Biol. Pharm. Bull. 30(11) 2075—2078 (2007)

the plant kingdom. A variety of biological properties have been ascribed to this class of compounds including antiinflammatory, hepatoprotective, gastroprotective, anti-ulcer, anti-HIV, anti-cancer, anti-diabetic, hypolipidemic, antiatherosclerotic and immunoregulatory effects. As a part of our project aimed at drug discovery based on pharmacological interference with glucose metabolism, we have been focused on research and development of pentacyclic triterpenes as natural and low-toxic anti-diabetic agents with preventive and therapeutic effects against ischemic diabetic complications. Maslinic acid (MA, 1, structure shown in Fig. 1), a pentacyclic triterpene acid abundant in olive fruit skin, has recently attracted much attention due to its anti-tumor, antiHIV and anti-oxidation activities. We have previously reported that maslinic acid and related pentacyclic triterpenes represent a new class of inhibitors of glycogen phosphorylase, and their glucose-lowering activity in diabetic mice induced by adrenaline might be due to, at least in part, modulation hepatic glycogen metabolism. Very recently, Fernandez-Navarro et al. reported that maslinic acid exhibited modulation effects of on hepatic glycogen metabolism in the rainbow trout, and claimed that their observation was in agreement with our findings. In the present study, the anti-diabetic effects of MA have been evaluated in KK-A mice because they are an excellent model that closely resembles type 2 diabetes in humans. The aim of this study is to test whether or not MA improves diabetes in obesity-linked type 2 diabetic KK-A mice.