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Indian Journal of Pharmacology, Vol. 43, No. 5, September-October, 2011, pp. 582-585 Short Communication Assessment of antidiabetic potential of Cinnamomum tamala leaves extract in streptozotocin induced diabetic rats Shradha Bisht, SS Sisodia Bhupal Nobels' P.G. College of Pharmacy, Udaipur, Rajasthan, India Date of Decision: 28-Dec-2010 Date of Acceptance: 20-Jul-2011 Code Number: ph11153 DOI: 10.4103/0253-7613.84977 Abstract Objective : To establish the effect of Cinnamomum tamala leaves extract on diabetes and diabetes induced dyslipidemia in streptozotocin-induced diabetic rats.Materials and Methods : Diabetes was induced by a single intravenous injection of streptozotocin (50 mg/kg body weight). Group I and II were kept as control and diabetic control respectively. And group III was further treated with ethanolic leaf extract of C. tamala (200 mg/kg body weight, orally) for a period of 40 days. Oral glucose tolerance test was performed before starting the experiment and blood glucose level was estimated. Statistical analysis was performed using one-way Analysis of Variance (using Statistical Package for the Social Sciences [SPSS] version 10.0) and student's 't'- test (Sigma Plot version 8.0). The values of P < 0.05 were considered as statistically significant. Results : Treatment of diabetic animals with Cinnamomum tamala extract significantly lowered the blood glucose level, and maintained body weight and lipid-profile parameters towards near normal range. Conclusion : The extract exhibited antidiabetic and antidyslipidemic effect. Further, chemical and pharmacological investigations are required to elucidate the exact mechanism of action of this extract and to isolate the active principles responsible for these effects. Keywords: Cinnamomum tamala , diabetes mellitus, dyslipidemia Introduction Diabetes mellitus (DM) is an endocrine disorder that is characterized by hyperglycemia [1] and altered metabolism of carbohydrates, lipid and proteins. It is caused by inherited and/or acquired deficiency in production of insulin by beta cells of pancreas or by the ineffectiveness of the insulin produced, which leads to hyperglycemia, and at later stages lipid metabolism is also affected. [1] There is usually an association between coronary heart disease or atherosclerosis and dyslipidaemia. [2],[3] Several groups of hypoglycaemic drugs are currently available to treat DM. However, their toxic side effects and sometimes diminution in response after prolonged use are problematic. A number of investigations, of oral antihyperglycemic agents from plants used in traditional medicine, have been conducted and many of the plants were found with good activity. [4],[5] The World Health Organization (WHO) has also recommended the evaluation of the plants effectiveness in conditions where we lack safe modern drugs. [6] This has lead an increasing demand of research on antidiabetic natural products which produce minimal or no side effects. [7] Cinnamomum (CT) Fr. Nees., belonging to family Lauraceae, is also known as Indian Cassia and the leaves are commonly called as bay leaves. The genus Cinnamomum is represented by about 350 species worldwide. Natural habitat is in the tropical and sub-tropical Himalayas at altitudes of 900-2500 m. Due to its aroma, the leaves are kept in clothes and also chewed to disguise bad mouth odor. The leaves of this tree have a clove like taste and a faintly pepper like odor. It is also used in Indian system of traditional medicines. Leaves and bark have aromatic, astringent, stimulant and carminative qualities and are used in rheumatism, colic, diarrhea, nausea and vomiting. Ancient literature has revealed that in the first century A.D., dried leaves and bark of this plant were prescribed for fever, anemia and body odor. Its seeds were crushed and mixed with honey or sugar and administered to children for dysentry or cough. [9] Only scarce data is available on effect of C. tamala on blood sugar level and lipid profile. Our aim was to explore the antihyperglycemic and antihyperlipidemic activity of the C. tamala leave extract in streptozotocin (STZ) induced diabetic animals and compare the effect with standard drug Glibenclamide. Streptozotocin is a deoxy-s [(methyl-nitrosoamino) carbonyl)-amino]-D gluco pyranose molecule that produces a selective toxic effect on β cells by generating free radicals and induces diabetes mellitus in most laboratory animals. Materials and Methods Chemicals STZ was obtained from Sigma chemicals, India. Blood Glucose level was estimated by Glucose oxidase-peroxidase strip (Accue-check® diagnostic kit). Serum total cholesterol (TC), triglyceride (TG) and High density lipoprotein (HDL)-cholesterol was estimated by using diagnostic kits (Erba Mannheim Cholesterol kit, Transasia Bio-Medicals Ltd., Daman). All the chemicals used were of analytical grade. Preparation of Extract The whole plant of C. tamala was collected