title: O-prenylated flavonoid, an antidiabetes constituent in Melicope lunu-ankenda.
abstract: BACKGROUND
  Melicope lunu-ankenda leaves are used to treat diabetes in folklore medicinal practices in India and Malaysia. Here we report the isolation of an O-prenylated flavonoid (3,5,4'-trihydroxy-8,3'-dimethoxy-7-(3-methylbut-2-enoxy)flavone; OPF) from the leaves of M. lunu-ankenda and its antidiabetes activity against type-2 diabetes mellitus (T2DM).
  
  
  METHODS
  OPF was isolated from M. lunu-ankenda leaves by extraction and repeated column chromatography and its structure was elucidated by IR, UV-vis, 1D-, 2D-NMR and mass spectral analyses. Blood glucose lowering activity of OPF was tested in normal rats by oral glucose tolerance test and its efficacy was tested in STZ-induced type-2 diabetic rats. SGOT, SGPT, ALP, serum urea, total triglycerides, total cholesterol and reduction in HDLC, protein and serum insulin levels in normal rats and STZ-induced type-2 diabetic rats were measured. Acute toxicity of OPF was tested at 500 mg/kg dose. Mechanism of antidiabetes action of OPF was elucidated by insulin release from RIN 5F cells.
  
  
  RESULTS
  OPF isolated from M. lunu-ankenda showed significant blood glucose lowering activity in oral glucose tolerance test on overnight fasted, glucose loaded normal rats and the optimum activity was observed at a dose of 10mg/kg body weight. In neonatal streptozotocin (STZ) induced diabetic rats, the OPF treatment for 20 days significantly ameliorated the derailed blood glucose levels, liver glycogen and serum biological parameters including insulin to normal levels. OPF on acute toxicity evaluation did not show any conspicuous toxic symptoms even at a higher dose of 500 mg/kg body weight in mice. On evaluating the mechanism of antidiabetes action, it was observed that, OPF induced insulin release from cultured RIN 5F cells in vitro from which it was evident that the OPF acts on pancreatic β-cells for insulin release thereby correcting the derailed blood glucose levels, serum biochemical parameters and ameliorate various diabetic complications in STZ-induced diabetic rats.
  
  
  CONCLUSIONS
  This study shows the potent antidiabetes activity of OPF and describes its mechanism of action. OPF is a promising candidate for the development of new generation anti-DM drugs. Isolation of the O-prenylated flavonoid justifies the use of M. lunu-ankenda for diabetic treatments in folklore practices.
authors: Phytochemistry and Phytopharmacology Division, Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Pacha-Palode, Thiruvananthapuram 695 562, Kerala, India.
authors: Sony
authors: S
authors: George
authors: Phytochemistry and Phytopharmacology Division, Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Pacha-Palode, Thiruvananthapuram 695 562, Kerala, India.
authors: S
authors: S
authors: Ajikumaran Nair
authors: Phytochemistry and Phytopharmacology Division, Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Pacha-Palode, Thiruvananthapuram 695 562, Kerala, India.
authors: Anil J
authors: AJ
authors: Johnson
authors: Department of Chemistry, Sri Paramakalyani College (Manonmaniam Sundaranar University, Tirunelveli), Alwarkurichi 627 412, Tamil Nadu, India.
authors: Ramaswamy
authors: R
authors: Venkataraman
authors: Phytochemistry and Phytopharmacology Division, Jawaharlal Nehru Tropical Botanic Garden and Research Institute, Pacha-Palode, Thiruvananthapuram 695 562, Kerala, India. Electronic address: sabulal@gmail.com.
authors: Sabulal
authors: S
authors: Baby
mesh_terms: D000818:Animals; D001786:Blood Glucose / Q000032:analysis; D003921:Diabetes Mellitus, Experimental / Q000097:blood / Q000188:drug therapy* / Q000378:metabolism; D003924:Diabetes Mellitus, Type 2 / Q000097:blood / Q000188:drug therapy* / Q000378:metabolism; D005419:Flavonoids / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use* / Q000633:toxicity; D006003:Glycogen / Q000378:metabolism; D007004:Hypoglycemic Agents / Q000302:isolation & purification / Q000494:pharmacology / Q000627:therapeutic use* / Q000633:toxicity; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D018515:Plant Leaves; D054876:Prenylation; D017208:Rats, Wistar; D027821:Rutaceae; D023382:Toxicity Tests, Acute
chemical_list: D001786:Blood Glucose; D005419:Flavonoids; D007004:Hypoglycemic Agents; D006003:Glycogen
keywords: Melicope lunu-ankenda; O-prenylated flavonoid; RIN 5F cells; Streptozotocin; Type 2 diabetes mellitus