Clerodane diterpenoid glycosides from the tuberous roots of Paratinospora sagittata: targeted isolation, structure characterization and immunomodulatory properties

Guided by the MS/MS-based molecular networking, eight previously undescribed clerodane diterpenoid glycosides, designated tinospinosides F-M (1-8), along with 12 known analogues (9-20), were isolated from the tuberous roots of Paratinospora sagittata. Structural elucidation of the undescribed compounds was achieved through comprehensive spectroscopic analyses (NMR, HRESIMS), with their absolute configurations confirmed via single-crystal X-ray diffraction, TD-DFT/ECD computational analyses, and chemical degradation. Immunomodulation evaluation on all the isolates revealed that compounds 6 and 7 exerted significant promoting effect toward NO production in RAW264.7 macrophages. Further study demonstrated that 6 could enhance the release of immune cytokines (e.g., TNF-α) and upregulate the protein expression of iNOS and COX-2, which was potentially mediated through the activation of NF-κB signaling pathway.