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Hypolipidaemic action of Tinospora cordifolia roots in alloxan diabetic rats
Journal of Ethnopharmacology 64 (1999) 53 – 57
Hypolipidaemic action of Tinospora cordifolia roots in alloxan diabetic rats P. Stanely Mainzen Prince, Venugopal P. Menon *, G. Gunasekaran Department of Biochemistry, Annamalai Uni6ersity, Annamalai Nagar, Tamil Nadu 608 002, India Received 26 February 1998; received in revised form 25 May 1998; accepted 1 June 1998
Abstract We undertook the present study to evaluate the hypolipidaemic effect of an aqueous extract of Tinospora cordifolia roots, an indigenous plant used in Ayurvedic medicine in India. Administration of the extract of T. cordifolia roots (2.5 and 5.0 g/kg body weight) for 6 weeks resulted in a significant reduction in serum and tissue cholesterol, phospholipids and free fatty acids in alloxan diabetic rats. The root extract at a dose of 5.0 g/kg body weight showed highest hypolipidaemic effect. The effect of T. cordifolia roots at 2.5 and 5.0 g/kg body weight was better than glibenclamide. Insulin restored all the parameters to near normal values. © 1999 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Tinospora cordifolia; Hypolipidaemic; Rats
1. Introduction Tinospora cordifolia (Menispermaceae) is widely used in Ayurvedic medicine as a tonic, vitalizer and as a remedy for metabolic disorders (Nadkarni, 1954; Chopra et al., 1958). The plant stem has been considered as an indigenous source of medicines to have antidiabetic (Gupta et al., 1967), immunomodulatory (Atal et al., * Corresponding author. Tel.: + 91 41 4420154; fax: + 91 41 4422987/23080.
1986), antihepatotoxic (Peer and Sharma, 1989) and antipyretic (Vedavathy and Rao, 1991) actions. There is a report showing that the leaves of T. cordifolia possess antidiabetic property in alloxan diabetic rabbits (Noreen et al., 1992). The roots of T. cordifolia possess antiulcer (Sarma et al., 1995) and antistress (Sarma et al., 1996) actions. There are no available reports on the effect of T. cordifolia root in diabetes. Therefore, we undertook the present investigation to evaluate the hypolipidaemic effect of T. cordifolia root extracts (TCREt) in alloxan diabetic rats.
0378-8741/99/$ - see front matter © 1999 Elsevier Science Ireland Ltd. All rights reserved. PII S0378-8741(98)00106-8
P.S.M. Prince et al. / Journal of Ethnopharmacology 64 (1999) 53–57
54
Table 1 Effect of TCREt on the cholesterol level Groups
Control Diabetic untreated Diabetic+TCREt (2.5 g/kg) Diabetic+TCREt (5.0 g/kg) Diabetic+TCREt (7.5 g/kg) Glibenclamide Insulin
Serum (mg/100 ml)
80.09 2.6 148.49 6.2** 109.39 6.1** 102.29 5.8** 146.39 5.8ns 111.29 5.5** 84.89 3.2**
(mg/100 g wet tissue) Liver
Heart
Kidney
295.4 9 9.2 504.4 9 15.9** 320.2 9 6.1** 304.2 9 7.3** 503.0 916.7ns 320.1 96.2** 298.3 914.8**
150.2 912.9 313.2 98.9** 195.2 94.5** 174.2 94.6** 312.0 99.2ns 176.1 96.8** 154.2 96.9**
490.6 9 8.9 758.4 9 16.4** 531.0 9 15.5** 522.0 9 15.6** 756.4 9 16.1ns 531.0 9 14.4** 500.2 9 20.9**
Values are mean 9S.D. from 12 rats in each group. Diabetic group is compared with normal group. Experimental groups are compared with diabetic group. Values are statistically significant ** PB0.001 and n.s. (not significant) as compared with respective control.
