Hypolipidemic effects of Hypericum Scabrum extract on the serum lipid profile and obesity in high-fat diet fed rats

Abstract

Diets included high-fat (HFD) and high calories intake is correlated with greater risk of obesity and oxidative stress, which lead to increase the risk of related diseases such as cardiovascular and metabolic disease. In the present study, we have examined the hypolipidemic activity of Hypericum Scabrum extract on HFD fed rats. Fifty-four male Wistar rats divided into six groups: 1) control, 2) H. Scabrum extract (100 mg/kg gavage per day), 3) H. Scabrum extract (300 mg/kg), 4) HFD, 5) HFD and H. Scabrum extract (100 mg/kg), 6) HFD and H. Scabrum extract (300 mg/kg). The groups were fed their diet and treatment for 3 months. Biochemical analysis showed elevated lipid serum profile in HFD rats compared to control group. H. Scabrum extract supplementation significantly ameliorated triglyceride, total cholesterol and LDL-cholesterol. H. Scabrum extract supplementation leading to increase HDL-cholesterol in HFD treated groups. This experiment showed that H. Scabrum extract decreased HFD complications and might be beneficial herbal drug for treatment of hyperlipidemia and obesity.

Keywords

High-fat diet Hypericum Scabrum obesity oxidative stress antioxidant

1. Introduction

Recently, the prevalence of obesity has increased dramatically, and it is leading to a global epidemic [1]. Obesity is a nutritional disorder and it has become the most common health problem in the world [2]. High caloric food intake such as diets rich in fats and sugars and lack of physical activity are common environmental factors associated with the growth of obesity [3]. Consumption of many calories which turned into triglycerides, leads to increase serum triglyceride (TG). Increased levels of serum TG and low-density lipoprotein cholesterol (LDL-C) have shown that unhealthy diet are primary determinants of diet-induced hyperlipidemia [4]. Obesity is associated with insulin resistance, diabetes and metabolic syndrome [5, 6]. Furthermore, dyslipidemia is one of the greatest risk factors contributing to the prevalence and severity of atherosclerosis, coronary heart disease and stroke, which are the primary cause of death in developed countries [7, 8].

It has been suggested that high serum cholesterol and low density lipoprotein cholesterol (LDL-C) levels induce oxidative stress [9]. Also hyperglycemia and hypertriglyceridemia plays a key role in vascular inflammation and leading to induce an endothelial injuries through the production of oxidative stress [10, 11]. Moreover, several studies have reported that the elevated blood lipids, particularly LDL-C, increase the production of reactive oxygen species (ROS). ROS-induced oxidative stress associated with the etiology of atherosclerosis and coronary heart disease [12, 13].

Figure 1.

Timeline of experiment.

Our previous study demonstrated the administration of high-fat diet to rats for 2–3 months is a simple way to induce metabolic syndrome, contributed with metabolic and oxidative disorders, without modulation of glycaemia [14, 15]. Also, other surveys have shown that intake of a high-fat diet for long times, reduced the superoxide dismutase (SOD), catalase (CAT) and glutathione (GSH) and increased lipid peroxidation, all of which can lead to oxidative stress and finally initiate serious diseases [16, 17].

Commonly, the first therapeutic purpose of medication of cardiovascular diseases and atherosclerosis is to decrease high levels of serum lipid’s profile, particularly LDL-C and triglycerides by drug and/or dietary intervention [18]. In this field, traditional medicines receive considerable interest for their presumed preventive effects on various diseases such as cancers and cardiovascular diseases. Accordingly, most hyperlipidemic subjects consume herbal medicines, which are rich in natural anti-oxidants, as the alternative therapeutic intervention to treat hyperlipidemia, and consequently to prevent atherosclerosis and cardiovascular disease complications [19].

Hypericum species are traditional medicinal herbs which are known as healing herbs. Hypericum Scabrum is an important genus in the family of Hypericaceae, that involves 484 species of herbs, shrubs and trees [20]. Generally, flowering parts of the Hypericum species are used as medicinal herbs [21]. Previous studies reported that H. scabrum L has anti-microbial activity. Moreover, it is used for its tranquilizer effect and has antiseptic, antidiarrhea, antihemorrhoid, antieczema, antipsoriasis, anthelmintic and antifungal activities [22]. One survey reported Hypericum perforatum L. treatments reduced body weight in rats within 15 days [23]. Our previous study, we demonstrated the anti-oxidant and anti-anxiety effects of this plant in high-fat diet fed rats [24]. The present study sought to investigate the possible beneficial antioxidant effect of H. scabrum L extracts on lipid serum profile and obesity in high-fat diet fed rats.

