Antidiabetic Effect of Helicteres isora Root in Streptozotocin Induced Diabetic Rats

Special Article - Glucose Tolerance Test

Austin J Endocrinol Diabetes. 2019; 6(1): 1067.

Antidiabetic Effect of Helicteres isora Root in Streptozotocin Induced Diabetic Rats

Zareen N1, Venkatesh S1*, Bolleddu R1, Dayanand RG2 and Ramesh M3

¹G. Pulla Reddy College of Pharmacy, India

²Siddha Central Research Institue, India

³Jubilant Biosys, India

*Corresponding author: Sama Venkatesh, Professor, G. Pulla Reddy College of Pharmacy, Hyderabad, India

Received: June 27, 2019; Accepted: July 17, 2019; Published: July 24, 2019


The anti hyperglycemic and hypolipidemic activities of butanolic extract of Helicteres isora root were investigated in streptozotocin induced diabetic rats along with its in vitro free radical scavenging activity. The butanolic extract was tested for its antidiabetic activity in streptozotocin-induced diabetes at an oral dose of 125 and 250 mg/kg by acute and chronic dosing. Treatment with butanolic extract of H. isora roots at dose of 125 and 250 mg/kg caused reduction of blood glucose by 29.49 and 32.23% respectively, within 1-hour time after oral treatment. Chronic administration of the butanolic extract at a dose of 125 and 250 mg/kg significantly reduced the blood glucose level by 41.38 and 54.18%, respectively on day 10. Whereas glibenclamide (5 mg/kg) caused a significant reduction of 26.94% in plasma glucose levels. Both butanolic extract at 250 mg/kg and glibenclamide had significantly lowered the triglyceride and total cholesterol levels. The decrease in triglyceride and total cholesterol levels could be through its control of hyperglycemia. Besides, the butanolic extract was also tested for its antioxidant activity by using diphenyl picryl hydrazyl radical assay method and it was found to effectively scavenge the free radical in vitro with an the IC50 of 26 μg/ml. The total phenol content of butanolic extract was found to be 480 mg GAE/gm of the extract. Butanolic extract of H. isora root at a dose of 250 mg/kg caused significant hypoglycemic and hypolipidemic activity in streptozotocin induced diabetic rats and hence can be considered as a potent anti diabetic agent. Effective dose can be concluded as 250 mg/kg.

Keywords: Helicteres isora; Roots; Antidiabetic activity; Streptozotocin induced diabetes; Free radical scavenging activity


Diabetes mellitus is a chronic condition characterized by high blood glucose due to an absolute or relative lack of insulin [1]. It ranks highly among the top ten disorders causing mortality throughout the world. It is a syndrome resulting from variable interaction of hereditary and environmental factors. In modern medicine still there is no satisfactory therapy available to cure diabetes mellitus although insulin therapy, oral hypoglycemic agents, restricted diet, exercises either singly or in combination constitute a major regime of therapy available for the present day diabetic patients. In a large number of cases, treatment with traditional medicine in the form of plant extracts has been reported to give remarkably good results.

Helicteres isora Linn., belongs to the family Sterculiaceae, is a sub deciduous large shrub or small tree and commonly known as East Indian Screw tree. Traditionally the juice of roots is claimed to be useful in cough, asthma, diabetes, stomach problems and intestinal infections [2-4]. The presence of cucurbitacin B and isocucurbitacin B was reported in roots [5]. The presence of antihyperglycemic properties in the butanolic extract of the roots of H. isora has been reported by us in glucose tolerance test [6] and alloxan induced diabetic rats [7]. The percentage reduction in blood glucose level is found to be 32 and 48 in glucose tolerance test and alloxan induced diabetic rats respectively at an oral dose of 250 mg/kg. Chakrabarti et al. (2002) reported a significant reduction in plasma glucose and insulin levels by 62 and 61% respectively at 300 mg/kg in insulin resistant and diabetic db/db mice [8]. Aqueous extract of the bark showed antidiabetic and hepatoprotective effect on Streptozotocin (STZ) induced diabetic rats [9]. The roots were reported to possess significant anti-inflammatory and antinociceptive properties [10,11].

The antihyperglycemic and hypolipidemic activity of H. isora root aqueous ethanol and butanolic extracts were reported in alloxan induced diabetic rats at a dose of 250 mg/kg body weight. The beneficial effects of these extracts were supported from histological examination of the liver, pancreas and kidney. Following the treatment with both extracts, the degenerative changes caused by alloxan in pancreatic cells were restored, particularly with the butanolic extract [12]. These results suggest H. isora root possesses antidiabetic principles and can be useful in the treatment of diabetes. However to develop an antidiabetic agent, the substance is required to be tested in various experimental models to determine the efficacy of the drug.

The mechanism of induction of diabetes by alloxan and streptozotocin are quite different. Hence the present study has been carried out to assess the effect of butanolic extract in streptozotocin induced hyperglycemia for its hypoglycemic and hypolipidemic properties at two different dose levels of 125 and 250 mg/kg body weight. In vitro antioxidant and total phenolic content were estimated.

