Research Article
Hypolipidaemic Activity of Rauwolfia serpentina Benth
Department of Biochemistry, University of Karachi, Karachi-75270, Pakistan
Shamsa K. Udani
Department of Biochemistry, Jinnah University for Women, Karachi-74600, Pakistan
High lipid content (hyperlipidaemia) leads to many life threatening conditions such as atherosclerosis, myocardial infarction, ischemic heart disease, stroke and other vascular diseases (Davignon and Cohn, 1996; Frishman, 1998). In all over the world the prevalence of hyperlipidaemia increases day by day either due to the genetic factor, unhealthy lifestyle or secondary to other diseases (Arif et al., 1990; El-Hazmi and Warsy, 2001) and becomes one of the major causes of death (Parab and Mengi, 2002; Aziz et al., 2004). Pakistan is also facing the same threat (Iqbal et al., 2004; Aziz et al., 2004; Jafary et al., 2007).
Rauwolfia serpentina benth (family: Apocynaceae) is a medicinally famous herb (Salma et al., 2008). Almost, 50 alkaloids have been isolated from root bark of this plant including reserpine, yohimbine, serpentine, deserpidine, ajmalicine, etc. (Klyushnichenko et al., 1995) which are used to treat hypertension (Von Poser et al., 1990) and breast cancer (Stanford et al., 1986). Beside hypertension, roots of this plant are also reported for the treatment of number of diseases such as insomnia, anxiety, excitement, schizophrenia, insanity, epilepsy, hypochondria, diarrhea, dysentery etc in Ayurveda medicines (Dastur, 1988; Kirtikar and Basu, 1993; Bhatara et al., 1997; Ghani, 1998; Tona et al., 1999).
The current research was conducted to investigate the effect of root powder of R.serpentina on lipid profile viz., triglycerides, total cholesterol, LDL-C, HDL-C and on enzymes viz., Alanine aminotransferase (ALT) and Lactate Dehydrogenase (LDH).
Animals: Rabbits weighing from 1-1.5 kg were purchased from local supplier of University of Karachi and used in the whole experiment. The rabbits were housed under uniform hygienic conditions with continuous airflow and maintained on a standard laboratory diet and water ad libitum.
Plant material: Roots of R. serpentina was purchased from Hamdard Dawakana, Sardar, Karachi and identified by expert in Botany department, University of Karachi, Karachi-75270, Pakistan. The voucher specimen has been kept in our department (KU/BCH/SAQ/02).
Hypolipidemic activity: Experimental rabbits were divided into control and test groups. Each group contains six rabbits. The grinded root powder of R. serpentina (30 mg/kg) suspended in 1 ml distilled water administrated orally to the test group for 12 days consecutively. While same volume of only distilled water was administrated orally to the control group for the same period. The blood was collected from marginal ear vein of rabbits on each 1st, 4th, 8th and 12th day of the trial from each group. Sera were separated and used to analyze biochemical parameters on Spectro UV-Visible Auto, PC Scanning Spectrophotometer, Labomed, Inc.
Biochemical analysis: Triglycerides, total cholesterol, HDL-C, Alanine aminotransferase (ALT) and Lactate Dehydrogenase (LDH) were determined by commercially available enzymatic kits (Human, USA). LDL-C was calculated by formula given in reagent kit (Randox, UK) as:
Statistical analyses: The data were analyzed by Students t-test (Graphpad Software, Quick Calcs Online calculators for Scientists). Differences considered significant with p<0.0001, p<0.01 and p<0.05. Values are expressed as Mean±standard Error Mean (S.E.M).
Effect of root powder of R.serpentina on lipid profile: A gradual significant decrease (p<0.0001) in triglyceride concentrations from 204.76-111.94 mg/dL were observed in test rabbits from 1st-12th day of oral treatment of root powder of R.serpentina (30 mg/kg). Whereas, the triglycerides were found in the range of 243.31-248.67 mg/dL in control rabbits treated with 1 mL distilled water orally for same period. The difference between control and test groups at each day interval was also found statistically significant with p<0.0001 (Table 1 and Fig. 1).
Oral administration of same dose of Rauwolfia was also induced a decrease in cholesterol concentrations of test rabbits from 184.76-151.08 mg/dL in 12 days trial (p<0.0001) as compared to control rabbits where it was ranging from 172.41-240.96 mg/dL (Table 1 and Fig. 2).
The most striking feature of present investigation is the huge decrease found in LDL-cholesterol levels of test rabbits from 33.31-10.85 mg/dL (p<0.0001). However, HDL-cholesterol levels were remained constant in test rabbits especially at 4th, 8th and 12th day of oral treatment but found higher than their respective control with p<0.05 (Table 1). Observed readings of LDL- and HDL-cholesterol concentrations of control rabbits are mentioned in Table 1.
