College of Food Science and Technology, Northwest University, 229 Taibai North Road, Xi'an, Shaanxi 710069, China.
Herbalife International of America, 950 W. 190th Street, Torrance, CA 90502, USA.
Food Funct. 2020 Feb 26;11(2):1560-1571. doi: 10.1039/c9fo03091c.
Previously, we have reported the opposite effects of compounds isolated from Lagerstroemia speciosa leaves on a glucose transport (GLUT4) assay. Ellagitannins from L. speciosa activated GLUT4, while ellagic acid derivatives showed an inhibitory effect. As part of our continuing research on anti-diabetic nutritional supplements, we herein compared the anti-diabetic effects of several extracts (LE1-8) from leaves of L. speciosa using different manufacturing processes based on the contents of ellagitannins and ellagic acid derivatives. Their anti-diabetic effects were evaluated through glucose uptake and adipocyte differentiation in 3T3-L1 cells in vitro as well as alloxan induced diabetic mice in vivo. These extracts were given to mice by gavage at doses of 0.25, 1.0, and 4.0 g per kg body weight once a day for 21 consecutive days. Results showed that LE1 (1.0 g kg-1), LE3 (1.0 or 4.0 g kg-1), LE4 (1.0 or 4.0 g kg-1), LE5 (0.25 or 1.0 or 4.0 g kg-1) and LE7 (1.0 or 4.0 g kg-1) showed significant anti-diabetic effects in alloxan-induced diabetic mice as indicated by the decreased levels of fasting blood glucose, body weight, serum biomarkers, tissue weight and body fat, and increased final insulin levels. LE8 (1.0 g kg-1) showed a moderate anti-diabetic effect as illustrated by the reduced fasting blood glucose level while LE2 and LE6 showed slight effects in alloxan-induced diabetic mice. The potential correlation of the content of ellagitannins, ellagic acid derivatives, and corosolic acid with the anti-diabetic activity was discussed.
先前，我们报道了从紫薇叶中分离得到的化合物对葡萄糖转运（GLUT4）测定的相反作用。紫薇叶中的鞣花单宁能激活 GLUT4，而鞣花酸衍生物则表现出抑制作用。作为我们对糖尿病营养补充剂的持续研究的一部分，我们在此比较了几种（LE1-8）提取物的抗糖尿病作用，这些提取物来自不同制造工艺的紫薇叶，基于鞣花单宁和鞣花酸衍生物的含量。通过体外 3T3-L1 细胞的葡萄糖摄取和脂肪细胞分化以及体内链脲佐菌素诱导的糖尿病小鼠来评估它们的抗糖尿病作用。这些提取物通过灌胃以 0.25、1.0 和 4.0 g/kg 体重的剂量每天给药一次，连续 21 天。结果表明，LE1（1.0 g/kg）、LE3（1.0 或 4.0 g/kg）、LE4（1.0 或 4.0 g/kg）、LE5（0.25 或 1.0 或 4.0 g/kg）和 LE7（1.0 或 4.0 g/kg）在链脲佐菌素诱导的糖尿病小鼠中表现出显著的抗糖尿病作用，表现为空腹血糖、体重、血清生物标志物、组织重量和体脂降低，以及最终胰岛素水平升高。LE8（1.0 g/kg）表现出中度的抗糖尿病作用，如空腹血糖水平降低所示，而 LE2 和 LE6 则在链脲佐菌素诱导的糖尿病小鼠中表现出轻微作用。讨论了鞣花单宁、鞣花酸衍生物和柯诺辛酸的含量与抗糖尿病活性的潜在相关性。
