Sasa quelpaertensis Nakai (Korean name, Jejujoritdae), belonging to a family Gramineae, is an edible bamboo grass endemic to Jeju Island, Korea. S. quelpaertensis is one of the most abundant plant species among the plant varieties in the area of Halla Mountain located in Jeju.1 Its dried leaves are being used as a tea for the treatment of diabetes and gastritis in the local community. Our previous chemical studies on the leaves of this plant resulted in the isolation of anti-tyrosinase compounds 1-5.
2In continuation of our efforts to explore biologically active compounds from plants in Jeju, 3 we further investigated on the leaves of this bamboo grass of which the ethyl acetate extract displayed free radical scavenging activities.Production of free radicals in a living organism is primarily initiated from superoxide, which is generated as by-products in normal cellular metabolism. Free radicals are extremely reactive chemical species and can make a random attack to cellular lipids, proteins and DNA to cause their deterioration. It has been reported that a series of human illness such as inflammation, cardiovascular disease, rheumatoid arthritis and premature body aging can be linked to the damaging action of reactive free radicals. 4 Therefore, it becomes of significance to develop novel free radical scavenging agents potentially applicable in medicinal or cosmetic preparations. In this study, besides the previously isolated compounds 1-5, nine compounds 6-15 were additionally isolated from the leaves of S. quelpaertensis. Among these, the alkene glycoside 6 was identified as a new compound. In addition, the rest of the compounds 7-15 were also isolated for the first time from this plant. Herein, we describe the structure characterization and the evaluation of radical scavenging activities for the compounds isolated from S. quelpaertensis.The plant extract was prepared using 70% ethanol from the leaves of S. quelpaertensis at room temperature. The extract was suspended in water and partitioned successively into n-hexane, ethyl acetate (EtOAc), and n-butanol. As DPPH radical scavenging activities were examined for the solvent fractions, EtOAc fraction showed relatively strong activity (22% inhibition at 50 µg/mL) compared to the other fractions. In order to identify the active constituents, EtOAc fraction was subjected to purification by various column chromatography to afford compounds 6-15 including a new compound 6 (Figure 1).The compound 6 was obtained as a colorless syrup. In the