Untargeted Metabolomics-Based Characterization of the Metabolic Profile and Antioxidant Activity of Ophiocordyceps sinensis and Its Substitutes

<i>Ophiocordyceps sinensis</i> represents a valuable medicinal resource. In this study, mechanisms underlying differences in chemical composition and antioxidant capacity among wild <i>O. sinensis</i> (GL), artificially cultivated <i>O. sinensis</i> (RG), and product of <i>O. sinensis</i> "Bailing" capsules (BL) were systematically investigated via in vitro antioxidant capacity assays and untargeted metabolomics. Results showed GL exhibited the highest total phenol (TPS) content and superior free radical scavenging activity. Additionally, superoxide dismutase (SOD) and peroxidase (POD) activities in RG were higher than those in BL. Correlation analysis of antioxidant indices demonstrated significant positive correlations between total phenols (TPS) and flavonoids (TF) with DPPH radical scavenging, ferric ion reducing antioxidant power (FRAP), hydroxyl radical scavenging rate, and superoxide anion radical scavenging rate (<i>p</i> < 0.01). A total of 6729 metabolites were detected, encompassing amino acids and their derivatives, lipids, and nucleotides and their derivatives, among other classes. Furthermore, metabolites exhibited distinct intergroup separation, indicating significant differences in metabolic profiles between <i>O. sinensis</i> and its substitute products. KEGG enrichment analysis showed that differential metabolites were mainly enriched in amino acid, lipid, and nucleotide metabolic pathways, among which the linoleic acid metabolic pathway was significantly downregulated. Key metabolites included γ-linolenic acid, 12(13)-EpOME-d, 9-HpODE, etc. Additionally, results of correlation analysis revealed that differential metabolites of lipids, nucleotides, and amino acids exhibited a significant positive correlation with antioxidant indices (<i>p</i> < 0.05). These findings suggest that the antioxidant capacity of <i>O. sinensis</i> and its substitutes may be regulated via linoleic acid metabolism, providing a theoretical basis for advancing targeted functional development of <i>O. sinensis</i> and its substitute products.