ABSTRACT
Objective To investigate the antidiabetic activity of Ocimum tenuiflorum L. (O. tenuiflorum) leaves used in the traditional medicine management of diabetes in Malaysia. Methods O. tenuiflorum leaves were extracted sequentially with hexane, chloroform, ethyl acetate, methanol, and water. The extracts were evaluated in terms of antidiabetic activity by using acute, subcutaneous glucose tolerance, and sub-chronic tests in streptozotocin-induced diabetic rats. The extracts were also subjected to phytochemical analyses. Results With an acute dose (1 g/kg), the methanol extracts showed significant reduction (31%) in fasting blood glucose (FBG) of the streptozotocin-induced diabetic rats. The FBG-decreasing effect of ethyl acetate extract was more rapid than that of the other extracts; the decreasing rates were 20% after 2 h, 21% after 3 h, and 8% after 5 and 7 h. After 7 h (31%), the effect of methanol extract on FBG was significantly lower than that of metformin. In the subcutaneous glucose tolerance test, only methanol and hexane extracts showed the similarity of metformin in diabetic rats. After 14 days, the effects of these extracts were similar to those of metformin (63.33%). The total flavonoid and phenolic contents of extracts decreased as the polarity of the extraction solvent increased. Conclusions The results obtained provide support for a possible use of O. tenuiflorum leaves in managing hyperglycemia and preventing the complications associated with it in type 2 diabetic.
ABSTRACT
<p><b>OBJECTIVE</b>To study the antidiabetic activity of Gynura procumbens (G. procumbens) used in the traditional management of diabetes in Southern Asia.</p><p><b>METHODS</b>G. procumbens leaves were extracted sequentially with graded percentage of ethanol in water (95%, 75%, 50%, 25% and 0%), and the extracts were tested for antidiabetic activity using acute (7 h), subcutaneous glucose tolerance test and sub-chronic (14 d) test in non-diabetic and streptozotocin-induced diabetic rats. The extracts were further subjected to phytochemical studies.</p><p><b>RESULTS</b>In acute dose (1 g/kg), the extracts significantly lowered fasting blood glucose (FBG) in streptozotocin-induced diabetic rats (P<0.05). However, the FBG-lowering effect of the 25% extract compared to the other extracts, was rapid (47% after 2 h) and the highest: 53%, 53% and 60% in the 3rd, 5th, and 7th h, respectively (P<0.05), comparable only to the effect of metformin. Furthermore, the extracts suppressed peak FBG in subcutaneous glucose tolerance test, but only the 0% and 25% extracts, and metformin sustained the decrease until the 90th min (P<0.05). Moreover, in the 14 days study, the 25% extract exerted the highest FBG-lowering effect, namely 49.38% and 65.43% on days 7 and 14, respectively (P<0.05), similar to the effect of metformin (46.26% and 65.42%). Total flavanoid and phenolic contents in the extracts were found to decrease with increase in polarity of extraction solvents. The composition of reference compounds (chlorogenic acid, rutin, astragalin and kaempferol-3-O-rutinoside) followed a similar trend.</p><p><b>CONCLUSIONS</b>G. procumbens contains antidiabetic principles, most extracted in 25% ethanol. Interaction among active components appears to determine the antidiabetic efficacy, achieved likely by a metformin-like mechanism.</p>