Aqueous extract of dioscorea opposita thunb. normalizes the hypertension in 2K1C hypertensive rats

Amat et al. BMC Complementary and Alternative Medicine 2014, 14:36 http://www.biomedcentral.com/1472-6882/14/36 RESEARCH ARTICLE Open Access Aqueous extract of dioscorea opposita thunb. normalizes the hypertension in 2K1C hypertensive rats Nurmuhammat Amat1*†, Raziya Amat1, Sajida Abdureyim2, Parida Hoxur3, Zulpiya Osman1, Dolkun Mamut4*† and Anake Kijjoa5 Abstract Background: Dioscorea opposita Thunb. (Huai Shan Yao, DOT), a common staple food in China, has been used for more than 2000 years in traditional Chinese medicine (TCM) to treat different systemic diseases including hypertension. The objective of this study was to investigate the possible antihypertensive effects of the aqueous extract of (DOT) in renovascular hypertensive rats as well as the mechanism in reducing blood pressure. Methods: The two-kidney one-clip (2K1C) Goldblatt model of renovascular hypertension was used in Wistar rats. Rats with captopril, low-dose DOT and high-dose DOT treated 2K1C groups for 6 weeks. The blood pressure, cardiac mass index (heart weight/body weight), plasma level of angiotensin-II (Ang-II), endothelin-1(ET-1), superoxide dismutase (SOD) and malondialdehyde (MDA) were evaluated. Results: DOT significantly reduced mean systolic and diastolic blood pressure after treatment. DOT also significantly increased plasma SOD activity but decreased plasma MDA concentration. Renal function was improved with captopril and DOT. DOT reduced plasma Ang-II activity and plasma ET concentration. They couldalso significantly reduce the left ventricular hypertrophy and cardiac mass index. Conclusions: Our results suggest that DOT may have an antihypertensive effect on hypertension by inhibit ET-converting enzyme and antioxidant activity, which warrant further exploration. Keywords: Antihypertensive, Dioscorea opposite Thunb, 2K1C experimental hypertension, Angiotensin-II, Endothelin-1, Hypertrophy Background Hypertension is the most common risk factor for myocardial infarction, stroke, heart failure, arterial fibrillation, aortic dissection and peripheral arterial diseases. It is among the most common chronic illnesses the world faces [1,2] and remains the leading cause of death worldwide and one of the world’s greatest public health problems. Although many new antihypertensive drugs with improved efficacy have been introduced to the market, they still possess serious side effects. On the one hand, nutrition and physical exercises are gaining more importance in the * Correspondence: ; † Equal contributors 1 Traditional Uighur Medicine Institute, Xinjiang Medical University, 830011 Urumqi, Xinjiang, PR China 4 Salamat Biotechnology Co., Ltd, Urumqi, Xinjiang 830011 PR China Full list of author information is available at the end of the article treatment of hypertension. On the other hand, attention has recently been focused on herbal and mineral preparations which are traditionally used as potential therapeutic agents in the prevention and management of cardiovascular diseases [3-6]. Chinese yam or Shan yao comprises various species of the genus Diascorea, which are widely cultivated in China and their tubers are used as food as well as for medicinal purposes. Shan yao has been considered as an important invigorant in traditional Chinese medicine (TCM) for many years [7]. However, the most important variety is Dioscorea opposita Thunb. or Huai Shan Yao in Chinese, which is used in TCM as a tonic for more than 2000 years. It is generally believed that an intake of the Chinese yam may be beneficial to improve the function of the spleen, stomach, kidney and lung. As a result, © 2014 Amat et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Amat et al. BMC Complementary and Alternative Medicine 2014, 14:36 http://www.biomedcentral.com/1472-6882/14/36 Page 2 of 10 it is used clinically for the treatment of poor appetite, chronic diarrhea, asthma, dry cough, frequent or uncontrollable urination, diabetes and emotional instability [8,9]. (Chinese Pharmacopoeia, 2005 edition). The Chinese yam contains a variety of phytochemicals, including saponins, starch, mucopolysaccharides, protein, amino acids, mucilage, polyphenols etc. [10-13]. Modern research showed that yam extract has many physiological functions such as anti-diabetic, anti-hypercholesterolemia, anti-acetaminophen-induced hepatotoxicity and nephrotoxicity as well as antioxidant activity [12,14-17]. Interestingly, the water yam (Dioscorea alata L.), another species Shan yao has been shown to possess antihypertensive activity in hypertensive animal models [18], suggesting that consumption of fresh yam tubers has potential health benefits for human beings. Moreover, powdered and liquid yam products are nowadays extensively used in a variety of food products in China and countries in the Far East. Due to the increasing concern about the influence of foods on health condition, we have investigated the effect of the aqueous extract of untreated control group (DOT) on hypertension. Of the various experimental or genetic models of hypertension, the Goldblatt chronic two-kidney, one-clip hypertension (2K1C) is a classical model of renovascular angiotensin-II-dependent hypertension. Experimental model of renal (Goldblatt) hypertension is one of the widely used models for the study of pathophysiology of hypertension and antihypertensive drugs [19]. The fact that the renin–angiotensin system (RAS) contributes critically to the pathophysiology of 2K1C Goldblatt hypertension is well established [20]. The 2K1C model, which exhibits a transient increase in the activity of RAS and a sustained rise in blood pressure, has been described as very close to human mature hypertension [21,22]. Thus, hypertension in this model is primarily the result of an augmented total peripheral resistance and, in mild cases of renal artery stenosis, bilateral reduction in renal-clearance function [23]. These physiological abnormalities are principally the result of a considerable increase in tissue and circulating levels, and direct actions of Ang-II [24]. Evidence shows that as the condition advances, the role of Ang-II in maintaining hypertension subsides, and other mediators become more effective in determining the level of blood pressure [25,26]. Therefore drugs acting on RAS are major factors in the treatment of hypertension. The occurrence of hypertension is related to many factors. A large number of clinical studies and animal experiments showed that there is a close relationship between hypertension and free radicals. In recent y (...truncated)