Evaluation of antinociceptive action of various fractions of methanolic extract of Terminalia bellirica roxb on diabetic neuropathic rats

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1 Evaluation of antinociceptive action of various fractions of methanolic extract of Terminalia bellirica roxb on diabetic neuropathic rats Shijna K 1*, Premkumar N 2, Kalai Kovan T 2 1 College of Pharmacy, Gulf Medical University, Ajman, UAE 2 Department Of Pharmacology, Krupanidhi College Of Pharmacy, Bangalore, India *Presenting Author ABSTRACT Objective: The study aimed to investigating the antinociceptive action of various fractions of methanolic extract of Terminalia Bellirica roxb on Diabetic neuropathic rats. Materials and Methods: Diabetes was induced in over night fasted male adult Sprague- Dawely rats by a single dose of intra peritoneal injection of streptozotocin 50mg/kg. Animals were divided into 8 groups, and treatment was started on 4 th week with n-butanol fraction (200 mg/ kg, p.o.), Ethyl acetate fraction (200 mg/ kg, p.o.), Water fraction (200 mg/ kg, p.o.), Fluoxetine (14.5 mg/kg, p.o.), Imipramine (10.5 mg/kg, p.o.) and Gallic acid(50 mg/kg, p.o.).pain threshold has been evaluated in each week with analgesic models like Eddys hot plate method, Tail immersion method and Formaline test. Results: Animals treated with Fluoxetine, Imipramine, Gallic Acid, n-butanol,ethyl acetate and Water fractions has given significant result when compared with Diabetic control in each analgesic models. Among the fractions the result varies with the amount of Gallic acid present in it. Conclusion: Antinociceptive properties of various fractions of methanolic extract of Terminalia bellirica is due to the presence of Gallic acid and effect is through the restoration of brain monoamines, like nor epinephrine, 5-hydroxy tyrptamine (5-HT) and dopamine level. Keywords: diabetic neuropathy, Terminalia bellirica, fluoxetine, imipramine, gallic Acid INTRODUCTION Due to perceived effectiveness, relatively low cost and minimal side effects in clinical experience, several species of plant have been used for hyperglycemic condition even when their biologically active compounds are unknown 1. Terminalia bellirica fruit is the main constituent of the ayurvedic formulation triphala. Terminalia bellirica belongs to the family Combretaceae. Its common name in Sanskrit is Bibhitakah. Studies have proved that Terminalia bellirica fruit has antidepressant, anti bacterial, anti malarial, anti HIV, anti mutagenic, hypolipidemic, immunomodulator, anti diabetic and antioxidant properties. It is also used in kidney and urinary disorder 2. Chief constituent of Terminalia bellirica fruit is poly phenol. The antioxidant activity of Terminalia bellirica is due to its phenolic content mainly Gallic acid. Gallic acid is a natural antioxidant present rich in Terminalia bellirica 3. Antidepressant agents such as Fluoxetine and Imipramine are currently used in the treatment of diabetic neuropathy. Drug tolerance on long term use is the drawback of Fluoxetine and Imipramine 4. The antidepressant activity of Terminalia bellirica fruit extract is due to its antioxidant activity 3. A previous study conducted in our lab has reported that the methanolic extract of Terminalia bellirica attenuated the diabetes induced neuropathic pain through a mechanism same as antidepressant drugs like Fluoxetine and Imipramine 5. Hence the current study was undertaken to assess the role of various fractions of methanolic extract of Terminalia bellirica fruit and gallic acid in diabetic induced neuropathic pain. 93

2 MATERIALS AND METHODS Animals The study was approved as per the guidelines of Institutional Animal Ethical Committe, and was carried out. Male Sprague Dawly rats weighing gm were selected for the study. Animals were lodged at 25 ± 5 C in a well-ventilated animal house under 12:12 h light dark cycle with a free access to food and water in an animal house approved by CPCSEA ( Committee for the Purpose of Control and Supervision on Experiments on Animals) (Ref:KCP/IAEC-31/ ). Drugs and Chemicals - From Natural remedies Pvt Ltd, Bangalore, methanolic extract of Terminalia bellirica roxb fruit (Patch no- PC/PT/ ) was collected. Fluoxetine and Imipramine (gifted samples from Torrent pharmaceuticals, Ahmadabad), Gallic acid (Merck Specialties Private Limited, Mumbai, India) were empoyed in the study. FRACTIONISATION OF METHANOLIC EXTRACT OF TERMINALIA BELLIRICA The dried methanol extract (100 g) was suspended in 200 ml of distilled water and was extracted successively and exhaustively with solvents in increasing order of