2. Materials and methods
2.1. Plant material T. cordifolia roots were collected fresh from Kanyakumari district, Tamil Nadu, India and dried. The plant was identified at the Herbarium of Botany Directorate in Annamalai University. A voucher specimen (No. 454) was deposited in the Botany Department of Annamalai University. The root was dried and ground by an electrical mill (mesh number 50). The powdered roots were kept in air tight containers in a deep freeze (− 4°C) until the time of use.
2.2. Preparation of the aqueous T. cordifolia root extract (TCREt) A suspension of 100 g of roots on 400 ml of distilled water was stirred magnetically overnight (12 h) at room temperature. This was repeated three consecutive times. The residue was removed by filtration and the extract evaporated below 40°C under reduced pressure in a rotary evaporator. The residual extract was dissolved in physiological salt solution and used in the study.
140–180 g) procured from the Central Animal House, Department of Experimental Medicine, Rajah Muthiah Medical College, Annamalai University were used in this study. The animals were fed on a pellet diet (Hindustan Lever, India) and water ad libitum. Diabetes was induced by an intraperitoneal injection of 150 mg/kg of alloxan monohydrate (Al-Shamaony et al., 1994). After 2 weeks rats with blood glucose levels of 200–280 mg/100 ml were taken for the study. Blood was taken from the eyes (venous pool) and glucose content was determined according to Sasaki et al. (1972).
2.4. Determination of cholesterol Cholesterol in serum and tissues were determined by the method of Zak et al. (1953).
2.5. Determination of phospholipids Phospholipids in serum and tissues were determined by the method of Zilversmit and Davies (1950).
2.6. Determination of free fatty acids 2.3. Preparation of diabetic animals Male albino rats Wistar strain (body weight
Free fatty acids in serum and tissues were determined by the method of Falholt et al. (1973).
P.S.M. Prince et al. / Journal of Ethnopharmacology 64 (1999) 53–57
55
Table 2 Effect of TCREt on the phospholipids level Groups
Control Diabetic untreated Diabetic+TCREt (2.5 g/kg) Diabetic+TCREt (5.0 g/kg) Diabetic+TCREt (7.5 g/kg) Glibenclamide Insulin
Serum (mg/100 ml)
105.49 3.2 137.09 3.5** 133.59 4.1** 130.4 9 4.3** 136.29 3.2a 134.2 9 3.8** 108.2 9 2.9**
(mg/100 g wet tissue) Liver
Heart
Kidney
1754.0 984.9 3560.9 9 98.4** 1786.1 976.4** 1771.2 9 74.8** 3558.4 972.9a 1789.2 9 81.3** 1759.0 982.6**
993.2 937.2 1835.4 9 77.8** 1033.2 940.2** 1022.4 9 39.3** 1830.2 945.7a 1034.1 942.1** 999.2 93.8**
1460.4 950.8 3312.4 9 98.2** 1508.2 9 47.8** 1483.5 946.2** 3308.4 9 47.8a 1509.1 9 44.9** 1464.0 9 45.8**
Values are mean 9S.D. from 12 rats in each group. Diabetic group is compared with normal group. Experimental groups are compared with diabetic group. Values are statistically significant ** PB0.001 a not significant as compared with respective control.
2.7. Experimental design In the experiment a total of 84 rats were used. Diabetes was induced 2 weeks before starting the treatment. After the induction of alloxan diabetes the rats were divided into seven groups as follows: Group 1, control rats given 0.5 ml of physiological salt solution; Group 2, untreated diabetic rats given 0.5 ml of physiological salt solution; Group 3, diabetic rats given T. cordifolia root extract (TCREt) (2.5 g/kg body weight) in physiological salt solution daily using an intragastric tube for 6 weeks; Group 4, diabetic rats given TCREt (5.0 g/kg body weight) in physiological salt solution daily using an intragastric tube for 6 weeks; Group 5, diabetic rats given TCREt (7.5 g/kg body weight) in physiological salt solution daily using an intragastric tube daily for 6 weeks; Group 6, diabetic rats given glibenclamide orally (600 mg/kg body weight) in physiological salt solution daily using an intragastric tube daily for 6 weeks; Group 7, diabetic rats given protamine zinc insulin intraperitoneally (6 units/kg body weight) daily for 6 weeks. Animals were deprived of food for at least 12 h but allowed free access to drinking water. After 42 days of treatment, the rats were sacrificed by cervical dislocation. Blood was collected and serum separated by centrifugation. Liver, kidney
and heart tissues were collected in ice cold containers.
