Co-administration effects of aqueous extract of turnip leaf and metformin in diabetic rats

There is a variety of experimentally proven medicinal plants having antidiabetic properties but data on herb-drug interaction are very limited. Earlier studies indicated that aqueous extract of turnip leaf (AETL) has hypoglycemic potential in diabetic animals. The present study was conducted to evaluate co-administration effects of AETL and metformin, a commonly used antidiabetic drug, in diabetic rats.

Metformin at the two different doses (50,100 mg/kg) and AETL at the dose of 400 mg/kg (separately or concurrent with metformin) were orally given to streptozotocin-induced diabetic rats for 4 weeks daily. Fasting blood glucose (FBG) was measured at the times 0, 7, 14, 21 and 28 days after investigation. At the end of study, liver enzymes activity [aspartate aminotransferase (AST) and alanine aminotransferase (ALT)] as well as liver histopathology were evaluated.

Both treatments could significantly decrease FBG levels when they administrated separately. Interestingly, co-administration of AETL and metformin in a dose dependent manner significantly improved hypoglycemic activity of metformin. While neither metformin nor AETL could ameliorate liver alterations alone, but in concomitant therapy they efficiently attenuated liver enzymes elevation and histological damages.

The results of the present study demonstrate that combination of metformin with AETL enhance the prior effectiveness and reduced the latter adverse effects by a synergistic interaction.