Antioxidant compounds were extracted from various parts of Sasa pahnata (Bean) Nakai, a bamboo plant whose leaves are commonly used to wrap foodstuffs such as Sushi in Japan. Highest concentrations of antioxidant compounds existed in the leaf part of S. pahnata. Steam explosion treatment followed by hot water and methanol extractions was used for separating the antioxidant compounds from S. palmata leaf. The steam explosion treatment is the physic al-chemical treatment which crushes a sample by sudden reduction of the pressure in reactor to atmospheric pressure after steaming the sample at high temperature and pressures. Sasa pahnata leaf was hydrolyzed by steaming and crushed by the rapid decompression. The optimal condition of steam explosion for the effective extraction of antioxidant compounds from S. pahnata was determined as a steam of temperature of 250 degrees C and a steaming time of 1 min. In these conditions 217.41 mg/(g-Sasa leaf) of phenolic compounds and 142.81 mg/(g-Sasa leaf) of radical scavenging activity, that was expressed as butylated hydroxyanisole (BHA), were obtained. (C) 2007 Elsevier Ltd. All rights reserved.