Gcmssolution software version 2

The GC-MS metabolomics data were analysed using the Shimadzu GCMSsolution software Version 2.53 (Shimadzu, Kyoto, Japan). The retention time correction of detected peaks was performed by adjusting it with the retention time of a standard alkane series mixture (C₁₀ to C₄₀) in the automatic adjustment of retention time (AART) function of the Shimadzu GCMSsolution software Version 2.53 (Shimadzu, Kyoto, Japan). Low-molecular-weight metabolites were identified by a commercially available GC/MS Metabolite Mass Spectral Database (Shimadzu Co., Kyoto, Japan). The GC/MS MS Metabolite Mass Spectral Database contained a mass spectral library (method files that specified the above-described analytical conditions) and the parameters for data analysis of 178 compounds (amino acids, fatty acids, and organic acids). A similarity index was calculated based on retention time and the confirmed ion and fragmentation pattern obtained in the mass spectrum of the low molecular weight metabolites. Peaks with a similarity index of less than 80 were processed as unknown molecules, while peaks with a similarity index more than 80 were identified metabolites. The peak height of 2-isopropylmalic acid was used as an internal standard to perform the semi-quantitative assessment (the peak height of each quantified ion was calculated and normalised using the peak height of internal standard).