Antitumor agents, 107. New cytotoxic 4-alkylamino analogues of 4'-demethyl-epipodophyllotoxin as inhibitors of human DNA topoisomerase II

A series of analogues of etoposide, the C-4 amino- and alkylamino-substituted 4'-demethyl-epipodophyllotoxins, have been synthesized and studied for their activity to inhibit type II human DNA topoisomerase as well as their activity in causing cellular protein-linked DNA breakage. Substitution of the glycosidic moiety of 1 by a 2"-hydroxyethylamino or 2"-methoxyethylamino chain at the C-4 beta position resulted in potent inhibitors of the human DNA topoisomerase II. This inhibitory activity correlates reasonably well with their activity in causing protein-linked DNA breakage in KB cells. The in vitro cytotoxicity (KB) appears to have no correlation with the inhibitory activity of the human DNA topoisomerase II.     

Antitumor agents, 99. Synthetic ring C aromatized podophyllotoxin analogues as potential inhibitors of human DNA topoisomerase II

Several ring C aromatized analogues of podophyllotoxin were synthesized for testing against human DNA topoisomerase II. The results indicate that aromatization of ring C gave rise to no inhibition of this enzyme at 200 microM. A comparison of the cytotoxicity among these compounds also demonstrates that a free hydroxyl group at C-4 contributes to significant cytotoxicity.     

Structures and cytotoxicity relationship of isoaaptamine and aaptamine derivatives.

A series of 9-O-acylisoaaptamine (3-14) and 4-N-acyl-dihydroaaptamine (16-19) derivatives have been prepared and evaluated for antitumor activity against murine P-388 and human tumor cells including KB16, A549, and HT-29 cell lines. All of compounds showed significant cytotoxicity against P-388 cells. Among them, compounds 9-11 showed potent activity as isoaaptamine (1). There was an apparent lack of linear relationship between cytotoxicity and carbon number of the side chain. The structure and activity relationship for these particular compounds are discussed.     

Potent antiviral potamogetonyde and potamogetonol, new furanoid labdane diterpenes from Potamogeton malaianus

New furanoid labdane diterpenes, potamogetonyde (3) and potamogetonol (4), together with two known compounds, potamogetonin (1) and 15,16-epoxy-12-oxo-8(17),13(16),14-labdatrien-20,19-olide (2), were isolated from the CH(2)Cl(2) extract of Potamogeton malaianus. The chemical structures of 1-4 were elucidated by the analyses of their spectral data, mainly by 1D and 2D NMR techniques. Potamogetonyde (3) and potamogetonol (4) exhibited potent antiviral (HSV-1) activity with respective IC(50) values of 8 and 3 microg/mL. Compounds 1-4 possessed cytotoxicity toward insect cells (fall armyworm and mosquito larvae, IC(50) of 11-72 microg/mL). Furanoid diterpenes 3 and 4 also exhibited cytotoxicity against the Vero cell line with respective IC(50)'s of 31 and 28 microg/mL, while 1 and 2 were inactive at 50 microg/mL. Compounds 1-4 were inactive (at 20 microg/mL) against KB and BC cell lines and showed only weak antimycobacterial activity against Mycobacterium tuberculosis H37Ra with minimum inhibitory concentrations of 50-100 microg/mL.     

New biphenyl compounds with DNA strand-scission activity from Clusia paralicola

Three new biphenyl derivatives, clusiparalicolines A (1), B (2), and C (3), were isolated from the roots of Clusia paralicola by bioassay-directed fractionation using the DNA strand-scission and the KB human cancer cell line cytotoxicity assays. Compounds 1 and 2 were found to be active in the DNA strand-scission assay, whereas all three compounds exhibited modest cytotoxicity against the KB cell line. The structures of 1-3 were elucidated by spectroscopic methods including 1D and 2D NMR techniques.     

1',2',3',4'-tetradehydrotubulosine, a cytotoxic alkaloid from Pogonopus speciosus.

Bioassay-guided phytochemical investigation of the stems of Pogonopus speciosus, using human oral epidermoid carcinoma (KB) cells as a monitor, led to the isolation of a novel alkaloid, 1',2', 3',4'-tetradehydrotubulosine (1), along with tubulosine (2) and psychotrine (3) as bioactive constituents. The structure of the novel compound was elucidated through 1D- and 2D-NMR spectroscopic methods. Alkaloids 1 and 3 showed weak cytotoxic activity against a panel of human cancer cell lines, with the potency of these compounds being markedly less than that of tubulosine (2).     

