Tapping the Philippines' Rich Biodiversity for the Treatment of Diabetes
The Philippines is a mega-diverse country, and is one of the 17 countries that contain two-thirds of the entire biological diversity of the Earth . This provides a fertile source of plant-derived bioactive agents for the treatment of diabetes, which is a disease that threatens a significant portion of the global population . Employing the oral glucose tolerance test, the hypoglycemic activity, in normoglycemic mice, of methanolic extracts of ten Philippine plants (Syzygium cumini, Morinda citrifolia, Andropogon citratus, Ipomoea aquatica, Mimosa pudica, Averrhoa bilimbi, Polymnia sanchifolia, Benincasa hispida, Anacardium occidentale, Helianthus annuus) folklorically used for the treatment of diabetes was determined. To elucidate the mechanism of action, the alpha glucosidase inhibitory activity of the active plant extracts was evaluated employing a spectrophotometric technique. Among the plant extracts tested, Benincasa hispida, Morinda citrifolia, and Helianthus annuus were found to show promising results in significantly lowering blood glucose level with 47.80%, 40.10% and 36.69% hypoglycemic activity, respectively, when administered orally at a dose of 5 mg/20 g mouse. In comparison, metformin, administered at a dose of 3 mg/20 g mouse gave a 48.95% hypoglycemic activity. The same plant extracts did not exhibit inhibitory activity against alpha glucosidase at a concentration of 1000 µg/mL implying a different mechanism of action for the observed blood glucose lowering activity. Isolation and identification of the active principles from these active plants are being pursued. Acknowledgements: The authors would like to thank the funding agencies who made this work possible: National Institutes of Health through the FIRCA Grant Prime Award No. 1R03TW008213 – 01A1, Subaward No. 0000007997 and the University of the Philippines Diliman. Special acknowledgment to the University of Maryland Baltimore County, Maryland, USA, the Institute of Chemistry and the Natural Sciences Research Institute, University of the Philippines Diliman, Quezon City, Philippines where all research support and collaborative work were done. References:  Mayers N, Mittermeier RA, et al. (2000) Nature, 403: 853 – 858.  Wild D, Roglik G, et al. (2004) Diabetes Care, 27(5): 1047 – 1053.