Ultrahigh Pressure Processing Produces Alterations in the Metabolite Profiles of Panax ginseng

Abstract

Ultrahigh pressure (UHP) treatments are non-thermal processing methods that have customarily been employed to enhance the quality and productivity of plant consumables. We aimed to evaluate the effects of UHP treatments on ginseng samples (white ginseng: WG; UHP-treated WG: UWG; red ginseng: RG; UHP-treated RG: URG; ginseng berries: GB; and UHP-treated GB: UGB) using metabolite profiling based on ultrahigh performance liquid chromatography-linear trap quadrupole-ion trap-tandem mass spectrometry (UHPLC-LTQ-IT-MS/MS) and gas chromatography time-of-flight mass spectrometry (GC-TOF-MS). Multivariate data analyses revealed a clear demarcation among the GB and UGB samples, and the phenotypic evaluations correlated the highest antioxidant activities and the total phenolic and flavonoid compositions with the UGB samples. Overall, eight amino acids, seven organic acids, seven sugars and sugar derivatives, two fatty acids, three notoginsenosides, three malonylginsenosides, and three ginsenosides, were identified as significantly discriminant metabolites between the GB and UGB samples, with relatively higher proportions in the latter. Ideally, these metabolites can be used as quality biomarkers for the assessment of ginseng products and our results indicate that UHP treatment likely led to an elevation in the proportions of total extractable metabolites in ginseng samples.

Keywords: Panax ginseng; antioxidant activity; mass spectrometry; multivariate analyses; ultrahigh pressure.

Figure 1

PCA score plots of P. ginseng samples analyzed by (a) gas chromatography time-of-flight mass spectrometry (GC-TOF-MS) and (b) ultrahigh performance liquid chromatography-linear trap quadrupole-ion trap-tandem mass spectrometry (UHPLC-LTQ-IT-MS/MS). $\square$: non-treated white ginseng (WG); $■$: UHP-treated white ginseng (UWG), $\square$: non-treated red ginseng (RG); $■$: UHP-treated red ginseng (URG), $\square$: non-treated ginseng berry (GB); $■$: UHP-treated ginseng berry (UGB).

Figure 2

Antioxidant activity assay (a) diammonium salt (ABTS); (b) fluorescence recovery after photobleaching (FRAP); (c) total phenolic contents; and (d) total flavonoid contents of Panax ginseng samples. Each value is expressed as mean ± SD (* p < 0.05, paired sample t-test). $▧$: non-treated white ginseng (WG), $■$: UHP-treated white ginseng (UWG), $▧$: non-treated red ginseng (RG), $■$: UHP-treated red ginseng (URG), $▧$: non-treated ginseng berry (GB), $■$: UHP-treated ginseng berry (UGB).

Figure 3

Orthogonal projection to latent structures-discriminant analysis (OPLS-DA) score plots analyzed using the (a) GC-TOF-MS and (b) UHPLC-LTQ-IT-MS metabolite datasets for ginseng berries. $\square$: non-treated ginseng berry (GB), $■$: UHP-treated ginseng berry (UGB).

Figure 4

Schematic representation of the relative metabolite contents visualized in respective metabolic pathways for ginseng berry samples (GB and UGB) that correspond to UHP treatments. The pathways were modified from the Kyoto Encyclopedia of Genes and Genomes (KEGG) database (http://www.genome.jp/keg/). The Y-axis of the histogram represents peak areas for respective metabolites. Data are mean values, and the error bars represent standard deviation values (n = 9). These metabolites were selected by VIP > 0.7 and p < 0.05.