Comparative 1H NMR metabolomics analysis of fresh pelagic sargassum reveals biochemical changes caused by under cryogenic and non-cryogenic sample transportations

• Published in: Regional studies in marine science 2025-01, Vol.81, Article 103955
• Main Authors: Peniche‑Pavía, Héctor A., Rosado‑Espinosa, Luis A., Collí‑Dulá, Reyna Cristina
• Format: Article
• Language: English
• Subjects: Chemometrics; Degradation; FTIR; Mannitol; Multivariate analysis; NMR; Phaeophyceae; Sargassum
• ISSN: 2352-4855; 2352-4855
• DOI: 10.1016/j.rsma.2024.103955

Sargassum biomass is known as a versatile raw material for good manufacturing. However, its quality must be evaluated before use or transformation. Previously, we have implemented FTIR spectroscopy to characterize the chemical composition changes of fresh Sargassum specimens undergoing deterioration by different means of transportation to the laboratory and damage occasioned by sunlight under outdoor conditions. However, FTIR limitations make identifying metabolites in complex mixtures difficult. In contrast, it is possible to achieve greater resolution in metabolite identifications using NMR spectroscopy, thus increasing the odds of successful Sargassum bioprospecting. Therefore, we used 1H NMR analysis by comparing the metabolic profiles of fresh (flash-frozen treatment conditions) and transported Sargassum samples (flash-frozen upon arrival in the laboratory). 1H NMR analysis revealed significant differences in the chemical composition, with fresh samples showing a rich profile of intracellular metabolites such as mannitol, laminitol, amino acids, and Krebs cycle intermediates. In contrast, samples that underwent transportation without cryogenic preservation showed signs of deterioration, indicated by an increase in anaerobic metabolites like acetate and formate. Additionally, the correlation analysis between 1H NMR data and FTIR results helped confirm the identification of specific IR peaks corresponding to metabolites like mannitol and inorganic compounds from Sargassum epibionts. The most significant findings highlight the necessity of flash-freezing and freeze-drying for mannitol extraction from Sargassum. This knowledge will be crucial for future experiments. Additionally, S. natans VIII has been identified as a potential mannitol source, while S. fluitans III and S. natans I showed higher concentrations of amino acids and amines. This approach demonstrates the potential of combining FTIR and 1H NMR spectroscopy for a more comprehensive understanding of Sargassum biomass, which is crucial for optimizing its use as a raw material in various applications.