Aqueous Extract of Unfermented Honeybush (Cyclopia maculata) Attenuates STZ-induced Diabetes and β-cell Cytotoxicity

Abstract

New strategies, which include β-cell protection, are required in the treatment of T2D, as current drugs demonstrate little or no capacity to directly protect the vulnerable β-cell against diabetes-induced cytotoxicity. In this study we investigated the ameliorative effect of pre-treatment with an aqueous extract of unfermented Cyclopia maculata (honeybush) on STZ-induced diabetes and pancreatic β-cell cytotoxicity in Wistar rats after demonstrating a protective effect in vitro in RIN-5F cells. The amelioration of STZ-induced diabetes was seen in the reduction of the area under the curve, determined by the oral glucose tolerance test, as well as fasting glucose levels in extract-treated rats. Pre-treatment with extract also improved serum triglyceride levels and the glucose-to-insulin ratio. Pre-treatment with the extract or the drug, metformin, increased the β-cell area in islets, with a concomitant increase in β-cell proliferation at the higher extract dose (300 mg/kg/d), but not the lower dose (30 mg/kg/d). Subsequently, the in vitro tritiated thymidine incorporation assay showed that the extract was not mitogenic in RIN-5F cells. STZ-induced elevation of plasma nitrite levels was reduced in extract-treated rats, but no changes were observed in their serum catalase, serum glutathione, liver lipid peroxidation and liver nitrotyrosine levels. Pre-treating the rats with extract ameliorated the diabetic effect of STZ in Wistar rats, with evidence of pancreatic β-cells protection, attributed to the presence of high levels of antioxidants such as the xanthones, mangiferin and isomangiferin.

Key words

Cyclopia maculata - Fabaceae - mangiferin - diabetes - streptozotocin - β-cell - glucose tolerance

