Hypoglycemic and Hypolipidemic Potentials of Psidium guajava in Alloxan Induced Diabetic Rats
N. Divya 1 and S. Ilavenil 2
1Department of Biochemistry, Pavendar Bharathidasan College of Arts and Science, Tiruchirappalli–620 024, Tamilnadu, India.
2Department of Biotechnology, PRIST University, Thanjavur–613 403, Tamilnadu, India.
Corresponding author: elanya.87@gmail.com
ABSTRACT:
Diabetes mellitus, a global public health problem, is now emerging as an epidemic world over. Over the last century changes in human behavior and lifestyle have resulted in a dramatic increase in the incidence of diabetes world over. Diabetes not only affects glucose metabolism but also lipid, a high risk factor for cardiovascular disease (CVD). Oral hypoglycemic agents and insulin is the mainstay of treatment of diabetes, they have prominent side effects and fail to significantly alter the course of diabetic complications. Plants have always been an excellent source of drugs and many of the currently available drugs have been derived directly or indirectly from them. Psidium guajava (Guava) is an economically important plant of high medicinal value. This study was undertaken to evaluate the hypoglycemic and hypolipidemic potential of ethanolic extract of Psidium guajava leaf on normal and alloxan induced diabetic rats. Male 6–8 week old albino rats were selected for the experiments and these were divided into five groups. Diabetes was induced by alloxan. Glucose, total cholesterol (TC), triglycerides (TG), high–density lipoprotein (HDL) cholesterol, low–density lipoprotein (LDL) cholesterol and very low–density lipoprotein (VLDL) cholesterol levels were measured. Significant decreases in the blood glucose level and TC, TG, and LDL cholesterol and increase in HDL cholesterol, were observed after 9 days treatment of ethanolic extract Psidium guajava leaf. It is concluded that the consumption of Psidium guajava possess blood glucose lowering properties but are also beneficial in decreasing the risk factors for CVD through lowering blood lipid levels.
KEYWORDS: Diabetes, cardiovascular disease, Psidium guajava, lipid profile
INTRODUCTION:
Diabetes mellitus, one of the most common endocrine metabolic disorders, has a significant impact on the health, quality of life, and life expectancy of patients as well as on the health care system1. With the number of cases projected to increase rapidly in the years to come, diabetes is a growing health challenge worldwide. The majority of physicians recognize that patients with diabetes are more likely to die from cardiovascular disease (CVD) than from diabetes itself. There is a high risk of CVD in people with type 2 diabetes, while cardiovascular deaths represent the top killer in this population2.
In India, indigenous remedies have been used in the treatment of diabetes since the time of Charaka and Sushruta (6th century BC)3.
Plants have always been an exemplary source of drugs and many of the currently available drugs have been derived directly or indirectly from them. Psidium guajava (Guava) is widely cultivated and its fruit is popular in world. The anti–diarrhoeal4, antipyretic5, antimicrobial6 and bio–antimutagenic7 properties of Psidium guajava leaf extract have been confirmed. Psidium guajava was also used as a hypoglycemic agent in folk medicine. The leaves and skin of the fruit have greater effects. Guava tea, the infusion of dried guava fruit and leaves, has recently become popular as a drink in Taiwan8. Moreover, the combined hypoglycemic and hypolipidemic activity of the extract has been reported in some animal models recently. Thus, the present study was carried out to evaluate the hypoglycemic and hypolipidemic potentials of Psidium guajava leaf extract on alloxan induced diabetic rat models.
MATERIALS AND METHODS:
Preparation of the extract: Fresh leaves of Psidium guajava were collected in Tiruchirappalli District during the months of January–February. The plant was authenticated by Botanist at the Bishop Heber College, Tiruchirappalli. Plant material was dried under shade at room temperature, pulverized by a mechanical grinder and sieved through 40 meshes. The powdered material (100 g) was extracted with 95% ethanol by hot continuous percolation method in a Soxhlet apparatus. The extract was then concentrated and dried under reduced pressure.
Animals: Male albino rats of 6–8 weeks age, weighing 150–180 g, were used. The animals were kept in clean and dry plastic cages, with 12h: 12h light–dark cycle at 25 ± 2ºC temperature and 45 – 55 % relative humidity. The animals were fed with standard pellet diet and water was given ad libitum. This study was carried out in the animal house of Biological and Bioinformatics Research Centre, Tiruchirappalli.
Introduction of experimental diabetes: A single dose (150 mg/kg body weight, i.p.) of alloxan monohydrate (1%) dissolved in sterile normal saline was used for induction of diabetes mellitus in the rats. Diabetes was confirmed 1 week after alloxan injection by determining the blood glucose concentration; only animals with blood glucose of 150–250 mg/dl were used for the experiment. The diabetic animals were allowed free access to tap water and pellet diet and were maintained at room temperature in plastic cages.
