Biol. Pharm. Bull. 28(8) 1404—1407 (2005)

and remarkable for its clinical heterogeneity. Despite recent advances in chemotherapy, the prognosis of advanced neuroblastoma is still very poor. However, some favorable types of neuroblastoma, especially in infants under 1 year of age, are known to regress spontaneously or mature even if widespread metastases to bone marrow, skin and/or liver (special stage: stage IVS) are present. Apoptosis is known to occur in normal development of nervous systems, and neuroblastoma is generated from neural crest cells when the apoptotic systems do not carry out. Delayed implementation of the normal apoptotic pathway has been proposed as an explanation for the spontaneous regression of favorable neuroblastoma. It is reported that resistance to apoptosis plays a contributory role in the mechanism of the aggressive behavior shown by advanced neuroblastoma. Acute lymphocytic leukemia, like advanced neuroblastoma, is also a pediatric disease that is difficult to treat, especially in older children or those with a high amount of leukemic cells in the peripheral blood. Angelica keiskei has been used traditionally in Japan as a diuretic, laxative, analeptic and galactagogue, and an A. keiskei extract was previously reported to affect metabolic activity and vasoconstriction in rats. Moreover, A. keiskei and a major chalcone constituent of this plant, xanthoangelol, reportedly have inhibitory effects against tumor promoter activity and metastasis. Xanthoangelol possesses a chalcone structure, and some compounds related to calchones are known to have antitumor activity and to induce apoptosis. Quercetin chalcone was reported to reduce the size of implanted colon-25 tumors in vivo. However, there has been no report on the effects of chalcones, including xanthoangelol, on neuroblastoma. In this study, we examined the antitumor effect and apoptosis-inducing activity of xanthoangelol against a human neuroblastoma cell line (IMR-32), and also a leukemia cell line (Jurkat) which have been widely used in previous studies of apoptosis.