Comprehensive chemical analysis of polyphenols in the ethyl acetate extract from the roots of Ephedra sinica Stapf and evaluation of its therapeutic effects on SU5416/hypoxia-induced pulmonary arterial hypertension rats

Pulmonary hypertension (PH) is a deadly disease with limited treatment options and poor long-term survival, necessitating the discovery of novel therapeutics. Our previous study has revealed that dimeric proanthocyanidins (PACs) mainly existed in the ethyl acetate extract from the roots of Ephedra sinica Stapf (ERE), however, its therapeutic effects on SU5416/hypoxia-induced pulmonary hypertension (PH) rats remain elusive. In this study, column chromatography combined with UPLC-LTQ-Orbitrap-HRMS analysis was performed to comprehensively characterize polyphenols in ERE. The therapeutic effects of ERE were investigated using the SU5416/hypoxia rat model, in which the rats were injected with SU5416 (20 mg/kg), followed by a three-week hypoxia exposure (10% O₂). Hemodynamic indicators determined by right heart catheterization, pulmonary arterial morphological changes assessed by histopathological analysis, cardiac function and pulmonary hemodynamics using echocardiography, as well as oxidative stress markers measured by corresponding kits were used to test the therapeutic effects of ERE. Moreover, 16S rRNA sequencing combined with untargeted metabolomics was employed to capture changes in gut microbiota and serum metabolites after ERE treatment. Comprehensive chemical analysis of polyphenols in ERE revealed various levels of proanthocyanidin monomers, dimers and trimers, especially A-type dimers. In vivo experiments showed that ERE decreased pulmonary arterial pressure, right ventricular hypertrophy, right ventricular free wall (RVFW) thickness and oxidative stress levels, increased pulmonary acceleration time (PAT) and alleviated pulmonary vascular remodeling in rats exposed to SU5416/hypoxia treatment. Meanwhile, ERE improved gut microbial dysbiosis and the disturbed glycerophospholipid metabolism. Collectively, this study presents the first report on the efficacy of A-type PACs from Ephedra sinica for the treatment of PH through regulating gut microbiota and host metabolism.