Comparison of various commercially available cinnamon barks using NMR metabolomics and the quantification of coumarin...

Cinnamon bark is an important spice worldwide. In this study, the chemical diversity of various commercially available cinnamon barks that differed in their production areas and utility applications (culinary spice or medicines) were investigated by the use of ¹H NMR metabolomics. Our results indicated that principle component analysis (PCA) and hierarchical cluster analysis (HCA) of the ¹H NMR spectra of the cinnamon bark methanolic extracts including the deduction of their species by nucleotide sequence analysis enabled differentiation of the cinnamon barks according to their species, production areas and utility applications. The constituents of Vietnam cinnamon were found to differ significantly from the other samples investigated based on PCA score plots and HCA constellation dendrograms. Coumarin was found to be a key compound for the discrimination of Vietnamese cinnamon by multivariate analysis of the ¹H NMR spectral data and direct comparison of the ¹H NMR spectra. In addition, coumarin was quantified using quantitative NMR methods. As a result, coumarin was contained in Vietnamese cinnamon at a higher level compared to other cinnamons. This study indicated that ¹H NMR metabolomics could deduce spices, utility, and producing area of commercially available cinnamon barks. Furthermore, combining quantitative ¹H NMR methods with ¹H NMR metabolomics enable quantification of coumarin in cinnamon bark on a single measurement.