EVALUATIN OF ANTIHYPERTENSIVE ACTIVITY OF SONCHUS ASPER L. IN RATS

Transcription

1 Acta Poloniae Pharmaceutica ñ Drug Research, Vol. 73 No. 2 pp. 425ñ431, 2016 ISSN Polish Pharmaceutical Society EVALUATIN OF ANTIHYPERTENSIVE ACTIVITY OF SONCHUS ASPER L. IN RATS MUHAMMAD NAVEED MUSHTAQ 1, MUHAMMAD SHOAIB AKHTAR 1, ALAMGEER 1, TASEER AHMAD 2, HAFEEZ ULLAH KHAN 1, SAFIRAH MAHEEN 1, HASEEB AHSAN 1, HUMA NAZ 1, HIRA ASIF 1, WAQAS YOUNIS 1 and NAZIA TABASSUM 1 1 Faculty of Pharmacy, University of Sargodha, Sargodha, Pakistan 2 Shifa College of Pharmaceutical Sciences, Shifa Tameer-e-Millat University, Islamabad, Pakistan Abstract: The present investigation was carried out to evaluate the effect of aerial parts of Sonchus asper L. in normotensive, glucose and egg feed diet induced hypertensive rats. Aqueous-methanolic extract of Sonchus asper in 250, 500 and 1000 mg/kg doses was studied in normotensive and glucose induced hypertensive rats using the non-invasive technique. The results obtained showed that the extract has significantly (p < p < 0.001) decreased the blood pressure and heart rate in dose dependent manner. The dose 1000 mg/kg of the extract produced the maximum antihypertensive effect and was selected for further experiments. The extract was found to prevent the rise in blood pressure of egg and glucose fed rats as compared to control group in 21 days study. The LD 50 of the plant extract was 3500 mg/kg b.w. in mice and sub-chronic toxicity study showed that there was no significant alteration in the blood chemistry of the extract treated rats. It is conceivable, therefore, that the aqueous-methanolic extract of Sonchus asper has exerted considerable antihypertensive activity in rats and has duly supported traditional medicinal use of plant in hypertension. Keywords: Sonchus asper, antihypertensive, rats, toxicity studies Cardiovascular diseases have become a serious medical problem throughout the world and are thought to be the most common cause of death by the year 2020 (1). According to National Health Survey of Pakistan, about one hundred thousand deaths occur every year in this country due to these diseases. Inspite of abundant use of synthetic medications, a large majority of populations in developing countries still rely on traditional herb remedies health needs (2). In addition, medicinal plants are regarded as an important tool for new drug development because of their free availability and cost effectiveness (3). Ethnobotanical surveys have indicated their vast use in the treatment of cardiovascular disorders (4-6). Sonchus asper L. (Family: Compositae) is an indigenous plant that has been traditionally used for the treatment of various ailments of liver, lungs, heart and kidneys. It is recommended for wounds, gastrointestinal infection, diabetes, cardiac dysfunction jaundice and even cancer (7, 8). The present study was conducted to evaluate effects of Sonchus asper on blood pressure of normotensive and diet induced hypertensive rats to validate its use in traditional medicine. EXPERIMENTAL Drugs and chemicals All chemicals used were of analytical grade. Methanol and glucose were purchased from Sigma Chemical Co. Animals Sprague-Dawley rats ( g) and albino mice (23-40 g) of either sex were used. These animals were housed in controlled environment (23-25 O C) in animal house, Faculty of Pharmacy, University of Sargodha, Sargodha. They were normally fed standard diet and tap water. All animals were treated according to the standard procedures. The study protocol was approved by the local ethical committee of Faculty of Pharmacy, University of Sargodha. * Corresponding author: naveedmushtaq46@gmail.com, phone:

2 426 MUHAMMAD NAVEED MUSHTAQ et al. Plant material Fresh green aerial parts of the Sonchus asper were collected from Sillanwali (Sargodha). The plant was identified and authenticated by Dr. Ameen Ullah Shah, taxonomist, Department of Biological Sciences, University of Sargodha. The plant material was dried under the shade, grounded by using a herbal grinder and stored at 4 O C for further experiments. A voucher sample (Sa ) has been deposited in Herbarium, Faculty of Pharmacy, University of Sargodha for future reference. Preparation of extract Aqueous-methanolic extract of Sonchus asper was prepared by taking a known amount of plant material and soaking in a mixture of distilled water (30%) and methanol (70%) for 72 h at room temperature. It was filtered through muslin cloth and then through filter paper. The solvent was evaporated under reduced pressure using a rotary evaporator. The extract was placed in Petri dishes for further drying and then it was lyophilized. The percentage yield of the dried extract was 17%. The extract was stored in well closed cellophane bags in refrigerator. Determination of hypotensive activity in normotensive rats Normotensive rats of either sex were randomly assigned into three groups (n = 6). Aqueousmethanolic extract of Sonchus asper was administered at doses 250, 500 and 1000 mg/kg b.w. to group 1, 2 and 3, respectively. The blood pressure and heart rate of animals were measured at 0, 2, 4 6 and 8 h after extract doses administration using non-invasive technique. For estimation of blood pressure, rats were placed in the NIBP restrainers and appropriate cuff with sensor was then mounted on its tail and warmed to about 33ñ35 O C. The tail cuff was inflated to a pressure well above the expected systolic blood pressure i.e., 250 mmhg and slowly released during which the pulses were recorded by using power lab data acquisition system and lab chart 5.0 software. Systolic blood pressure (SBP), mean blood pressure (MBP) and heart rate were measured directly using pulse tracing while diastolic blood pressure (DBP) was calculated from SBP and MBP using formula: DBP = (3MBP - SBP)/2 (9, 10). Determination of antihypertensive activity in glucose induced hypertensive rats The experiment was performed according to previously described method with some modifications (9). Briefly, rats of either sex were randomly assigned into three groups (n = 6) and were provided 10% glucose solution instead of tap water for 21 consecutive days. At 22 nd day, animals in group 2, 3 and 4 were treated with 250, 500 and 1000 mg/kg doses of aqueous-methanolic extract. The blood pressure and heart rate of animals in all groups were measured at 0, 2, 4, 6 and 8 h after drug treatments. Egg feed induced hypertensive rats Sprague Dawley rats of either sex were divided into two groups (n = 6). Group I was given a specially prepared egg feed diet for 21 consecutive days in order to produce cholesterol-induced hypertension. Animals in group II were given egg feed diet and crude extract of Sonchus asper in 1000 mg/kg dose for the same time period. Animals in all the Table 1. Effects of aqueous-methanolic extract of Sonchus asper on systolic (SBP), mean (MBP) and diastolic (DBP) blood pressure (in mm of Hg) and heart rates (HR in beats/min) in normotensive rats. Time (h) Treatment with aqueous-methanolic extract of Sonchus asper 250 mg/kg 500 mg/kg 1000 mg/kg SBP MBP DBP HR SBP MBP DBP HR SBP MBP DBP HR 0 h ± 2.4 ± 0.77 ± 0.9 ± 10.4 ± 0.45 ± 0.73 ± 0.6 ± 9.82 ± 1.03 ± 0.32 ± 0.82 ± h ± 2.30 ± 0.89 ± 0.68 ± 6.5 a ± 1.52 ± 0.59 ± 0.7 ± 5.13 a ± 3.2 a ± 2.00 ± 3.45 ± 4.60 b 4 h ± 4.69 ± 2.5 a ± 1.03 ± 4.78 b ± 2.58 a ± 1.1 a ± 1.1 ± 7.65 b ± 2.1 b ± 1.46 ± 1.5 a ± 5.09 c 6 h ± 1.8 b ± 3.7 b ± 0.8 ±8.6 b ± 2.7 b ± 2.3 b ± 0.4 a ± 7.2 b ± 1.6 c ± 1.6 b ± 2.65 b ± 5.21 c 8 h ± 1.72 ±2.78 ± 0.78 ± 8.31 ± 2.60 ± 2.3 ± 1.13 ± 6.3 ± 1.40 c ± 1.54 c ± 2.05 c ± 4.21 c Results are expressed as the means ± S.E.M (n = 6), a = (p < 0.05), b = (p < 0.01), c = (p < 0.001) vs. control (0 h).