Collection of blood and experimental setup: Animals were classified into five groups of six rats each. Group I served as control and received normal saline (2 ml/kg body weight). Group II treated with alloxan monohydrate 150 mg/kg served as diabetic control. Group III treated with ethanolic leaf extract of Psidium guajava (500 mg/kg body weight). Group IV treated alloxan monohydrate and ethanolic leaf extract of Psidium guajava (500 mg/kg body weight). Group V treated with alloxan monohydrate and glibenclamide (5mg/kg body weight) served as reference standard. Glucose and lipid profile was estimated at the end of the study (9 day).
Statistical analysis: Statistical analysis was performed with SPSS 14 statistical software package. All the values were expressed as mean ± standard deviation. The differences of means were compared using Student’s t–test. P values < 0.05 were considered as significant.
RESULTS:
The hypoglycemic and hypolipidemic activity of Psidium guajava leaf extract was shown in Table 1. The concentration of glucose was significantly higher (P<0.001) in alloxan treated rats (Group II), as compared to normal control animals (Group I). These constituents were found to attain a near normal level in plasma of Psidium guajava treated rats (Group III, P<0.009), alloxan+Psidium guajava treated rats (Group IV, P<0.001) and alloxan+glibenclamide treated rats (Group V, P<0.001). The concentration of total cholesterol (TC) was significantly (P<0.001) higher in alloxan treated rats (Group II), as compared to normal control animals (Group I). These constituents were found to attain a near normal level in plasma of Psidium guajava treated rats (Group III, P<0.001), alloxan+Psidium guajava treated rats (Group IV, P<0.01) and alloxan+glibenclamide treated rats (Group V, P<0.001) rats.
The concentration of triglycerides (TG) was significantly (P<0.01) higher in alloxan treated rats (Group II), as compared to normal control animals (Group I). These constituents were found to attain a near normal level in plasma of Psidium guajava treated rats (Group III, P<0.009), alloxan+Psidium guajava treated rats (Group IV, P<0.03) and alloxan+glibenclamide treated rats (Group V, P<0.001). The concentration of high-density lipoprotein (HDL) cholesterol was significantly (P<0.001) lower in alloxan treated rats (Group II), as compared to normal control animals (Group I). This was found to attain a near normal level in plasma of Psidium guajava treated rats (Group III, P<0.001). There were no significant changes found in alloxan+Psidium guajava treated rats (Group IV) and alloxan+glibenclamide treated rats (Group V).
The concentration of low-density lipoprotein (LDL) cholesterol was significantly (P<0.001) higher in alloxan treated rats (Group II), as compared to normal control animals (Group I). These constituents were found to attain a near normal level in plasma of Psidium guajava treated rats (Group III, P<0.002), alloxan+Psidium guajava treated rats (Group IV, P<0.03) and alloxan+glibenclamide treated rats (Group V, P<0.005). The concentration of very low-density lipoprotein (VLDL) cholesterol was significantly (P<0.009) higher in alloxan treated rats (Group II), as compared to normal control animals (Group I). These constituents were found to attain a near normal level in plasma of Psidium guajava treated rats (Group III, P<0.008), alloxan+Psidium guajava treated rats (Group IV, P<0.02) and alloxan+glibenclamide treated rats (Group V, P<0.001).
DISCUSSION:
The occurrence of diabetes is rapidly rising all over the globe at an alarming rate emerging as a major health problem in urban population in India. Diabetes produces disturbances in lipid profiles and hyperglycaemia also generates reactive oxygen species, which in turn cause lipid peroxidation and membrane damage9. Furthermore, the mortality rate in diabetic subjects who have experienced CHD is much higher than in non–diabetic subjects 10-12.
With the distinctive traditional medical opinions and natural medicines mainly originated in plants, traditional medicine offers good clinical opportunities and shows a bright future in the therapy of diabetes mellitus and its complication. India is well known for its herbal wealth13,14. In the indigenous Indian system of medicine good numbers of plants were mentioned for the cure of diabetes and some of them have been experimentally evaluated and active principle were isolated13,14. World Health Organization15 has also recommended the evaluation of the effective of plants in conditions where there are no safe modern drugs16,14.
