Bromophenols from the red alga Rhodomela confervoides

Six new bromophenols, 3-bromo-4,5-bis(2,3-dibromo-4,5-dihydroxybenzyl)pyrocatechol (1), 2,2',3-tribromo-3',4,4',5-tetrahydroxy-6'-hydroxymethyldiphenylmethane (2), 2,2',3-tribromo-3',4,4',5-tetrahydroxy-6'-ethyloxymethyldiphenylmethane (3), (+/-)-2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)propylaldehyde (4), (+/-)-2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)propylaldehyde dimethyl acetal (5), and 3-bromo-4,5-dihydroxybenzoic acid methyl ester (6), together with eight known bromophenols, 3-bromo-4,5-dihydroxybenzaldehyde (7), 2,3-dibromo-4,5-dihydroxybenzyl alcohol (lanosol, 8), 2,3-dibromo-4,5-dihydroxybenzyl methyl ether (9), 2,3-dibromo-4,5-dihydroxybenzyl ethyl ether (10), 2,3-dibromo-4,5-dihydroxybenzylaldehyde (11), bis(2,3-dibromo-4,5-dihydroxybenzyl) ether (12), 3-bromo-4-(2,3-dibromo-4,5-dihydroxybenzyl)-5-methoxymethylpyrocatechol (13), and 2,2',3,3'-tetrabromo-4,4',5,5'-tetrahydroxydiphenyl methane (14), were isolated from the red alga Rhodomela confervoides. Their structures were elucidated by chemical and spectroscopic methods including IR, HRFABMS, and 1D and 2D NMR techniques.     

Bromophenols coupled with derivatives of amino acids and nucleosides from the red alga Rhodomela confervoides

Three new bromophenols coupled with pyroglutamic acid derivatives and one bromophenol coupled with deoxyguanosine were obtained from the red alga Rhodomela confervoides. By spectroscopic methods including 2D NMR and single-crystal X-ray structure analysis their structures were elucidated as N-(2,3-dibromo-4,5-dihydroxybenzyl)methyl pyroglutamate (1), N-(2,3-dibromo-4,5-dihydroxybenzyl)pyroglutamic acid (2), N-[3-bromo-2-(2,3-dibromo-4,5-dihydroxybenzyl)-4,5-dihydroxybenzyl]methyl pyroglutamate (3), and 2-N-(2,3-dibromo-4,5-dihydroxybenzylamino)deoxyguanosine (4), respectively. Compounds 1-4 were evaluated against several microorganisms and human cancer cell lines, but found inactive. To our knowledge this is the first report of bromophenols coupled with amino acid or nucleoside derivatives through the C-N bond.     

Dibenzyl bromophenols with diverse dimerization patterns from the brown alga Leathesia nana

Six novel dibenzyl bromophenols (1-6) with different dimerization patterns and two propyl bromophenol derivatives (7 and 8), together with 11 known bromophenol derivatives, were isolated from the ethanolic extract of the brown alga Leathesia nana. On the basis of spectroscopic methods the structures of the new compounds were determined as 5,6'-diethyloxymethyl-3,4,2'-tribromo-2,3',4'-trihydroxydiphenyl ether (1), 2-(2,3-dibromo-4,5-dihydroxybenzyl)-3,5-dihydroxy-4-methoxybenzyl alcohol (2), 6-(2,3-dibromo-4,5-dihydroxybenzyl)-2,3-dibromo-4,5-dihydroxy benzyl methyl ether (3), 9,10-dihydro-9,10-dimethoxy-3,4,7,8-tetrabromo-1,2,5,6-tetrahydroxyanthracene (4), (+)-3-(2,3-dibromo-4,5-dihydroxyphenyl)-4-bromo-5,6-dihydroxy-1,3-dihydroisobenzofuran (5), rel-(4aS,10aR)-(+/-)-6,7-dibromo-4a-hydroxy-3,8-dihydroxymethyl-10a-methoxy-1,4,4a,10a-tetrahydrodibenzo[b,e][1,4]dioxin-1-one (6), (E)-2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)propenal (7), and 2-methyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)-1-propanol (8). Some compounds including 3 showed in vitro selective cytotoxicity against several human cancer cell lines. This is the first brown alga to be reported containing bromophenols.     

