Antidiabetic, antihyperlipidemic and antioxidant properties of ethanol extract of Grewia asiatica Linn. bark in alloxan-induced diabetic rats.

BACKGROUND: Inspite of introduction of oral hypoglycemic agents, diabetes and its related complications remains to be a major clinical problem. The aim of this study was to investigate the antidiabetic, antihyperlipidemic and antioxidant activities of Grewia asiatica (Linn) stem bark in alloxan induced diabetic rats. METHODS: Diabetes was induced by a single dose of intraperitoneal injection of alloxan (110 mg/kg) in Norwegian Long Evans rats. Ethanol extract of barks from Grewia asiatica (GAE 200 and 400 mg/kg) and metformin (150 mg/kg) were orally administered once daily for 15 days. Blood glucose levels and body weights of rats were measured on 0, 5, 10 and 15 days of oral treatment. At the end of the experiment the rats were sacrificed and blood sample were collected for the measurement of total cholesterol (TC), triglycerides (TG), very low density lipoproteins (VLDL), low density lipoproteins (LDL), high density lipoproteins (HDL), SGOT and CK-MB. Analysis of liver glycogen content and histopathlogy of pancreas were carried out. In vitro DPPH free radical scavenging activity, total phenolic and total flavonoid content of GAE were also determined. RESULTS: After 15 days of oral administration of GAE at doses of 200 and 400 mg/kg increased survival rate and showed a significant attenuation in blood glucose and lipid profile in diabetic rats. Oral ingestion of GAE significantly reduced the SGOT and CK-MB levels and restored liver glycogen content when compared to diabetic control. The effects of GAE on SGOT, CK-MB and liver glycogen content were dose-dependent. The diabetic rats treated with GAE showed significant improvement in normal cellular population size of islets. Phytochemical screening of GAE revealed the presence of flavonoid, steroid, tannin and phenolic compounds. Total phenolic content was 44.65 ± 3.17 mg of gallic acid equivalent per gm of GAE extract and the total flavonoid content was 39.11 ± 4.65 mg of quercetin equivalent per gm of GAE extract. In DPPH scavenging assay, IC50 values of GAE and ascorbic acid were found 76.45 and 12.50 µg/ml, respectively. CONCLUSION: We demonstrated that ethanol extract of barks from G. asiatica possess glucose, lipid lowering efficacy, restored liver glycogen and protects pancreas from oxidative damage in alloxan-induced diabetic rats. Thus, the results of the present study provide a scientific rationale for the use of G. asiatica in the management of diabetes and its related complications.

Antidiabetic and antioxidant activities of ethanolic extract of Semecarpus anacardium (Linn.) bark.

BACKGROUND: Diabetes mellitus is a global health problem and constantly increasing day by day. The number of diabetic people in world is expected to rise to 366 million in 2030. The available drugs for diabetes, insulin or oral hypoglycemic agents have one or more side effects and search for new antidiabetic drugs with minimal or no side effects from medicinal plants is a challenging for us. The present study was undertaken to investigate the antidiabetic and antioxidant activity of Semecarpus anacardium (Linn.) (abbreviated as SF). METHODS: The antidiabetic activity was determined by using alloxan-induced diabetic rats. After 15 days of treatment, serum biochemical parameters such as TC, TG, LDL, HDL, SGOT and SGPT were estimated. The survival rate, body weight, organ weight, liver glycogen and blood parameters (RBC and Hb) were also measured. The antioxidant activity was measured by DPPH free radical scavenging assay. Phytochemical screening, total phenolic and total flavonoid content were determined by using standard methods. RESULTS: The results showed that the survival rate was 100% in rats of Group SA 400. The effect of extract on blood glucose level in Groups SA 100, SA 200 and SA 400 were dose-dependent throughout the treatment period. No significant changes in organ weight to body weight ratio were observed, liver weights significantly improved in Groups SA 200 and SA 400. The bark extract exhibited significant (p < 0.05) anti-diabetic activity with lowering TC, TG, LDL level dose-dependently and protected liver which may be partially explained by attenuation of SGOT and SGPT levels and increases liver glycogen. The percentage of Hb and RBC counts were negatively correlated with the doses of extracts. In DPPH scavenging assay, IC50 values of SA extract and ascorbic acid were found 72.24 µg/ml and 17.81 µg/ml, respectively. Phytochemical screening showed the presence of steroids, triterpenoids, flavonoids, glycosides, saponins, and tannins that were contribute to biological activity. CONCLUSIONS: These results indicated that stem barks of S. anacardium possess strong anti-diabetic and antioxidant potentials and support traditional medicinal use for the treatment of diabetes mellitus and good source for natural antioxidants.

Oral glucose tolerance test (OGTT) in normal control and glucose induced hyperglycemic rats with Coccinia cordifolia l. and Catharanthus roseus L.

The aim of this study is to investigate the hypoglycemic effects of petroleum ether, chloroform and ethyl acetate fractions isolated from ethanolic extracts of Coccinia cordifolia and Catharanthus roseus on normal control and orally glucose-induced hyperglycemic rats. Single doses (150 mg/kg) of different fractions of C. cordifolia and C. roseus extracts were intraperitonelly administered. The serum blood glucose level was obtained by pricking the tail vein using glucometer at time 0, 30, 60, 90, 150 and 270 minutes. In the orally glucose induced hyperglycemic rats, chloroform-coccinia (CHCl3-CC) fraction showed maximum reduction of blood glucose level by 21.94% on 60 minute of the experiment. On the other hand maximum reduction (p<0.05) of 17.92% was observed for petroleum ether-catharanthus (PET-CR) on 30 minute of the experiment. Metformin HCl was used as standard drug. Our results indicate that the CHCl3-CC fraction is relatively more potent than other fractions of C. cordifolia. Similarly the PET-CR is found to be better than other fractions of catharanthus. Phytochemical screening test results showed that chloroform fraction of C. cordifolia contain saponins and flavonoids compounds, which are known to be hypoglycemic. On the other hand petroleum ether fraction of C. roseus contains tannins, flavonoids and alkaloid compounds produced varying degree of blood sugar reduction. On the pharmacological point of view C. cordifolia and C. roseus appears to be a valuable plant, which can be useful, at least as an adjunct, in the therapy of diabetes.