-resolution accurate mass data are directly exported to the Mass Frontier software program and processed automatically according to the workflow.
The powerful tools help you to establish characteristic fragment filtering easier and better. Enjoy the fun of fishing and learn more from the following links:
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Single-Laboratory Validation Study of a Method for Screening and Identification of Phosphodiesterase Type 5 Inhibitors in Dietary Ingredients and Supplements Using Liquid Chromatography/Quadrupole-Orbital Ion Trap Mass Spectrometry: First Action