Materials and Methods

Plant material

H. isora roots were collected from the Srisailam forests, Andhra Pradesh (A.P), India. Dr. S.T. Ramachandrachari, Taxonomist, Kama Reddy Degree College, Kama Reddy, A.P, India performed the botanical identification. A voucher specimen [HI/ RT/09] is being maintained in the Phytochemistry and Pharmacognosy Department of G. Pulla Reddy College of Pharmacy, Hyderabad. The roots were cleaned, cut and air dried and grounded into powder. The dried powder material was passed through sieve number 60 and stored in an air tight container.

Preparation of butanolic extract of H. isora roots

The dried root powder (5 kg) of H. isora was extracted with 80% aqueous ethyl alcohol at room temperature by maceration for seven days. To the concentrated ethanolic extract, 500 ml water was added and fractionated with chloroform, ethyl acetate and butyl alcohol. The yields of chloroform, ethyl acetate, butanol and left over aqueous extracts were 0.48, 0.25, 0.90 and 0.55% w/w respectively. The butanolic extract was used in the present study.


Male Wistar albino rats (160-180 g) were used for the study and procured from M/S. Mahaveer Agencies, Hyderabad. They were fed with standard diet (Hindustan lever, India) and water ad libitum. Animals were maintained in standard environmental conditions throughout the experiment during quarantine period. Animals described as fasted have been deprived of food for 16 h but had been allowed free access to water. The experiment was carried out according to the Committee for the Purpose of Control and Supervision of Experimentation on Animals (CPCSEA) guidelines and the Institutional Animal Ethics Committee approved all the procedures.

Induction of diabetes

Diabetes was induced by single intraperitoneal injection of STZ (Sigma-Aldrich, Milwaukee, WI, USA) at a dose of 65 mg/kg in 0.1 M citrate buffer. Since STZ is capable of producing hypoglycemia as a result of massive pancreatic insulin release, rats were treated with 10% glucose solution. Five days later blood samples were drawn and glucose levels were determined to confirm the development of diabetes (>250 mg/dl).

Effect of H. isora root extract on STZ induced diabetic rats [13,14]

The fasted diabetic rats were divided into four groups each containing 6 animals. Control rats (Group I) received distilled water orally, while the butanol extract at a dose of 125 and 250 mg/ kg were given orally to the animals of II and III groups. Group IV animals served as positive control and received glibenclamide (5 mg/kg). Group V served as normal group which received distilled water. 100 μl of blood samples were collected just prior to and at 1, 3 and 5 h after drug administration from retro orbital puncture. Plasma was separated and glucose levels were measured by glucose oxidation method using commercially available diagnostic kits (Span Diagnostics, India).

The action of H. isora roots was also tested after a longer duration of treatment [15]. The diabetic rats were divided into 4 groups of 10 rats each. Group I served as untreated diabetic control and received distilled water. Group II and III animals received H. isora butanolic extract 125 and 250 mg/kg, respectively as a fine aqueous suspension orally. Group IV animals served as positive control and received glibenclamide orally at a dose of 5 mg/kg. Group V served as normal group and received distilled water. Treatment was continued for 10 consecutive days, once daily. Blood samples were collected just prior to and on days 1 and 10 of extract administration. Plasma samples were used to measure glucose, total cholesterol, triglycerides and urea levels (Span Diagnostics, India).

Determination of DPPH radical scavenging activity [16,17]

A commercially available and stable free radical DPPH (2, 2-diphenyl-1-picryl hydrazyl) soluble in methanol was used to evaluate the antioxidant potential of H. isora. DPPH in its radical form has an absorption peak at 517 nm, which disappears on reduction by an antioxidant compound. Different concentrations of the butanolic extract (10-100 μg/ml) were added to 2 ml of freshly prepared DPPH solution. Absorbance was measured at 517 nm, 1 h after the reaction started. The percentage inhibition of DPPH in the reaction medium (% Radical Scavenging Capacity) was calculated by comparison with the control. Curcumin was used as standard. From the obtained % Radical Scavenging Capacity (%RSC) values, the IC50 value was calculated which represents the concentration of the scavenging compound that caused 50% neutralization. IC50 value was obtained by linear regression method using % activity and concentration.

%RSC was calculated by the following formula:


ABLANK – absorbance of the reagent blank

ASAMPLE - absorbance of the sample

Determination of total phenolic compounds

The total phenolic compounds in butanolic extract of H. isora root was determined by using Folin Ciocalteau Phenol Reagent method and absorbance was determined at 760 nm [18,19]. Gallic acid was used as standard. The total phenolic content in the extract was expressed as mg/gm of Gallic Acid Equivalents (GAE).

Statistical analysis

All values were expressed as mean ± SEM. Results were analysed statistically by using Analysis Of Variance (ANOVA) followed by Dunnett’s test. Values of p ‹ 0.05 were considered significant.


The results of butanolic extract of H. isora root in STZ induced diabetic rats are presented in Table 1. The fasting blood glucose levels of diabetic rats were 260-290 mg/dl. The significant fall in blood glucose levels at both the test dose levels were observed from 1 h after the extract administration. The butanolic extract at a dose of 250 mg/kg showed highest blood glucose lowering action at 3 h (47%), while at 125 mg/kg dose the reduction is 39%. Treatment of diabetic rats with standard glibenclamide produced 15% reduction of blood glucose. In untreated diabetic animals the blood glucose levels did not change significantly.