3 Evaluation of antihypertensive activity of Sonchus asper L. in rats 427 Table 2. Effects of aqueous-methanolic extract of Sonchus asper on systolic (SBP), mean (MBP) and diastolic (DBP) blood pressure (in mm of Hg) and heart rates (HR in beats/min) in glucose induced hypertensive rats. Time (h) Treatment with aqueous-methanolic extract of Sonchus asper 250 mg/kg 500 mg/kg 1000 mg/kg SBP MBP DBP HR SBP MBP DBP HR SBP MBP DBP HR 0 h ± 2.32 ± 0.67 ± 0.91 ± 10.0 ± 0.48 ± 0.71 ± 0.78 ± 9.80 ± 1.00 ± 0.36 ± 0.84 ± h ± 2.02 ± 0.59 ± 0.6 ± 6.6 a ± 1.62 ± 0.59 ± 0.78 ± 7.13 a ± 3.2 a ± 2.24 ± 3.75 ± 4.70 bb 4 h ± 4.6 ± 2.5 a ± 1.08 ± 4.67 b ± 1.48 a ± 1.2 a ± 1.11 ± 8.65 b ± 2.76 b ± 1.48 a ± 1.51 a ± 5.1 cc 6 h ± 1.8 b ± 3.5 b ± 0.8 ± 8.1 b ± 2.81 b ± 2.47 b ± 0.8 a ± 7.2 b ± 1.6 c ± 1.6 b ± 2.75 b ± 5.22 cc 8 h ± 1.8 b ± 3.6 b ± 0.89 ± 8.02 b ± 2.83 b ± 2.2 c ± 0.8 b ± 7.2 b ± 1.5 c ± 1.3 c ± 2.2 c ± 4.12 cc Results are expressed as the means ± S.E.M. (n = 6), a = (p < 0.05), b = (p < 0.01), c = (p < 0.001) vs. control (0 h). Table 3. Effects of treatment with aqueous-methanolic extract of Sonchus asper on various other biochemical parameters in rats. Parameters Untreated Treated with extract Control values (1000 mg/kg) ALT (IU/L) 40.1 ± ± 1.69 o AST(IU/L) 90.1 ± ± 1.09 o ALP(IU/L) 70.0 ± ± 1.94 o Triglycerides (mg/dl) 89.2 ± ± 1.74 o Total cholesterol (mg/dl) 60.5 ± ± 1.02 o LDL (mg/dl) ± ± 1.09 o HDL (mg/dl) 33.4 ± ± 2.02 o Values are expressed as the means ± SEM (n = 6) where o = non-significant as compared to control. groups were given normal saline instead of tap water ad libitum. Blood pressure and heart rate of each of these groups were measured at week 0, week 1, week 2, and week 3 using NIBP measuring apparatus (11). Glucose fed hypertensive rats Sprague Dawley rats of either sex were randomly assigned into two groups (n = 6). Group I received 10% glucose solution instead of tap water for 21 consecutive days. Animals in group II were given 10% glucose solution and crude extract of Sonchus asper in 1000 mg/kg dose. Animals were fed on standard diet. Blood pressure and heart rate of these groups were measured at week 0, week 1, week 2, and week 3 using NIBP measuring apparatus (9, 12). Acute toxicity test The aim of this experiment was to determine the LD 50 of the crude extract of Sonchus asper in mice. Mice of either sex, weighing g were randomly divided into five groups of 2 animals each. Group 1 served as control and received normal saline (10 ml/kg) while Group 2, 3, 4, 5 and six were given different doses of aqueous-methanolic extract of Sonchus asper in an ascending order i.e., 500, 1000, 2000, 3000, 4000 mg/kg, respectively. The mortality rate and any signs of toxicity were observed for 24 h. All the doses were administered by intraperitoneal route. The highest dose, which did not kill any animal, and the lowest dose, which killed only one mouse were noted. LD 50 were calculated from the arithmetic mean of these two doses (13). Subchronic toxicity study Rats of either sex were randomly divided into two groups (n = 6). The first group was the control and received normal saline (5 ml/kg b.w., p.o.) and group 2 was given 1000 mg/kg b.w. of aqueousmethanolic extract of Sonchus asper for 29 days.

