Antihyperglycemic activity of fruit extracts of Sri Lankan endemic species <i>Garcinia quaesita</i> Pierre “Rathgoraka” and its isolated compound, garcinol

The dried fruit of Garcinia quaesita Pierre (Clusiaceae), is a well-known endemic spice in Sri Lanka and has been documented in traditional medicine as an antidiabetic agent. The antihyperglycemic effect of cold water, hot water, water : acetone fruit extracts of G. quaesita and its isolated compound, garcinol in streptozotocin-induced diabetic rats was studied. The percentage improvements of glucose tolerance upon total area under the oral glucose tolerance curve in cold water, hot water and water:acetone extracts of G. quaesita (1.0 g/kg) were 6.2%, 7.4 % and 8.1%, respectively. The isolated compound, garcinol at the three selected doses (10 mg/kg, 20 mg/kg, 30 mg/kg), showed a dose dependent, antihyperglycemic activity of 23.6%, 26.5 %, 31.1 % respectively compared to glibenclamide (0.5 mg/kg) (36.1%) (p&lt;0.05). The selected extracts of G. quaesita exhibited significant antihyperglycemic activity in streptozotocin-induced diabetic rats. The isolated compound, garcinol has significantly higher antihyperglycemic activity than the respective crude extracts. Accordingly, endemic dried fruits of G. quaesita and its isolated compound garcinol are promising antihyperglycemic agents and /or drug leads that would be beneficial in the management of diabetes mellitus