Rare quinochalcone C-glycosides with vasoprotective activities from Carthamus tinctorius L

Myocardial ischemia/reperfusion injury (MI/RI) is an inevitable consequence of reperfusion therapy for ischemic myocardium. Endothelial protection and therapeutic angiogenesis are pivotal strategies for attenuating MI/RI and restoring myocardial perfusion. To investigate the chemical basis underlying the vasoprotective potential of Carthamus tinctorius, we utilized both in vivo (PTK787-induced intersegmental vessel injury in zebrafish) and in vitro (OGD/R-injured HUVECs) assays. The 30% EtOH eluate obtained from D101 macroporous resin chromatography of the Carthamus tinctorius extract exhibited significant pro-angiogenic and endothelial-protective activities. Subsequent HPLC-UV-guided fractionation afforded seven previously undescribed quinochalcone C-glycosides (QCGs, 1-7). Their structures were established by comprehensive spectroscopic analysis, including HRMS (ESI), 1D/2D NMR, UV, IR, CD, and NMR chemical shift calculations. Saffloquinoside G (1) is a monomeric QCG bearing a furan moiety, whereas carthorquinosides CH (2-7) are rare dimers consisting of quinochalcone and flavonol glucoside units linked by a methylene or methine unit. Biological evaluation demonstrated that all dimeric QCGs restored the formation of PTK787-injured intersegmental vessels. Notably, compounds 1 and 2 significantly increased HUVEC viability under OGD/R conditions. Compound 2 also promoted cell migration and tube formation, concomitantly upregulating angiogenic markers (VEGF, CD31, and Ki-67). SILAC-based proteomic profiling identified angio-associated migratory cell protein (AAMP) as a potential target of 2. CETSA and DARTS assays confirmed the direct interaction between 2 and AAMP, and molecular dynamics simulations revealed moderate conformational rearrangements upon binding. Further studies revealed that 2 rescued PTK787-impaired intersegmental and subintestinal vessels in a dose-dependent manner in vivo.