2. Material and methods

2.1 Animals

Adult male Wistar rats (220 $\pm$ 10 g) were purchased from Animal house of Hamadan University of Medical Sciences, hamadan, Iran. Rats were accommodated in groups of five per cage in an tempratured-controlled room at 22 $\pm$ 2 ${}^{\circ}$ C under natural 12/12 h light/dark cycle, with and 60 $\pm$ 5% relative humidity. Unlimited access to tap water and rat chow diet was prepared for rats during the experiment. All procedures of care of animals were approved by the local ethics committee of Hamadan University of Medical Sciences, also conform to the Guide for the Care and Use of Laboratory Animals published by the U.S. National Institutes of Health (NIH Publication number 85–23, revised 1996).

After one week of acclimation in new environment, the animals were divided randomly into six groups, with 6 rats in each groups: (1) Control group, was fed a standard diet; (2) Extract 100 mg/kg (Ext100) group, was fed the standard diet and treated by H. scabrum extract (100 mg/kg once a day); (3) Extract 300 mg/kg (Ext300) group, was fed the standard diet and treated by H. scabrum extract (300 mg/kg once a day); (4) HFD group, was fed high-fat diet; (5) HFD $+$ Ext100 group, was fed high-fat diet and treated by H. scabrum extract (100 mg/kg once a day); (6) HFD $+$ Ext300 group, was fed high-fat diet and treated by H. scabrum extract (300 mg/kg once a day). All diets were obtained from Research Diets. The standard diet was a standard laboratory rodent chow containing 10% energy from fat, and high-fat diet contained 45% energy from fat. Experimental timeline is shown in Fig. 1.

Figure 2.

Effects of H. scabrum extract on the plasma lipid profile in rats receiving a high-fat diet. The high-fat diet resulted in significant increase of serum lipids profile including TC, TG, HDL-C and LDL-C. (A) The TC level was significantly lower in the groups treated with H. scabrum extract than the HFD group. (B) The TG level was significantly lower in the groups fed with H. scabrum extract than that of the HFD group. (C) The LDL-C level was significantly lower in the groups treated with H. scabrum extract than that of the HFD group. (D) The HDL-C level was significantly higher in the groups fed with H. scabrum extract than that of the HFD group. ${}^{***}P<$ 0.001, ${}^{****}P<$ 0.0001 compared with the control group, ${}^{{\#}}P<$ 0.05, ${}^{{\$}}P<$ 0.0001, ${}^{{\#}{\#}}P<$ 0.01, ${}^{{\$}{\$}}P<$ 0.01, ${}^{{\#}{\#}{\#}}P<$ 0.001, ${}^{{\$}{\$}{\$}}P<$ 0.001, ${}^{{\#}{\#}{\#}{\#}}P<$ 0.0001 and ${}^{{\$}{\$}{\$}{\$}}P<$ 0.0001 compared with the HFD group. Data are expressed as the mean $\pm$ SEM for 6 samples per treatment group.

2.2 Hypericum scabrum extract

H. scabrum aerial parts were gathered in spring season of Kurdistan Mountains. This plant was identified at the Botanic Institute, Hamadan University of Medical Sciences, Iran. A voucher specimen was deposited in the Pharmacognosy and Biotechnology Department, Pharmacy faculty, Hamadan University of Medical Sciences, Iran. The aerial and flowering parts of this plant were dried in a shadow, avoiding sunlight. Dried plants subsequently were ground into powder [25, 26]. The extract was provided with 10 g of dried plant powder and 100 mL of 70% ethanol as the solvent [25, 26, 27]. The plant’s extraction was done using the maceration method for 72 hour at room temperature and in darkness [26]. Afterward, the solution of extraction was filtered three times and then dried on a rotary evaporator at 40 ${}^{\circ}$ C, the yielding of extraction was 18.5% of extract [26]. The final distillate was stored at $-$ 20 ${}^{\circ}$ C, cold normal saline was used for further dilution. H. scabrum extract at a dose of 100 mg/kg and 300 mg/kg was gavaged to two groups that received standard diet and two groups that received high-fat diet for 3 months. These doses were chosen based on the results of previous studies [28, 29].

2.3 Sample collection

After three months of treatment, the rats were anesthetized and the blood samples were collected from vena cava, centrifuged at 5000 $\times$ g for 15 minutes after 30 minutes of collection into heparinized tubes. Plasma samples were collected and transferred to Eppendorf tubes for analyses [30].

