See discussions, stats, and author profiles for this publication at: https://www.researchgate.net/publication/236153692 Antidiabetic study of combined extracts of Vernonia amygdalina, Ocimum gratissimum, and Gongronema latifolium on alloxaninduced diabetic rats ARTICLE · APRIL 2013 DOI: 10.4103/2229-5119.110345 CITATIONS 2 READS 553 4 AUTHORS, INCLUDING: Jude E Okokon University of Uyo 107 PUBLICATIONS 574 CITATIONS SEE PROFILE Available from: Jude E Okokon Retrieved on: 05 February 2016
Journal of Natural Pharmaceuticals, Volume 4, Issue 1, January-June, 201328
Address for correspondence:Dr. Jude E. Okokon,Department of Pharmacology and Toxicology, Faculty of Pharmacy, University of Uyo, Uyo, Nigeria.E-mail: judeefi [email protected]
Departments of Pharmacology and Toxicology,
1Pharmacognosy and Traditional Medicine, and
2Pharmaceutical and Medicinal Chemistry, Faculty of
Pharmacy, University of Uyo, Uyo, Nigeria
Antidiabetic study of combined extracts of Vernonia amygdalina, Ocimum gratissimum, and Gongronema latifolium on alloxan-induced diabetic rats
Jude E. Okokon, Uwemedimo F. Umoh1, Benjamin A. J. Ekpo1, Emmanuel I. Etim2
ABSTRACT
Introduction: Herbal products are often used as combinations of some herbs for the treatment of diseases in traditional medicine. The anti-diabetic activities of polyherbal combinations of Vernonia amygdalina (V. amygdalina), Gongronema latifolium (G. latifolium), and Ocimum gratissimum (O. gratissimum) used in folkloric management of diabetes. Materials and Methods: The various polyherbal combinations of V. amygdalina, G. latifolium, and O. gratissimum (100 mg/kg each) were evaluated for anti-diabetic activity in alloxan induced diabetic rats. The anti-diabetic activities during acute and prolonged studies were investigated. Glibenclamide, 10 mg/kg, was used as positive control. Blood glucose level (BGL) was measured at intervals by using glucometer. Results: Treatment of alloxan diabetic rats with the various herbal combinations caused signifi cant (P < 0.001) reductions in the BGL of the diabetic rats both in acute and prolonged treatment (2 weeks). The activities of various combined extracts were comparable and more pronounced than that of glibenclamide and compared to that of glibenclamide in the prolonged study. Conclusion: The anti-diabetic activities of the various herbal combinations confi rm the folkloric use of these polyherbal remedies.
Ethnomedicine is an integral part of the culture of people of Akwa Ibom State[1] and about 75% of the people rely on traditional medicine for health-care delivery.[2] Majority of the people still patronize herbal remedies despite the availability of orthodox medicine in their management of some diseases and ailments. Besides, polyherbal therapy (practice) is a common practice in the Ibibio traditional medicine as combination of roots/leaves and stem barks of various plants are often use in the treatment of a single disease. Moreover, polyherbal therapy is said to be a current pharmacological principle having the advantage of producing maximum effi cacy with minimum side effects.[3] According to Tiwari and Rao,[4] polyherbal therapies have the synergy, potentiative, agonistic/antagonistic pharmacological agents within themselves, that work together in a dynamic way to produce therapeutic effi cacy with minimum side-effects. Diabetes is one of the diseases treated by herbalist of Ibibio tribe using polyherbal combinations.
Ethnobotanical information from some traditional medicine practioners revealed that Vernonia amygdalina (V. amygdalina), Ocimum gratissimum (O. gratissimum), and Gongronema latifolium (G. latifolium) constitute bulk of the many polyherbal combinations use in the area for the treatment of diabetes. Ajibesin et al.,[1] in their ethnobotanical survey of Akwa Ibom State documented the three plants as anti-diabetic remedies used in the region. Several workers have reported on the anti-diabetic/hypoglycemic activities V. amygdalina,[5-7] O. gratissimum,[6,8-10] and G. latifolium.[6,11-13] In this study, we investigated the effi cacy of the different combinations of the three plants on alloxan induced diabetic rats as used in ethnomedical therapy of diabetes in Akwa Ibom State to ascertain their potency.
MATERIALS AND METHODS
Plant materialsFresh leaves of V. amygdalina Del. (compositae), O. gratissimum Linn. (Labiaceace), and G. latifolium Benth.
