Pseudo-targeted metabolomics analysis of the therapeutic effect of phenolics-rich extract from Se-enriched green tea (Camellia sinensis) on LPS-stimulated murine macrophage (RAW264.7)

Abstract

Selenium (Se)-enriched green tea (Se-Te) has been recognized as a possible source of Se supplements, while the effect of Se enrichment on function of polyphenols in green tea is still unclear. In this study, a pseudo-targeted metabolomics strategy was carried out to reveal the regulatory mechanism of polyphenols extracted from Se-Te and regular green tea (Re-Te) on inflammatory response at cellular level. A novel analysis strategy using UHPLC/ESI Q-Orbitrap combined with MS-IOP was applied to profile the dynamic changes of metabolites in LPS-stimulated RAW264.7 macrophages during polyphenols incubation. A total of 128 characteristic variables (VIP > 1, p < 0.05) were screened in Se-Te group and the results of bioinformatics analysis and quantitative research indicated that in addition to the 6 conventional immune protective pathways involved in tea polyphenols, Se-enriched polyphenols were also participated in 3 unique antioxidant enzyme activation pathways, including phenylalanine, tyrosine and tryptophan biosynthesis, phenylalanine metabolism and pantothenate and CoA biosynthesis. The result of weight calculation based on topological analysis indicated that the promoting synthesis of antioxidant enzymes was the main mechanism of Se-Te polyphenols to inhibit inflammation. However, compared with Re-Te group, the intracellular B vitamin pathway in Se-Te group was disturbed, which is related to the fact that Se supplementation can promote the synthesis of selenoprotein and catalyze the reduction of thioredoxin by NADPH, thus blocking the signaling pathways of B vitamins. This study comprehensively explored the immune protective mechanism of polyphenols extracted from Se-Te and Re-Te under natural growth conditions, which could give a better understanding of the potential nutritional value of Se-Te as a widely used Se supplement.

Keywords: Cell metabolism; Inflammatory response; Molecular mechanism; Polyphenols; Pseudo-targeted metabolomics; RAW264.7 macrophages; Se-enriched green tea.