The proteomic profiling of calenduloside E targets in HUVEC: design, synthesis and application of biotinylated probe BCEA

We previously found the total saponins from the medicinal herb Aralia elata, which exhibited strong antioxidative and anti-apoptotic effects. calenduloside E (CE) is one of the major triterpenoid saponin compounds isolated from these total saponins. However, the endothelial protection effect and the probable protein targets of CE have not been fully characterized. In the present study, a biotin-conjugated CE analogue (BCEA) was employed as a molecular probe to research and analyse its protein targets and signaling pathways. Compared with its parental compound CE, BCEA exhibited a similar protective effect against ox-LDL induced HUVEC damage. A chemical proteomic approach identified 128 proteins that related to the cell survival signaling pathways as the targets for BCEA. Meanwhile some of these cell survival signaling pathways that showed a higher P-value in KEGG pathway analysis were associated with anti-apoptotic activity. Moreover, further evaluation with flow cytometry, JC-1 staining assays and cleaved caspase-3 activity confirmed the anti-apoptotic effect of BCEA. Taken together, these results suggested that CE can improve cell viability most likely through anti-apoptotic mechanisms, and provided the basis for the further optimization of the endothelial protection compounds.