Eucommia ulmoides Leaf Polyphenols Alleviate Hypertension and Modulate Gut Microbiota and Metabolic Profiles in Spontaneously Hypertensive Rats

Eucommia ulmoides leaves, a traditional edible and medicinal resource, are a rich source of bioactive polyphenols. In this study, male Wistar rats served as the normal control, while spontaneously hypertensive rats were randomized into model, positive control (nifedipine, 6.0 mg/kg/d), and low-, medium-, and high-dose groups receiving 1.25, 2.50, and 3.75 mL/kg/d of the polyphenol extract (n = 8/group) via intragastric gavage for 4 weeks. The extract supplementation significantly reduced systolic and diastolic blood pressure to approximately 166.33 mmHg and 113.93 mmHg, respectively, thereby improving vascular function (p < 0.05), accompanied by alleviation of lipid metabolism disorders and oxidative stress. In addition, it mitigated intestinal injury and enhanced gut barrier integrity. Notably, it reshaped the gut microbiota by enriching beneficial bacteria and suppressing harmful taxa, which is associated with increased production of short-chain fatty acids. Integrated metabolomics analysis further demonstrated that it modulated multiple metabolic pathways, particularly arachidonic acid and tryptophan metabolism, which are closely linked to vascular homeostasis, inflammation, and oxidative stress. Collectively, these findings indicate that the antihypertensive effects of the polyphenol extract are potentially linked to the regulation of the gut microbiota–metabolite axis, highlighting its promising application as a functional food ingredient for cardiovascular health.