Cignarella A, Nastasi M, Cavalli E, Puglisi L
Institute of Pharmacological Sciences, University of Milano, Italy.
Thromb Res. 1996 Dec 1;84(5):311-22. doi: 10.1016/s0049-3848(96)00195-8.
Vaccinium myrtillus L. (blueberry) leaf infusions are traditionally used as a folk medicine treatment of diabetes. To further define this therapeutical action, a dried hydroalcoholic extract of the leaf was administered orally to streptozotocin-diabetic rats for 4 days. Plasma glucose levels were consistently found to drop by about 26% at two different stages of diabetes. Unexpectedly, plasma triglyceride (TG) were also decreased by 39% following treatment. Subsequent to the latter observation, possible lipid-lowering properties of the extract were investigated on other models of hyperlipidaemia and ciprofibrate, a well-established hypolipidaemic drug, was used as a reference compound. Both drug reduced TG levels of rats on hyperlipidaemic diet in a dose-dependent fashion. When administered at single doses over the same experimental period, blueberry and ciprofibrate were effective in lowering TG concentrations in ethanol-treated normolipidaemic animals and in genetically hyperlipidaemic Yoshida rats. Unlike ciprofibrate, however, blueberry failed to prevent the rise in plasma TG elicited by fructose and did not affect free fatty acid levels in any of the above experimental conditions. In rats treated with Triton WR-1339, blueberry feeding induced an hypolipidaemic activity one hour after injection but proved to be ineffective at later time points, thus suggesting that its hypolipidaemic action may reflect improved TG-rich lipoprotein catabolism. In addition, ciprofibrate and the extract were tested for antithrombotic activity using a collagen-triggered model of venous thrombosis in diabetic and Yoshida rats. Only ciprofibrate, however, significantly reduced thrombus formation in diabetics, possibly because of its effects on free fatty acid metabolism, whereas no effect was observed in Yoshida rats. In conclusion, the present findings indicate that active consituent(s) of Vaccinium myrtillus L. leaves may prove potentially useful for treatment of dyslipidaemiae associated with impaired TG-rich lipoprotein clearance.
欧洲越橘叶浸剂传统上被用作治疗糖尿病的民间药物。为了进一步明确这种治疗作用，将叶的干燥水醇提取物口服给予链脲佐菌素诱导的糖尿病大鼠4天。在糖尿病的两个不同阶段，血浆葡萄糖水平持续下降约26%。出乎意料的是，治疗后血浆甘油三酯（TG）也下降了39%。基于后一观察结果，在其他高脂血症模型上研究了该提取物可能的降脂特性，并将环丙贝特（一种公认的降血脂药物）用作参考化合物。两种药物均以剂量依赖性方式降低高脂血症饮食大鼠的TG水平。在相同实验期间单剂量给药时，蓝莓和环丙贝特在乙醇处理的正常血脂动物和遗传性高脂血症吉田大鼠中均能有效降低TG浓度。然而，与环丙贝特不同的是，蓝莓不能预防果糖引起的血浆TG升高，并且在上述任何实验条件下均不影响游离脂肪酸水平。在用Triton WR-1339处理的大鼠中，喂食蓝莓在注射后1小时诱导了降血脂活性，但在随后的时间点证明无效，因此表明其降血脂作用可能反映了富含TG的脂蛋白分解代谢的改善。此外，使用糖尿病和吉田大鼠的胶原触发静脉血栓形成模型测试了环丙贝特和提取物的抗血栓活性。然而，只有环丙贝特能显著减少糖尿病大鼠的血栓形成，这可能是由于其对游离脂肪酸代谢的影响，而在吉田大鼠中未观察到任何作用。总之，目前的研究结果表明，欧洲越橘叶的活性成分可能对治疗与富含TG的脂蛋白清除受损相关的血脂异常具有潜在的用途。