2.8. Statistical analysis All the grouped data were statistically evaluated and the significance of various treatments was calculated using Student’s t-test. All the results were expressed as mean9 S.D. from 12 rats in each group.
3. Results The control rats had the blood glucose of 80.39 9.26 mg/dl while untreated diabetic rats showed 290.8 9 9.65 mg/dl. TCREt treated rats showed (2.5 g/kg and 5.0 g/kg body weight) significantly lower blood glucose levels (115.29 6.76 mg/dl and 102.0 98.46 mg/dl) when compared to untreated diabetic rats. TCREt at higher doses (7.5 g/kg body weight) did not show any significant change in blood glucose (287.499.45 mg/dl). Glibenclamide treatment showed significant reduction in blood glucose (117.69 8.42 mg/dl) in diabetic rats. Insulin treatment tends to bring back the glucose levels to near normal in diabetic rats (86.89 7.36 mg/dl). Table 1 shows the levels of serum and tissue cholesterol in control and experimental rats. The
56
P.S.M. Prince et al. / Journal of Ethnopharmacology 64 (1999) 53–57
Table 3 Effect of TCREt on the free fatty acid level Groups
Control Diabetic untreated Diabetic+TCREt (2.5 g/kg) Diabetic+TCREt (5.0 g/kg) Diabetic+TCREt (7.5 g/kg) Glibenclamide Insulin
Serum (mg/100 ml)
79.59 4.6 159.49 7.9** 107.29 2.7** 97.29 12.3** 158.79 17.4a 110.29 10.3** 82.596.8**
(mg/100 g wet tissue) Liver
Heart
Kidney
695.2 9 25.3 1190.1 979.6** 740.2 921.4** 724.4 9 22.9** 1188.4 925.5a 743.1 9 20.7** 698.4 922.2**
500.4 9 30.4 1884.6 9 84.6** 538.4 9 28.8** 523.9 9 28.4** 1882.3 9 29.5a 540.2 9 24.6** 504.4 9 18.6**
718.9 9 43.8 1694.4 998.2** 752.29 26.9** 740.4 9 29.5** 1692.3 920.9a 757.1 928.2** 721.3 922.6**
Values are mean 9 S.D. from 12 rats in each group. Diabetic group is compared with normal group. Experimental groups are compared with diabetic group. Values are statistically significant ** PB0.001. a not significant as compared with respective control.
serum and tissue cholesterol were significantly higher in diabetic rats as compared to control rats. Oral administration of TCREt at 2.5 g/kg, 5.0 g/kg body weight and glibenclamide significantly decreased the cholesterol as compared to untreated diabetic rats. The level of serum and tissue phospholipids in control and experimental rats is given in Table 2. Phospholipids levels were significantly higher in both serum and tissues in diabetic rats as compared to control rats. Oral administration of TCREt (at 2.5 g/kg and 5.0 g/kg body weight) and glibenclamide significantly lowered the phospholipids as compared to untreated diabetic rats. Table 3 demonstrates the serum and tissue levels of free fatty acids in control and experimental rats. There was a significant elevation in serum and tissue free fatty acids during diabetes when compared with the corresponding control rats. Oral administration of TCREt (at 2.5 g/kg and 5.0 g/kg body weight) and glibenclamide significantly decreased the levels of free fatty acids as compared to untreated diabetic rats. For all the parameters studied, TCREt at a dose of 7.5 g/kg body weight showed a regression of therapeutic effect. TCREt at a dose of 5.0 g/kg body weight showed highest hypolipidaemic effect. The effect of TCREt at a dose of 2.5 and 5.0 g/kg body weight was better than glibenclamide. Insulin restored all the parameters to near normal values.
