Effect of Air Drying on the Metabolic Profile of Fresh Wild and Artificial Cordyceps sinensis

Abstract

Fresh and dried Cordyceps sinensis are widely used by the public for medicinal and health purposes. However, the differences between them have not been examined. In this study, fresh wild and artificial C. sinensis (WFC and AFC) were dried to obtain dried wild and artificial C. sinensis (WDC and ADC). Non-targeted GC-MS was used to analyze the metabolic profile characteristics of the four groups of samples. The results showed that air drying significantly altered the composition and content of C. sinensis, mainly in the form of higher abundance of organic acids and derivatives and lower abundance of lipids and lipid-like molecules in fresh C. sinensis. Hierarchical cluster analysis (HCA) and quantitative analyses showed that air drying increased the abundance of Valine, Zinniol, Urocanate, Vulpinic acid, and Uridine 5'-diphosphate, and decreased Xanthotoxol, Vitexin-4-o-glucoside, Val-trp, and Wogonin. These differentially accumulated metabolites (DAMs) were also shown to be potential biomarkers for C. sinensis. KEGG enrichment analysis identified lysine biosynthesis as the most significantly enriched pathway. Annotation of these DAMs to lysine biosynthesis revealed that citrate cycle and pyruvate metabolism entered lysine biosynthesis via 2-oxohlutarate and Homocitrate, respectively, resulting in significant enrichment of L-saccharopine and L-lysine content was significantly higher. Alanine, aspartate, and Glutamate metabolism synthesized more L-aspartate to promote L-lysine synthesis. Thus, high levels of L-lysine result in lysine degradation and pymolysine, which are the most active metabolic pathways during the drying of fresh C. sinensis and indirectly lead to differences in metabolic profiles.

Keywords: Cordyceps sinensis; air drying; lysine biosynthesis; metabonomics.

Figure 1

Four groups’ samples of C. sinensis. (WFC) wild fresh C. sinensis; (AFC) artificially fresh C. sinensis; (WDC) wildly dried C. sinensis; (ADC) artificially dried C. sinensis.

Figure 2

Total ion chromatograms of QC (quality control), ADC, WDC, WFC, and AFC non-targeted metabolomics methods. The numbers in the figure are retention times.

Figure 3

(A) Classification histogram of metabolites identified in the top 10 superclasses. (B) The expression of the top six superclasses in the four groups’ sample. Different capital letters in the same group showed significant differences at the level of p < 0.05.

Figure 4

Multivariate statistical analysis of four groups samples. (A) PCA analysis of four groups samples. (B) Cluster analysis of four groups’ samples. (C) UMAP of four groups samples.

Figure 5

DAMs analysis of the four groups’ samples. (A) scatterplot of DAMs. (B) Numbers of upregulated and downregulated DAMs in four groups samples. (C) Dendrogram and heatmap of four groups samples (C. sinensis) from different origins based on top 20 differential metabolites content.

Figure 6

Differentially expressed metabolic pathway (top 20) in the four groups’ samples of C. sinensis. On the left is WFC vs. ADC and on the right is AFC vs. ADC.

Figure 7

KEGG maps of key DAMs in the four groups’ samples of C. sinensis. The colored box in front of each metabolite indicates the corresponding log₂ FC value. The dashed boxes indicate different metabolic pathways.