2.4 Determination of serum lipid profiles

Plasma total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), Low density lipoprotein cholesterol (LDL-C) and triglyceride (TG) concentration were measured by commercially available kits, Biosystem Products, Spain. These kits use enzymatic methods and measurements were done by reflectance spectrophotometry as previously reported [31, 32].

Figure 3.

(A) Weight of the rats at the start of the experiment were not vary significantly. (B) Weight of the rats at the end of the experiment showed significant difference in treated groups compared to HFD group. ${}^{**}p<$ 0.01 compared to control group, ${}^{\#}p<$ 0.05 and ${}^{{\#}{\#}}p<$ 0.01 compared to HFD group.

2.5 Statistical analysis

Data were analyzed using SPSS Version 24 (SPSS Inc., IL, USA). The data from the biochemical parameters were analyzed with a one-way ANOVA. Tukey’s multiple comparison tests were performed to analyze the significance of the differences between the groups, when appropriate. Statistical significance was set at $P<$ 0.05.

3. Results

3.1 Plasma lipid levels

As shown in Fig. 2A–C, the levels of plasma TC, TG, and LDL-C in the high-fat diet fed rats group were significantly higher than those in the standard diet fed rats group. Plasma TG levels were remarkably higher in the HFD group than the normal control group ( $P<$ 0.001). Plasma TG concentration of the H. scabrum extract-treated groups were significantly lower compared to the HFD group (EXT100 and EXT300; $P<$ 0.001, HFD $+$ EXT100 and HFD $+$ EXT300; $P<$ 0.01). Rats which received the H. scabrum extract had a lower plasma TC level compared to the HFD group (EXT100 and EXT300; $P<$ 0.001, HFD $+$ EXT100 and HFD $+$ EXT300; $P<$ 0.01). Treatment with a H. scabrum extract significantly lowered plasma LDL-C concentrations compared to the HFD group (EXT100 and EXT300; $P<$ 0.001, HFD $+$ EXT100 and HFD $+$ EXT300; $P<$ 0.05).

As shown in Fig. 2D, the HDL-C levels of rats in the HFD group were significantly lower than those of the control group ( $P<$ 0.0001). In addition, H. scabrum extract-treated rats had a higher HDL-C level compared to the HFD group (EXT100 and EXT300; $P<$ 0.0001, HFD $+$ EXT100 and HFD $+$ EXT300; $P<$ 0.001).

3.2 Weight determination

The body weight was measured at the before and after the experiment. The post hoc analysis of body weight at the end of the experiment showed that body weight of HFD group was significantly higher compared to the normal groups, and the body weight of HFD group treated with H. scabrum extract was significantly lower compared with the HFD group (Fig. 3).

4. Discussion

The aim of the present research was to show the effects of H. scabrum extract on obesity and lipid profiles of HFD fed rats. In this experiment, plasma TC, TG, LDL-Cholesterol were shown to be significantly increased, and plasma HDL-Cholesterol was shown to be decreased in high-fat fed rats. These results are consistent with Aouadi et al., who attributed these changes to endogenous synthesis [33], and Gulam Mohammed Husain et al. reported that high-fat diet fed Animals showed significant improvement in body weight compared to those fed with standard diet [23]. The deleterious effects of high-fat diet on the lipid serum profile and obesity, as observed in this study, were somehow expected since HFD induced impairment in lipid metabolism and anti-oxidative mechanism have previously been reported [14, 15].

In the last few decades we have witnessed the increasing popularity of natural medicine in developed countries [34]. Oral administration of H. scabrum extract reversed the changes induced by HFD. In our study, H. scabrum extract treatment remarkably decreased the plasma TG, TC, and LDL-C levels in HFD fed rats. Treatment by this extract also elevated plasma HDL-C concentration in animals fed by HFD. These findings indicate that H. scabrum extract could alleviate lipid profiles through lipid metabolism. Previous studies indicated similar results, as Hypericum perforatum aqueous extracts were found to reduce serum LDL-C in the control of Hypericum perforatum extract group and the hyperlipidemia with treatment by Hypericum perforatum extract group, and total cholesterol was significantly reduced in the control of Hypericum perforatum extract group in rats [26]. Another study was conducted by Habib et al. reported that treatment by total extract of Hypericum perforatum at the dose dependent manner could reduce the levels of total cholesterol, TG, LDL-C [26]. Accordingly, Asgari et al. demonstrated that Hypericum perforatum extract significantly reduced the levels of triglyceride, cholesterol, LDL-C, oxidized LDL-C and increased HDL-C in the rabbits that received standard diet and cholesterol (1% of food content) [35]. Moreover, in agreement with our findings, one study showed ethanol extract of Hypericum significantly lowered LDL-cholesterol and total cholesterol levels in the high cholesterol diet fed rabbits [36].

