International Journal of Clinical Case Reports 2024, Vol.14, No.5, 262-275 http://medscipublisher.com/index.php/ijccr 268 appearance, histopathology, and serum chemistry evaluation (Lang et al., 2005). The minimum effective dose was identified as 600 mg/kg, which effectively reduced systolic blood pressure in male SHRs. In a long-term study, SHRs were treated with 300 mg/kg/day of lignan extracts for 16 weeks, resulting in significant blood pressure reduction and inhibition of aldose reductase activity, similar to the effects observed with captopril and epalrestat (Li et al., 2013). This study further supports the safety and efficacy of Eucommia ulmoides in managing hypertension over extended periods. In conclusion, in vivo studies have demonstrated that Eucommia ulmoides is effective in reducing blood pressure in hypertensive animal models, with both short-term and long-term benefits. The dose-response relationship indicates that higher doses yield more significant hypotensive effects, and the safety profile suggests that Eucommia ulmoides is well-tolerated at therapeutic doses. These findings highlight the potential of Eucommia ulmoides as a natural antihypertensive agent with a favorable safety and efficacy profile. 6 Clinical Studies and Human Trials 6.1 Overview of clinical trials involving Eucommia ulmoides Eucommia ulmoides, commonly known as Du-Zhong, has been the subject of various clinical trials aimed at evaluating its efficacy and safety in treating hypertension. One notable study involved a controlled clinical trial that assessed an aqueous bark extract of Eucommia standardized to eight percent pinoresinol di-beta-D-glucoside (PG) for blood pressure (BP) reduction in humans. This study included 24 healthy adult subjects with BP between 120-160/80-100 mmHg, who were randomized to receive 500 mg of Eucommia extract three times daily for eight weeks. The results indicated that the Eucommia extract was well-tolerated and effective in reducing BP (Figure 2) (Greenway et al., 2011). Another significant clinical trial was a multicenter, randomized, double-blind, placebo-controlled study that evaluated the efficacy of Quanduzhong capsules, which contain an extract of Eucommia ulmoides, in treating low-to-moderate risk grade 1 hypertension patients. This trial involved 60 patients and demonstrated that the Quanduzhong capsules significantly reduced both systolic and diastolic blood pressure (SBP and DBP) after a four-week treatment period (Xu et al., 2023). The hypotensive effects and safety aspect of beverages containing Eucommia leaf glycosides were examined in a randomized double-blind, placebo-controlled, parallel group study. The subjects were high normotensive and mild hypertensive adult male and female subjects. Test or placebo meals were given one time per a day for 12 weeks. The results revealed that the systolic blood pressure (SBP) was significantly reduced after 4 weeks of intake in the test-meal group. The diastolic blood pressure (DBP) was also significantly reduced after 6 weeks of intake. In contrast, no changes in blood pressure were observed during the trial in the placebo group. Between the two groups, there was a significant difference in SBP at 8, 10, and 12 weeks and in DBP at 10 and 12 weeks (Tsukamoto et al., 2007). 6.2 Efficacy in reducing blood pressure in humans The efficacy of Eucommia ulmoides in reducing blood pressure has been demonstrated in several human studies. In the controlled clinical trial mentioned earlier, the Eucommia extract reduced BP by an average of 7.5/3.9 mmHg after two weeks of treatment, indicating a significant antihypertensive effect. This reduction in BP is attributed to the beta-adrenergic blocking activity of the Eucommia extract, which was confirmed through a human fat cell assay that showed a reduction in isoproterenol-stimulated lipolysis (Greenway et al., 2011). The multicenter clinical trial involving Quanduzhong capsules also reported significant reductions in BP. After four weeks of treatment, the mean office SBP decreased by 7.62 mmHg, and the mean DBP decreased by 4.66 mmHg. These results highlight the potential of Eucommia ulmoides as an effective treatment for hypertension (Xu et al., 2023).
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