Abstract
Objective: The present study was undertaken to investigate the anti-diabetic activity of methanol extract of stem-bark of cashew [Anacardium occidentale Linn. (Anacardiaceae)] in alloxan-induced diabetic rats.
Methods: The extract (200 mg kg-1 body weight, p.o) was administered daily for 28 days, 48 hrs after alloxan injection (100 mg kg-1 body weight, i.v.). At the end of the experimental period, all animals were fasted for 12 hrs. Blood glucose, plasma lipids, ascorbic acid, electrolytes and thiobarbituric acid reactive substances (TBARS; marker of lipid peroxidation) were determined.
Results: The alloxan-diabetic rats treated with the extract showed significant reductions (p<0.05) in fasting blood glucose, total cholesterol, triglyceride, LDL-cholesterol, TBARS and potassium concentrations and significant increases (p<0.05) in plasma concentrations of HDL-cholesterol, HDL-cholesterol/total cholesterol ratio, HDL-cholesterol/LDL-cholesterol ratio and ascorbic acid when compared with the untreated alloxandiabetic rats. Plasma concentrations of sodium, magnesium and calcium were comparable (p>0.05) in all the experimental groups.
Conclusion: The results of the present study indicate that oral administration of methanol extract of cashew stem-bark might reduce diabetic-related cardiovascular complications through improved lipid profile and reduced oxidative stress. The study also supports the public belief among the Yoruba in the south-west of Nigeria, that cashew extract could be a useful agent in the prevention and management of diabetes.
Keywords: Anacardium occidentale Linn., anti-diabetic activity, antioxidant activity, cashew, hypolipidaemia, rat
Résumé
Cette étude était faite pour investiguer l’activité antidiabétique d’extrait méthanoïque de l’écorce du cashew [Anacardium occidentale Linn.(Anacardiacée)] Chez les rats diabétiques induits par l’alloxan. L’extrait (200 mg kg-1 de poids corporel, p.o) était administré journalierement pour 28 jours, 48 heures après une injection d’alloxan (100 mg kg-1 de poids corporel, i.v.). A la fin de la période expérimentale, tous les animaux étaient à jeune pour 12 heures. Le taux du glucose sanguin, lipides plasmatiques, acide ascorbique, les électrolytes et l’acide thiobarbiturique substances réactives (TBARS; marqueur de peroxydation de lipide) étaient déterminés. Les résultats montraient que les rats diabétiques traités avec l’alloxan plus l’extrait du cashew démontrait des réductions significatives (p<0.05) du glucose sanguine a jeune, du cholestérol total, triglycéride, LDLcholestérol, TBARS , des concentrations de potassium et augmentait significativement (p<0.05) des
concentrations plasmiques de HDL-cholestérol, HDL-cholestérol/ proportion total de cholestérol, HDLcholestérol/proportion de LDL-cholestérol et l’acide ascorbique lorsque comparé avec les rats diabétiques non traités a l’ alloxan. Les concentrations plasmatiques du sodium, magnésium et calcium étaient comparable (p>0.05) chez tous les groupes expérimentés. En conclusion, les résultants de cette étude indiquent que l’administration des extraits méthanoïques des tiges du cashew pourrait réduire les complications cardiovasculaires liées au diabète par l’amélioration du profile des lipides et réduire le stress d’oxydation. Aussi, cette étude supporte la croyance populaire des yorubas au sud-ouest du Nigeria que l’extrait du cashew pourrait être un agent utile dans la prévention et les soins du diabète.
Correspondence: L.A. Olatunji. Department of Physiology, College of Health Sciences, University of Ilorin, P.M.B 1515, Ilorin, Nigeria. e-mail: tunjilaw04@yahoo.com
References
Defronzo RA. The triumvirate: beta cell, muscle, liver. A collision responsible for NIDDM Diabetes. 1988; 37: 667-687.
Burns TW. Endocrinlogy. In; Pathology Physiology. 6th Edition. (Edited by W.A. Sodeman and T.M. Sodeman 1979; 1002-1046.
Bowman WC and Rand MJ. Endocrine function of the pancreas. In; Textbook of Pharmacology. (2nd Ed. Blackwell scientific Pubs. Oxford, England. 1995; 1943-1963
George P and Ludvik B. Lipid and Diabetes. J. Clin. B. Card. 2000; 3:159-162.
Sacks DB. Implication of the revised criteria for diagnosis and classification of diabetes mellitus. Clin. Chem. 1997; 43: 2230-2233.
Maxwell SRJ. Prospects for the use of antioxidant therapies. Drugs 1995; 49: 345-361.
Heinecke JW. Oxidative stress: New approaches to diagnosis and prognosis in atherosclerosis. Am. J. Cardiol. 2003; 91: 12A-16A.
Sinclair AT, Girling AJ, Gray L, et al. Disturbed handling of ascorbic acid in diabetic patients with or without microangiopathy during high dose ascorbate supplementation. Diabetolagia 1991; 34: 171-175.