Therefore, this study showed that H. scabrum extract might be considered as candidate agents for adjuvant therapy in lowering blood TG, total cholesterol and LDL-C. The beneficial antioxidant effect of H. scabrum extract on animal models has also been reported in our previous studies [24]. These findings indicate that, ingredients of H. scabrumprobably act as lipid-lowering agents and might be beneficial in preventing hyperlipidemia and oxidative stress. In this line, another study reported that cholesterol level decrease after administration of Hypericum perforatum extract, and this study suggested cholesterol-lowering effect is probably caused by increased fecal excretion of biliary acids and cholesterol, and inhibition of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) [27].

Lipid-lowering property of H. scabrum is also mediated, albeit in part, by the anti-oxidant pathway that assayed by activity of anti-oxidant’s enzymes such as glutathione peroxidase or the levels of lipid peroxidation. In our previous study H. scabrum extract increased the plasma antioxidant capacity and oxidation resistance by raising the activity of antioxidant enzymes (Catalase, Glutathione peroxidase) and GSH level, and also by decreasing the plasma malondialdehyde level [24, 37]. One of the major component of oxidative defense system is GSH, which is consumed by the glutathione reductase (GR) to detoxify peroxides produced due to increased lipid peroxidation [20], and another important one is MDA, which is an important indicator of lipid peroxidation. Also catalase and super oxide dismutase (SOD) are important enzymes, which could clear oxidant’s spices [38]. Although hyperlipidemia is the important cause for atherosclerosis and lipid peroxidation [39]. In agreement with our study, another research revealed that increased levels of hepatic LP, FRAP and increased SOD activity were rameliorated in the rats treated with Hypericum scabrum oils. Furthermore, the lowered GSH levels were compensated with the Hypericum scabrum oils adminstration [40]. In another study, it was found that the anti-oxidant ability of ethanol extracts of H. scabrum L. and H. retusum against the protein oxidation and DNA damage [41], and accordingly, the ethanol extract of Hypericum significantly decreased the serum MDA levels in the high cholesterol diet fed rabbits [36].

Hypericum extract’s effects were associated with the component of this plant. Primary component of Hypericum species contain hypericin, tannins, flavonoids, phenolic acids, quercetin, hyperoside, isoquercitrin, chlorogenic acid and rutin [20]. Anti-oxidant’s potency of several species of Hypericum have been examined and reported previously [42, 43]. According to Zou et al. the free radical scavenging of Hypericum perforatum extract might be linked to its abaundant quantities of flavonoid compounds [44].

In the present study we found that this extract effectively inhibited body weight gain of rats consumed HFD. Accordingly, another study showed that Hypericum perforatum extract suppressed the increase in body weight induced by high-fat diet in dose-dependent manner [23]. In this line, it is a well-known fact that, serotonin is an important neurotransmitter in the brain and there is an inverse relationship between the level of brain serotonin signaling and food intake, this fact means when brain serotonin signaling is raised, food consumption is decreased, and vice versa [45, 46]. One antiobesity acting mechanism reported for H. perforatum is the quantity of serotonin present within synaptosomes and inhibiting the synaptosomal uptake of serotonin [23, 47]. Also whole plant extract of Hypericum species showed anti-depressive ability by modify neurotransmitter levels in the brain. The anti-depressive, anti-carcinogenic and anti-microbial activities of these plants are currently under investigation [48, 49, 50]. On the other hand, our previous study showed protective ability of H. scabrum extract on learning and memory impairment induced by HFD [37]. All these findings showed probable activity of this extract on the brain and suggest effect of this on neurotransmitters production and activity. This increased level of serotonin reduces the food intake and suppresses the appetite [51]. Anti-obesity effects of H. scabrum extract can be explained by serotonin signaling, that needs more examination to determine this mechanism.

It can be concluded that the results of the present study and our previous studies showed that H. scabrum has the potential anti-obesity, anti-oxidant and hypolipidemic effects. As a final conclusion, H. scabrum could be suggested as supplementation to hyperlipidemia patient.

Footnotes

Acknowledgments

This research was supported by a grant (Grant number: 94011852) of the Neurophysiology Research Center, Hamadan University of Medical Sciences, Hamadan, Iran.

Conflict of interest

There is no conflict of interest.

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