4. Discussion In our experiment, we have observed higher levels of serum lipids in alloxan diabetic rats. The level of serum lipids is usually raised in diabetes, and such an elevation represents a risk factor for coronary heart disease (Al-Shamaony et al., 1994). Lowering of serum lipids levels through dietary or drugs therapy seems to be associated with a decrease in the risk of vascular disease (Rhoads et al., 1976). The abnormal high concentration of serum lipids in diabetes is mainly due to the increase in the mobilization of free fatty acids from the peripheral depots, since insulin inhibits the hormone sensitive lipase. On the other hand, glucagon, catecholamines and other hormones enhance lipolysis. The marked hyperlipemia that characterizes the diabetic state may therefore be regarded as a consequence of the uninhibited actions of lipolytic hormones on the fat depots (Al-Shamaony et al., 1994). In our study we have also observed higher levels of cholesterol, phospholipids and free fatty acids in liver, kidney and heart in alloxan diabetic rats. Similar results have been reported by other workers in alloxan diabetic rats (Suresh Kumar and Menon, 1992) The ability of T. cordifolia root extract to reduce the levels of serum and tissue lipids in diabetic animals have never been studied before. The
P.S.M. Prince et al. / Journal of Ethnopharmacology 64 (1999) 53–57
results of this study shows that a continuous administration of an aqueous extract of T. cordifolia root for 6 weeks prevents elevation of serum and tissue lipids secondary to the diabetes state. The hypolipidaemic effect of TCREt can be explained as a direct reduction in the blood glucose concentration. Although we have tried three levels of TCREt—2.5, 5.0 and 7.5 g/kg body weight the hypolipidaemic effect was only detectable in the 2.5 g and 5.0 g dose. At 7.5 g level there was no significant alteration. It is not clear, why there is no significant effect at 7.5. Maybe some of the components in the water extract at higher doses show no effect. In this context an aqueous extract of Syzigium cumini seeds at high doses did not show significant hypolipidaemic effect in alloxan diabetic rats (Stanely Mainzen Prince and Menon, 1997). Thus our study shows that an aqueous extract of T. cordifolia roots possess hypolipidaemic action in alloxan diabetic rats.
References Al-Shamaony, L, Al-Khazraji, S.M., Twaij, H.A., 1994. Hypoglycaemic effect of Artemisia herba alba.11. Effect of a valuable extract on some blood parameters in diabetic animals. Journal of Ethnopharmacology 43, 167–171. Atal, C.K., Sharma, M.L, Kaul, A., Khajuria, A., 1986. Immunomodulating agents of plant origin. 1. Preliminary screening. Journal of Ethnopharmacology 18, 133–141. Chopra, R.N., Chorpa, I.C., Handa, K.L., Kapur, L.D., 1958. Indigenous Drugs of India, Calcutta, 2nd ed, p. 426. Falholt, K., Falholt, W., Lund, B., 1973. An easy calorimetric method for routine determination of free fatty acids in plasma. Clinica Chimica Acta 46, 105–111. Gupta, S.S., Verma, S.C.L., Garg, V.P., Mahesh, R., 1967. Antidiabetic effects of Tinospora cordifolia. Part 1. Effect
57
on fasting blood sugar level, glucose tolerence and adrenaline induced hyperglycaemia. Indian Journal of Medical Research 55 (7), 733 – 745. Nadkarni, A.K., 1954 reprinted (1976). Indian Materia Medica, Bombay, 3rd revised ed, p. 1221. Noreen, W., Abdul, W., Syed-Abdul-Wahid, S., 1992. Effect of Tinospora cordifolia on blood glucose and total lipid levels of normal and alloxan diabetic rabbits. Planta Medica 58 (2), 131 – 136. Peer, F., Sharma, M.C., 1989. Therapeutic evaluation of Tinospora cordifolia in CCL4 induced hepatopathy in goats. Indian Journal of Veterinary