Yue DK, McLennan S, Fisher E et al. Ascorbic acid metabolism and polyol pathway in diabetes. Diabetes 1989; 38: 257-261.
Bode AM, Yavarow CR, Fry DA et al. Enzymatic basis of diabetes mellitus. Clin. Chem. 1993; 43: 2230-2233.
U.K. Prospective Diabetes Study Group. Tight blood pressure control and risk of macrovascular and microvascular complications in Type 2 diabetes. UKPDS 38. Br. Med. J. 1998; 317: 703-713.
Akinpelu DA. Antimicrobial activity of Anarcardium occidentale bark. Fitoterapia 2001; 72(3): 286-287.
Ojewole JA. Potentiation of the antiinflamatory effect of Anarcardium occidentale (Linn.) stem-bark aqueous extract by grape fruit juice. Methods Find. Exp. Clin. Pharmacol. 2004; 26(3): 183-188.
Runnie I, Salleh MN, Mohamed S, et al. Vasorelaxation induced by common edible tropical plant extracts in isolated rat aorta and mesenteric vascular bed. J. Ethnopharmacol. 2004; 92(2-3): 311-316.
Olatunji LA, Okwusidi JI and Soladoye AO. Antidiabetic effect of Anacardium occidentale stem-bark in fructose-diabetic rats. Pharmaceutical Biol. 2005; 43: 589-593.
Kamtchouing P, Sokeng SD, Moundipa PF, et al. Protective role of Anarcardium occidentale extract against streptozocin-induced diabetes in rats. J. Ethnopharmacol. 1998; 62: 95-99.
Friedewald WT, Levy RI and Friedrickson DS. Estimation of the concentration of low-density lipoprotein cholesterol in plasma, without use of preparative ultracentrifuge. Clin. Chem. 1972; 18: 499-502.
Richard M, Portal B, Meo J, et al. Malondialdehyde kit evaluated for determination of plasma and lipoproteins fractions that react with thiobarbituric acid. Clin. Chem. 1992; 38: 704-709.
Zannoni V, Lynch M, Goldstein S et al. Rapid micromethod for the determination of ascorbic acid in plasma and tissues. Biochem. Med. 1974; 11: 42-48.
Knopp RH, Retzlaff B, Aikawa K et al. Management of patients with diabetic hyperlipidemia. Am. J. Cardiol. 2003; 91 (Suppl.): 24E-28E.
Lino CS, Diogenes JPL, Pereira BA, et al. Antidiabetic activity of Bauhinia forficata extracts in alloxan-diabetic rats. Biol. Pharm. Bull. 2004; 27 (1): 125-127.
Chen YD, Howard J, Huang V, et al. Dissociation between plasma triglyceride concentration and tissue lipoprotein lipase deficiency rats. Diabetes 1980; 29: 643-647.
Black DM. Therapeutic targets in cardiovascular disease: a case for high-density lipoprotein cholesterol. Am. J. Cardiol. 2003; 91 (7A): 40E-43E.
Baynes JW. Role of oxidative stress in the development of complication in diabetes mellitus. Diabetes 1991; 40: 405-412.
Hunt JV, Dean RT and Wolff SP. Hydroxyl radical production and autooxidative glycosilation. Glucose autoxidation as the cause of protein damage in the experimental glycation model of diabetes mellitus and aging. Biochem. J. 1988; 256: 205-212.
Toborek M and Henning B. Fatty acid-mediated effects on the glutathione redox cycle in cultured endothelial cells. Am. J. Clin. Nutr. 1994; 59: 60-65.
Cohen RA, Dysfunction of vascular endothelium in diabetes mellitus. Circulation 1993; 87 (suppl. 5): 67-76.
Timimi FK, Ting HH, Haley LA et al. Vitamin C improves endothelium-dependent vasodilation in patients with insulin-dependent diabetes mellitus. J. Am. Coll. Cardiol. 1998; 31: 552-557.
Keaney JR, Gaziano JH and Xu A. Dietary anti-oxidants preserve endothelium-dependent vessel relaxation in cholesterol-fed rabbit. Proc. Natl. Acad. Sci. U.S.A. 1993; 90: 11880-11884.
Frei B, England L and Ames BN. Ascorbate is an outstanding anti-oxidant in human blood plasma. Proc. Natl. Acad. Sci. U.S.A. 1989; 86: 6377-6381.
O’Connel BJ and Genest J. High-density lipoproteins and endothelial function.Circulation 2001; 104: 1978-1983.
Jarman PR, Kehley AM and Mather HM. Hyperkalaemia in diabetes: prevalence and associations. Postgrad. Med. J. 1995; 71: 551-552.
Cox M, Sterns RH and Singer I. The defense against hyperkalemia: the roles of insulin and aldosterone. N. Engl. J. Med. 1978; 299: 525-532.
Zierler KL. Hyperpolarization of muscle by insulin in a glucose-free environment. Am. J. Physiol. 1959; 197: 524-526.
Burton SD, Mondon CE and Ishida T. Dissociation of potassium and glucose efflux in isolated perfused rat liver. Am. J. Physiol. 1967; 212: 261-266.