Analysis of differential metabolites of spikes of Prunella vulgaris at different stages based on UPLC-MS/MS

Abstract

Prunella vulgaris, aptly named for its withering at the summer solstice, displays significant variation in quality arising from differing harvest time. However, research on the chemical composition changes of its spikes at various stages is limited, and the specific metabolites remain unclear. In order to elucidate the metabolites and metabolic pathways of the spikes of P. vulgaris, the current study deployed ultra-performance liquid chromatography-tandem mass spectrometry(UPLC-MS/MS) and targeted metabolomics to characterize the compound variability in the spikes of P. vulgaris across different periods. Multivariate statistical techniques such as principal component analysis(PCA) and orthogonal partial least squares-discriminant analysis(OPLS-DA) were used to identify the differences in metabolites, and relevant metabolic pathways were analyzed. A total of 602 metabolites were identified by metabolomics, of which organic acids and their derivatives were the most abundant, followed by flavonoids. Multiple differential metabolites, including p-hydroxybenzoic acids and gallic acids were identified based on variable importance in projection(VIP)>1 and P<0.05. The results of enrichment analysis suggested that isoflavonoids biosynthesis, aminobenzoate degradation, benzoate degradation, anthocyanins biosynthesis, metabolic pathways, microbial metabolism in different environments, secondary plant metabolite biosynthesis, tryptophan metabolism, and phenylpropanoid synthesis were the main metabolic pathways. These results intend to elucidate the dynamic changes of differential metabolites of P. vulgaris and provide a theoretical basis for further study of the harvesting mechanism of spikes of P. vulgaris.