No abstract

Thirty-five limonoids, including 15 of the azadiradione type (1-15), five of the gedunin type (16-20), four of the azadirachtin type (21-24), nine of the nimbin type (25-33), and two degraded limonoids (34, 35), isolated from Azadirachta indica seed extracts, were evaluated for their cytotoxic activities against five human cancer cell lines. Seven compounds (3, 6, 7, 16, 18, 28, and 29) exhibited cytotoxic activity against one or more cell lines. Among these compounds, 7-deacetyl-7-benzoylepoxyazadiradione (7), 7-deacetyl-7-benzoylgeduin (18), and 28-deoxonimbolide (28) exhibited potent cytotoxic activity against HL60 leukemia cells with IC(50) values in the range 2.7-3.1 μM. Compounds 7, 18, and 28 induced early apoptosis in HL60 cells, observed by flow cytometry. Western blot analysis showed that compounds 7, 18, and 28 activated caspases-3, -8, and -9 in HL60 cells. This suggested that compounds 7, 18, and 28 induced apoptotic cell death in HL60 cells via both the mitochondrial- and the death receptor-mediated pathways. Futhermore, compound 7 was shown to possess high selective cytotoxicity for leukemia cells since it exhibited only weak cytotoxicity against a normal lymphocyte cell line (RPMI 1788).

Six chalcones from Angelica keiskei KOIDZUMI (Ashitaba in Japanese) and two chalcones from Humulus lupulus L. (hop) were examined for their cytotoxicity in two human neuroblastoma cell lines (IMR-32 and NB-39) and normal cells (primary culture of rat cerebellar granule cells) by [3-(4,5)-dimethyl-2-thiazolyl]-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay. All chalcones exhibited cytotoxicity against neuroblastoma cells, and two of them (isobavachalcone and xanthoangelol H) had no effect on normal cells even at high concentration (10 ؊4 M) exposure. Typical morphologic features of apoptosis, including cell shrinkage, chromatin condensation, nuclear fragmentation and formation of apoptotic bodies, were observed in isobavachalcone-treated cells by Hoechst 33342 staining. Western blot analysis showed that isobavachalcone significantly reduced pro-caspase-3 and pro-caspase-9, and subsequently increased the level of cleaved caspase-3 and cleaved caspase-9 in both neuroblastoma cell lines. Moreover, Bax was markedly induced by isobavachalcone application. These results suggest that isobavachalcone induces apoptotic cell death in neuroblastoma via the mitochondrial pathway and has no cytotoxicity against normal cells. Therefore, isobavachalcone may be applicable as an efficacious and safe drug for the treatment of neuroblastoma.

Six lanostane-type triterpene acids (1a-6a), isolated from Poria cocos , and their methyl ester (1b-6b) and hydroxy derivatives (1c-6c) were prepared. Upon evaluation of the cytotoxic activity of these compounds against leukemia (HL60), lung (A549), melanoma (CRL1579), ovary (NIH:OVCAR-3), breast (SK-BR-3), prostate (DU145), stomach (AZ521), and pancreas (PANC-1) cancer cell lines, 11 compounds (5a, 6a, 2b-5b, 1c, and 3c-6c) exhibited activity with single-digit micromolar IC(50) values against one or more cell lines. Poricotriol A (1c), a hydroxy derivative of poricoic acid A (1a), exhibited potent cytotoxicities against six cell lines with IC(50) values of 1.2-5.5 μM. Poricotriol A induced typical apoptotic cell death in HL60 and A549 cells on evaluation of the apoptosis-inducing activity by flow cytometric analysis. Western blot analysis in HL60 cells showed that poricotriol A activated caspases-3, -8, and -9, while increasing the ratio of Bax/Bcl-2. This suggested that poricotriol A induced apoptosis via both mitochondrial and death receptor pathways in HL60. On the other hand, poricotriol A did not activate caspases-3, -8, and -9, but induced translocation of apoptosis-inducing factor (AIF) from mitochondria and increased the ratio of Bax/Bcl-2 in A549. This suggested that poricotriol A induced apoptosis via the mitochondrial pathway mostly by translocation of AIF, independent from the caspase pathway in A549. Furthermore, poricotriol A was shown to possess high selective toxicity in lung cancer cells since it exhibited only weak cytotoxicity against a normal lung cell line (WI-38).

Neuroblastoma is the most common solid pediatric tumor 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.1) It is reported that resistance to apoptosis plays a contributory role in the mechanism of the aggressive behavior shown by advanced neuroblastoma.2) 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 3,4) and vasoconstriction 5) in rats. Moreover, A. keiskei and a major chalcone constituent of this plant, xanthoangelol, reportedly have inhibitory effects against tumor promoter activity 6,7) and metastasis. 8) 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. 9) 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. MATERIALS AND METHODS Materials Xanthoangelol(3Ј-C-geranyl-2Ј,4,4Ј-trihydroxychalcone) was isolated from the stem exudate of A. keiskei 6) and dissolved in dimethyl sulfoxide (DMSO) (final concentration 0.2%). IMR-32 and Jurkat were maintained in RPMI-1640 medium (Invitrogen) supplemented with 100 U/ml penicillin, 100 mg/ml streptomycin and 10% fetal bovine serum (FBS) (Invitrogen). The cells were maintained at 37°C/5% CO 2 in a humid environment.Trypan Blue Exclusion Assay The cells ( 1ϫ10 6 ) were plated into a 60-mm dish and maintained for 24 h. Xanthoangelol (final concentrations 10 Ϫ6 , 10 Ϫ5, 10 Ϫ4 M) and vehicle were applied for 48 h. For the IMR-32 cell protocol, the cells were stripped using 0.05% trypsin-EDTA solution after washing them in phosphate-buffered saline (Ϫ). They were then washed in RPMI-1640 medium (with 10% FBS) and counted with a phase-contrast microscope immediately after addition of an equal volume of 1% tr...