Medicine 9 (2), 154 – 156. Rhoads, G.G., Gulbrandse, C.L., Kagan, A., 1976. Serum lipoproteins and coronary artery disease in a population study of Hawaiian Japanese men. New England Journal of Medicine 294, 293 – 298. Sarma, D.N.K., Khosa, R.L., Chansouria, J.P.N., Sahai, M., 1995. Antiulcer activity of Tinospora cordifolia Miers and Centella asiatica (L.) extracts. Phytotherapy Research 9 (8), 589 – 590. Sarma, D.N.K., Khosa, R.L., Chansouria, J.P.N., Sahai, M., 1996. Antistress activity of Tinospora cordifolia and Centella asiatica (L.) extracts. Phytotherapy Research 10 (2), 181 – 183. Sasaki, T., Matsy, S., Sonae, A., 1972. Effect of acetic acid concentration on the colour reaction in the O-toluidine boric acid method for blood glucose estimation. Rinsho Kagaku 1, 346 – 353. Stanely Mainzen Prince, P., Menon, V.P., 1997. Hypolipidaemic effect of Syzigium cumini (Jamun) seeds in alloxan diabetic rats. Medical Science Research 25 (12), 819 – 821. Suresh Kumar, J.S., Menon, V.P., 1992. Peroxidative changes in experimental diabetes mellitus. Indian Journal of Medical Research 96, 176 – 181. Vedavathy, S., Rao, K.N., 1991. Antipyretic activity of six indigenous medicinal plants of Tirumala Hills, Andhra Pradesh, India. Journal of Ethnopharmacology 33, 1 – 2. Zak, B., Boyle, A.J., Zlatkis, A., 1953. A method for the determination of cholesterol. Journal of Clinical Medicine 41, 486 – 492. Zilversmit, D.B., Davies, A.K., 1950. Micro method for the determination of plasma phospholipid by trichloroacetic acid precipitation. Journal of Laboratory Clinical Medicine 35, 155 – 160.
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Hypolipidaemic action of Tinospora cordifolia roots in alloxan diabetic rats P. Stanely Mainzen Prince, Venugopal P. Menon *, G. Gunasekaran Department of Biochemistry, Annamalai Uni6ersity, Annamalai Nagar, Tamil Nadu 608 002, India Received 26 February 1998; received in revised form 25 May 1998; accepted 1 June 1998
Abstract We undertook the present study to evaluate the hypolipidaemic effect of an aqueous extract of Tinospora cordifolia roots, an indigenous plant used in Ayurvedic medicine in India. Administration of the extract of T. cordifolia roots (2.5 and 5.0 g/kg body weight) for 6 weeks resulted in a significant reduction in serum and tissue cholesterol, phospholipids and free fatty acids in alloxan diabetic rats. The root extract at a dose of 5.0 g/kg body weight showed highest hypolipidaemic effect. The effect of T. cordifolia roots at 2.5 and 5.0 g/kg body weight was better than glibenclamide. Insulin restored all the parameters to near normal values. © 1999 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Tinospora cordifolia; Hypolipidaemic; Rats
1. Introduction Tinospora cordifolia (Menispermaceae) is widely used in Ayurvedic medicine as a tonic, vitalizer and as a remedy for metabolic disorders (Nadkarni, 1954; Chopra et al., 1958). The plant stem has been considered as an indigenous source of medicines to have antidiabetic (Gupta et al., 1967), immunomodulatory (Atal et al., * Corresponding author. Tel.: + 91 41 4420154; fax: + 91 41 4422987/23080.
1986), antihepatotoxic (Peer and Sharma, 1989) and antipyretic (Vedavathy and Rao, 1991) actions. There is a report showing that the leaves of T. cordifolia possess antidiabetic property in alloxan diabetic rabbits (Noreen et al., 1992). The roots of T. cordifolia possess antiulcer (Sarma et al., 1995) and antistress (Sarma et al., 1996) actions. There are no available reports on the effect of T. cordifolia root in diabetes. Therefore, we undertook the present investigation to evaluate the hypolipidaemic effect of T. cordifolia root extracts (TCREt) in alloxan diabetic rats.
