The use of natural materials to treat illness has a long history. Natural products and traditional Chinese medicines have been pursued across the world, often as a parallel course to other drug discovery endeavors. The complex nature of plant and animal extracts requires a metabolomic-style approach to determine the active constituents of a product.
These products often do not derive their activity from a single ingredient but from a balance of multiple components acting in concert. The study of variations components and therapeutic response to preparations from different regions, seasonal changes, and strains are all areas of interest as researchers try to understand the mechanism of action and how to improve upon these interesting therapeutics.
Mass spectrometers based on Orbitrap™ technology aid in this research by providing high-resolution, accurate-mass data for the analysis of complex organic extracts.
Plant or animal samples must be extracted for study. Representative extraction of the sample provides a more complete understanding of the components within. These samples are often complex by their very nature and require separation by high performance chromatographic techniques before being introduced to the mass spectrometer.In addition, to accurately determine the components of interest, biological and technical replicates are commonly prepared to help account for biological and preparation variability.
Research-based natural products efforts often require the identification of many components within an extract.Sample preparation of the extract must be representative of all the components to assure that the active materials are not missed. Plant samples are often ground in liquid nitrogen to create a powder that can be extracted with a strong solvent.These initial samples may be further processed by (U)HPLC fractionation prior to analysis by mass spectrometry, which allows for more separation of components for identification in the subsequent (U)HPLC analysis.
Mass spectrometry is the idea tool for profiling and identifying components in complex natural medicines. LC-ESI-MS is capable of ionizing and analyzing a broad chemical space and is often the starting point for most work.A typical plant extract may contain well over 500 components, any combination of which may contribute to the efficacy. This complexity requires separation in time by (U)HPLC; however, even the most aggressive gradients will lead to coelution. Separation in mass, especially by high resolution instruments like the Thermo Scientific Q Exactive MS™, provide additional separation power. This separation can be used to perform differential analysis on samples from different crops, regions, or strains to identify differences between them.
The ability to resolve and detect the components is only part of the problem; acquiring data sufficient to identify them is key. The high ion transmission and high scan speed of the Q Exactive MS acquires HCD fragmentation on multiple compounds within a run with high quality, allowing for mass and fragment based library searching.
The analysis of traditional Chinese medicines and natural products research can often mirror metabolomic research applications. Early research applications often require identification of the components of interest in the source of the traditional medicine. Studies across samples of different strains, or from different regions with known differences in potency, can help to determine the components of interest. Differential analysis techniques and statistical analysis tools in SIEVE help to find the important components in our complex samples, while mass-based library searching can give us initial indications of potential identities.
When components of interest are identified, determination of their structure is often required. In addition to mass-based library searching of public or proprietary libraries, fragmentation interpretation combined with accurate mass elemental composition determination can help to elucidate the structure. Tools available in Thermo Scientific Mass Frontier software enable fragmentation analysis and annotation and allow for the creation of compound libraries of identified structures that can be used for fragment-based compound searching.
All stages of traditional Chinese medicine and natural product research can benefit from the robust mass accuracy and high resolution of mass spectrometers powered by Orbitrap™ technology.