STUDIES ON THE BIOACTIVE CONSTITUENTS OF AURANTII-FRUCTUS-IMMATURUS

An ethanol extract of ''Kijitsu'' (Aurantii Fructus Immaturus, Citrus aurantium L.) collected in China was assessed for the antitumor activi ty using murine leukemia P388 in vivo, and the extract was found to be active by the antitumor bioassay in vivo and in vitro. The extract wa s separated into a petroleum ether-soluble fraction and an ethyl aceta te-soluble fraction. Fractionation was carried out using an index of c ell-growth inhibitory activity against mouse leukemia L1210 cells to i solate antitumor active substances or compounds. The active compounds were purified employing silica gel column chromatography and HPLC. The antitumor effect of the isolated active compounds was studied. Five c ompounds, auraptene, marmin, tangeretin, nobiretin and 5-[(6',7'-dihyd roxy-3',7'-dimethyl-2-octenyl) oxy]psoralen were isolated from Citrus aurantium L. Though they are all known compounds, 5[(6',7'-dihydroxy-3 ',7'-dimethyl-2-octenyl)oxy] psoralen from this plants was first isola ted. These compounds showed a cell-growth inhibitory effect against L1 210 and K562 in vitro.