Okokon, et al.: Antidiabetic activities of polyherbal combinations on diabetic rats
(Asclapiadaceace) were collected in August, 2008 from the Medicinal plants farm of Faculty of Pharmacy, University of Uyo, Uyo, Nigeria. The plant was identifi ed and authenticated by Dr. Margaret Bassey, a taxonomist in the Department of Botany, University of Uyo, Uyo, Nigeria.
ExtractionThe fresh leaves (2 kg) of each plant were air-dried separately on laboratory table for 2 weeks and reduced to powder. The powder (100 g) of each plant was macerated in 95% ethanol (300 mL) for 72 h (cold extraction). The liquid fi ltrates obtained were concentrated in vacuo at 40°C. The extracts were stored in a refrigerator at 4°C until used for experiment reported in this study.
AnimalsAlbino Wistar rats (155-165 g) of either sex were obtained from the University of Uyo animal house. They were maintained on standard animal pellets (Guinea Feed) and water ad libitum. Permission and approval for animal studies were obtained from the College of Health Sciences Animal Ethics Committee, University of Uyo.
Induction of diabetesThe animals were fasted overnight and diabetes was induced by a single intraperitoneal injection of a freshly prepared solution of alloxan (150 mg/kg body weight) in ice cold 0.9% sodium chloride (NaCl) saline solution. The animals were allowed to drink 5% glucose solution overnight to overcome the drug-induced hypoglycemia. Control rats were injected with normal saline alone. After 72 h for the development of diabetes, rats with moderate diabetes having glycosuria and hyperglycemia (blood glucose level (BGL) range above 200 mg/dl) were considered as diabetic and used for the drug treatment. The leaf extracts of the three plants in aqueous solution were administered to rats orally through a gavage at a concentration of 100 mg/kg body weight/rats/day for 14 days.
Experimental designThe animals were divided into six groups of six rats each and treated as follows:• Group I: Diabetic rats administered orally with
combined leaf extracts of G. latifolium, V. amygdalina, and O. gratissimum (GVOE) at a dose of 100 mg/kg/day each extract in aqueous solution for 14 days.
• Group II: Diabetic rats given leaf extracts of O. gratissimum and G. latifolium (OGE) at a dose of 100 mg/kg/day in aqueous solution orally for 14 days.
• Group III: Diabetic rats administered orally with leaf extracts of G. latifolium and V. amygdalina (GVE) at a dose of 100 mg/kg/day each extract in aqueous solution for 14 days.
• Group IV: Diabetic rats administered orally with leaf extract of O. gratissimum and V. amygdalina (OVE) at a dose of 100 mg/kg/day each extract in aqueous solution for 14 days.
• Group V: Diabetic rats given glibenclamide (10 mg/kg/day) for 14 days in aqueous solution orally for 14 days.
• Group VI: Diabetic control rats.
The fasting BGLs of all the rats were recorded at regular intervals during the experimental period. For acute study, the BGL was monitored after 1, 3, 5, and 7 h of administration of a single dose of the extract and at the end of 1, 3, 5, 7, 10, 12, and 14 days for prolonged treatments. The BGL was monitored in the blood of the diabetic rats by tail tipping method. The blood was dropped on the dextrostix reagent pad and was inserted into microprocessor digital blood glucometer and the readings were noted.[14]
Statistical analysisData are reported as mean ± standard error of the mean (SEM) and were analyzed statistically using one-way analysis of variance followed by Tukey–Kramer multiple comparison test and values of P < 0.001 and 0.05 were considered signifi cant.[15]
RESULTS
During acute study of the effects of the combined extracts on BGL of the diabetic rats, all the groups treated with combined leaf extracts exhibited signifi cant (P < 0.001) reductions in BGL compared to control and the effects were more pronounced than those of the group treated with glibenclamide (10 mg/kg). Though, all the combined extracts-treated groups had comparable activities, the group treated with the combined leaf OGE had the most signifi cant reduction after 7 h (80.97%,7 h), followed by those treated with GVE (79.21%, 7 h), GVOE (76.93%, 7 h), and OVE (74.90%,7 h) [Table 1].
During prolonged study, the combined extracts-treated groups and glibenclamide treated group produced sustained signifi cant (P < 0.001) reduction in BGL of the diabetic compared to control [Table 2]. The effect of the combined extracts and that of glibenclamide were comparable on day 15. A more pronounced effect was observed in the group treated with a combined extracts of the three plants, i.e., GVOE.
