THE HYPOGLYCAEMIC EFFECT OF OLEANONIC ACID ISOLATED FROM PILEA ELIZABETHAE IN A RAT MODEL
Objective: The objective of this study is to isolate and identify the chief hypoglycaemic component of Pilea elizabethae
Methods: The chief hypoglycaemic component of Pilea elizabethaewas isolated and identified. The bio-directed purification of the chief hypoglycaemic agents contained in Pilea elizabethae followed a sequence of steps alternating oral glucose tolerance test (OGTT) bioassay and chromatographic methods. The ethyl acetate crude extract which was most hypoglycaemic in activity was flash chromatographed on silica gel using a gradient hexane-ethyl acetate solvent system of increasing polarity. Elucidation of the chemical structures of R-E2Gii was determined using NMR and FT-IR spectroscopy, melting point determination and comparison with literature. The Pilea elizabethae extracts were tested for hypoglycaemic activity in Sprague-Dawley albino rats using the oral glucose tolerance test (OGTT) method. Isolated hypoglycaemic compounds obtained after bio-directed purification were identified through nuclear magnetic resonance (NMR) spectroscopy and infra-red (IR) spectroscopy.
Results: Bio-directed purification of Pilea elizabethae extracts yielded a hypoglycaemic principle that were coded R-E2Gii. By comparison of its NMR chemical shift values and physical properties with literature values, R-E2Gii found to be the triterpenoid oleanonic acid [C30H40O3; M. W=124]. The isolate R-E2Gii demonstrated significant hypoglycaemic activity. When administered intravenously, values were as low as 4.87Â±0.09 mmol/l thirty minutes post-load compared with 5.63Â±0.19 mmol/l for the control (p<0.006). An increase in dosage up to 10 mg/kg body weight amplified the post-prandial hypoglycaemic effect of R-E2Gii. Comparison of the hypoglycaemic effect of R-E2Gii with glibenclamide showed that the isolate was only mildly effective in reducing post-prandial hyperglycaemia. Hexane-ethyl acetate extracts from Pilea elizabethae was found to possess anti-hyperglycaemicactivity on OGTT.Conclusion: Bio-directed purification of the hexane-ethyl acetate extracts and using nuclear magnetic resonance (NMR) spectroscopy and infra-red (IR) spectroscopy revealed oleanonic acid, that may be responsible for the anti-hyperglycaemic properties of this extract.
2. Roglin G, Unwin N, Bennett PH, Mathers C, Tuomilehto J, Nag S, et al. The burden of mortality attributable to diabetes: realistic estimates for the year 2000. Diabetes Care 2000;28:2130-5.
3. Colberg SR, Sigal RJ, Fernhall B, Regensteiner JG, Blissmer BJ, Rubin RR, et al. Exercise and type 2 diabetes. Diabetes Care 2010;33:e147-e167.
4. Hu FB. Globalization of diabetes: the role of diet lifestyle and genes. Diabetes Care 2011;34:1249-57.
5. Eisenberg DM, Kessler RC, Van Rompay MI, Kaptchuk TJ, Wilkey SA, Appel S, et al. Perceptions about complementary therapies relative to conventional therapies among adults who use both: results from a national survey. Ann Int Med 2001;135:344-51.
6. Lennox PH, Henderson CL. Herbal medicine use is frequent in ambulatory surgery patients in Vancouver, Canada: Lâ€™usage de plante medicinal est frequent chez les patients de chirurgie ambulatorie Ã Vancouver, Canada. Can J Anesth 2003;50:21-5.
7. Craig WJ. Health-promoting properties of herbs. Am J Clin Nut 1999;70:491S-499S.
8. Paul P, Bansal P, Mudgal J, Nayak PG, Pannakal K, Priyadarsini I, et al. Antidiabetic, antihyperlipidemic, and antioxidant effects, of the flavonoid-rich fraction of Pilea microphylla (L.) in high-fat diet, streptozotocin-induced diabetes in mice. Exp Toxicol Pathol 2012;64:651-8.
9. Modarresi CA, Ibrahim D, Fariza SS. Antioxidant, antimicrobial activity and toxicity test of Pilea microphylla. Int J Microbiol 2010;2010:826-30.
10. Prabhakar KR, Veerapur VP, Bansal P, Parihar VK, Reddy KM, Bhagath KP, et al. Antioxidant and radioprotective effect of the active fraction of Pilea microphylla (L.) ethanolic extract. Chem Biol Interact 2007;165:22-32.