Novel bioactive clerodane diterpenoids from the leaves and twigs of Casearia sylvestris

Fractionation of a methanol extract of the leaves and twigs of Casearia sylvestris, as directed by activity against KB cell cytotoxicity, led to the isolation of three novel clerodane diterpenoids, casearvestrins A-C (1-3). The structures of 1-3 were deduced from one- and two-dimensional NMR experiments, including relative stereochemical assignments based on ROESY correlations and COSY coupling constants. All three compounds displayed promising bioactivity, both in cytotoxicity assays against a panel of tumor cell lines and in antifungal assays via the growth inhibition of Aspergillus niger in a disk diffusion assay.     

Catalytic inhibition of eukaryotic topoisomerases I and II by flavonol glycosides extracted from Vicia faba and Lotus edulis

Topoisomerases are essential enzymes involved in all processes of DNA metabolism, and their inhibitors have been identified as potential anticancer agents. The present study examined the effect of nine polyphenolic compounds derived from parts of two unique varieties of the Leguminosae, Vicia faba and Lotus edulis, on the activity of eukaryotic topoisomerases. We identified polyphenolic compounds that act as catalytic inhibitors of wheat germ topoisomerase I (IC50: 120-350 μM), human topoisomerase I (IC50: 110-260 μM), and human topoisomerase II (IC50: 240-600 μM) activities. Some compounds inhibited all enzymatic activities to a similar extent, while others exhibited specificity toward individual enzymes. The strongest catalytic inhibitor of all the examined enzymes was a kaempherol glycoside with an acetyl group linked to a sugar moiety. In addition, this compound inhibited the growth of human cancer cell lines MCF7, HeLa, and HepG2. The inhibition of topoisomerase I and II activities observed by the specific compounds possibly implies a role as potential agents in the prevention and therapy of cancer.     

Bulbinelonesides A-E,phenylanthraquinone glycosides from the roots of Bulbinella floribunda

The roots of Bulbinella floribunda have been analyzed for the phenolic constituents, resulting in the isolation of five new phenylanthraquinone glycosides, named bulbinelonesides A-E (1-5), along with two known phenylanthraquinones, (+)-M-knipholone (6) and (+)-M-isoknipholone (7). The structures of the new compounds were determined on the basis of extensive spectroscopic analysis, including 2D NMR, and the results of enzymatic hydrolysis. Although the new compounds 3-5, whose absolute stereochemistry of the unsymmetric biaryl moiety was determined to be P by the CD spectrum, did not show apparent cytotoxicity against cultured HSC-2 tumor cells and HPC normal cells, the new compounds 1 and 2, as well as the known compounds 6 and 7, whose biaryl bond was assigned as M, exhibited a tumor-specific cytotoxicity against HSC-2 cells comparable to or slightly weaker than etoposide, used as a positive control.     

Antitumor agents. 203. Carbazole alkaloid murrayaquinone A and related synthetic carbazolequinones as cytotoxic agents

Murrayaquinone A (1) and murrayafoline A (3), isolated from the root bark of Murraya euchrestifolia, were identified as cytotoxic compounds. Murrayaquinone A (1) demonstrated significant cytotoxicity against SK-MEL-5 and Colo-205 cells, with ED(50) values of 2.58 and 3.85 microg/mL, respectively. In contrast, murrayafoline A (3) exhibited marginal or weak cytotoxicity against SK-MEL-5, Colo-205, HCT-8, KB, and A-549 tumor cell lines, with ED(50) values ranging from 5.31 to 7.52 microg/mL. In total, 20 carbazole alkaloids (1-20), isolated previously by Furukawa et al. from various plant sources were also evaluated for their cytotoxic profiles in the NCI's human disease-oriented, 60-cell line, in vitro antitumor screening protocol. Compounds 3 and 15 showed potent cell-line selective cytotoxicity against MOLT-4 cells, with log GI(50) values of -8.60 and -8.49 M, respectively, while 12 demonstrated better selectivity against the colon cancer subpanel. Moreover, synthetic 2-methyl- or 3-methyl-carbazolequinone derivatives with various substituents in the A-ring were evaluated against KB, SK-MEL-5, Colo-205, and HCT-8 tumor cells. 6-Methoxy- (21), 6-methyl- (22), and 6-chloro- (24) 3-methyl-carbazolequinones demonstrated significant cytotoxicity against SK-MEL-5 cells, with ED(50) values of 0.55, 0.66, and 0.83 microg/mL, respectively. Compounds 21 and 22 were also significantly cytotoxic toward KB cells, with ED(50) values of 0.76 and 0.92 microg/mL, respectively, and 21 displayed a similar level of toxicity against Colo-205 cells (ED(50) 0.87 microg/mL).     

