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 Table of Contents  
ORIGINAL ARTICLE
Year : 2018  |  Volume : 15  |  Issue : 1  |  Page : 68-72

Hypolipidemic effect of oral administration of aqueous leaf extract of Senna occidentalis in rats


Department of Biochemistry, Faculty of Basic Medical Sciences, Bayero University, Kano, Nigeria

Date of Web Publication23-Mar-2018

Correspondence Address:
Dr. A M Gadanya
Department of Biochemistry, Faculty of Basic Medical Sciences, Bayero University, Kano
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/njbcs.njbcs_16_17

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  Abstract 


Introduction: Senna occidentalis is a medicinal plant which is called “rai–rai” or “rai dorai” in Hausa. It is among the most commonly used plants that form the basis of primary healthcare for a majority of people living in rural and remote areas in Nigeria and other third world countries. Hyperlipidemia is a condition which is characterized by elevated levels of serum lipid profile. It is associated with many diseases such as atherosclerosis, cardiovascular diseases, and diabetes. Aims and Objectives: This study was aimed at assessing the effect of oral administration of aqueous leaf extract of S. occidentalis on serum lipid profile in rats. Materials and Methods: Phytochemical screening and effect of aqueous leaf extract of S. occidentalis on lipid profile was conducted. Thirty male albino rats were divided into six groups of 5 rats each. Group I was normal control, group II hyperlipidemic control, groups III, IV, and V were hyperlipidemic rats orally administered with 500 mg/kg, 250 mg/kg, and 166 mg/kg of aqueous leaf extract of S. occidentalis, respectively, for 4 weeks, and group VI were hyperlipidemic rats orally administered with 10 mg/kg of ruvastatin for 4 weeks. At the end of the fourth week, the animals were sacrificed and their serum total cholesterol (TC), triglycerides (TG), high density lipoprotein (HDL), and low density lipoprotein (LDL) levels were determined. Results: Results of phytochemical screening revealed the presence of tannins, saponins, cardiac glycosides, resins, and flavonoids. Significant (P < 0.05) increase in the serum TC, TG, and LDL-chol were observed in groups II, III, IV, V, and VI when compared with that of the control rats. Significant (P < 0.05) decrease in mean serum TG, TC and LDL-chol levels were found in rats orally administered with 500 mg/kg of aqueous leaf extract of S. occidentalis and those orally administered with 10 mg/kg of rosuvastatin when compared with group II. Rats orally administered with 250 mg/kg of the aqueous leaf extract were found to have significantly lower (P < 0.05) mean serum TC and LDL-chol when compared with that of group II (test control). Conclusion: It could be suggested that aqueous leaf extract of S. occidentalis at 500 mg/kg could cause antihyperlipidemic effect against dietary-induced hyperlipidemia.

Keywords: Hyperlipidemia, lipid profile, Senna occidentalis, rats


How to cite this article:
Gadanya A M, Muhammad S U. Hypolipidemic effect of oral administration of aqueous leaf extract of Senna occidentalis in rats. Niger J Basic Clin Sci 2018;15:68-72

How to cite this URL:
Gadanya A M, Muhammad S U. Hypolipidemic effect of oral administration of aqueous leaf extract of Senna occidentalis in rats. Niger J Basic Clin Sci [serial online] 2018 [cited 2021 Jun 16];15:68-72. Available from: https://www.njbcs.net/text.asp?2018/15/1/68/228353