Bromophenols coupled with nucleoside bases and brominated tetrahydroisoquinolines from the red alga Rhodomela confervoides

Three new bromophenols C-N coupled with nucleoside base derivatives (1-3) and three new brominated 1,2,3,4-tetrahydroisoquinolines (5-7), together with a new brominated tyrosine derivative (4), have been isolated from polar fractions of an ethanolic extract of the red alga Rhodomela confervoides. By spectroscopic and chemical methods including HRMS and 2D NMR data, their structures were determined as 7-[3-bromo-2-(2,3-dibromo-4,5-dihydroxybenzyl)-4,5-dihydroxybenzyl]-3,7-dihydro-1H-purine-2,6-dione (1), 7-(2,3-dibromo-4,5-dihydroxybenzyl)-3,7-dihydro-1H-purine-2,6-dione (2), 9-[3-bromo-2-(2,3-dibromo-4,5-dihydroxybenzyl)-4,5-dihydroxybenzyl]adenine (3), (-)-8S-(3-bromo-5-hydroxy-4-methoxy)phenylalanine (4), (-)-3S-8-bromo-6-hydroxy-7-methoxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid (5), methyl (-)-3S-8-bromo-6-hydroxy-7-methoxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (6), and methyl (-)-3S-6-bromo-8-hydroxy-7-methoxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylate (7). Compounds 5-7 were semisynthesized by using 4 as the starting material.     

Bromophenol derivatives from the red alga Rhodomela confervoides

Eight new bromophenol derivatives, 2,3-dibromo-4,5-dihydroxybenzyl methyl sulfoxide (1), 4-(2,3-dibromo-4,5-dihydroxyphenyl)-3-butene-2-one (2), 2-(3-bromo-5-hydroxy-4-methoxyphenyl)-3-(2,3-dibromo-4,5-dihydroxyphenyl)propionic acid (3), 2-(3-bromo-5-hydroxy-4-methoxyphenyl)-3-(2,3-dibromo-4,5-dihydroxyphenyl)propionic acid methyl ester (4), 2-phenyl-3-(2,3-dibromo-4,5-dihydroxyphenyl)propionic acid (5), 4'-methoxy-2',3',3'-tribromo-4',5',5'-trihydroxydiphenylacetic acid (6), and 3-bromo-5-hydroxy-4-methoxyphenylacetic acid (7) and its methyl ester (8), together with a known bromophenol, 3-bromo-5-hydroxy-4-methoxybenzoic acid (9), were isolated from the red alga Rhodomela confervoides. Their structures were elucidated by spectroscopic methods including IR, EIMS, FABMS, ESIMS, HRFABMS, HRESIMS, 1D and 2D NMR, and single-crystal X-ray structure analysis. Compounds 1-4, 8, and 9 were found inactive against several human cancer cell lines and microorganisms.     

褐藻小粘膜藻中的溴酚化合物

目的 :对褐藻小粘膜藻进行化学成分研究。方法 :利用正相硅胶柱色谱 ,SephadexLH 2 0柱色谱、反相HPLC及重结晶等分离手段和IR ,MS及NMR等结构鉴定方法。结果 :从小粘膜藻中分离鉴定了 6个溴酚类化合物 ,分别为 2 ,2′ ,3,3′ 四溴 4 ,4′,5 ,5′ 四羟基二苯甲烷 (1) ,2 ,2′,3 三溴 3′ ,4 ,4′ ,5 四羟基 6′ 乙氧甲基二苯甲烷 (2 ) ,2 ,3 二溴 4 ,5 二羟基苯甲醇 (3) ,2 ,3 二溴 4 ,5 二羟基苯甲基甲醚 (4) ,3 溴 4 羟基苯甲酸 (5 )及 2 溴 4 ,5 二羟基苯甲醛 (6 )。结论 :这些化合物均为首次从该属海藻中发现。     

Highly brominated mono- and bis-phenols from the marine red alga Symphyocladia latiuscula with radical-scavenging activity

