Vascular protective effects of aqueous extracts of Tribulus terrestris on hypertensive endothelial injury.

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Abstract

Angiotensin II (Ang II) is involved in endothelium injury during the development of hypertension. Tribulus terrestris (TT) is used to treat hypertension, arteriosclerosis, and post-stroke syndrome in China. The present study aimed to determine the effects of aqueous TT extracts on endothelial injury in spontaneously hypertensive rats (SHRs) and its protective effects against Ang II-induced injury in human umbilical vein endothelial cells (HUVECs). SHRs were administered intragastrically with TT (17.2 or 8.6 g·kg-1·d-1) for 6 weeks, using valsartan (13.5 mg·kg-1·d-1) as positive control. Blood pressure, heart rate, endothelial morphology of the thoracic aorta, serum levels of Ang II, endothelin-1 (ET-1), superoxide dismutase (SOD) and malonaldehyde (MDA) were measured. The endothelial injury of HUVECs was induced by 2 × 10-6 mol·L-1 Ang II. Cell Apoptosisapoptosis, intracellular reactive oxygen species (ROS) was assessed. Endothelial nitric oxide synthase (eNOS), ET-1, SOD, and MDA in the cell culture supernatant and cell migration were assayed. The expression of hypertension-linked genes and proteins were analyzed. TT decreased systolic pressure, diastolic pressure, mean arterial pressure and heart rate, improved endothelial integrity of thoracic aorta, and decreased serum leptin, Ang II, ET-1, NPY, and Hcy, while increased NO in SHRs. TT suppressed Ang II-induced HUVEC proliferation and apoptosis and prolonged the survival, and increased cell migration. TT regulated the ROS, and decreased mRNA expression of Akt1, JAK2, PI3Kα, Erk2, FAK, and NF-κB p65 and protein expression of Erk2, FAK, and NF-κB p65. In conclusion, TT demonstrated anti-hypertensive and endothelial protective effects by regulating Erk2, FAK and NF-κB p65.

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Phytopharmacological overview of Tribulus terrestris

Saurabh Chhatre, Tanuja Nesari, Gauresh Somani … (2014)

Tribulus terrestris (family Zygophyllaceae), commonly known as Gokshur or Gokharu or puncture vine, has been used for a long time in both the Indian and Chinese systems of medicine for treatment of various kinds of diseases. Its various parts contain a variety of chemical constituents which are medicinally important, such as flavonoids, flavonol glycosides, steroidal saponins, and alkaloids. It has diuretic, aphrodisiac, antiurolithic, immunomodulatory, antidiabetic, absorption enhancing, hypolipidemic, cardiotonic, central nervous system, hepatoprotective, anti-inflammatory, analgesic, antispasmodic, anticancer, antibacterial, anthelmintic, larvicidal, and anticariogenic activities. For the last few decades or so, extensive research work has been done to prove its biological activities and the pharmacology of its extracts. The aim of this review is to create a database for further investigations of the discovered phytochemical and pharmacological properties of this plant to promote research. This will help in confirmation of its traditional use along with its value-added utility, eventually leading to higher revenues from the plant.

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The KDEL receptor modulates the endoplasmic reticulum stress response through mitogen-activated protein kinase signaling cascades.

Katsushi Yamamoto, Hiromichi Hamada, Hiroshi Shinkai … (2003)

The accumulation of misfolded proteins in the endoplasmic reticulum (ER) evokes the ER stress response. The resultant outcomes are cytoprotective but also proapoptotic. ER chaperones and misfolded proteins exit to the secretory pathway and are retrieved to the ER, during which process the KDEL receptor plays a significant role. Using an expression of a mutant KDEL receptor that lacks the ability for ligand recognition, we show that the impairment of retrieval by the KDEL receptor led to a mis-sorting of the immunoglobulin-binding protein BiP, an ER chaperone that has a retrieval signal from the early secretory pathway, which induced intense ER stress response and an increase in susceptibility to ER stress in HeLa cells. Furthermore, we show that the ER stress response accompanied the activation of p38 mitogen-activated protein (MAP) kinases and c-Jun amino-terminal kinases (JNKs) and that the expression of the mutant KDEL receptor suppressed the activation of p38 and JNK1 but not JNK2. The effect of the expression of the mutant KDEL receptor was consistent with the effect of a specific inhibitor for p38 MAP kinases, because the inhibitor sensitized HeLa cells to ER stress. We also found that activation of the KDEL receptor by the ligand induced the phosphorylation of p38 MAP kinases. These results indicate that the KDEL receptor participates in the ER stress response not only by its retrieval ability but also by modulating MAP kinase signaling, which may affect the outcomes of the mammalian ER stress response.

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Angiotensin-converting enzyme 2 activation improves endothelial function.

Rodrigo A. Fraga-Silva, Fabiana P Costa-Fraga, Tatiane M. Murça … (2013)

Diminished release and function of endothelium-derived nitric oxide coupled with increases in reactive oxygen species production is critical in endothelial dysfunction. Recent evidences have shown that activation of the protective axis of the renin-angiotensin system composed by angiotensin-converting enzyme 2, angiotensin-(1-7), and Mas receptor promotes many beneficial vascular effects. This has led us to postulate that activation of intrinsic angiotensin-converting enzyme 2 would improve endothelial function by decreasing the reactive oxygen species production. In the present study, we tested 1-[[2-(dimetilamino)etil]amino]-4-(hidroximetil)-7-[[(4-metilfenil)sulfonil]oxi]-9H-xantona-9 (XNT), a small molecule angiotensin-converting enzyme 2 activator, on endothelial function to validate this hypothesis. In vivo treatment with XNT (1 mg/kg per day for 4 weeks) improved the endothelial function of spontaneously hypertensive rats and of streptozotocin-induced diabetic rats when evaluated through the vasorelaxant responses to acetylcholine/sodium nitroprusside. Acute in vitro incubation with XNT caused endothelial-dependent vasorelaxation in aortic rings of rats. This vasorelaxation effect was attenuated by the Mas antagonist D-pro7-Ang-(1-7), and it was reduced in Mas knockout mice. These effects were associated with reduction in reactive oxygen species production. In addition, Ang II-induced reactive oxygen species production in human aortic endothelial cells was attenuated by preincubation with XNT. These results showed that chronic XNT administration improves the endothelial function of hypertensive and diabetic rat vessels by attenuation of the oxidative stress. Moreover, XNT elicits an endothelial-dependent vasorelaxation response, which was mediated by Mas. Thus, this study indicated that angiotensin-converting enzyme 2 activation promotes beneficial effects on the endothelial function and it is a potential target for treating cardiovascular disease.