NOVEL LIPID-LOWERING PROPERTIES OF VACCINIUM-MYRTILLUS L LEAVES, A TRADITIONAL ANTIDIABETIC TREATMENT, IN SEVERAL MODELS OF RAT DYSLIPIDEMIA - A COMPARISON WITH CIPROFIBRATE

Vaccinium myrtillus L. (blueberry) leaf infusions are traditionally us ed as a folk medicine treatment of diabetes. To further define this th erapeutical action, a dried hydroalcoholic extract of the leaf was adm inistered orally to streptozotocin-diabetic rats for 4 days. Plasma gl ucose levels were consistently found to drop by about 26% at two diffe rent stages of diabetes. Unexpectedly, plasma triglyceride (TG) were a lso decreased by 39% following treatment. Subsequent to the latter obs ervation, possible lipid-lowering properties of the extract were inves tigated on other models of hyperlipidaemia and ciprofibrate, a well-es tablished hypolipidaemic drug, was used as a reference compound. Both drug reduced TG levels of rats on hyperlipidaemic diet in a dose-depen dent fashion. When administered at single doses over the same experime ntal period, blueberry and ciprofibrate were effective in lowering TG concentrations in ethanol-treated normolipidaemic animals and in genet ically hyperlipidaemic Yoshida rats. Unlike ciprofibrate, however, blu eberry failed to prevent the rise in plasma TG elicited by fructose an d did not affect free fatty acid levels in any of the above experiment al 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 hypo lipidaemic action may reflect improved TG-rich lipoprotein catabolism. In addition, ciprofibrate and the extract were tested for antithrombo tic activity using a collagen-triggered model of venous thrombosis in diabetic and Yoshida rats. Only ciprofibrate, however, significantly r educed thrombus formation in diabetics, possibly because of its effect s on free fatty acid metabolism, whereas no effect was observed in Yos hida rats. In conclusion, the present findings indicate that active co nsituent(s) of Vaccinium myrtillus L. leaves may prove potentially use ful for treatment of dyslipidaemiae associated with impaired TO-rich l ipoprotein clearance. Copyright (C) 1996 ELsevier Science Ltd.