Evaluation of the anti-diabetic property of Morinda lucida leaves in streptozotocin-diabetic rats

The hypoglycaemic and anti-hyperglycaemic activities of a methanol extract of Morinda lucida Benth. (Rubiaceae) leaves were studied in normal and stre ptozotocin-diabetic rats. In normal rats, the extract demonstrated a significant (P < 0 . 05) and dos e-dependent hypoglycaemic activity within 4 h after oral administration. Th e plasma glucose level of 400 mg kg(-1) of the extract at 4 h was 42 . 5 +/ - 0 . 4 mg/100mL (control 67 . 4 +/- 1 . 2 mg/100 mL). After 12 h, the plas ma glucose level of rats administered 50, 100, 200 or 400 mg kg(-1) extract fell to 51 . 9 +/- 1 . 2, 47 . 3 +/- 0 . 8, 43 . 1 +/- 0 . 4 and 40 . 0 +/ - 0 . 5 mg/100 mL, respectively. In hyperglycaemic rats, the extract produc ed a significant (P < 0 . 05) anti-diabetic effect from day 3 after oral ad ministration, with 400 mg kg(-1) extract-treated animals having a plasma gl ucose: level of 248 . 7 +/- 5 . 3 mg/100 mL compared with glibenclamide (10 mg kg(-1))-treated animals with a plasma glucose level of 251 . 5 +/- 5 . 8 mg100 mL. These results suggest that the leaves of Morinda lucida have a strong gluco se lowering property when administered to streptozotocin-treated rats.