11. Hui W, Li M. Two new triterpenoids from rhodomyrtus tomentosa. Phytochemistry 1976;15:1741-3.
12. Campos AM, Oliveira FS, Iracema M, Machado L, Braz-filho R, Matos FJ. Triterpenes from Cedrela odorata. Phytochemistry 1991;30:1225-9.
13. Seo S, Tomita Y, Tori K. Carbon-13 nmr spectra of urs-12-enes and application to structural assignments of components of Isodon japonicas hara tissue cultures. Tetrahedron Lett 1975;16:7-10.
14. Paolisso G, Giugliano D, Ceriollo A. Oxidative stress and diabetic vascular complications. Diabetes Care 1996;19:257-67.
15. Mortz E, Ceriello A. Is oxidative stress the pathogenic mechanism underlying insulin resistnance, diabetes and cardiovascular disease? The common soil hypothesis revisited. Arterioscler Thromb Vasc Biol 2004;24:816-23.
16. Fujiwara Y, Hayashida A, Tsurushima K, Nagai R, Yoshitomi M, Daiguji N, et al. Triterpenoids isolated from Zizyphus jujuba inhibit foam cell formation in macrophages. J Agric Food Chem 2011;59:4544-52.
17. Misra N, Sharma M, Raj K, Dangi A, Srivastava S, Misra-Bhattacharya S. Chemical constituents and antifilarial activity of Lantana camara against human lymphatic filariid Brugia malayi and rodent filariid acanthocheilonema viteae maintained in rodent hosts. Parasitol Res 2007;100:439-48.
18. Ghosh S, Das Sarma M, Patra A, Hazra B. Anti-inflammatory and anti-cancer compounds isolated from ventilago madraspatana Gaertn, Rubia cordifolia Linn. and lantana camara Linn. J Pharm Pharmacol 2010;62:1158-66.
19. Nguyen AT, Fontaine J, Malonne H, Claeys M, Luhmer M, Duez P. A sugar ester and an iridoid glycoside from Scrophularia ningpoensis. Phytochemistry 2005;66:1186-91.
20. Begum S, Zehra SQ, Siddiqui BS. Two new pentacyclic triterpenoids from lantana camara LINN. Chem Pharm Bull (Tokyo) 2008;56:1317-20.
21. Misra S, Dutta AK, Choudhury A, Ghosh A. Oxidation of oleanolic acid ofAvicennia officinalis leaves to oleanonic acid in the natural environment of Sunderban mangrove ecosystem. J Chem Ecol 1985;11:339-42.
22. Jager S, Trojan H, Kopp T, Laszczyk MN, Scheffler A. Pentacyclic triterpene distribution in various plants-rich sources for a new group of multi-potent plant extracts. Molecules 2009;14:2016-31.
23. Castellano JM, Guinda A, Delgado T, Rada M, Cayuela JA. Biochemical basis of the antidiabetic activity of oleanolic acid and related pentacyclic triterpenes. Diabetes 2013;62:1791-9.
24. Jung SH, Ha YJ, Shim EK. Insulin-mimetic and insulin-sensitizing activities of a pentacyclic triterpenoid insulin receptor activator. Biochem J 2007;403:243-50.
25. Zhang YN, Zhang W, Hong D. Oleanolic acid and its derivatives: new inhibitor of protein tyrosine phosphatase 1B with cellular activities. Bioorg Med Chem 2008;16:8697-705.
26. Feng J, Zhang P, Chen X, He G. PI3K and ERK/Nrf2 pathways are involved in oleanolic acid-induced heme oxygenase-1 expression in rat vascular smooth muscle cells. J Cell Biochem 2011;112:1524-31.
27. Liu J, Sun H, Duan W, Mu D, Zhang L. Maslinic acid reduces blood glucose in KK-Ay mice. Biol Pharm Bull 2007;30:2075-8.
28. Azevedo MF, Camsari C, Sa CM, Lima CF, Fernandes-Ferreira M, Pereira-Wilson C. Ursolic acid and luteolin-7-glucoside improve lipid profiles and increase liver glycogen content through glycogen synthase kinase-3. Phytother Res 2010;24 (Suppl 2):S220-S224.
29. Huang TH-W, Yang Q, Harada M. Pomegranate flower extract diminishes cardiac fibrosis in Zucker diabetic fatty rats: modulation of cardiac endothelin-1 and nuclear factor-kappaB pathways. J Cardiovasc Pharmacol 2005;46:856-62.