polarity. The suspension mixture was extracted with ethyl acetate (200 ml X 3) and ethyl acetate fraction was collected. After extraction with ethyl acetate, the mother liquor was extracted with n-butanol (200 ml X 3) and separated the n-butanol fraction. The remaining mother liquor was the water fraction. Each fraction was freed of solvent by distillation under reduced pressure. The yield of each fraction was recorded viz., ethyl acetate fraction (g), n-butanol fraction (g) and water fraction (g) 6. PRELIMINARY PHYTOCHEMICAL INVESTIGATION OF VARIOUS FRACTIONS Various fractions of methanolic extract of Terminalia bellirica underwent a qualitative analysis to investigate the presence of various phytochemical constituents like polyphenol, triterpenoides, glycosides, phytosterols, saponins, tannins and flavonoids 7. THIN LAYER CHROMATOGRAPHY OF GALLIC ACID Stationary phase: Precoated silica gel G plate. Mobile phase : Ethyl Acetate: Toluene: Formic acid (2.2:1.1:1.1) Visualization : UV at 254 nm, after spraying with FeCl 3 reagent 3. Retention factor (Rf) = Distance traveled by the fractions Distance traveled by the solvent Diabetic neuropathic pain models Introduction of diabetes Diabetes was brought on over night fasted male adult Sprague- Dawely rats weighing g by a single dose of intra peritoneal injection of streptozotocin 50mg/kg, dissolved in citrate buffer ph 4.4. After 48 h of streptozotocin injection the plasma glucose level were checked. Diabetic animals showing plasma glucose more than 250 mg/dl were selected for diabetic neuropathic studies 8. Treatment protocol (Each study group comprise of six rats) Normal control Diabetic control Diabetic groups receiving curative treatment Ethyl acetate fraction (200 mg/kg, p.o.) water fraction.(200 mg/ kg, p.o.) N-butanol fraction (200 mg/kg, p.o.) Fluoxetine (14.5 mg/kg, p.o.) 4 Imipramine (10.5 mg/kg, p.o.) 4 Gallic acid (50 mg/kg, p.o) Neuropathic pain models Development of diabetic neuropathy has been checked by using various models, every model has particular mechanism of action in pain transmission. Behavioral studies were assessed by using hot plate method and tail flick method. Each of these two models sensitivity towards hyperalgesia and allodynia were evaluated, and by using formalin test hyperlgesia towards chemical stimuli also assessed out. i) EDDYS HOT PLATE METHOD Animals were placed on Eddy s hot plate maintained at 55±1. The time between 94

3 keeping the animal on the plate and the occurance of either licking of the hind paw, shaking,or jumping off from the plate were recorded as response latency. The response latency was measured before and after drug treatment at 30, 60, 90, 120, and 180 min. The cut off time of hot plate is 15 sec 9. ii) TAIL FLICK TEST 5 cm of rat tail was immersed in 50 ±.5 o c warm water. The reaction time was time taken by the rat to deflect their tail and was determined before and at 15, 30, 45, and 60 min after the administration of drugs. 15 second were the maximum reaction time 10. iii) FORMALIN TEST Formalin (50µl of 0.5% solution for diabetic animal and 1% for non-diabetic animal) injected sub-dermally into the dorsal hind paw. Rats were then immediately placed in observation chamber and pain like behavior licking\biting and flinching behaviors were counted in each 5 min intervals for 60 min.the sum of the flinches was grouped to focus specific phases of the test. Phase 1 is defined as the initial measuring of flinches(0-10 mnts), quiescent phase is in between measuring flinches(10-20mnts) and phase 2 is the measuring flinches in 20-60mnts 11. STATISTICAL ANALYSIS All the data were expressed as mean±sem. By Student s t-test significance of difference between two groups was evaluated. Following ANOVA for multiple comparisons.significant differences were there in ANOVA, then post hoc analysis with Tukey s test has been performed. Pb0.05 was considered statistically significant. RESULT FRACTIONISATION OF METHANOLIC EXTRACT OF TERMINALIA BELLIRICA Three fractions of methanolic extract of Terminalia bellirica have fractionized out namely n-butanol, Ethyl acetate and water fraction. PRELIMINARY PHYTOCHEMICAL INVESTIGATION Phytochemical test revealed the existence of polyphenol, triterpenoides, glycosides, phytosterols, saponins, tannins and flavonoids. THIN LAYER CHROMATOGRAPHY (TLC) OF GALLIC ACID Thin layer chromatography was done for each fraction and detected the presence of gallic acid in each fraction. QUANTITATIVE ANALYSIS BY HPLC By HPLC method particular quantity of gallic acid in each fraction has to be calculated. Table 1: Quantity of gallic acid in each fraction Fractions