The hypoglycaemic and anti-hyperglycaemic activities of a methanol extract of Morinda lucida Benth. (Rubiaceae) leaves were studied in normal and streptozotocin-diabetic rats.
In normal rats, the extract demonstrated a significant (P < 0.05) and dose-dependent hypoglycaemic activity within 4h after oral administration. The plasma glucose level of 400 mg kg−1 of the extract at 4h was 42.5 ± 0.4 mg/100 mL (control 67.4 ± 1.2 mg/100 mL). After 12h, the plasma 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 produced a significant (P < 0.05) anti-diabetic effect from day 3 after oral administration, with 400 mg kg−1 extract-treated animals having a plasma glucose 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 mg/100 mL.
These results suggest that the leaves of Morinda lucida have a strong glucose lowering property when administered to streptozotocin-treated rats.