In our preliminary screening study on the anti-inflammatory activity, eight triterpenes, one sterol, and one chalcone were isolated from the CH(2)Cl(2)-soluble extract of the stems and leaves of Rhus sylvestris Siebold and Zucc (Anacardiaceae). On the basis of their spectroscopic data, these compounds were identified as 10alpha-cucurbitadienol (1), glut-5-en-3-ol (2), beta-amyrin acetate (3), beta-amyrin (4) and lupeol (5), cycloart-24-en-3-one (6), cycloart-25-en-3,24-dione (7), 24-hydroxycycloart-25-en-3-one (8), beta-sitosterol (9), and 2'-hydroxy-4,4'-dimethoxychalcone (10). All of them were isolated from this plant for the first. Furthermore, the compounds in non-cytotoxic concentrations (0-1.0microM) were tested for their ability to block inflammatory cytokine secretion in the presence of LPS in the murine RAW264.7 macrophage cell line. Among the compounds that were tested, compounds 8 and 9 reduced the LPS-induced secretion of IL-6, as well as TNF-alpha, in a mouse RAW264.7 macrophage cell line. Moreover, compounds 2, 3, 7, and 10 specifically diminished only the secretion of TNF-alpha even in 0.01microM concentrations. It is thus suggested that they are potential therapeutics of TNF-alpha-related diseases and conditions, such as transplant rejection, type II diabetes, and atherosclerosis.