0378-8741/99/$ - see front matter © 1999 Elsevier Science Ireland Ltd. All rights reserved. PII S0378-8741(98)00106-8
P.S.M. Prince et al. / Journal of Ethnopharmacology 64 (1999) 53–57
54
Table 1 Effect of TCREt on the cholesterol level Groups
Control Diabetic untreated Diabetic+TCREt (2.5 g/kg) Diabetic+TCREt (5.0 g/kg) Diabetic+TCREt (7.5 g/kg) Glibenclamide Insulin
Serum (mg/100 ml)
80.09 2.6 148.49 6.2** 109.39 6.1** 102.29 5.8** 146.39 5.8ns 111.29 5.5** 84.89 3.2**
(mg/100 g wet tissue) Liver
Heart
Kidney
295.4 9 9.2 504.4 9 15.9** 320.2 9 6.1** 304.2 9 7.3** 503.0 916.7ns 320.1 96.2** 298.3 914.8**
150.2 912.9 313.2 98.9** 195.2 94.5** 174.2 94.6** 312.0 99.2ns 176.1 96.8** 154.2 96.9**
490.6 9 8.9 758.4 9 16.4** 531.0 9 15.5** 522.0 9 15.6** 756.4 9 16.1ns 531.0 9 14.4** 500.2 9 20.9**
Values are mean 9S.D. from 12 rats in each group. Diabetic group is compared with normal group. Experimental groups are compared with diabetic group. Values are statistically significant ** PB0.001 and n.s. (not significant) as compared with respective control.
2. Materials and methods
2.1. Plant material T. cordifolia roots were collected fresh from Kanyakumari district, Tamil Nadu, India and dried. The plant was identified at the Herbarium of Botany Directorate in Annamalai University. A voucher specimen (No. 454) was deposited in the Botany Department of Annamalai University. The root was dried and ground by an electrical mill (mesh number 50). The powdered roots were kept in air tight containers in a deep freeze (− 4°C) until the time of use.
2.2. Preparation of the aqueous T. cordifolia root extract (TCREt) A suspension of 100 g of roots on 400 ml of distilled water was stirred magnetically overnight (12 h) at room temperature. This was repeated three consecutive times. The residue was removed by filtration and the extract evaporated below 40°C under reduced pressure in a rotary evaporator. The residual extract was dissolved in physiological salt solution and used in the study.
140–180 g) procured from the Central Animal House, Department of Experimental Medicine, Rajah Muthiah Medical College, Annamalai University were used in this study. The animals were fed on a pellet diet (Hindustan Lever, India) and water ad libitum. Diabetes was induced by an intraperitoneal injection of 150 mg/kg of alloxan monohydrate (Al-Shamaony et al., 1994). After 2 weeks rats with blood glucose levels of 200–280 mg/100 ml were taken for the study. Blood was taken from the eyes (venous pool) and glucose content was determined according to Sasaki et al. (1972).
2.4. Determination of cholesterol Cholesterol in serum and tissues were determined by the method of Zak et al. (1953).
2.5. Determination of phospholipids Phospholipids in serum and tissues were determined by the method of Zilversmit and Davies (1950).
2.6. Determination of free fatty acids 2.3. Preparation of diabetic animals Male albino rats Wistar strain (body weight
Free fatty acids in serum and tissues were determined by the method of Falholt et al. (1973).
