Serum Metabolomics Study Based on LC-MS and Antihypertensive Effect of Uncaria on Spontaneously Hypertensive Rats

Hindawi Evidence-Based Complementary and Alternative Medicine Volume 2018, Article ID 9281946, 11 pages https://doi.org/10.1155/2018/9281946 Research Article Serum Metabolomics Study Based on LC-MS and Antihypertensive Effect of Uncaria on Spontaneously Hypertensive Rats Ana Liu,1 Yan-Jun Chu,2 Xiaoming Wang,1 Ruixue Yu,1 Haiqiang Jiang ,3 Yunlun Li ,2 Honglei Zhou,1 Li-Li Gong,3 Wen-Qing Yang,2 and Jianqing Ju2 1 Pharmacy School, Shandong University of Traditional Chinese Medicine, Jinan 250355, China Traditional Chinese Medicine Clinical Research Base for Hypertension of Affiliated Hospital, Shandong University of Traditional Chinese Medicine, Jinan 250011, China 3 Experimental Center, Shandong University of Traditional Chinese Medicine, Jinan 250355, China 2 Correspondence should be addressed to Haiqiang Jiang; and Yunlun Li; Received 13 July 2017; Revised 15 October 2017; Accepted 26 November 2017; Published 4 April 2018 Academic Editor: Bhavanath Jha Copyright © 2018 Ana Liu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Our previous studies have shown that Uncaria has an important role in lowering blood pressure, but its intervention mechanism has not been clarified completely in the metabolic level. Therefore, in this study, a combination method of HPLC-TOF/MS-based metabolomics and multivariate statistical analyses was employed to explore the mechanism and evaluate the antihypertensive effect of Uncaria. Serum samples were analyzed and identified by HPLC-TOF/MS, while the acquired data was further processed by partial least squares discriminant analysis (PLS-DA) and orthogonal partial least squares discriminant analysis (OPLS-DA) to discover the perturbed metabolites. A clear cluster among the different groups was obtained, and 7 significantly changed potential biomarkers were screened out. These biomarkers were mainly associated with lipid metabolism (dihydroceramide, ceramide, PC, LysoPC, and TXA2) and vitamin and amino acids metabolism (nicotinamide riboside, 5-HTP). The result indicated that Uncaria could decrease the blood pressure effectively, partially by regulating the above biomarkers and metabolic pathways. Analyzing and verifying the specific biomarkers, further understanding of the therapeutic mechanism and antihypertensive effect of Uncaria was acquired. Metabolomics provided a new insight into estimate of the therapeutic effect and dissection of the potential mechanisms of traditional Chinese medicine (TCM) in treating hypertension. 1. Introduction Hypertension, a complex and multifactorial disease, is closely associated with gene, environment, and metabolic factor, also the most vital risk factor for cardiovascular disease and chronic kidney disease [1]. With the development of study, various theories had been proposed on the pathogenesis of hypertension. Previous research had indicated that endothelial dysfunction might be a crucial mechanism in pathogenesis of hypertension [2]. Under the damage of endothelial cells, active molecules such as ATP and 5-HT would be released. Because these molecules inhibited the activities of NO, CGRP, and other relaxing factors, the activities of ET and TXA2 were increased. Finally, these substances would lead to the increasing blood pressure level [3–5]. In another study, hypertension was considered as a neurogenic disease and it is proposed that the pathology of hypertension was significantly associated with multiple factors in neuroendocrine system [6]. In modern medicine, the hypertension had been studied from above perspectives. In the treatment of hypertension, the traditional Chinese medicine (TCM) has formed a unique theoretical system and control methods. Chinese herbal medicines provided rational means for hypertension. Uncaria was employed in treating hypertension as a safe and effective therapy due to characteristics of multiple targets, 2 Evidence-Based Complementary and Alternative Medicine multiple pathways, and fewer side effects [7]. Uncaria, with Chinese name of Gouteng and the Latin name of Uncaria rhynchophylla (Miq.) from Chinese Pharmacopoeia 2015 version, was firstly recorded in the Chinese medical classics “Compendium of Materia Medica.” Rhynchophylline and isorhynchophylline are the mainly bioactive components in Uncaria [8, 9]. Our previous studies indicated that Uncaria had effects on lowering blood pressure, protecting vascular endothelial cell, and inhibiting vascular smooth muscle proliferation [10, 11]. The antihypertensive mechanism of Uncaria is still unclear, although it has been in widespread application. In modern medicine, the holistic and systemic properties of TCM are consistent with the characters of metabolomics. Therefore, metabolomics might be the bridge between TCM and modern medicine. So metabolomics could be employed to perform such a comprehensive investigation. Metabolomics, as an important branch of systems biology, provides a comprehensive insight into the rule of metabolite changes. The metabolic variations of organism could be able to be systematically explored with the comprehensive analysis of metabolic result [12]. At present, metabolomics has been widely used in animal model validation [13], disease diagnosis [14], drug toxicity evaluation [15], and drug research and development [16]. And it could evaluate and interpret therapeutic effects of some Chinese medicines [17–19]. Metabolomics analysis required highdensity information on a wide range of compound classes and chemistries, as well as high precision. Many technologies, including NMR, GC-MS, LC-MS, and CE-MS [20], have been developed to perform metabolomics analysis. Because of its high sensitivity, high precision, low sample size, and good reproducibility, LC-MS became one of the most frequent significant tools in metabolomics researches [21]. In this study, the metabolic profiling in serums of spontaneously hypertensive rats (SHRs) and drug treated SHRs was analyzed by HPLC-MS. Both antihypertensive efficacy and potential mechanism of Uncaria were explored in our experiment. The results of this paper provided further evidence to understand the pathology of hypertension and the intervention effects of Uncaria. results of precision, stability, repeatability, and recovery in the determination of Uncaria content were also illustrated in the supplementary material. Acetonitrile of HPLC grade was purchased from Merck (Darmstadt, Germany). Formic acid of HPLC grade was obtained from Tedia (Fairfield, OH, USA). Distilled water was produced by Milli-Q Reagent water system (Millipore, MA, USA). Others were of analytical grade. 2. Materials and Methods 2.1. Chemicals and Reagents. The dried Uncaria (collected in Huaihua, Hunan, China) was authenticated as stem and branch with hook from Uncaria rhynchophylla (Miq.) by Professor (...truncated)