Matrix free LDI-HRMS combined with MixONat assisted 13C-NMR dereplication: A chemometric approach to identify bioactive natural products from crude extracts

Natural Products (NPs) are known for a wide range of interesting biological effects [1]. Avoiding the repetitive isolation of previously described NPs and time-consuming bioassay guided fractionation strategies, the early-on identification of active metabolites from complex mixture has become a key element of NPs research. Merging chemical profiling with biological data, chemometrics [2] represent a cornerstone of this strategy. In the process, Ultra High-Performance Chromatography (UPLC) coupled with High Resolution Mass Spectrometry (HRMS) is considered as method of first choice for data acquisition. Despite its indubitable assets, UPLC-HRMS may nevertheless encounter certain limitations linked to solvent limitation, ionizability of analytes and the differentiation of (stereo)isomers. Addressing these issues, matrix free laser desorption ionization-HRMS (LDI-HRMS) [3] assisted by 13C NMR dereplication (MixONat) [4] may provide alternative methodological approaches. As a working example, a holistic chemometric approach was applied using UPLC-qTOF versus LDI-HRMS assisted by 13C NMR for the identification of anti-AGEs NPs (ability to prevent the formation of advanced glycation end products [5]) from Garcinia parvifolia bark extracts.

The chemometric analyses permitted to highlight several markers as potentially active. While both, UPLC and LDI-MS, facilitated the detection of the same active markers into the PLS (loadings plot), MixONat confirmed the presence of rubraxanthone (1), isocowanol (2) and parvixanthone G (3). Subsequently, the anti-AGEs assay revealed a very good activity for these three compounds. Overall, our results showed that a joint LDI-HRMS and 13C NMR approach ([Fig. 1]) provides a simple and efficient strategy for the chemical characterization of major active constituents in extracts.

Fig. 1 

• References

• 1 Newman DJ. et al. Natural Products as Sources of New Drugs over the Nearly Four Decades from 01/1981 to 09/2019. J Nat Prod 2020; 83: 770-803
• 2 Kellogg JJ. et al. Biochemometrics for Natural Products Research: Comparison of Data Analysis Approaches and Application to Identification of Bioactive Compounds. J Nat Prod 2016; 79: 376-386
• 3 Schinkovitz A. et al. Matrix-Free Laser Desorption Ionization Mass Spectrometry as a Functional Tool for the Analysis and Differentiation of Complex Phenolic Mixtures in Propolis: A New Approach to Quality Control. Anal Bioanal Chem 2018; 410: 6187-6195
• 4 Bruguière A. et al. 13C NMR Dereplication Using MixONat Software: A Practical Guide to Decipher Natural Products Mixtures. Planta Med 2021; 87: 1061-1068 https://sourceforge.net/projects/mixonat/
• 5 Derbré S. et al. Automating a 96-Well Microtiter Plate Assay for Identification of AGEs Inhibitors or Inducers: Application to the Screening of a Small Natural Compounds Library. Anal Bioanal Chem 2010; 398: 1747-1758

Publication History

Article published online:
12 December 2022