P.S.M. Prince et al. / Journal of Ethnopharmacology 64 (1999) 53–57
55
Table 2 Effect of TCREt on the phospholipids level Groups
Control Diabetic untreated Diabetic+TCREt (2.5 g/kg) Diabetic+TCREt (5.0 g/kg) Diabetic+TCREt (7.5 g/kg) Glibenclamide Insulin
Serum (mg/100 ml)
105.49 3.2 137.09 3.5** 133.59 4.1** 130.4 9 4.3** 136.29 3.2a 134.2 9 3.8** 108.2 9 2.9**
(mg/100 g wet tissue) Liver
Heart
Kidney
1754.0 984.9 3560.9 9 98.4** 1786.1 976.4** 1771.2 9 74.8** 3558.4 972.9a 1789.2 9 81.3** 1759.0 982.6**
993.2 937.2 1835.4 9 77.8** 1033.2 940.2** 1022.4 9 39.3** 1830.2 945.7a 1034.1 942.1** 999.2 93.8**
1460.4 950.8 3312.4 9 98.2** 1508.2 9 47.8** 1483.5 946.2** 3308.4 9 47.8a 1509.1 9 44.9** 1464.0 9 45.8**
Values are mean 9S.D. from 12 rats in each group. Diabetic group is compared with normal group. Experimental groups are compared with diabetic group. Values are statistically significant ** PB0.001 a not significant as compared with respective control.
2.7. Experimental design In the experiment a total of 84 rats were used. Diabetes was induced 2 weeks before starting the treatment. After the induction of alloxan diabetes the rats were divided into seven groups as follows: Group 1, control rats given 0.5 ml of physiological salt solution; Group 2, untreated diabetic rats given 0.5 ml of physiological salt solution; Group 3, diabetic rats given T. cordifolia root extract (TCREt) (2.5 g/kg body weight) in physiological salt solution daily using an intragastric tube for 6 weeks; Group 4, diabetic rats given TCREt (5.0 g/kg body weight) in physiological salt solution daily using an intragastric tube for 6 weeks; Group 5, diabetic rats given TCREt (7.5 g/kg body weight) in physiological salt solution daily using an intragastric tube daily for 6 weeks; Group 6, diabetic rats given glibenclamide orally (600 mg/kg body weight) in physiological salt solution daily using an intragastric tube daily for 6 weeks; Group 7, diabetic rats given protamine zinc insulin intraperitoneally (6 units/kg body weight) daily for 6 weeks. Animals were deprived of food for at least 12 h but allowed free access to drinking water. After 42 days of treatment, the rats were sacrificed by cervical dislocation. Blood was collected and serum separated by centrifugation. Liver, kidney
and heart tissues were collected in ice cold containers.
2.8. Statistical analysis All the grouped data were statistically evaluated and the significance of various treatments was calculated using Student’s t-test. All the results were expressed as mean9 S.D. from 12 rats in each group.
3. Results The control rats had the blood glucose of 80.39 9.26 mg/dl while untreated diabetic rats showed 290.8 9 9.65 mg/dl. TCREt treated rats showed (2.5 g/kg and 5.0 g/kg body weight) significantly lower blood glucose levels (115.29 6.76 mg/dl and 102.0 98.46 mg/dl) when compared to untreated diabetic rats. TCREt at higher doses (7.5 g/kg body weight) did not show any significant change in blood glucose (287.499.45 mg/dl). Glibenclamide treatment showed significant reduction in blood glucose (117.69 8.42 mg/dl) in diabetic rats. Insulin treatment tends to bring back the glucose levels to near normal in diabetic rats (86.89 7.36 mg/dl). Table 1 shows the levels of serum and tissue cholesterol in control and experimental rats. The
56
P.S.M. Prince et al. / Journal of Ethnopharmacology 64 (1999) 53–57
Table 3 Effect of TCREt on the free fatty acid level Groups
Control Diabetic untreated Diabetic+TCREt (2.5 g/kg) Diabetic+TCREt (5.0 g/kg) Diabetic+TCREt (7.5 g/kg) Glibenclamide Insulin
Serum (mg/100 ml)
79.59 4.6 159.49 7.9** 107.29 2.7** 97.29 12.3** 158.79 17.4a 110.29 10.3** 82.596.8**
(mg/100 g wet tissue) Liver
Heart
Kidney
695.2 9 25.3 1190.1 979.6** 740.2 921.4** 724.4 9 22.9** 1188.4 925.5a 743.1 9 20.7** 698.4 922.2**
500.4 9 30.4 1884.6 9 84.6** 538.4 9 28.8** 523.9 9 28.4** 1882.3 9 29.5a 540.2 9 24.6** 504.4 9 18.6**
718.9 9 43.8 1694.4 998.2** 752.29 26.9** 740.4 9 29.5** 1692.3 920.9a 757.1 928.2** 721.3 922.6**
Values are mean 9 S.D. from 12 rats in each group. Diabetic group is compared with normal group. Experimental groups are compared with diabetic group. Values are statistically significant ** PB0.001. a not significant as compared with respective control.