  Introduction Top


The use of plant extracts in traditional medicine is a worldwide practice. Medicinal plants form the basis of primary healthcare for a majority of people living in rural and remote areas in Nigeria and other third world countries. Many inhabitants of the world essentially rely on herbal medicine for their primary healthcare needs. In some cases, plants offer alternative healthcare services for curing ailments and diseases where patients are poor or live far away from hospitals. Numerous medicinal plants have been found and put into use in ethnomedicine by traditional healers in the management of many diseases.[1] Medicinal plants are plants that possess therapeutic properties or exert beneficial pharmacological effect on animals. Although there are no apparent morphological characteristics in medicinal plants, growing them is medicinally important. It is now established that plants which naturally synthesize and accumulate some secondary metabolites e.g., alkaloids, glycosides, tannins, volatile oils, and certain minerals and vitamins possess medicinal properties. These medicinal plants, which are often called traditional medicines, need to be evaluated, given due recognition, and developed to improve their efficacy, safety, availability, and wide application at low cost.[2]Senna occidentalis belongs to the family leguminosae, subfamily caesalpinoidae. It is botanically classified as both S. occidentalis and Cassia occidentalis. It is a small, erect, animal herb that can be up to 2 m tall and is found abundantly in rainforests and tropical areas of the world. Senna has compound leaves with narrow linear-to-oval-shaped dark green leaflets. In the spring and summer, it has yellow pea-like flowers which are followed by brown pods containing brown seeds. Leaves, fruit, and flowers of Senna are used for medicinal purposes. It is one of the plants employed in ethnomedicine in many parts of the world. It is commonly called “Rai–Rai” in Hausa.

S. occidentalis has a rich history in natural medicine. In Brazil, the roots are used as a tonic, diuretic, fever tuberculosis, anemia, liver complaints, and for reconstituting general body weakness.[3] The leaves are also used in Brazil for treating gonorrhea, fever, urinary tract infection, edema, and menstrual problems.[4] In many countries around the world, fresh and/or dried leaves of S. occidentalis are crushed and brewed into tea and applied externally for treating skin disorders, wounds, skin fungi, and other parasitic diseases.[5] In Nigeria, the leaves of S. occidentalis are used in treating various skin infections. Leaf decoction is also made for treating typhoid, fever, constipation, as well as a diuretic.

Hyperlipidemia is a major cause of a chain of events leading to atherosclerotic plaque. A prime cause of hyperlipidemia is overconsumption of fats, particularly saturated fatty acids. If these postulations are correct, lowering blood lipid concentration should reduce mortality and morbidity from diseases associated with high lipid concentration such as heart disease and diabetes. Therefore, this study was aimed at assessing the effect of oral administration of aqueous leaf extract of S. occidentalis in rats.


  Materials and Methods Top


Collection and preparation of plant material

S. occidentalis leaves were collected from Bayero University Kano, Nigeria. It was identified at the Plant Science Department of Bayero University Kano. It was dried in shade and pulverized into a powder. Subsequently, 200 g of the powder were weighed and soaked in 400 cm 3 of distilled water for 24 hours. The mixture was filtered using Whatmann filter paper no. 1, the filtrate was dried. The dried extract was reconstituted, and the volume of the extract to be administered was determined based on the weight of the rats and required dose, using the relation:

Vol (cm 3) = weight of the rat (kg) × dose (mg/kg)/ Concentration of the extract (mg/cm 3)

Experimental animals

Thirty male and female albino rats weighing between 80 g and 120 g were obtained from the Zoological Department of Bayero University Kano. They were housed in cages in a well-ventilated room at room temperature under standard condition and free access to water and food throughout the period of the experiment. They were fed with standard vital feed diet (growers pelletized manufactured by grand cereals Ltd. a subsidiary of UAC of Nigeria). The experiments were performed according to the principles of animal care in the laboratory.[6]

Preparation of high cholesterol diet

Cholesterol rich diet was formulated according to the model described by Hossam and Arafa:[7]

Cholesterol (100 g) and cholic acid (50 g) in 1 l of coconut oil and supplementation of egg yolk were thoroughly mixed with the grower mash feed.

Experimental design

Twenty-five albino rats were fed daily with a high cholesterol diet for 6 weeks during which time remarkable increase in weight (i.e., sign of obesity) was observed. Five rats were given normal standard vital feed diet (growers pelletized manufactured by grand cereals Ltd.); they served as the normal control group. The former were then divided into five equal groups consisting of five rats each.

  • Group I: Normal control group (nonhypercholesterolemic, no extract was administered)
  • Group II: Hypercholesterolemic control (no extract was administered)
  • Group III: Orally administered with 500 mg/kg aqueous leaf extract of S. occidentalis daily for 4 weeks after induction of hypercholesterolemia
  • Group IV: Orally administered with 250 mg/kg ALESO daily for 4 weeks after induction of hypercholesterolemia
  • Group V: Orally administered with 166 mg/kg aqueous leaf extract of S. occidentalis daily for 4 weeks after induction of hypercholesterolemia
  • Group VI: Orally administered with 10 mg/kg rusavastatin daily for 4 weeks after induction of hypercholesterolemia.


