Research on Chemical Constituents of Tibetan Medicine Synotis solidaginea and Effects of SS-2 on Melanoma Cells

ObjectiveTo study the chemical constituents of Synotis solidaginea (SS) from Tibet. In our previous research, it was found that the extract of Synotis solidaginea stems has potential inhibitory activity against the proliferation of melanoma cells. Therefore, we hope to separate, extract and structurally identify the extracts of Synotis solidaginea stems, and determine the main components that exert potential inhibitory activity on the proliferation of melanoma cells.MethodsThe compounds were separated and purified using silica gel, polyamide, reversed phase C18 column chromatography, and preparative high performance liquid chromatography. The structure of each compound was identified based on the spectral data and literature comparisons. To verify the inhibitory activity of each component against melanoma cells, cell and enzyme assay were conducted.ResultsA total of 7 compounds were isolated from the dichloromethane extract of Synotis solidaginea. The irimofen lactone structure compound SS-1 and SS-5 were isolated from Synotis solidaginea for the first time. Among these, irimofin sesquiterpenoid compound SS-2 exhibited strong inhibitory activity against B16F10 of melanoma cells. Meanwhile, the iremorphene sesquiterpenoid SS-2 exhibited significant tyrosinase inhibitory activity, and the docking results explained the mechanism of its action.DiscussionSolidaginea has laid the foundation for the prevention and treatment of melanoma with the active ingredients of Tibetan medicine.