Several oximes of triterpenes with a 17-beta hydroxyl and abietane derivatives are inhibitors of pyruvate dehydrogenase kinase (PDK) activity. The oxime 12 and dehydroabietyl amine 2 exhibit a blood glucose lowering effect in the diabetic ob/ob mouse after a single oral dose of 100 mu mol/kg. However, the mechanism of the blood glucose lowering effect is likely unrelated to PDK inhibition. (C) 1999 Elsevier Science Ltd. All rights reserved.