Animals in all the groups were sacrificed 24 hours after the last treatment and blood samples were collected for analysis of serum lipid profile total cholesterol (TC), triglycerides (TG), high density lipoprotein (HDL), and low density lipoprotein (LDL).

Statistical analysis

Results were expressed as mean ± standard deviation and analyzed using one-way analysis of variance (ANOVA) using the Statistical Package for Social Sciences (SPSS) version 20 (NY; IBM Corp. released 2011). P value of 0.05 or less was considered to be significant.


  Results Top


Results of qualitative phytochemical screening of aqueous leaf extract of S. occidentalis are presented in [Table 1]. The results of the analysis indicated the presence of tannins, flavonoids, saponins, cardiac glycosides, and resins.
Table 1: Phytochemical constituents of aqueous leaf extract of S. occidentalis

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Results of the effect of aqueous leaf extract of S. occidentalis on body weight gain of hyperlipidemic rats after 4 weeks of oral administration are depicted in [Figure 1]. There was no significant difference in the weight of all the different groups before the induction of hypercholesterolemia. Significant increase (P< 0.05) in weight after hypercholesterolemic induction was observed in all the groups except group I. The results after treatment with 500 mg/kg (group III), 250 mg/kg (group IV), and 166 mg/kg (group V) S. occidentalis, as well as 10 mg/kg rosavastatin (group VI) were compared with hyperlipidemic control group, and no significant difference (P< 0.05) was detected.
Figure 1: Effect of aqueous leaf extract of S. occidentalis on rats body weight. Results are expressed as mean ± SD, n = 5. a: Significant difference (P < 0.05) when compared with Initial weight, b: Significant difference (P < 0.05) when compared with HC.

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Results of the effect of aqueous leaf extract of S. occidentalis on lipid profile (HDL-Cho, LDL-Cho, TC, and TG) of hyperlipidemic rats after 4 weeks of the treatment are depicted in [Figure 2]. Significant increase (P< 0.05) in serum TG, LDL-Cho, and TC in hypercholesterolemic control group (group II) was observed when compared with the normal control (group I). Significant decrease (P< 0.05) in serum TC and LDL-cholesterol were observed in rats orally administered with aqueous leaf extract of S. occidentalis in a dose-dependent pattern (500 mg/kg > 250 mg/kg > 166 mg/kg) when compared with hypercholesterolemic control. There was also a significant decrease in serum TG in group III (500 mg/kg aqueous leaf extract of S. occidentalis) and group VI (10 mg/kg dose of rosuvastatine) rats when compared with hypercholesterolemic control group. From the results [Figure 2], no significant difference (P < 0.05) was observed in serum HDL-cho level of hypercholesterolemic control and aqueous leaf extract of S. occidentalis treated rats. A dose-dependent antihyperlipidemic effect was observed. All the groups showed significant increase (P< 0.05) in TC, LDL-C, and TG when compared with normal control group (in group I) and no significant difference (P< 0.05) was observed in HDL-Cho. 500 mg/kg aqueous leaf extract of S. occidentalis-treated rats (group III) and 10 mg/kg rusavastatin-treated rats (group VI) showed significant decrease (P< 0.05) in TC, LDL, and TG and produced insignificant increase (P< 0.05) in HDL-Cho (good cholesterol) when compared with hyperlipidemic control rats (group II).
Figure 2: Effect of aqueous leaf extract of S. occidentalis on rats' TC, TG, HDL-Cho and LDL-cho. Results are expressed as mean ± SD, n = 5. a: Significant difference (P < 0.05) when compared with GI, b: Significant difference (P < 0.05) when compared with GII, c: Significant difference (P < 0.05) when compared with GIII, d: Significant difference (P < 0.05) when compared with GIV, e: Significant difference (P < 0.05) when compared with GV.

