In the field of food and nutrition, complex natural products (NPs) are typically obtained from cells/tissues of diverse organisms such as plants, mushrooms, and animals. Among them, edible fruits, grains, and vegetables represent most of the human diet. Because of an important dietary dependence, the comprehensive metabolomic analysis of dietary NPs, performed holistically via the assessment of as many metabolites as possible, constitutes a fundamental building block for understanding the human diet. Both mass spectrometry (MS) and nuclear magnetic resonance (NMR) are important complementary analytic techniques, covering a wide range of metabolites at different concentrations. Particularly, 1-dimensional 1H-NMR offers an unbiased overview of all metabolites present in a sample without prior knowledge of its composition, thereby leading to an untargeted analysis. In the past decade, NMR-based metabolomics in plant and food analyses has evolved considerably. The scope of the present review, covering literature of the past 5 y, is to address the relevance of 1H-NMR–based metabolomics in food plant studies, including a comparison with MS-based techniques. Major applications of NMR-based metabolomics for the quality control of dietary NPs and assessment of their nutritional values are presented.

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Proanthocyanidins (PACs) are plant-derived, multifunctional compounds that possess high interactivity with extracellular matrix (ECM) components. The documented affinity of PACs for type-I collagen is directly correlated with their structural features and degree of polymerization. In this investigation, centrifugal partition chromatography (CPC) was used to sequentially deplete less active monomeric and polymeric PACs from a crude Pinus massoniana bark extract to create refined mixtures enriched in oligomeric PACs. The ability of these oligomeric PACs to modify the mechanical properties of the dentin collagen matrix and their biocompatibility with dental pulp cells (DPCs) was evaluated in an innovative biomimetic environment. The refined mixtures displayed high interactivity with dentin collagen as demonstrated by a significant increase (> 5-fold) in the modulus of elasticity of the dentin matrix. In a simplified model of the dentin-DPC complex, DPCs embedded within their native ECM in the presence of PAC-treated dentin exhibited increased proliferation. Quantitative gene expression analyses indicated that exposure to PAC-treated dentin increased the expression of key biomineralization and odontogenic differentiation regulators, including RUNX2, BMP2, OCN, and DSPP. LC-MS/MS analysis revealed that PACs two to four units long (dimers, trimers, and tetramers) were being released from dentin into media, influencing cell behavior. Overall, the results suggested that PAC dimers, trimers, and tetramers are not only biocompatible, but enhance the differentiation of DPCs towards a phenotype that favors biomineralization. PAC-enriched refined mixtures can influence the field of biomaterials and regeneration by serving as renewable, non-cytotoxic agents that can increase the mechanical properties of biomaterials.

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