Four new highly brominated and fully substituted mono- and bis-phenols, 1-(2,3,6-tribromo-4,5-dihydroxybenzyl)pyrrolidin-2-one (1), 1,2-bis(2,3,6-tribromo-4,5-dihydroxyphenyl)ethane (2), 6-(2,3,6-tribromo-4,5-dihydroxybenzyl)-2,5-dibromo-3,4-dihydroxybenzyl methyl ether (3), and 2,3,6-tribromo-4,5-dihydroxybenzyl methyl sulfone (4), were characterized from the marine red alga Symphyocladia latiuscula. In addition, five known bromophenols, bis(2,3,6-tribromo-4,5-dihydroxyphenyl)methane (5), bis(2,3,6-tribromo-4,5-dihydroxybenzyl) ether (6), 2,3,6-tribromo-4,5-dihydroxybenzyl methyl ether (7), 2,3,6-tribromo-4,5-dihydroxymethylbenzene (8), and 2,3,6-tribromo-4,5-dihydroxybenzaldehyde (9), were also isolated and identified. The structures of these compounds were elucidated by spectroscopic methods including 1D and 2D NMR as well as by low- and high-resolution mass spectrometric analysis. Structurally, all of these compounds are highly brominated and fully substituted, and contain one or two 2,3,6-tribromo-4,5-dihydroxyphenyl unit(s) in each of the molecules. In addition, compound 4 possesses a unique sulfone structural feature. Each of the isolated compounds was evaluated for alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical-scavenging activity and all were found to be potent, with IC50 values ranging from 8.1 to 24.7 microM, compared to the known positive control butylated hydroxytoluene (BHT), with an IC50 of 81.8 microM.     

Bromophenols from the marine red alga Polysiphonia urceolata with DPPH radical scavenging activity

Three new (1-3) and three known (4-6) bromophenols were isolated and identified from the marine red alga Polysiphonia urceolata. On the basis of extensive analysis of spectroscopic data, the structures of these compounds were determined to be 7-bromo-9,10-dihydrophenanthrene-2,3,5,6-tetraol (1), 4,7-dibromo-9,10-dihydrophenanthrene-2,3,5,6-tetraol (2), 1,8-dibromo-5,7-dihydrodibenzo[ c,e]oxepine-2,3,9,10-tetraol (3), urceolatol (4), 3-bromo-4,5-dihydroxybenzaldehyde (5), and 3,5-dibromo-4-hydroxybenzaldehyde (6). Each of the isolated compounds was evaluated for alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radical scavenging activity, and all were found to be potent, with IC50 values ranging from 6.1 to 35.8 microM, compared to the positive control, butylated hydroxytoluene (BHT), with an IC50 of 83.8 microM.     

Sulfur-containing polybromoindoles from the Formosan red alga Laurencia brongniartii

Five new sulfur-containing polybromoindoles, 2-methylsulfinyl-3-methylthio-4,5,6-tribromoindole (1), 3-methylsulfinyl-2,4,6-tribromoindole (2), 4,6-dibromo-2,3-di(methylsulfinyl)indole (3), 3,3'-bis(2'-methylsulfinyl-2-methylthio-4,6,4',6'-tetrabromo)indole (4), and 3,3-bis(4,6-dibromo-2-methylsulfinyl)indole (5), as well as seven known sulfur-containing polybromoindoles, 3-methylthio-2,4,6-tribromoindole (6), 3-methylthio-2,4,5,6-tetrabromoindole (7), 4,6-dibromo-2,3-di(methylthio)indole (8), 2,3-di(methylthio)-4,5,6-tribromoindole (9), 4,6-dibromo-2-methylsulfinyl-3-(methylthio)indole (10), 4,6-dibromo-2-(methylthio)indole (11), and 3,3-bis(4,6-dibromo-2-methylthio)indole (12), have been isolated from the Formosan red alga Laurencia brongniartii. The structures were elucidated by extensive spectral analysis, and their cytotoxicity against selected cancer cells was measured in vitro.     

