Eucommia ulmoides Oliv

Micucci, M., Bolchi, C., Budriesi, R., Cevenini, M., Maroni, L., Capozza, S., Chiarini, A., Pallavicini, M. & Angeletti, A., 2020, Antihypertensive phytocomplexes of proven efficacy and well-established use: Mode of action and individual characterization of the active constituents, Phytochemistry (112222) 170, pp. 1-19 : 5

2.4. Eucommia ulmoides Oliv

Eucommia ulmoides Oliv. Is a medicinal plant widely used for medical purposes in China. In Traditional Chinese Medicine, in fact, it is used as a treatment for hypertension, rheumatoid arthritis, kidney deficiency pain, weak bones, bone fractures and joint diseases, as well as lower back pain (Xing et al., 2019).

The main compounds isolated from E. ulmoides are lignans, flavonoids, iridoids, phenolic acids, steroids and terpenoids. Fatty acids, polysaccharides, amino acids, microelements, vitamins were also detected (He et al., 2014).

The antihypertensive effect of E. ulmoides leaves and bark occurs by several mechanisms, including inhibition of cAMP phosphodiesterase activity, modulation of NO and renin-angiotensin system, a direct blood vessel relaxant effect and an increase in coronary flow (Kwan et al., 2004; Luo et al., 2010; Hosoo et al., 2015). In particular, the vasorelaxant effect of E. ulmoides bark water extracts is, at least in part, endothelium-dependent, as it was antagonized by L-NAME and bluemethilene (Kwan et al., 2004). The water extract of the leaves also possesses vasorelaxant, endothelium-dependent properties (Jin et al., 2008).

Singly studied constituents of E. ulmoides extracts are depicted in Fig. 4 . They are the iridoids (cyclopentanpyrans) geniposidic acid and asperuloside, to which increased levels of adiponectin have been imputed (Hosoo et al., 2017) and, in the case of geniposidic acid, also enhanced secretion of atrial natriuretic peptide from cardiomyocytes (Nakamura et al., 2018). The glucosides of monoepoxylignans related to olivil and of bisepoxylignans related to pinoresinol have been proposed for inhibition of hypertensive vascular remodelling (Gu et al., 2011) and for enhancing plasma level of NO and lowering levels of angiotensin II and renin activities (Luo et al., 2010). A controlled, randomized clinical trial showed that the administration of 3 g of an E. ulmoides bark extract standardized to eight percent pinoresinol di-β- Dglucoside reduces BP, has β- adrenergic blocking activity and is well tolerated (Greenway et al., 2011).

Among the flavonoids, wogonin and its iduronic acid derivative, wogonoside, may contribute to the hypotensive effect by inhibiting both Ca 2+ influx and Ca 2+ release in isolated rat aorta (Qu et al., 2015), while oroxylin A may be relevant to the vasorelaxant effect by acting through an endothelium-dependent mechanism which involves endothelin 1 receptors (Akinyi et al., 2014) and the quercetin 3-galattoside, hyperin, may exert ACE inhibition (Nileeka Balasuriya and Vasantha Rupasinghe, 2011).

Figures

Fig. 4. Constituents of E. ulmoides Oliv. singly studied for antihypertensive effects.