• References

• 1 Hassan Z, Yam MF, Ahmad M, Yusof AP. Antidiabetic properties and mechanism of action of Gynura procumbens water extract in streptozotocin-induced diabetic rats. Molecules 2010; 15: 9008-9023
• 2 Marchetti P, Prato SD, Lupi R, Guerra SD. The pancreatic beta-cell in human type 2 diabetes. Nutr Metab Cardiovasc Dis 2006; 16: 3-6
• 3 Bonora E. Protection of pancreatic beta-cells: is it feasible?. Nutr Metab Cardiovasc Dis 2008; 18: 74-83
• 4 Szkudelski T. The mechanism of alloxan and streptozotocin action in beta cells of the rat pancreas. Physiol Res 2001; 50: 537-546
• 5 Ho E, Chen G, Bray TM. Alpha-phenyl-tert-butylnitrone (PBN) inhibits NFkappaB activation offering protection against chemically induced diabetes. Free Radic Biol Med 2000; 28: 604-614
• 6 Kaneto H, Kajimoto Y, Miyagawa JI, Matsuoka TA, Fujitani Y, Umayahara Y, Hanafusa T, Matsuzawa Y, Yamasaki Y, Hori M. Beneficial effects of antioxidants in diabetes – possible protection of pancreatic β-cells against glucose toxicity. Diabetes 1999; 48: 2398-2406
• 7 Robertson RP. Antioxidant drugs for treating beta-cell oxidative stress in type 2 diabetes: Glucose-centric versus insulin-centric therapy. Discovery Medicine. Available at http://www.discoverymedicine.com Accessed September 28, 2010
• 8 Wan L, Chen C, Xiao Z, Wang Y, Min Q, Yue Y, Chen J. In vitro and in vivo antidiabetic activity of Swertia kouitchensis extract. J Ethnopharmacol 2013; 147: 622-630
• 9 Anitha S, Rose AML. Comparative evaluation of antihyperglycaemic effect of various parts of Salacia chinensis L. J Med Sci (Pakistan) 2013; 13: 493-496
• 10 Muruganandan S, Gupta S, Kataria M, Lal J, Gupta PK. Mangiferin protects the streptozotocin-induced oxidative damage to cardiac and renal tissues in rats. Toxicology 2002; 176: 165-173
• 11 Joubert E, Gerlderblom WC, Louw A, De Beer D. South African herbal teas: Aspalathus linearis, Cyclopia spp. and Athrixia phylicoides – a review. J Ethnopharmacol 2008; 119: 376-412
• 12 Joubert E, Joubert ME, Bester C, De Beer D, De Lange JH. Honeybush (Cyclopia spp.): From local cottage industry to global markets – the catalytic and supporting role of research. S Afr J Bot 2011; 77: 887-907
• 13 Muller CJF, Joubert E, Gabuza K, De Beer D, Fey SJ, Louw J. Assessment of the antidiabetic potential of an aqueous extracts of honeybush (Cyclopia intermedia) in streptozotocin and obese insulin resistant Wistar rats. In: Rassoli I, ed. Phytochemicals/bioactivities and impact on health. Rijeka, Croatia: Intech-Open Acess Publisher; 2011: 313-332
• 14 Joubert E, Richards ES, Van der Merwe JD, De Beer D, Manley M, Gelderblom WCA. Effect of species variation and processing on phenolic composition and in vitro antioxidant activity of aqueous extracts of Cyclopia spp. (honeybush tea). J Agric Food Chem 2008; 56: 954-963
• 15 Malherbe CJ, Willenburg E, de Beer D, Bonnet SL, van der Westhuizen JH, Joubert E. Iriflophenone-3-C-glucoside from Cyclopia genistoides: isolation and quantitative comparison of antioxidant capacity with mangiferin and isomangiferin using on-line HPLC antioxidant assays. J Chromatogr B Analyt Technol Biomed Life Sci 2014; 951–952: 164-171
• 16 Dudhia Z, Louw J, Muller C, Joubert E, De Beer D, Kinnear C, Pheiffer C. Cyclopia maculata and Cyclopia subternata (honeybush tea) inhibits adipogenesis in 3 T3-L1 pre-adipocytes. Phytomedicine 2013; 20: 401-408
• 17 Sellamuthu PS, Arulselvan P, Muniappan BP, Fakurazi S, Kandasamy M. Mangiferin from Salacia chinensis prevents oxidative stress and protects pancreatic β-cells in streptozotocin-induced diabetic rats. J Med Food 2013; 16: 719-727
• 18 Miura T, Ichiki H, Hashimoto I, Iwamoto N, Kato M, Kubo M, Ishihara E, Komatsu Y, Okada M, Ishida T, Tanigawa K. Antidiabetic activity of a xanthone compound, mangiferin. Phytomedicine 2001; 8: 85-87
• 19 Leiro J, Arranz JA, Yáñez M, Ubeira FM, Sanmartín ML, Orallo F. Expression profiles of genes involved in the mouse nuclear factor-kappa B signal transduction pathway are modulated by mangiferin. Int Immunopharmacol 2004; 4: 763-778
• 20 Sarkar A, Sreenivasan Y, Ramesh GT, Manna SK. Beta-D-glucoside suppresses tumor necrosis factor-induced activation of nuclear transcription factor kappaB but potentiates apoptosis. J Biol Chem 2004; 279: 33768-33781
• 21 Mahmoud AM, Ashour MB, Abdel-Moneim A, Ahmed OM. Hesperidin and naringin attenuate hyperglycemia-mediated oxidative stress and proinflammatory cytokine production in high fat fed/streptozotocin-induced type 2 diabetic rats. J Diabetes Complications 2012; 26: 483-490
• 22 Ceriello A, Taboga C, Tonutti L, Quagliaro L, Piconi L, Bais B, Da Ros R, Motz E. Evidence for an independent and cumulative effect of postprandial hypertriglyceridemia and hyperglycemia on endothelial dysfunction and oxidative stress generation: effects of short- and long-term simvastatin treatment. Circulation 2002; 106: 1211-1218
• 23 Muruganandan S, Srinivasan K, Gupta S, Gupta PK, Lal J. Effect of mangiferin on hyperglycemia and atherogenicity in streptozotocin diabetic rats. J Ethnopharmacol 2005; 97: 497-501
• 24 Pal PB, Sinha K, Sil PC. Mangiferin, a natural xanthone, protects murine liver in Pb (II) induced hepatic damage and cell death via MAP kinase, NFκB and mitochondria dependent pathways. PLoS One 2013; 8: e56894
• 25 Miyake Y, Yamamotoi K, Osawa T. Isolation of eriocitrin (eriodictyol 7-rutinoside) from lemon fruit (Citrus limon BURM. f.) and its antioxidative activity. Food Sci Technol Int Tokyo 1997; 3: 84-89
• 26 Garg A, Garg S, Zaneveld LJD, Singla AK. Chemistry and pharmacology of the citrus bioflavonoid hesperidin. Phytother Res 2001; 15: 655-669
• 27 Fujimoto H, Hirase T, Miyazaki Y, Hara H, Ide-Iwata N, Nishimoto-Hazuku A, Saris CJM, Yoshida H, Node K. IL-27 Inhibits hyperglycemia and pancreatic islet inflammation induced by streptozotocin in mice. Am J Pathol 2011; 179: 2327-2336
• 28 Mabley JG, Suarez-Pinzon WL, Hasko G, Salzman AL, Rabinovitch A, Kun E, Szabo C. Inhibition of poly (ADP-ribose) synthetase by gene disruption or inhibition with 5-iodo-6-amino-1, 2-benzopyrone protects mice from multiple-low-dose-streptozotocin-induced diabetes. Br J Pharmacol 2001; 133: 909-919
• 29 Chellan N, De Beer D, Muller CJF, Joubert E, Louw J. A toxicological assessment of Athrixia phylicoides aqueous extract following chronic ingestion in a rat model. Hum Exp Toxicol 2008; 27: 819-825
• 30 Maurad N, Zager R, Neveu P. Semi-automated enzymatic method for determining serum triglycerides by use of the Beckman DSA 560. Clin Chem 1973; 19: 116-118
• 31 Grisham MB, Johnson GG, Lancaster jr. JR. Quantitation of nitrate and nitrite in extracellular fluids. Methods Enzymol 1996; 268: 237-246