Ethyl acetate fraction 14.0% n-butanol fraction 24.9% Water fraction 0.24% Result(% of gallic acid) ANTINOCICEPTIVE EFFECT OF VARIOUS FRACTIONS OBTAINED FROM METHANOLIC EXTRACT OF TERMINALIA BELLIRICA IN DIABETIC NEUROPATHIC BEHAVIORAL MODELS i) Effect of various fractions obtained from methanolic extract of Terminalia bellirica in hot plate test. After 3 weeks, diabetes animals displayed a significant reduction (p<0.001) in reaction time when correlated to normal control indicated the hypersensitivity towards thermal stimuli. Curative treatment has started at the beginning of 4 th week and continued to 6 th week. Diabetic animals treated with Fluoxetine,Imipramine, Gallic acid, n-butanol fraction, and ethyl acetate fraction has exhibited a significant (p<0.001) increase in reaction time 6.7, 6.02, 7.38, 6.6, 6.58 sec when compared to diabetic control(2.59 sec) (Figure.1). ii) Effect of various fractions obtained from methanolic extract of Terminalia bellirica in hot water tail immersion test. 95

4 Figure 1: Hot plate test All values are mean ± SEM, n=6, P<0.001 A when compared to normal control group, P<0.001 B when compared to diabetic control. Figure 2: Hot water tail immersion All values are mean ± SEM, n=6, P<0.001 A when compared to normal control group, P<0.01 C, P<0.001 B when compared to diabetic control group Figure.2 Figure 3: Formalin test (Curative treatment) All values are mean ± SEM, n=6, P<0.001 A when compared to normal control group, P<0.001 B, P<0.01 C when compared to diabetic control group Fig: 3 96

5 Diabetic animals treated with Fluoxetine, Imipramine, Gallic acid, n-butanol fraction, ethyl acetate fraction(p<0.001) and water fraction has displayed a significant (p<0.01) increase in reaction time 6.29, 6.535, 6.72, 6.52, 6.09, 5.02 sec when compared to diabetic control(2.72sec) (Figure.2). iii) Effect of various fractions obtained from methanolic extract of Terminalia bellirica in Formalin test. Treatment groups Fluoxetine, Imipramine, Gallic acid, N-butanol fraction, and ethyl acetate fractions of methanolic extract of Terminalia bellirica was significantly (p<0.001) decreased flinches 3.33, 8, 0, 0, 0, respectively in 1 st phase when compared to diabetic control(21.33). There was no significant result among the treated drugs. All treatments significantly (p<0.001) decreased flinches in Q phase when compared to diabetic control (15.33). Except water other treatment did not shown flinches in Q phase. In 2 nd phase groups treated with Fluoxetine (12.33), Imipramine (17), Gallic acid (5.33), N-butanol fraction (6), Ethyl acetate fraction( 10) and water fraction (33.33) of methananolic extract of Terminalia bellirica significantly decreased flinches when compared to diabetic control (66.33). N-butanol fraction has found to be more active than the remaining fractions (Figure.3). DISCUSSION Diabetic neuropathy is characterized as the symptoms of peripheral nerve dysfunction in diabetic patient and it developed gently and comprised of small and large sensory fibers. The symptoms include unability to sense pain, lack of temperature sensation, and developing neuropathic pain, which follow a glove and stocking distribution that starting in the lower limbs, first affecting the toes, and then progressing upward. The pathologic features are nodal widening and segmental demyelination, axonal degeneration and loss, basement membrane thickening and microvascular lesions and in last stages there is complete loss of both sensory and motor nerve function 12. In the current study, the fractions of TB were used to evaluate its action in diabetes induced neuropathy in rats. The risk factor for the development of Diabetic neuropathy is durable hyperglycemia. The studies of DCCT have shown that with optimal glycemic control, momentous reduction in augmentation of clinical neuropathy, motor conduction velocity and autonomic dysfunction in type-1 diabetes 13. Alloxan induced diabetes in rats could be markedly inhibited by the use of Triphala Due to hypoxic in nature, peripheral diabetic neuropathy leads to decrease in nerve blood flow produce endoneurial hypoxia. In diabetic rats free radicals like superoxide anion, peroxynitrites damages endothelial dependent vascular relaxation of epineural arterioles of the sciatic nerve leading to a decrease in sciatic nerve blood low 14. In painful diabetic neuropathy antidepressants (fluoxetine and imipramine) and anticonvulsants are commonly aimed to reduce the intensity of pain 4. Antidepressant effect of fluoxetine (specific serotonin reuptake inhibitor) can be significantly reversed by p-cpa (serotonin synthesis inhibitor) in TST, recommend that fluoxetine has antidepressant effect through serotonergic system. In TST reserpine produced significant increase in immobility period 4 and 24 hrs of treatment. TB extracts reversed reserpine induced depression recommended that antidepressant like effect of TB extracts may be through the reclamation of brain monoamines, like norepinephrine, 5-hydroxy tyrptamine (5-HT) and dopamine levels 3. 