In-vitro cytotoxic activities of the major bromophenols of the red alga Polysiphonia lanosa and some novel synthetic isomers

Bioassay-guided fractionation was applied to the cytotoxic chloroform fraction of the red alga Polysiphonia lanosa. The major compounds of the most active fraction were identified using GLC-MS analysis as lanosol (1), methyl, ethyl, and n-propyl ethers of lanosol (1a, 1b, and 1c, respectively), and aldehyde of lanosol (2), although 1b appears to be an artifact arising during the fractionation procedure. These compounds and other known bromophenols were synthesized in addition to four novel isomers (3, 3a-c). The cytotoxic activities of all the synthetic compounds were determined against DLD-1 cells using the MTT assay. Compounds with IC(50) < 20 micromol were also tested against HCT-116 cells. Compound 3c (2,5-dibromo-3,4-dihydroxybenzyl n-propyl ether) was the most active compound against both cell lines (IC(50) = 1.72 and 0.80 micromol, respectively), and its effect on the cell cycle was studied using flow cytometry.     

Cytotoxic 4-phenylcoumarins from the leaves of Marila pluricostata

Bioassay-guided fractionation of the CH(2)Cl(2) extract of the leaves of Marila pluricostata led to the isolation of 17 naturally occurring 4-phenylcoumarins, three of them, 5-hydroxy-8,8-dimethyl-4-phenyl-9,10-dihydro-8H-pyrano-[2,3-f]chromen-2-one (1), 5-hydroxy-8,8-dimethyl-4-phenyl-6-propionyl-9,10-dihydro-8H-pyrano-[2,3-f]chromen-2-one (2), and 5,7-dihydroxy-8-(3-methylbut-2-enyl)-4-phenylchromen-2-one (3), are new natural compounds; the remaining (4-17) are known mammea-type coumarins. Their structures were established by spectroscopic means. All compounds were tested in cytotoxicity assays against the MCF-7, H-460, and SF-268 human cancer cell lines.     

New bromotyrosine derivatives from an association of two sponges, Jaspis wondoensis and Poecillastra wondoensis

Three new bromotyrosine derivatives (4-6) were isolated from an association of two sponges, Jaspis wondoensis and Poecillastra wondoensis, along with the previously described (E,E)-psammaplin A (1), (E,Z)-psammaplin A (2), psammaplin D (3), bisaprasin (7), and (3-bromo-4-hydroxyphenyl)acetonitrile (8). The structures of the new compounds were established on the basis of NMR and MS spectroscopic analysis. The compounds 1, 3, and 5-7 displayed significant cytotoxicity against human lung (A549), ovarian (SK-OV-3), skin (SK-MEL-2), CNS (XF498), and colon (HCT15) cancer cell lines. Compounds 3-7 were further evaluated for antibacterial activity against methicillin- or ofloxacin-resistant Staphylococcus strains. Compound 4 exhibited more potent antibacterial activity than meropenem against several strains.     

Antiproliferative effects of compounds derived from plants of Northeast Brazil

Ten compounds derived from plants indigenous to Northeast Brazil were examined for antiproliferative effects on human cells in vitro. The effects of these phytochemicals on cell growth were determined by the MTT microtitre assay with 3-day continuous drug exposure. Three human cell lines were used: CEM leukaemia, SW1573 lung tumour and CCD922 normal skin fibroblasts. Four active compounds were found with IC(50) values less than 10 microg/mL in the two cancer cell lines. Oncocalyxones A and C, both 1,4-anthracenediones from Auxemma oncocalyx (Boraginaceae), showed cytotoxicity with mean IC(50) values of 0.8-2, 7-8 and 12-13 microg/mL against CEM, SW1573 and CCD922, respectively. One diterpene and one flavonoid, both from Egletes viscosa (Compositae), were also active. 12-Acetoxy-hawtriwaic acid lactone was cytotoxic with mean IC(50) values of 6, 10 and 10 microg/mL, respectively. 4,5-Dihydroxy-3,3,7, 8-tetramethoxy flavone (ternatin) was only growth-inhibitory with mean IC(50) values of 2, 1 and 10 microg/mL, respectively. These four most active compounds were examined further for their effects on DNA integrity and on DNA synthesis. All but ternatin caused substantial DNA damage and marked inhibition of 5-bromo-2'-deoxyuridine incorporation within 24 h. This study demonstrated the antiproliferative activity of four novel phytochemicals, three of which are DNA-reactive and inhibit DNA synthesis. Further studies are warranted to evaluate these compounds for antitumour potential.     