Table 1. Effect of ethanolic leaf extract of Psidium guajava on glucose and lipid profile in alloxan induced diabetic rats
|
Groups |
Glucose (mg/dl) |
Total cholesterol (mg/dl) |
Triglycerides (mg/dl) |
High–density lipoprotein cholesterol (mg/dl) |
Low–density lipoprotein cholesterol (mg/dl) |
Very low–density lipoprotein cholesterol (mg/dl) |
|
Group I |
107.5±9.4 |
149.1±29.8 |
106.5±13.0 |
37.0±3.4 |
90.3±32.2 |
21.3±2.6 |
|
Group II |
172.6±9.6 a |
231.1±28.3 a |
142.8±27.1 a |
17.0±4.6 a |
185.6±32.6 a |
28.5±5.3 a |
|
Group III |
114.5±9.6 b |
159.8±4.5 b |
85.1±17.1 b |
34.6±2.9 b |
108.0±7.5 b |
17.1±3.1 b |
|
Group IV |
117.6±5.4 c |
183.1±4.3 c |
110.8±4.8 c |
24.5±8.3 c |
136.6±10.5 c |
22.0±1.2 c |
|
Group V |
106.6±7.6 c |
164.3±9.6 d |
67.6±15.0 d |
22.8±9.4 d |
128.0±9.4 d |
13.5±2.8 d |
Values are expressed as mean ± SD for six animals in each group
a as compared with group I, b as compared with group II, c as compared with group II and d as compared with group II
(P<0.05)
Mukhtar et al. 17 analyzed the antidiabetic properties of an ethanol extract of the stem bark of Psidium guajava. They showed that ethanol stem bark extract exhibited statistically significant hypoglycaemic activity in alloxan induced hyperglycaemic rats but was devoid of significant hypoglycaemic effect in normal and normal glucose loaded rats. Shen et al. 18 reported the effect of aqueous and ethanol soluble solid extracts of Psidium guajava leaves on hypoglycemia and glucose metabolism in streptozotocin and nicotinamide induced type 2 diabetic rats. They showed that acute and long–term feeding tests showed a significant reduction in the blood sugar level in diabetic rats. Long–term administration of Psidium guajava leaf extracts increased the blood insulin level and glucose utilization in diabetic rats. Their results also indicated that the activities of hepatic hexokinase, phosphofructokinase and glucose–6–phosphate dehydrogenase in diabetic rats fed with aqueous extracts were higher than in the normal diabetic group. On the other hand, diabetic rats treated with the ethanol extract raised the activities of hepatic hexokinase and glucose–6–phosphate dehydrogenase only. Their experiments provided evidence to support the antihyperglycemic effect of Psidium guajava leaf extract and the health function of Psidium guajava leaves against type 2 diabetes.
Recently, Kazi Rafiq et al.19 investigated the effect of freshly prepared aqueous extracts of Psidium guajava, Momordica charantia, Coccinia indica leaves and their combination on blood glucose level and neuropathic pain in streptozotocin induced hyperglycemic rats. Treatment with freshly prepared leaf aqueous extracts significantly reduced blood glucose in diabetic rats. Blood glucose lowering effect of the combination treatment was significantly greater than individual treatments. Oral glucose tolerance test also showed the improvement of glucose tolerance by each extracts. Ju–Wen et al.20 evaluated the hyperglycemic effect of Psidium guajava leaf extract. They mainly assessed the glycation process of protein as by its active compound that causes inhibitory action on it. Their study was done to inhibit the glycation process in albumin/glucose ratio model and it was compared with the extract of polyphenon 60, a polyphenol product extracted from green tea and also with standard antiglycation agent, aminoguanidine. Reports showed that Psidium guajava leaf extracts inhibition upon is calculated to be 95% at 50Lg/ml. Such as, the leaf extract of Psidium guajava consists of many compounds and among it, the phenolic compound showed effective inhibition on glycation of albumin and mainly quercitin showed 95% inhibition at 100 Lg/ml. Thus, they reported that the leaf extract of Psidium guajava has anti–diabetic activity and also prevents the diabetic complications.
Prashant et al.21 evaluated the hypolipidaemic and hepatoprotective effects of Psidium guajava raw fruit peel in experimental diabetes. The Psidium guajava fruit extract showed its effect upon triglyceride levels of extract treated group by having hypotriglyceridaemic potential and is expediency in treating diabetic patients. Their study thus provided a result of Psidium guajava fruit aqueous extract having hypolipidaemic effects will be beneficial for type 2 diabetic patients. Our results also support the hypoglycemic and hypolipidemic activity of Psidium guajava
CONCLUSION:
In conclusion, our study revealed that the ethanolic extract Psidium guajava leaves possess potent hypoglycemic as well as hypolipidemic properties in alloxan induced diabetic rats as compared with glibenclamide and provided a new therapeutic possibility against diabetes and diabetes related complications.
REFERENCES:
1. Lucy Dey, Anoja S Attele, Chun–Su Yuan. Alternative Therapies for Type 2 Diabetes, Altern Med Rev.2002; 7(1):45–58.
2. Sultan A, Thuan JF, Avignon A . Primary prevention of cardiovascular events and type 2 diabetes. should we prioritize our interventions? Diabetes Metab. 2006; 32:559–567.