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  Discussion Top


Body weight gain in hypercholesterolemic control rats [Figure 1] was significantly (P< 0.05) higher than weight gain in normal control rats. This is an indication of successful induction of hyperlipidemia as a result of high cholesterol rich diet. Rats fed with a diet supplemented with 100 g cholesterol and 50 g cholic acid in coconut oil with egg for 21 days served as the experimental model. This is in accordance with a previous finding reported by Hossam and Arafa,[7] that feeding rats with high cholesterol diet for 7 consecutive days results in marked hypercholesterolemia. The mechanism of action of cholic acid is an increase (by two-fold) in cholesterol absorption and a concomitant suppression of cholesterol 7-alpha hydroxlyase activity that results in decreased cholesterol excretion.[8] Cholic acid improves cholesterol absorption by its emulsifying property. However, in the present study, no favorable changes in body weight were detected after administration of S. occidentalis leaf extract dosing. Feeding the animals with a high cholesterol diet enriched with coconut oil and egg produced a significant (P< 0.05) elevation in serum cholesterol concentration, as well as increase in TG and LDL-Cho concentrations with decrease in the level of good cholesterol carrier HDL. Significant increase (P< 0.05) in blood cholesterol of animals fed with high cholesterol rich diet was observed when compared to normal control. The mean level of serum total cholesterol of the normal control rats increased steadily from 155.69 mg/dl to 304.03 mg/dl in hypercholesterolemic control. LDL-Cho also increases from 93.80 mg/dl to 218.75 mg/dl and TG concentration increases from 146.85 mg/dl in normal control to 295.96 mg/dl in hypercholesterolemic control and subsequent reduction of HDL-C from 32.52 mg/dl to 26.09 mg/dl in hypercholesterol control [Figure 2]. This is because dietary cholesterol raises TC, LDL-Cho, and TG levels. The intake of cholesterol rich food has been positively related to hypercholesterolemia and the risk of cardiovascular diseases.[9] Thus, it can be suggested that S. occidentalis leaf extract could have an effect on dietary cholesterol which could result in reduction in the level of cholesterol in the blood. This is similar to the work of Jorge et al.[10] who carried out work on the effect of eggplant juice on plasma lipid levels.

The hypolipidemic activity of aqueous leaf extract of S. occidentalis observed could be as a result of receptor site saturation and/or possible inhibition of activity by other components of the plant.[11] The qualitative phytochemical analysis of the plant indicated the presence of the following compounds; saponins, cardiac glycoside, flavonoids, resins, and tannins. Flavonoids block the angiotensin converting enzymes (ACE) that raise blood pressure. By blocking the suicide enzyme cyclooxygenase that breaks down prostaglandins, they prevent platelet stickiness and hence platelet aggregation. Tannins also protect the vascular system and strengthen the tiny capillaries that carry oxygen and essential nutrients to all cells.[12] The reduction in the serum TC levels following the administration of the extract could be attributed to reduction in the concentration of acetyl CoA resulting from decreased B-oxidation of fatty acids because acetyl CoA is a key substrate in the biosynthesis of cholesterol.[13] Although the acetyl CoA level was not measured, the hypocholesterolemic effect observed in this study could also be attributed to the presence of saponins. Saponins lower blood cholesterol by binding with cholesterol in the intestinal lumen, thereby preventing its absorption. Increased bile acid excretion is offset by enhanced bile acid synthesis from cholesterol in the liver and the consequent lowering of serum cholesterol.[14]

The mechanism of hypolipidemic effects of aqueous leaf extract of S. occidentalis could be by reduced cholesterol absorption from the intestinal tract, possibly mediated either by the fiber or phytochemical content. The decrease in the absorption of exogenous cholesterol and increased metabolism of endogenous cholesterol into bile acids in the liver leads to increased expression of LDL receptor on hepatocytes, as well as increased clearance of LDL-Cho from the plasma.[13] Another possible mechanism through which lipid lowering drugs (bile acid sequestrant) act is by binding to bile acid in intestine, which impairs its reabsorption from the intestine. The depletion of bile acid pool leads to upregulation of cholesterol 7-α-hydroxylase and increased conversion of cholesterol to bile acids. This causes an increased demand for cholesterol by the hepatic cells, resulting in the dual effect of increased transcription and activity of HMG-CoA reductase and increased number of hepatic LDL receptors. These compensatory effects result in increased clearance of LDL-Cho from blood, resulting in decreased serum LDL-C levels. Serum TG levels may increase or remain unchanged.[15]