DISCUSSION
The anti-diabetic effects of different combinations of leaf extracts of G. latifolium, V. amygdalina and O. gratissimum use in polyherbal therapy of diabetes
Okokon, et al.: Antidiabetic activities of polyherbal combinations on diabetic rats
Journal of Natural Pharmaceuticals, Volume 4, Issue 1, January-June, 201330
were evaluated in this study. The results showed that the various combinations: G. latifolium and O. gratissimum; G. latifolium and V. amygdalina; G. latifolium, V. amygdalina, and O. gratissimum; and O. gratissimum and V. amygdalina, had signifi cant antihyperglycemic activity which was more than that of glibenclamide (in acute study) and comparable in effect to glibenclamide (during prolonged study). Within the treatment period (14 days) the various combined extracts’ effects demonstrated synergism as the extracts appeared to complement each other thereby reducing the BGL of the diabetic rats to normal. This was clearly demonstrated in the group administered combination of the three extracts during prolonged study. The results of this study collaborates the advantages of polyherbal articulated by Tiwari and Rao.[4] Furthermore, the results of this study support earlier reports of anti-diabetic potentials of these plants.[5-10] Different mechanism of actions of anti-diabetic plants have been proposed such as potentiation of insulin effect either by increasing the pancreatic secretion of insulin from the cells of islets of Langerhans or its release from bound insulin,[16] inhibition of hepatic glucose production,[17] inhibition of intestinal glucose absorption,[18] or correction of insulin resistance.[19] These three extracts may have exerted their anti-diabetic effects by utilizing one or more of the above mechanisms. A combination of these mechanisms could have resulted in the signifi cant anti-diabetic activity
observed in this study, which is likely to be sustained and better than that of a single extract. Moreover, sulfonyl ureas, including glibenclamide, produce hypoglycemia in normal as well as diabetic animals by stimulating the pancreatic -cells to release more insulin.[20] These extracts’ combinations maybe working through a similar mechanism like glibenclamide as the results gotten from the combinations and glibenclamide were comparable. Secondary metabolites have been reported to be involved in anti-diabetic activity of many plants.[21] Reports have shown that these plants have various phytochemical constituents in common such as alkaloids, steroids, glycosides, saponins, tannins, terpenes, and fl avonoids.[8,22,23] In addition to anti-diabetic properties of these plants, each of the plants has been reported of different activities geared towards alleviation of complications usually associated with diabetes. For example, V. amygdalina has been reported to be hepatoprotective[24] and antioxidant,[25] G. latifolium, antioxidant, hepatoprotective and hypolipidaemic,[11,26] O. gratissimum, antioxidant[27] and others. All these activities complements the anti-diabetic activities of these plants and are advantageous to antagonize and resolve any side effects any of the extracts could have posed. The effectiveness of polyherbal combination has been reported widely. V. amygdalina and Azadirachta indica combination has been shown to be very effective.[3]
Table 1: Eff ect of polyherbal combinati ons on blood glucose levels of alloxan diabeti c rats aft er a single dose
Drug Dose (mg/kg) Blood glucose level (mg/dl) (mean±SEM)
*P<0.001 when compared to control. n=6 per group. GVOE: Gongronema la folium, Vernonia amygdalina and Ocimum gra ssimum combined extracts, OGE: Ocimum gra ssimum and Gongronema la folium combined extracts, GVE: Gongronema la folium and Vernonia amygdalina combined extracts, OVE: Ocimum gra ssimum and Vernonia amygdalina combined extracts, SEM: Standard error of the mean
Table 2: Eff ect of polyherbal combinati ons on blood glucose levels of alloxan diabeti c rats during prolonged treatment
*P<0.001 when compared to control, n=6 per group. GVOE: Gongronema la folium, Vernonia amygdalina and Ocimum gra ssimum combined extracts, OGE: Ocimum gra ssimum and Gongronema la folium combined extracts, GVE: Gongronema la folium and Vernonia amygdalina combined extracts, OVE: Ocimum gra ssimum and Vernonia amygdalina combined extracts, SEM: Standard error of the mean
Okokon, et al.: Antidiabetic activities of polyherbal combinations on diabetic rats
The fi nding of this study confi rms the effi cacy of the various polyherbal combinations used traditionally by herbalists of Ibibio tribe of Akwa Ibom State, Nigeria for the management of diabetes which are of advantage. Further studies into polyherbal combinations used in the management of diabetes are encouraged to support the advantage of polytherapy.
ACKNOWLEDGMENT
The authors are grateful to Mr. Nsikan Malachy of Pharmacology and Toxicology Department, University of Uyo, Uyo, N igeria for his technical assistance.
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Cite this article as: Okokon JE, Umoh UF, Ekpo BA, Etim EI. Antidiabetic study of combined extracts of Vernonia amygdalina, Ocimum gratissimum, and Gongronema latifolium on alloxan-induced diabetic rats. J Nat Pharm 2013;4:28-31.
Source of Support: Nil. Confl ict of Interest: No.
