Unfolding the structural complexity of natural products using alternative NMR methods

NMR spectroscopy is a well-established analytical platform with many applications in natural products. Aside from its conventional use in structure elucidation or quantification, less common NMR approaches such as pure shift (PSYCHE), J-Resolved (JRES) or Diffusion-Ordered Spectroscopy (DOSY) could provide a different angle in the analysis of complex natural matrices. Therefore, the current work is aimed to exploit an NMR-based platform and alternative tools in the study of natural products. As a case study, different plant resins were analysed. Initially, two-dimensional (2D) and pseudo-2D spectra, among them JRES and PSYCHE, were used for chemical characterisation. Additionally, taking advantage of variations in the molecular translational diffusion of different compound classes, DOSY was successfully implemented for the first time in Chios Mastic Gum (CMG), managing to separate its polymer (poly-β-myrcene) and triterpenoids from other chemical categories. This approach could be applied to different matrices comprising compounds with various diffusion coefficients. Moreover, Statistical Total Correlation Spectroscopy (STOCSY), a novel tool in the study of natural products, was employed in an NMR-based metabolite profiling approach for the authenticity assessment of CMG [1] [2] [3]. Through STOCSY, peaks’ correlations across ¹H NMR spectra were highlighted, aiding in the structure elucidation of tentative biomarkers. To conclude, alternative NMR approaches could have an extensive application and provide simplicity in rather complex natural media.

Funding ERDF, “RESEARCH–CREATE-INNOVATE”, Hyper-Mastic (project code: Τ2ΕΔΚ-00547).

Conflict of Interest

The authors declare no conflict of interest.

• References

• 1 Beteinakis S, Papachristodoulou A, Kolb P, Roesch P, Schwarzinger S, Mikros E, Halabalaki M.. NMR-based metabolite profiling and application of STOCSY towards the quality and authentication assessment of European EVOOs. Molecules 2023; 28: 1738
• 2 Lemus Ringele GB, Beteinakis S, Papachristodoulou A, Axiotis E, Mikros E, Halabalaki M.. NMR Metabolite Profiling in the Quality and Authentication Assessment of Greek Honey-Exploitation of STOCSY for Markers ldentification. Foods 2022; 11: 2853
• 3 Beteinakis S, Papachristodoulou A, Gogou G, Katsikis S, Mikros E, Halabalaki M.. NMR-Based Metabolic Profiling of Edible Olives – Determination of Quality Parameters. Molecules 2020; 25: 3339

Publication History

Article published online:
16 November 2023