serum and tissue cholesterol were significantly higher in diabetic rats as compared to control rats. Oral administration of TCREt at 2.5 g/kg, 5.0 g/kg body weight and glibenclamide significantly decreased the cholesterol as compared to untreated diabetic rats. The level of serum and tissue phospholipids in control and experimental rats is given in Table 2. Phospholipids levels were significantly higher in both serum and tissues in diabetic rats as compared to control rats. Oral administration of TCREt (at 2.5 g/kg and 5.0 g/kg body weight) and glibenclamide significantly lowered the phospholipids as compared to untreated diabetic rats. Table 3 demonstrates the serum and tissue levels of free fatty acids in control and experimental rats. There was a significant elevation in serum and tissue free fatty acids during diabetes when compared with the corresponding control rats. Oral administration of TCREt (at 2.5 g/kg and 5.0 g/kg body weight) and glibenclamide significantly decreased the levels of free fatty acids as compared to untreated diabetic rats. For all the parameters studied, TCREt at a dose of 7.5 g/kg body weight showed a regression of therapeutic effect. TCREt at a dose of 5.0 g/kg body weight showed highest hypolipidaemic effect. The effect of TCREt at a dose of 2.5 and 5.0 g/kg body weight was better than glibenclamide. Insulin restored all the parameters to near normal values.
4. Discussion In our experiment, we have observed higher levels of serum lipids in alloxan diabetic rats. The level of serum lipids is usually raised in diabetes, and such an elevation represents a risk factor for coronary heart disease (Al-Shamaony et al., 1994). Lowering of serum lipids levels through dietary or drugs therapy seems to be associated with a decrease in the risk of vascular disease (Rhoads et al., 1976). The abnormal high concentration of serum lipids in diabetes is mainly due to the increase in the mobilization of free fatty acids from the peripheral depots, since insulin inhibits the hormone sensitive lipase. On the other hand, glucagon, catecholamines and other hormones enhance lipolysis. The marked hyperlipemia that characterizes the diabetic state may therefore be regarded as a consequence of the uninhibited actions of lipolytic hormones on the fat depots (Al-Shamaony et al., 1994). In our study we have also observed higher levels of cholesterol, phospholipids and free fatty acids in liver, kidney and heart in alloxan diabetic rats. Similar results have been reported by other workers in alloxan diabetic rats (Suresh Kumar and Menon, 1992) The ability of T. cordifolia root extract to reduce the levels of serum and tissue lipids in diabetic animals have never been studied before. The
P.S.M. Prince et al. / Journal of Ethnopharmacology 64 (1999) 53–57
results of this study shows that a continuous administration of an aqueous extract of T. cordifolia root for 6 weeks prevents elevation of serum and tissue lipids secondary to the diabetes state. The hypolipidaemic effect of TCREt can be explained as a direct reduction in the blood glucose concentration. Although we have tried three levels of TCREt—2.5, 5.0 and 7.5 g/kg body weight the hypolipidaemic effect was only detectable in the 2.5 g and 5.0 g dose. At 7.5 g level there was no significant alteration. It is not clear, why there is no significant effect at 7.5. Maybe some of the components in the water extract at higher doses show no effect. In this context an aqueous extract of Syzigium cumini seeds at high doses did not show significant hypolipidaemic effect in alloxan diabetic rats (Stanely Mainzen Prince and Menon, 1997). Thus our study shows that an aqueous extract of T. cordifolia roots possess hypolipidaemic action in alloxan diabetic rats.
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