Bioactive cembrane diterpenoids of Anisomeles indica

Five new cembrane-type diterpenoids with a trans-fused alpha-methylene-gamma-lactone (1-5), a new flavonoid glucoside (6), and 17 known compounds were isolated from a methanol extract of Anisomeles indica. The structures of 1-6 were elucidated by spectroscopic analysis, and the absolute configuration of compound 1 was determined using the modified Mosher's method. Compound 8 (4,5-epoxovatodiolide) exhibited cytotoxicity against a small panel of human cancer cell lines. Additionally, compounds 4 and 7 (ovatodiolide) exhibited selective antiplatelet aggregation activities toward collagen, while compounds 4, 5, and 8 showed inhibitory effects on antiplatelet aggregation induced by thrombin.     

Sesquiterpenes from the red alga Laurencia tristicha

Seven new sesquiterpenes (1-7), together with seven known sesquiterpenes, aplysin (8), aplysinol (9), gossonorol (10), 7,10-epoxy-ar-bisabol-11-ol (11), 10-epi-7,10-epoxy-ar-bisabol-11-ol (12), johnstonol (13), and laurebiphenyl (14), have been isolated from the red alga Laurencia tristicha. The structures of new compounds were established as laur-11-en-2,10-diol (1), laur-11-en-10-ol (2), laur-11-en-1,10-diol (3), 4-bromo-1,10-epoxylaur-11-ene (4), cyclolauren-2-ol (5), laurentristich-4-ol (6), and ar-bisabol-9-en-7,11-diol (7) by means of spectroscopic methods including IR, HRMS, and 1D and 2D NMR techniques. Compound 6 possessed a novel rearranged skeleton. All compounds were tested against several human cancer cell lines including lung adenocarcinoma (A549), stomach cancer (BGC-823), hepatoma (Bel 7402), colon cancer (HCT-8), and HELA cell lines. Laurebiphenyl (14) showed moderate cytotoxicity against all tested cell lines, with IC(50) values of 1.68, 1.22, 1.91, 1.77, and 1.61 microg/mL, respectively. Other compounds were inactive (IC(50) > 10 microg/mL).     

Structural modification of berberine alkaloids in relation to cytotoxic activity in vitro

The cytotoxicity of two protoberberine alkaloids: berberine and lincangenine, their 8-hydroxy-7,8-dihydro-derivatives and tetrahydroprotoberberine:thaicanine, was evaluated. The cellular responses through the [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide] (MTT) method were measured in Hela (uterus carcinoma), SVKO3 (ovary carcinoma), Hep-2 (larynx carcinoma), primary culture from mouse embryon, and human fibroblast cells at the concentration: 10-1000 ppm (microg/ml) for 24 h. Berberine showed the highest cytotoxicity among the compounds tested, giving LC50 values for all cell lines at the concentration of 10 ppm. The results indicated that the cytotoxicity was notably decreased by structural changes, i.e. by modulation of the planarity caused by the introduction of hydroxyl group at C-8 and concomitant saturation of double bond between N-C8 in protoberberine molecules. In the case of berberine, the cytotoxic effect changed from 98.8 (berberine) to 39% for 8-hydroxydihydroberberine at the concentration of 100 ppm in Hela cells line. The same effect was observed with lincangenine and 8-OH-lincangenine (cytotoxicities 70 and 25%, respectively, at 1000 ppm in SVKO3 cells). On the other hand, these compounds showed a low selectivity for the different human cancer cell lines tested.     

Investigation of brominated tryptophan alkaloids from two thorectidae sponges: Thorectandra and Smenospongia

