Discovery and identification of natural alkaloids with potential to impact insulin resistance syndrome in Cyclocarya paliurus. (Batal) leaves by UPLC-QTOF-MS combined with HepG2 cells.

Cyclocarya paliurus (Batal.) leaves, which contain a range of bioactive compounds, have been used as a traditional Chinese medicine homologous food since ancient times. However, there is a paucity of literature on comprehensive studies of alkaloids in the leaves of Cyclocarya paliurus (Batal.). For the first time, this study aimed to discover and identify alkaloids extracted from Cyclocarya paliurus (Batal.) leaves by ultra-high performance liquid chromatography-quadrupole-time-of-flight tandem mass spectrometry (UPLC-QTOF-MS). A total of ten alkaloids have been identified from Cyclocarya paliurus (Batal.) leaves based on accurate mass spectra (mass accuracy, isotopic spacing and distribution) and comparison to fragmentation spectra reported in the literature. In vitro, alkaloids alleviated insulin resistance by increasing glucose consumption and glycogen content in insulin resistance HepG2 cells. The RNA-seq and western blotting results showed that alkaloids could upregulate the expression of phosphatidylinositol 3-kinase (PI3K), and increase the phosphorylation of insulin receptor protein kinase B (AKT). This study not only clarified the chemical constituents and revealed that diverse alkaloids also presented from Cyclocarya paliurus (Batal.) leaves, also, it will provide chemical information on potential compounds for developing new drugs.