3. Grover JK, Vats V. Shifting Paradigm from conventional to alternate medicine An introduction on traditional Indian medicine, Asia Pacific Biotechnology News 2006; 5 (1):28–32.
4. Lutterodt GD, Inhibition of gastrointestinal release of acetylcholine by quercetin as a possible mode of action of Psidium guajava leaf extracts in the treatment of acute diarrhoeal disease, Journal of Ethnopharmacology.1989; 25: 235–247.
5. Olajide OA, Awe SO, Makinde JM .Pharmacological studies on the leaf of Psidium guajava, Fitoterapia.1999; 70(1): 25–31.
6. Jaiarj P, Khoohaswan P, Wongkrajang Y, Peungvicha P, Suriyawong P, Saraya M., Ruangsomboon O. Anticough and antimicrobial activities of Psidium guajava Linn 1999; leaf extract, Journal of Ethopharmacology. 67: 203–212.
7. Matsuo T, Hanamure N, Shimoi K, Nakamura, Y and Tomita I. Identification of (+)–gallocatechin as a bio–antimutagenic compound in Psidium guava leaves. Phytochemistry. 1994; 36: 1027–1029.
8. Chen HY, and Yen GC. Antioxidant activity and free radical scavenging capacity of extracts from guava (Psidium guajava L leaves), Food Chemistry. 2007; 101: 686–694.
9. Hunt JV, RT Dean and SP Wolff, Hydroxyl radical production and autooxidative glycosylation. Glucose autooxidation as the cause of protein damage in the experimental glycation model of diabetes and aging, Biochemical Journal. 1988; 256 pp. 205–212.
10. Abbott RD, Donahue RP. Kannel WB, Wilson PW. The impact of diabetes on survival following myocardial infarction in men vs women, the Framingham Study. JAMA. 1988; 260: 3456–60.
11. Herlitz J , Karlson BW, Edrardsson N, Emanuelsson H., Hjalmarson A Prognosis in diabetics with chest pain or other symptoms suggestive of acute myocardial infarction, Cardiology. 1992; 80: 237–45.
12. Miettinen H., Lehto S, Salomaa V, Mahonen M., Niemela M., Haffner SM, Pyorala K, Tuomilehto J. for the FINMONICA Myocardial Infarction Register Study group (199 Impact of diabetes on mortality after the first myocardial infarction, Diabetes Care.1998; 21: 69–75.
13. Grover JK, S Yadav and V Vats. Medicinal plants of India with anti–diabetic potential, J Ethnopharmacol. 2002; 81: 81–100.
14. Prasad SK , Alka Kulshreshtha and N Taj Qureshi. Antidiabetic Activity of Some Herbal Plants in Streptozotocin Induced Diabetic Albino Rats, Pakistan Journal of Nutrition. 2009; 8(5): 551–557.
15. World Health Organisation. Diabetes mellitus. 2nd rep, Geneva WHO Technical report series. 1980; 646.
16. Upadhaya VP and Pandey K. Ayurvedic by Indigenous Resources, Diabetes Mellitus in Developing Countries.In: Bajaj, J.S. (Ed.). New Delhi. 1984.
17. Mukhtar HM, Ansari SH, Bhat ZA, Naved T, Singh P. Antidiabetic activity of an ethanol extract obtained from the stem bark of Psidium guajava (Myrtaceae). Pharmazie. 2006; 61(8):725–7.
18. Shen SC, FC Cheng and NJ Wu. Effect of guava (Psidium guajava Linn.) leaf soluble solids on glucose metabolism in type 2 diabetic rats, Phytother Res2008; 22: 1458–1464.
19. Kazi Rafiq, Shamshad Sherajee, J Akira Nishiyama, Sufiun and Mahbub Mostofa. Effects of indigenous medicinal plants of Bangladesh on blood glucose level and neuropathic pain in streptozotocin–induced diabetic rats, African Journal of Pharmacy and Pharmacology. 2009; 3(12): 639–645
20. Ju–wen Wu., Chiu Lan Hsieh., Hsiao–Yun Wang, Hui Yin Chen., Inhibitory effects of guava (Psidium guajava L) leaf extracts and its active compounds on the glycation process of protein. Food chemistry.2009; 113:78–84.
21. Prashant Kumar Rai, Shikha Mehta and Geeta Watal. Hypolipidaemic and hepatoprotective effects of Psidium guajava raw fruit peel in experimental diabetes. Indian J Med Res. 2010; 131: 820–824.
Received on 18.11.2011 Modified on 02.12.2011
Accepted on 14.12.2011 © RJPT All right reserved
Research J. Pharm. and Tech. 5(1): Jan. 2012; Page 125-128