Effect of root powder of R. serpentina on cardiac and liver specific enyzmes: The LDH levels were found ranging from 33.33-50.00 U/L in control rabbits. Where, as a constant value of 29.70 U/L (p<0.0001) was observed in test rabbits treated with root powder (30 mg/kg) for 12 days consecutively (Table 2).
The ALT levels in control and test rabbits ranged between 18.52-23.18 and 17.84-27.79 U/L, respectively (Table 2).
Researchers have diverted their attention toward natural sources to find out new hypolipidaemic agent with less side effects (Mashour et al., 1998) because therapeutic uses of commercially available lipid lowering drugs are associated with side effects (Ghatak and Asthana, 1995). Rauwolfia serpentina has a significant place in the treatment of hypertension both Ayurvedic and Western medicines (Craig, 1999).
Fig. 1: | Changes in triglycerides level (mg/dL) at different day intervals in control treated with distilled water (1 mL) and test rabbits treated with root powder of R. serpentina (30 mg/kg). Each column represents mean±SEM (n = 6). *** and # = p<0.0001= test compared with respective control and day 1 compared with day 12 in test rabbits, respectively |
Fig. 2: | Changes in cholesterol level (mg/dL) at different day intervals in control treated with distilled water (1 mL) and test rabbits treated with root powder of R. serpentina (30 mg/kg). Each column represents mean±SEM (n = 6). * = p<0.05 and *** = p<0.0001 represent significant differences from respective control and # = p<0.0001 represents difference between 1 and 12 day of treatment in test rabbits |
The present investigation demonstrate the efficacy of root powder of Rauwolfia in lowering the serum levels of triglycerides, cholesterol, Low Density Lipoprotein Cholesterol (LDL-C) and increasing level of high density lipoprotein (HDL-C), is the promising feature of any drug that is necessary for the treatment of hyperlipidaemia and other cardiovascular diseases. It is widely accepted that high concentrations of cholesterol, triglycerides and LDL-C are the major risk factors of cardiovascular diseases including hypertension (Smith et al., 2004; Posta et al., 2006).
In the present study, a significant fall was observed in TG levels of test rabbits treated with root powder consecutively for 12 days. This decrease may be due to enhance the activity of lipase enzyme that hydrolyzes TG under normal condition (Sharma et al., 1997) or increase excretion of TG via feces (Sukla et al., 2004).
Table 1: | Effect of root powder of Rauwolfia serpentina on lipid profile (mg/dL) |
Each value is the mean±S.E.M. (n = 6). * = p<0.05, ** = p<0.01 and *** = p<0.0001 represent significant differences from respective control and # = p<0.0001 compared 12th day from 1st day of test |
Table 2: | Effect of root powder of Rauwolfia serpentina on enzyme level (U/L) |
Each value is the mean±S.E.M (n = 6). * = p<0.05, ** = p<0.01 and *** = p<0.0001 represent significant differences from respective control |
Where as the decrease in cholesterol level may be due to decrease in resorption of endogenous cholesterol or an increase in the rate of secretion into intestinal tract or both (Bahramika and Yazdanparast, 2008). The root powder of R. serpentina may also become a good agent for the treatment of atherosclerosis by showing a decrease in serum level of LDL-C of test rabbits. The relationship between LDL-C and atherosclerosis has already been reported (Frishman, 1998). On the other hand, oral administration of root powder consecutively for 12 days induce increase in HDL-C level of test rabbits as compared to control group but it remain constant from 4th-12th day. It might possible that HDL-C level may be increased if root powder is used for >12 days or it may restore. The research is still in progress to prove this claim.
The effect of root powder of R. serpentina on liver and cardiac function was evaluated by measuring the serum ALT and LDH levels respectively. Our study showed that normal activities of ALT and LDH were observed in both control and test rabbits. These observations proved that R. serpentina had no toxicity on both important organs of the body.
Conclusion: The data of present investigation clearly indicate that root powder of R. serpentina is a potent hypolipidaemic agent especially having hypotriglyceridemic and hypocholesterolemic effects with undetectable side effects on liver and cardiac functions. Due to the significant effect of root powder on lipid profile, research is still going on in lab to investigate the same hypolipidemic activity in different extracts of root powder. This may lead to activity-guided fractionation of that particular extract in order to know the phytochemical composition, isolation, structure elucidation of some of the bioactive constituents followed by establishing the most probable mechanism of action of reducing serum lipids.
The authors highly appreciate the financial support provided by Jinnah University for Women, Karachi-74600, Pakistan, for conducting this investigation. Special thanks to Dr. Syed Nazar-ul-Hasnain, Professor and Chairman, Department of Biochemistry Zia Uddin Medical University for critical reading and suggestions on the manuscript.