5-HT is a neurotransmitter is involved in the pain transmission. Opioid drugs are utilizing this neurotransmitter for its analgesic activity which inhibits the pain transmission to the dorsal horn of spinal cord. Previous studies have suggested that tricyclic antidepressant interacted with opioid receptor which could account for its analgesic action 97

6 through by direct activation of opioid system and indirectly by enhancing the release of opioid peptides 4. Previous result from our laboratory reported that extract of Terminalia bellirica and fluoxetine acted though the opioid system because the antinociceptive action of these was blocked by prior administration of naloxone (Narcotic antagonist).there is evidence of dearrangement of oxidant and antioxidant system in depression. Hence antidepressant activity of TB extracts could be due to its antioxidant property 3. The primary constituent of Terminalia bellirica is polyphenol. There is evidence that polyphenolic content of Terminalia bellirica especially gallic acid is having antioxidant activity and may be responsible for its usefulness in diabetic neuropathy 3. In light of the above information the present studies have evaluated the antinociceptive action of various fraction of Terminalia bellirica that depends upon the amount of gallic acid present in each fraction. CONCLUSION For painful diabetic neuropathy antidepressant drugs like Fluoxetine and Imipramine are the main option for reducing the intensity of pain. The current study presented the antinociceptive action of n-butanol, ethyl acetate and water fraction of methanolic extract of Terminalia bellirica fruit significantly depends upon the amount of gallic acid present in each fraction. It is concluded that the antioxidant property of TB, due to presence of gallic acid could be responsible of the treatment of diabetic neuropathy. REFERENCES 1. Daisy P, Balasubramanian K, Rajalakshmi M, et al. Insulin mimetic impact of Catechin isolated from Cassia fistula on the glucose oxidation and molecular mechanisms of glucose uptake on Streptozotocin-induced diabetic Wistar rat. Phytomedicine. 2010;17: Khare CP. Encyclopedia of Indian medicinal plants. Springer. 2004: Dhingra D, Valecha R. Evaluation of antidepressant-like effect of aqueous and ethanolic extracts of Terminalia bellirica Roxb fruits in mice. Indian J Exp Biol. 2007;45(7): Singh VP, Jain NK, Kulkarni SK. Research report on the antinociceptive effect of fluoxetine, a selective serotonin reuptake inhibitor. Brain Research. 2001;915: Rao S, Karimian H, Razavi M, et al. Antinociceptive effect of terminalia bellirica in diabetic peripheral neuropathy: a comparison with fluoxetin, imipramine and quercetin. Lat Am J Pharm. 2012;31(4): Choudhary GP. Wound healing activity of the methanolic extract Terminallia bellirica roxb fruits. Natural product radiance. 2008;7(1): Khare CP. Encyclopedia of Indian medicinal plants. Springer. 2004: Diabetes Control and Complications Trial Research Group. The effect of intensive treatment of diabetes on the development and progression of long-term complications in insulin-dependent diabetes mellitus. N Engl J Med 1993;329: Saivasanthi V, Gowthamigoud, Swathi K, et al. Evaluation of Caralluma Fimbrita for analgesic,anti inflammatory and anxiolytic activities. Int J Pharma 2011; 1(1): Wang YX, Bowersox SS, Pettus M, Gao DA. Antinociceptive Properties of Fenfluramine, a Serotonin Reuptake Inhibitor, in a Rat Model of Neuropathy. J Pharmacol Exp Ther. 1999;291(3): Calcutt NA, Jorge MC, Yaksh TL, et al. Tactile allodynia and formalin hyperalgesia in streptozotocin-diabetic rats: Effects of insulin, aldose reductase inhibition and lidocaine. Pain. 1996;68: Sridhar GR. Painful diabetic neuropathy. Int j diab dev countries. 1999;17: DCCT Research Group. The effect ofintensive diabetes therapy on the development and progression of neuropathy. Ann Intern Med. 1995;122: Coppey LJ, Gellett JS, Davidson EP, et al. Effect of treating streptozotocin-induced diabetic rats with sorbinil, myoinositol or aminoguanidine on endoneurial blood flow, motor nerve conduction velocity and vascular function of epineurial arterioles of the sciatic nerve. Int J Exp Diabetes Res. 2002;3:21. 98