Chemical investigation of an NCI-DTP collection of Thorectandra sp. and a UCSC collection of Smenospongia sp. yielded six new brominated tryptophan derivatives: 6-bromo-1'-hydroxy-1',8-dihydroaplysinopsin (4), 6-bromo-1'-methoxy-1',8-dihydroaplysinopsin (5), 6-bromo-1'-ethoxy-1',8-dihydroaplysinopsin (6), (-)-5-bromo-N,N-dimethyltryptophan (7), (+)-5-bromohypaphorine (8), and 6-bromo-1H-indole-3-carboxylic acid methyl ester (11). Additionally, the known compounds aplysinopsin (1), 1',8-dihydroaplysinopsin (2), 6-bromo-1',8-dihydroaplysinopsin (3), (1H-indole-3-yl)acetic acid (9), and (6-bromo-1H-indol-3-yl)acetic acid methyl ester (10) were also encountered. The structures of 4-8 and 11 were confirmed on the basis of analysis of (1)H and (13)C (1D and 2D) NMR data as well as comparison to known compounds. Compounds 1, 3-8, 10, and 11 were found to inhibit the growth of Staphylococcus epidermidis with either weak or moderate MICs.     

Brominated labdane-type diterpenoids from an Okinawan Laurencia sp

From an unidentified species of Laurencia collected from Okinawan waters two novel brominated metabolites, 1 and 2, along with known halogenated compounds, 2,10-dibromo-3-chloro-alpha-chamigrene (3) and microcladallene A (4), were isolated and identified. The structures of these new compounds were established as ent-labdane-type bromoditerpenes, (1S,3R,5S,6S,8S,9S,10R,13R)-1-acetoxy-3-bromo-6-hydroxy-8,13-epoxy-labd-14-ene (1) and (3R,5S,6S,8S,9S,10R,13R)-3-bromo-6-hydroxy-8,13-epoxylabd-14-en-1-one (2), by interpretation of their spectroscopic data as well as by X-ray crystallographic analysis.     

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??OBJECTIVE To study the chemical constituents from the fruits of Forsythia suspensa (Thunb.) Vahl.. METHODS Compounds were isolated by a combination of various chromatographic techniques including column chromatography over macroporous resin, Sephadex LH-20 and reversed-phase HPLC. Their structures were elucidated by physiochemical properties and spectral analysis. RESULTS Sixteen compounds were isolated and identified as 3,4,??-trihydroxy-methyl phenylpropionate (1), protocatechaldehyde (2), vanillic acid (3), p-hydroxybenzoic acid (4), p-hydroxylbenzylalcohol (5), p-hydroxyphenylethyl alcohol (6), 2-(4-methoxyphenyl) acetaldehyde (7), 2-(4-hydroxyphenyl)acetic acid (8), 4-hydroxyphenethyl 2-(4-hydroxyphenyl)acetate (9), p-coumatic acid (10), methyl 2-(4-hydroxyphenyl)acetate (11), 3,4-dihydroxyphenylethanol (12), 1,2,4-benzentriol (13), 1-(4-hydroxyphenyl)-2,3-dihydroxypropan-1-one(14), 4-hydroxybenzaldehyde (15), and isovanillic acid (16). CONCLUSION Compounds 1-3, 5, 7, 9, 11, and 14 are isolated from this plant for the first time.     

Deoxyartemisinin derivatives from photooxygenation of anhydrodeoxydihydroartemisinin and their cytotoxic evaluation

Photooxygenation of anhydrodeoxydihydroartemisinin (4) followed by chromatographic separation of the reaction mixture yielded the new compounds alpha- (5) and beta-hydroperoxydeoxyartemisitene (8) and the formate ester 7, together with two previously reported compounds, 6 and 9. Reduction of 5 using polymer-bound triphenylphosphine afforded the new compound dihydrodeoxyartemisitene (10). Treatment of 10 with a catalytic amount of BF(3)-OEt(2) yielded the C(2)-symmetrical dimer bis(dihydrodeoxyartemisitene) ether (11) and two new compounds, dihydrodeoxyartemisitene methyl ether (12) and the dimer 13, as minor products. Dehydroacetoxylation of 5 using acetic anhydride in pyridine afforded deoxyartemisitene (14). The identities of the new compounds (5, 7, 8, 10-14) were deduced from their spectral data and by chemical derivatization. The stereochemistry of dimer 11 was defined on the basis of X-ray crystallographic analysis. All compounds were evaluated in vitro in the National Cancer Institute drug-screening program consisting of 60 human cancer cell lines derived from nine different tissues. Of the compounds tested, deoxyartemisitene (14) demonstrated significant cytotoxicity against a number of human cancer cell lines.