from the Forest of Dehradun at an altitude of 2200 meters. The Plant was identified and authenticated and the voucher specimen (A-40) has been kept at the herbarium of Sardar Bhagwan Singh Institute Of Biomedical Sciences and Research, Balawala, Deharadun, Uttrakhund. The leaves were washed in tap water and then left to dry at room temperature for 2-3 days. The dried leaves were then ground to Coarse to fine powder in a mixer and then extracted with 95% ethanol using a soxhlet apparatus for 15 hours. After filtration, the filtrate was concentrated at 65°C by a rotavapor. The concentrate was then freeze dried to yield dried powder. Animals Male Wistar rats weighing between 180-220 g were used in the study with the approval of the animal ethical committee of Bhupal Nobels' P.G.College of Pharmacy, Udaipur, Rajasthan. All animals were cared for in accordance with the principles and guidelines of the Institutional Animal Ethics Committee of B.N. College of pharmacy, Udaipur, constituted as per the directions of the Committee for the Purpose of Control and Supervision of Experiments on Animals (CPCSEA). Induction of Diabetes Diabetes was induced in rats by tail vein injection of streptozotocin (50 mg/kg, i.v.) dissolved in normal saline. Forty eight hours after streptozotocin administration blood samples were drawn by retroorbital puncture and glucose levels was determined. The diabetic rats exhibiting blood glucose levels in the range of 275 to 300 mg/100 ml were selected for the studies. [10] Glibenclamide (500 mg/kg) was used as reference standard. The dose of Glibenclamide was selected based on previous reports. [11] A preliminary toxicity study was designed to demonstrate the appropriate safe dose range that could be used for subsequent experiments. Dose of C. tamala was selected by carrying out the acute toxicity study (staircase method). [12] Following four groups of rats (n = 6) were taken.
Body weight was determined at regular intervals. Oral Glucose Tolerance test The oral glucose tolerance test was performed in overnight fasted normal animals. Rats divided into three groups were administered 2% gum acacia solution, ethanolic extract of CT (200 mg/kg), and glibenclamide (0.25 mg/kg), respectively. Glucose (2 g/kg) was fed 30 minutes after the administration of samples. Blood was withdrawn from the retro-orbital sinus at 0, 30, 60, 90 and 120 min of samples administration. [13] Blood glucose levels were estimated by glucose oxidase-peroxidase reactive strips. Biochemical Estimation in Streptozotocin - Induced Model Blood glucose (FBG) concentration of all the four experimental groups was determined by glucometer during different phases of the experiment. Serum was isolated from the blood collected on 40 th day of experimental work and serum total cholesterol (TC), triglyceride (TG) and HDL-cholesterol were estimated by using diagnostic kits. Very low density lipoprotein (VLDL) and low density lipoprotein (LDL) cholesterol were calculated as per Friedewald's [14] equation i.e. [INLINE:1] And LDL-cholesterol = Serum total-cholesterol - VLDL cholesterol - HDL cholesterol. Results were expressed in mg/dl. Data and Statistical Analysis Results are expressed as mean ± Standard Error of Mean (SEM). Statistical analysis was performed using one-way Analysis of Variance (ANOVA) using SPSS (version 10.0) and student's 't'-test using Sigma Plot (version 8.0). The values of P < 0.05 were considered as statistically significant. Results Body Weight Body weight was measured in gram. All animals treated with streptozotocin in diabetic control group II showed a significant (P0 < 0.001) loss in body weight (g) (from 191.27 ± 4 to 152 ± 2.25) which was persistently observed till the end of the study period. In group III, animals were gained some weight after 40 days of C. tamala extract treatment. (From 193 ± 7 to 209.2 ± 4). The weight gain of the extract treated animal was similar to animals in group IV i.e. glibenclamide treated. Oral Glucose Tolerance test [Table - 1] shows the changes in blood sugar level during oral glucose tolerance test. There was a significant increase in blood sugar level in animal of control group having 2% gum acacia solution from 82.33 ± 2.58 to 90 ± 1.78 mg/dl. Group receiving Glibenclamide (0.25 mg/kg) showed a significant (P < 0.05) decrease in blood glucose level in every 30 minutes interval from 84.66 ± 2.16 to 78.33 ± 1.36 mg/dl, while group receiving ethanolic extract of Cinnamomum tamala showed a significant and continuous decrease from 82.33 ± 2.73 to 76.66 ± 1.75 mg/dl in blood sugar level till 90 minutes. When it was observed after 120 minutes, it had reached the normal level i.e 81.5 ± 2.07 mg/dl. Blood Glucose Level There was a persistent increase in blood sugar level of streptozotocin induced diabetic control group i.e. from 283.16 ± 3.32 to 372.16 ± 3.31 mg/dl. Compared to normal control group, extract treated group (group III) showed gradual and moderate antihyperglycemic effect