Metabolomics approach for discrimination of water extracts of Citrus-type crude drugs using NMR and HR-LC-MS

A metabolic study on the differentiation of Citrus-type crude drugs (CCDs) was carried out for quality evaluation. Recently, we reported approximately five possible classifications for methanol extracts of CCDs based on metabolomics using NMR [1], and compared with HR-LC-MS based on metabolomics [2]. In this study, we analyzed water extracts of CCDs using NMR and HR-LC-MS for metabolic discrimination, and compared their contributors with that of methanol extracts and their discrimination because CCDs are usually used as the ingredient of decoction in the traditional Japanese medicine. The water extracts of four CCDs (33 samples); Kijitsu, Tohi, Chimpi and Kippi, were analyzed using ¹H- and ¹³C-NMR and HR-LC-ESI-MS. These data were processed using different analysis software and the resulting data sets were then imported into a multivariate statistical analysis software. The PCA score plots indicated the discrimination of the water extracts of CCDs into the same three groups in both NMR and LC-MS analyses. This discrimination was the same as the results of methanol extracts. In the loading plots, naringin and neohesperidin were identified as contributors for discrimination by both NMR and LC-MS analyses. α- and β-Glucose and sucrose were identified as contributors by the NMR only. Limonene, identified as a contributor in the methanol extracts of CCDs was not identified as a contributor in the water extracts. In contrast, four flavonoids and two coumarins were identified as contributors by the LC-MS only. These results suggested that the combined NMR- and LC-MS-based metabolomics are applicable to discriminate water extracts of CCDs.

• References

• 1 Tsujimoto T, Yoshitomi T, Maruyama T, Yamamoto Y, Hakamatsuka T, Uchiyama N. ¹³C NMR-based metabolic fingerprinting of Citrus-type crude drug towards their quality control. J Pharm Biomed Anal 2018; 161: 305-312.
• 2 Uchiyama N, Tsujimoto T, Yoshitomi T, Maruyama T, Yamamoto Y, Hakamatsuka T. Comparison of NMR and LC-MS for metabolic profiling of Citrus-type crude drugs. GA2018.