Biological and mechanistic activities of xanthorrizol and 4-(1',5'-dimethylhex-4'-enyl)-2-methylphenol isolated from Iostephane heterophylla

Xanthorrizol (1) and 4-(1',5'-dimethylhex-4'-enyl)-2-methylphenol (2) were identified as the principal antimicrobial components of a CH(2)Cl(2)-MeOH (1:1) extract derived from Iostephane heterophylla. Compound 2 is a new natural product, but has been synthesized. Both compounds exhibited low level activity (MICs of 16-32 microg/mL) against methicillin-resistant staphylococci and vancomycin-resistant enterococci. They were either inactive or poorly active against Gram-negative bacteria and yeast. Mechanistic studies performed in Escherichia coli imp suggested nonspecific inhibition of DNA, RNA, and protein synthesis by both of these compounds. Compound 1 was tested in an in vivo model; it did not provide protection to mice infected with Staphylococcus aureus.     

Cytotoxic and apoptosis-inducing activities of limonoids from the seeds of Azadirachta indica (neem)

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).     

Phloroglucinols with prooxidant activity from Garcinia subelliptica

A new phloroglucinol, garcinielliptone HF ( 1), possessing an unprecedented skeleton, and the tautomeric pair of garcinielliptone FC ( 2/ 2a) were isolated from the heartwood and pericarp of Garcinia subelliptica, respectively. Their structures, including relative configurations, were elucidated by means of spectroscopic methods. The ability of compounds 1 and 2/ 2a to induce DNA-cleavage activity was examined using supercoiled plasmid pBR322 DNA. In the presence of Cu(II), compounds 1 and 2/ 2a caused significant breakage of pBR322 DNA. The involvement of H2O2 and O2 (*-), and H2O2, O2 (*-), and OH (*) in 1- and 2/ 2a-mediated scission, respectively, was established by inhibition or no protection of DNA breakage by various oxygen radical scavengers. Thus, in the presence Cu(II), 1 and 2/ 2a may show a prooxidant effect on DNA and induce cell death.     

Antitumour effects of selected plant polyphenols,gallic acid and ellagic acid,on sensitive and multidrug‐resistant leukaemia HL60 cells

The aim of this study was to examine the antitumour effects of plant phenolic acids, gallic acid (GA) and ellagic acid (EA), on human promyelocytic leukaemia sensitive HL60 cell line and its resistant sublines exhibiting two MDR phenotypes: HL60/VINC (overexpressing P‐glycoprotein) and HL60/MX2 (characterized by the presence of mutated α isoform of topoisomerase II). Both studied compounds exerted comparable cytotoxic activities towards sensitive HL60 cells and their MDR counterparts. It was also found that GA and EA modulated the cellular level of reactive oxygen species in a dose‐dependent and time‐dependent manner. Furthermore, it was demonstrated that GA (IC₉₀) and EA (IC₅₀ and IC₉₀) significantly increased the percentage of sub‐G1 subpopulation of all studied leukaemia cells causing oligonucleosomal DNA fragmentation. Both compounds used at IC₉₀ triggered mainly the apoptotic death of these cells. However, GA had no effect on the activity of caspase‐3 as well as caspase‐8 in sensitive HL60 cells and their MDR counterparts. In contrast, EA provoked a significant activation of these caspases in all studied leukaemia cells. It was also found that lysosomes were not involved in triggering programmed death of sensitive HL60 and MDR cells by GA and EA.     

黄花蒿内生菌IFB-E012发酵液的化学成分

目的：对黄花蒿内生菌Myrothecium roridum IFB—E012发酵液乙酸乙酯萃取物进行分离纯化,寻找具有新和／或强生物活性的化合物。方法：采用硅胶柱层析、SephadexLH-20凝胶柱层析等色谱方法进行成分的分离纯化,并利用波谱学技术对化合物进行结构鉴定。采用MTT法和尿酸形成量测定法分别评价化合物的细胞毒活性和黄嘌呤氧化酶抑制活性。结果：从IFB—E012发酵液中分离获得5个化合物,分别鉴定为7,8-二甲基异咯嗪（lumichrome,1）、胡萝卜苷（daucosterol,2）、对羟基苯甲酸（p-hydroxybenzoicacid,3）、尿嘧啶（uracil,4）和烟酸（nicotinic acid,5）。lumichrome对人鼻咽癌KB细胞和黄嘌呤氧化酶有抑制活性,其IC50分别为（14．46±0．13）μmol．L^-1和（60．32±0．48）μmol．L^-1。结论：Lumichrome具有较强的细胞毒活性和黄嘌呤氧化酶抑制活性,有待进一步深入研究。     

Inhibition of Human Topoisomerases I and II by Simocyclinone D8

Simocyclinone D8 is an antibiotic isolated from Streptomyces antibioticus Tü 6040 that inhibits the supercoiling activity of DNA gyrase. It also exhibits an inhibitory effect on human topoisomerase II and an antiproliferative activity against some cancer cell lines. Our biochemical studies have revealed that simocyclinone D8 can inhibit the catalytic activity of human topoisomerase I. Thus, simocyclinone D8 is a dual catalytic inhibitor of human topoisomerases I and II.     