i.e from 287.66 ± 2.16 to 188.5 ± 2.42 mg/dl. The plasma glucose level of extract treated animals was significantly less than the pretreatment level (Day 1). However, the antihyperglycemic effect produced by Glibenclamide (group IV) was more pronounced than C. tamala extract i.e. from 286.6 ± 3.01 to 125.16 ± 2.63 mg/dl [Table - 2]. Lipid Profile Compared to normal control group (NC), the level of serum TC, TG, LDL and VLDL cholesterol was significantly ( P < 0.001) increased, whereas the level of HDL-cholesterol was significantly ( P < 0.001) reduced in untreated diabetic rats (DC) [Table - 3]. After treatment of group III with C. tamala leaf extract, the level of serum TC, TG, LDL and VLDL-cholesterol reduced significantly ( P < 0.001), whereas, the level of serum HDL-cholesterol was significantly increased. Glibenclamide treatment reduced the level of TC, TG, LDL and VLDL-cholesterol and enhanced the level of HDL-cholesterol. Discussion Streptozotocin-induced hyperglycemia has been described as a useful experimental model to study the activity of hypoglycemic agents. Streptozotocin enhances free radical formation and/or produces defects in antioxidant defense system, resulting in destruction of b cells of the pancreas which may lead to hyperglycemia. In the present study, administration of ethanolic extract of CT to diabetic rats (Groups III) increased bodyweight significantly, which was comparable to experiments of Chakrobarty and Das. [15] Results of the present study are supported partially by the findings of Perez et al.,[16] who also observed significant (P < 0.05) increase in body weight after treatment with extract of Ficus carica (fig tree) leaves in streptozotocin-diabetic rats, which may be due to the lipid lowering activity of the extract or indirectly due to the influence on various lipid regulation systems. Evaluation of the ethanolic extract of C. tamala leaves in normoglycemic and STZ - hyperglycemic rats indicated that the extract possesses hypoglycemic and antihyperglycemic activities. Experiments of Chakrobarty and Das [15] also support our finding that the administration of C. tamala leaves extract in diabetic rats restored the level of blood glucose to near normal levels. Hyperlipidemia has been reported to accompany hyperglycemic states. A significant increase in the total cholesterol, TG, LDL and VLDL levels were in accordance to earlier studies. [17] Repeated administration of ethanolic extract of C. tamala prevented the elevation of TC, TG, LDL and VLDL-cholesterol level in diabetic rats indicating the C. tamala had a beneficial effect on the hyperlipidemia induced by STZ. Phytochemical investigation of C. tamala leaf extract showed the presence of saponins, phytosterols, fatty acids, carbohydrates, monoterpene, sesquiterpene, geraniol and linolol. Thus, on chemical basis, it may be concluded that combined activity of these compound may be responsible for antidiabetic activity as it is known that steroids, terpenoids and tannins, polysaccharides compounds possess antidiabetic activity. [18] The chemical constituents viz. p-cymene, cinnamicaldehyde, eugenol, linolool, alpha and beta-pinene, limonene, 3, 3, 4, 5, 7, -pentahydroxyflavone, kaempferol-3-o-saphoroside, kapeferol-3-o-glucopyranoside and quercetin-3-o-rutenoside, [19] have been reported earlier from this plant. Our finding indicates that the ethanolic extract of C. tamala leaves commonly used in cooking may be useful for treatment of diabetes associated with hyperlipidemia. The possible mechanism of action of the leaves extract may be by promoting the insulin release from the undestroyed b-cells or its action may be insulin like as reported by Chandola et al.[20] Observations suggest that extract could be improving the oral glucose tolerance by increasing the availability of insulin. Conclusion Ethanolic extract of C. tamala exhibit significant antiyperglycemic activities in STZ-induced rats. The extract also showed improvement in lipid profile, body weight and oral glucose tolerance test (OGTT) results, hence might be valuable in diabetes. However, further chemical and pharmacological investigations are required to elucidate the exact mechanism of action of this extract and to isolate the active principles responsible for such effects. At present, work is in process to isolate the active constituents responsible for such effects. Acknowledgement The authors are greatly thankful to Management, SBS (PG) Institute of Biomedical Sciences and Research, Balawala, Dehradun (U.K.) for helping us in identifying the plant and authenticating it. Authors are also immensely thankful to the management, B.N. (PG) College Of Pharmacy, Udaipur, (Raj.) for providing us with the required facilities and support.References
Copyright 2011 - Indian Journal of Pharmacology The following images related to this document are available:Photo images[ph11153t3.jpg] [ph11153t1.jpg] [ph11153t2.jpg] |
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