4 428 MUHAMMAD NAVEED MUSHTAQ et al. Food and water intake of animals were observed during this period. At 30 th day, blood was collected from overnight fasted rats of each group by cardiac puncture for the determination of serum biochemical parameters. For the determination of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP), total cholesterol, triglycerides, low-density lipoprotein (LDL) and high density lipoprotein (HDL) levels, blood samples were collected in clot activator gel tubes. The serum was separated by centrifuging the blood samples at 2000 rpm for 10 min. Serum biochemical parameters were then measured by using commercially available reagent kits (14). Statistical analysis The results were expressed as the means ± standard error of the mean (S.E.M) and statistical analysis was carried out by Studentís t-test; p < 0.05 was considered statistically significant. RESULTS Effect of crude extract of Sonchus asper on blood pressure and heart rate of normotensive rats The crude extract of Sonchus asper showed a significant decrease in the SBP, DBP, MBP and heart rate (HR) of normotensive rates at all the tested doses in dose dependent manner. The maximum decrease in all these parameters was observed at 1000 mg/kg dose (Table 1). Effect of crude extract on blood pressure and heart rate of glucose induced hypertensive rats The crude extract of Sonchus asper produced significant decrease in SBP, DBP, MBP and heart rates of glucose induced hypertensive rats in dose dependent fashion. The dose 1000 mg/kg exhibited maximum effect by decreasing the blood pressure and heart rate persistently for 8 h both in normotensive and glucose induced hypertensive rats so, it was selected for further experiments (Table 2). Effect of crude extract on blood pressure and heart rate of egg feed diet fed rats Figures 1 and 3 shows the effect of aqueousmethanolic extract on blood pressure and heart rate of rats receiving the egg feed diet for 21 days. It has been clearly depicted that the treatment with extract of Sonchus asper significantly prevented SBP, DBP, MBP and heart rates to increase in egg feed treated rats as compared to control. Effect of crude extract on blood pressure and heart rate of glucose induced hypertensive rats The effect of aqueous-methanolic extract on blood pressure and heart rate has been shown in Figures 2 and 3. The extract exhibited the significant antihypertensive effect by preventing the SBP, DBP, MBP and heart rate to increase in the rats that were administered 1000 mg/kg dose of extract at daily basis for 21 days. Figure 1. Antihypertensive activity of aqueous-methanol extract of Sonchus asper in egg feed treated rats. Key: a = (p < 0.05), b = (p < 0.01), c = (p < 0.001) compared to control

5 Evaluation of antihypertensive activity of Sonchus asper L. in rats 429 Figure 2. Antihypertensive activity of aqueous-methanol extract of Sonchus asper in glucose fed rats. Key: a = (p < 0.05), b = (p < 0.01), c = (p < 0.001) compared to control Figure 3. Effect of aqueous-methanol extract of Sonchus asper on heart rate of egg fed and glucose fed rats. Key: b = (p < 0.01), c = (p < 0.001) compared to control Acute and sub-chronic toxicity The crude extract was tested for its acute toxicity in mice. LD 50 of the crude extract of Sonchus asper was found to be 3500 mg/kg in mice. In subchronic toxicity studies, the extract did not caused significant alterations in serum ALT, AST and ALP levels. Total cholesterol, triglycerides, LDL levels and HDL levels were also not changed in the extract treated rats as compared to control group. DISCUSSION Medicinal plants have been used as traditional herbal remedies since ancient times. The increasing use of medicinal plants in the treatment of various diseases is due to the extraction and development of several successful drugs and chemotherapeutic agents from plants. Herbal drugs are widely used today due to their minimal adverse effects and low cost (15). Many scientists are conducting research throughout the globe to explore the therapeutic values of the plants to ensure their use in the modern therapy. Sonchus asper has been used for the treatment of various diseases in traditional medicine. In the current study, it was investigated for its antihypertensive effect in rats. The aqueous-methanolic extract of Sonchus asper caused the decrease in blood pressure and heart rate in concentration dependent fashion in normotensive and glucose