Cytotoxic and DNA interaction activities of extracts from medicinal plants used in Argentina

Eight crude extracts from seven Argentine plants with cancer-related ethnobotanical uses have been subjected to a bioscreening study to detect cytotoxic activity. The plants studied were: Aristolochia triangularis, Baccharis grisebachii, Bolax gummifera, Eupatorium hecatanthum, Erythrina crista-galli, Pterocaulon polystachium and Salpichroa origanifolia. Crown gall tumour inhibition, DNA interaction and cytotoxicity towards KB cells were assayed using the potato disc, the DNA-methyl green (DNA-MG) and the KB cells cytotoxicity bioassays respectively. The results obtained indicate that A. triangularis (ED50=47 microg/ml), B. gummifera (ED50=32 microg/ml) and E. hecatanthum (ED50=35 microg/ml) contained cytotoxic compounds against KB cells. All of the plants studied inhibited the growth of crown gall tumours, showing correlation between the experimental data and the uses reported for these plants. Moreover, the results obtained for the extracts of E. hecatanthum and P. polystachium indicate the presence of compounds that interact with DNA (48 and 22% of absorbance decrease, respectively). The results obtained suggest that cytotoxicity could play an important role in the activities claimed for the plants under study.     

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??OBJECTIVE To investigate the effect of 1-cyclopropyl-6-fluoro-7-(piperazin-1-yl)-3-[5-benzylsulfanyl-4-(3,4,5-trimethoxybenzylidene) amino-4H-1,2,4-triazol-3-yl]-quinolin-4(1H)-one (M27) on apoposis in hepatocarcinoma SMMC-7721 cells in vitro. METHODS SMMC-7721 cells, colon adenocarcinoma cells(HCT-116)and leukemia cell line JURKET were treated by M27 with different concentrations for different time in vitro, the inhibitory effect of M27 and its precursor ciprofloxacin on the cell proliferation were examined by MTT assay. Cell apoptosis was determined by Hoechst 33258 fluorescence staining and TUNEL assay. The effect of M27 on topoisomerase ?? activity was measured using agarose gel electrophoresis by Plasmid pBR322 DNA as the substrate. Mitochondrial membrane potential(????m)was measured by high content screening imaging system. The p53,Caspase-9,Caspase-3,Caspase-8,Bcl-2,Bax and cytochrome C protein expressions were determined by Western blotting analysis. RESULTS The proliferation of the cancer cells was inhibited by M27 at 10-60 ??mol??L^-1 in time-and dose-dependent manner. Ciprofloxacin showed weak cytotoxicity against SMMC-7721 cell. SMMC-7721 cells treated by M27 with different concentrations for 24 h increased the percentage of apoptosis cells obviously (P<0.05) with a decrease in the mitochondrial membrane potential. Compared with control group, M27 influenced obviously DNA topoisomerase ?? activity, stimulated DNA cleavage and inhibited DNA reunion mediated by topoisomerase ??. In addition, M27 increased protein expression of p53, Bax, Caspase-8, Caspase-9, Caspase-3, as well as the cleaved activated forms of Caspase-9, Caspase-8 and Caspase-3 significantly, whereas the expression of Bcl-2 decreased. There was a significant increase of cytochrome C in the cytosol after 24 h of treatment with M27 and a decrease in the mitochondrial compartment. CONCLUSION M27 as a fluoroquinolone derivative exerted potent anticancer activity through the mechanism of eukaryotic topoisomerase ?? poisoning. The growth inhibition is mainly mediated via apoptosis-associated mitochondrial dysfunction and regulation of Bcl-2 signaling pathways.     

9-硝基喜树碱衍生物的合成及体外抗肿瘤活性

 目的寻找高效低毒的9-硝基喜树碱类抗肿瘤新化合物。方法设计合成了7个9-硝基喜树碱季氨盐类衍生物,经1H-NMR,IR,MS分析确证化合物的结构,利用MTT法考察了这些化合物的体外抑制肿瘤细胞活性,并通过分子生物学方法评价了这些化合物的拓扑异构酶Ⅰ抑制活性。结果7个化合物的体外细胞毒活性都低于喜树碱和topotecan,其中化合物7,9,11的细胞毒活性与氟尿嘧啶相似。化合物7,9,10,12显示了较好的拓扑异构酶Ⅰ抑制活性。结论该类水溶的9-硝基喜树碱衍生物的抗肿瘤活性值得进一步研究。     

New cytotoxic furanosesterterpenes from an Okinawan marine sponge,Ircinia sp

Five new sesterterpenes have been isolated from a lipophilic extract of a sponge, Ircinia sp., and their structures elucidated by spectroscopic and chemical methods. The absolute configurations of two metabolites (1, 3) were established by chemical degradation. These compounds showed moderate cytotoxicity against KB cells.