Another possible mechanism could be that S. occidentalis works in same manner with statins (atorvastatin, fluvastatin, lovastatin, pitavastatin, pravastatin, rosuvastatin, and simvastatin) which lower the plasma and hepatic cholesterol concentrations by suppressing HMG-CoA reductase, an enzyme that catalyzes the committed step in cholesterol synthesis.[16] In the current study, the maximum efficacy of the extract was seen in the group administered with the highest dose. The association between a low level of HDL-cholesterol and an increased risk of CVD has been well established through epidemiology and clinical studies.[17] Despite the very large body of epidemiologic evidence identifying low HDL-Cho as a powerful risk factor in humans, there are very few intervention studies that have put this proposition directly to the test. While there are several human intervention studies in which drug-induced elevations of HDL-Cho are associated with a reduction in atherosclerosis, most of these trials were not designed specifically to test the benefits of raising the level of HDL-Cho. A recent study in humans provides support to the proposition that raising the level of HDL-Cho is of substantial therapeutic advantage.[18] This was a small study in which a preparation of reconstituted HDL was infused into human participants. The result was consistent with a profound protective action of HDL-Cho based on the epidemiologic data. It is reasonable to recommend HDL-cholesterol target >38.89 mg/kg (1.0 mmol/L). In this study, aqueous leaf extract of S. occidentalis led to a slight elevation of serum HDL-cholesterol even though is not significant (P< 0.05), indicating its promising role against CVD. The mechanism for the atherogenic effect may be through counteracting LDL-cholesterol by promoting the reverse cholesterol transport pathway through inducing an efflux of excess accumulated cellular cholesterol.[18] Another mechanism could be HDL particles possess some anti-inflammatory and antioxidant properties, preventing the oxidation of LDL-cholesterol and the expression of cellular adhesion molecules and monocyte recruitment.[19]

The finding of this study provides some biochemical basis for the use of leaf extract of S. occidentalis as an antihyperlipidemic agent that could be attributed to some phytochemical contents of the plant.


  Conclusion Top


Aqueous leaf extract of S. occidentalis at 500 mg/kg could cause antihyperlipidemic effect against dietary-induced hyperlipidemia. The antihyperlipidemic potential of the plant could be attributed to some phytochemical contents of the plant.

Similar study should be carried out to evaluate the hypolipidemic potential of other parts of the plant using different solvents extracts. It may also be recommended to conduct bioassay-guided study to isolate the active components of S. occidentalis.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

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Jorge PA, Neyra LC, Osaki RM, Almeida E, Bragagnolo N. Effect of eggplant on plasma lipid levels, lipidic peroxidation and reversion of endothelial dysfuntion in experimental hyper-cholesterolemia. Arg Bras Cardiol 1998;70:87-91.  Back to cited text no. 10
    
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Fonseca VA, Rosenstock J, Wang, AC, Truitt KE, Jones MR. Colesevelam HCl improves glycemic control and reduces LDL cholesterol in patients with inadequately controlled type 2 diabetes on sulfonylurea-based therapy. Diabetes Care 2008;31:1479-484.  Back to cited text no. 15
    
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Nelson DL, Cox MM. Lehninger principle of biochemistry. 4th ed. WH freeman and company; 2004. p. 75-343.  Back to cited text no. 16
    
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Nissen S, Tsunoda T, Tuzcu E, Schoenhagen P, Cooper C, Yasin M, et al. Effect of recombinant ApoA-I Milano on coronary atherosclerosis in patients with acute coronary syndromes: A randomized controlled trial. JAMA 2003;290:2292-300.  Back to cited text no. 18
    
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Yokozawa T, Cho EJ, Sasaki S, Satoh A, Okamoto T, Sei Y. The protective role of chinese prescription kangen-karyu extract on diet-induced hypercholesterolemia in rats. Bio Pharm Bull 2006;29:760-5.  Back to cited text no. 19
    


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