6 430 MUHAMMAD NAVEED MUSHTAQ et al. treated rats. The dose of 1000 mg/kg of aqueousmethanolic extract showed the more pronounced effect and was selected for further studies. The results have shown that the extract reduced the blood pressure more in hypertensive rats as compared to normotensive rats. The results are in line with our previous study (9). The extract also prevented the increase in blood pressure in glucose and egg feed diet treated rats in 21 days study. It has been studied previously that administration of glucose for an extended time period results in production of reactive oxygen species (ROS) that are responsible for increase in blood pressure (12, 16). The antioxidant effect of Sonchus asper has been reported. The Sonchus asper possesses certain phytochemicals viz. polyphenol, flavonoids and proanthocyanidins (17). It is suggested that the lowering blood pressure effect of the plant might be due to the presence of these phytochemical constituents which counteract the reactive oxygen species. This is consistent with the previous studies (11). Egg feed induced hypertensive model in rats has also been used for study the antihypertensive effect of the plant. The increased blood pressure in egg feed diet fed rats has been reported due to high cholesterol level and dyslipidemia. The presence of saturated fats in egg yolk leads to hypercholesterolemia, which is a major risk factor of hypertension (18). The administration of the crude extract in high cholesterol diet treated rats prevented the rise in blood pressure as compared to untreated controls and this effect may be due to the presence of some constituent(s) with hypolipidemic property. The previous studies have shown that secondary metabolite attenuate the endothelial dysfunction by decreasing the level of bad cholesterol (LDLs) and production of nitric oxide (19). Previously, it has been found that the alkaloids in plants reduced the blood pressure through vasorelaxation caused by production of increased nitric oxide and prostacyclin. Hussain et al. reported the presence of alkaloids in Sonchus asper and it is possible that the blood pressure lowering effect of crude extract of Sonchus asper may be due to these phytochemical constituents (7). The acute toxicity study has shown that the median lethal dose (LD 50 ) of the extract was 3500 mg/kg in mice and the extract was safe in concentrations used to carry out the antihypertensive studies. Previously, toxicity studies of certain plants have shown that they are not safe for use as they are harmful for the body indicating the alteration of the lipid profile and liver enzymes in animals. Hence, the extract was administered for one month to study its possible adverse effects in rats. The blood chemistry of the extract treated rats was not altered in subchronic toxicity study, which shows that the plant drug does not produce any harmful effect on lipid profile and liver enzymes of rats. Our results are in consistency with the already published work in which the leaf extract of Nauclea latifolia was reported for its cardiovascular effect without significantly altering the lipid profile of treated animals (20). CONCLUSIONS The aqueous-methanolic extract of Sonchus asper possesses certain phytochemical constituent(s) that exert the antihypertensive effect. However, further studies are required for the isolation of active constituent(s) and elucidation of exact mechanism of action. Acknowledgments This study has been carried out by the fundings provided by Higher Education Commission (HEC), Pakistan through Indigenous PhD Fellowship Program. The authors are thankful to Dr. Ameen Ullah Shah, Department of Biological Sciences, University of Sargodha for his cooperation regarding identification of the plant. REFERENCES 1. Akhtar M.S., Bashir S, Malik M.N., Manzoor R.: Pak. J. Pharm. Sci. 26, 1197 (2013). 2. Ghayur M.N., Janssen L.J.: Nat. Rev. Cardiol. 7, 1 (2010). 3. Du Y.L., Chen X.N.: World Clin. Drugs 26, 592 (2005). 4. Mahady G.: J. Cardiovasc. Nurs. 16, 21 (2002). 5. Ayele Y., Urg K., Engidawork E.: Phytother. Res. 24, 1457 (2010). 6. Patel S.S., Verma N.K., Ravi V., Gauthaman K., Soni N.: Int. J. App. Res. Nat. Prod. 3, 22 (2010). 7. Hussain I., Ullah R., Khan N., Ayaz S., Ahmad S. et al.: Afr. J. Pharm. Pharmacol. 5, 1813 (2011). 8. Khan M.R., Haroon J., Khan R.A, Bokhari J., Shabbir M., Rashid U.: J. Med. Plants Res. 5, 2514 (2011). 9. Alamgeer, Akhtar M.S., Jabeen Q., Akram M., Khan H.U. et al.: Trop. J. Pharm. Res. 12, 393 (2013). 10. Saleem R., Ahmad M., Ahmed S.I., Azeem M., Khan RA., Rasool N.: Phytother. Res. 19, 881 (2005).

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