Pre-hypertension is a transitional stage from normotension to hypertension. Obesity, a risk factor for Pre-hypertension, not only leads to increased blood pressure but also promotes the development of metabolic syndrome. Metabolic syndrome, also known as insulin resistance syndrome, is a common condition that includes insulin resistance, abdominal obesity, hypertension, and dyslipidemia (significantly elevated total cholesterol(TC), low-density lipoprotein cholesterol(LDL), and reduced high-density lipoprotein cholesterol(HDL) levels)(McCracken, Monaghan et al., 2018).Pre-hypertension and metabolic syndrome are lifestyle diseases exacerbated by obesity, as both disease processes are strongly associated with body weight (Kachur, Morera et al., 2018, Kokubo & Kamide, 2009).An elevated visceral obesity index leads to increased blood pressure(Leite, Cota et al., 2021). Especially, the obese or have metabolic syndrome have higher vasoconstriction, which increases blood pressure via endothelin receptor A (Rocha, Templeton et al., 2014).The prevalence of metabolic syndrome among young adults in the United States is increasing yearly (Hirode & Wong, 2020). Therefore, the treatment of obesity and Pre-hypertension is of great significance.
Obesity is a risk factor for the development of metabolic syndrome in humans(Sumner, Khalil et al., 2012), and the adipose tissue, is central to the development and progression of metabolic syndrome, contributing to the development of hypertension(Katsimardou, Imprialos et al., 2020, Kotsis, Stabouli et al., 2010, Kumari, Kumar et al., 2019). As overnutrition leads to adipocyte hypertrophy or proliferation, hypertrophic adipocytes grow beyond their blood supply, inducing a hypoxic state (Halberg, Wernstedt-Asterholm et al., 2008)could further lead to cellular necrosis, producingpro-inflammatory factors, and increasing blood pressure.Increased serum TG levels exacerbate insulin resistance, which activates the sympathetic nervous system, upregulates angiotensin II receptors, and reduces nitric oxide synthesis, leading to increased heart rate and blood pressure(Mancia, Bousquet et al., 2007, Tziomalos, Athyros et al., 2010). Free fatty acids associated with obesity also contribute to elevated blood pressure(Iannello, Milazzo et al., 2007).Triglycerides(TG) are the most abundant lipids in the body, contributing to the development and progression of hypertension by forming large amounts of free fatty acids, disrupting the integrity of vascular endothelial cells, inactivating nitric oxide oxidation, and causing endothelial dysfunction(Lundman, Eriksson et al., 1997). Studies showed that diglycerides have important functions in lowering blood lipids, reducing visceral fat, and inhibiting weight gain by inhibiting the accumulation of TC in the body(Nagao, Watanabe et al., 2000).
TCM is widely used in China and Asia, and many herbs or herbal extracts are effective in controlling blood pressure and lowering blood lipids(Tian, Zhang et al., 2020, Zhang, Liu et al., 2020). The TCM prescription San-Zi-Yang-Qin Decoction (SZD)originated from "Han Shi Yi Tong",comprises three traditional Chinese medicines:Semen Raphani(dried ripe seeds of Raphanus sativus L.), Perilla frutescens (L.) Britt.(ried ripe fruits of the plant Perilla), and Sinapis alba L.( dried ripe seeds ofSinapis alba L.).As the most used drug in prescription, modern pharmacological studies have shown that Semen Raphani contains a variety of active compounds with antihypertensive effects, such as alkaloids and sinapine(Gao, Wang et al., 2022). The alkaloids in the aqueous extract of Semen Raphani were found to have significant antihypertensive effects, improving vascular endothelial damage in hypertensive rats(Li, Jiang et al., 2015b). In addition, the water-soluble alkaloids showed significant protective effects against oxidative damage by reducing serum malondialdehyde levels and enhancing superoxide dismutase activity in vivo(Sham, Yuen et al., 2013, Tian, Jiang et al., 2018, Xu, Li et al., 2017).As compositional indicators and pharmacologically active components (Li, Yang et al., 2015a), sinapine is present in the form of sinapine thiocyanate (ST) in Semen Raphani and Semen Sinapis(Guan, Lin et al., 2022), ST has been shown to have clear antihypertensive effects (Guan et al., 2022)and inhibit vascular inflammation by inhibiting the secretion of adhesion factors by the vascular endothelium (Li et al., 2015a). In addition, STreducedthe expression of coagulation-related factors in vascular endothelial cells, thereby inhibiting the thrombotic state caused by endothelial inflammatory injury (Li, Zhang et al., 2017)andimproving hypertensive endothelial dysfunction by inhibiting the activation of nucleoside-bound leucine-rich repeat receptor inflammasome (Liu, Yin et al., 2020). Perillae Fructus seeds are a good source of fatty acid components such as oleic, linoleic, and linolenic acids(Ahmed, 2018),which are expected to have various health benefits in humans such as lowering serum cholesterol and TC levels, and preventing excessive visceral adipose tissue growth (Asif, 2011, Yu, Qiu et al., 2017).In this study, SZD emphasized the dosage of Semen Raphaniin the proportion of drugs to increase the amount ofST, improvingthe antihypertensive effect of SZD. TCMhaslong been used in China for the treatment of various diseases with good results(Guo, Luo et al., 2020, Wu, Zhang et al., 2019), whereas the efficacy and therapeutic goals of SZD for obesity Pre-hypertension are unclear due to the lack of modern scientific and technological support.
In recent years, metabolomics has been increasingly applied to reveal the mechanism of efficacy of herbal prescriptions for the treatment of diseases, especially the untargeted and targeted metabolomics approaches based on liquid chromatography-mass spectrometry.Non-targeted metabolomics is the most comprehensive coverage of metabolites possible (Patti, Yanes et al., 2012),providing a larger number of metabolites (Wang, Chen et al., 2017, Yang & Lao, 2019, Yin & Xu, 2014),however, the reproducibility and linear range of metabolites are limited (Zhang, Wu et al., 2020, Zheng, Zhao et al., 2020).Targeted metabolomics is the absolute quantification of specific metabolites (Griffiths, Koal et al., 2010). It can provide a wide linear range, high reproducibility, and sensitivity compared to non-targeting, but low efficiency and narrow coverage of metabolite detection (Wei, Li et al., 2010).Therefore, a pseudo-targetedmetabolomics strategy is proposed to combine the advantages of non-targeting and targeting to establish an alternative to non-targeting methods with high sensitivity, high specificity, and excellent quantitative capabilities(Chen, Kong et al., 2013, Li, Ruan et al., 2012). Rich metabolite information from untargeted metabolic profiles based on UPLC-Q-Orbitrap-MS ensures high coverage(Zheng et al., 2020),expanding the linear range of target metabolites for selected metabolites,improvingdetection accuracy and accurate identification of potential biomarkers(Xu, Li et al., 2019).
This study constructed a high-salt + high-fat rat model of obese Pre-hypertension. Then, the therapeutic effect of SZD on obese Pre-hypertension was evaluated by combining blood pressure, body weight, Lee's index, and biochemical parameters in serum. Finally, a non-targeted metabolomics approach was used to analyze the metabolites associated with SZD intervention in the obese Pre-hypertension rat model, and a pseudo-targeted metabolomics approach was used to analyze the changes in metabolite levels associated with SZD intervention and to characterize the specific metabolic pathways associated with SZD intervention.