Identification of Ziyuglycoside II from a Natural Products Library as a STING Agonist.

Given the emerging pivotal roles of stimulator of interferon genes (STING) in host pathogen defense and immune-oncology, STING is regarded as a promising target for drug development. Cyclic dinucleotides (CDNs) are the first-generation STING agonists. However, their poor metabolic stability and membrane permeability limits their therapeutic application. In contrast, small-molecule STING agonists show superior properties such as molecular weight, polar character, and delivery diversity. The quest for a potent small-molecular agonist of human STING remains ongoing. In our study, through an IRF/IFN pathway-targeted cell-based screen of a natural products library, we identified a small-molecular STING agonist, Ziyuglycoside II, termed ST12, with potent stimulation of the IRF/IFN and NF-κB pathways. Furthermore, its binding to the C-terminal domain of human STING, detected by bio-layer interferometry, indicates that ST12 is a human STING agonist. Further Tanimoto similarity analysis with existing small-molecule STING agonists indicates that ST12 is a lead compound with a novel core structure for the further optimization.