P388 Leukemia Cells Research Articles

Apigenin, an Anticancer Active Compound Isolated from Macaranga gigantifolia Leaves

Apigenin, a flavonoid compound has been isolated from the ethyl acetate fraction of methanol extract of Macaranga gigantifolia leaves. Isolation and purification of apigenin conducted using chromatographic method, and chemical structure characterized based on spectroscopic data. In vitro anticancer activity test against murine leukemia P-388 cell line showed potential activity with IC 50 14.13 μg/mL. Key words: apigenin, flavones, Macaranga gigantifolia , anticancer, murine leukemia P-388 cell line.

Synthesis, structure and cytotoxic activity of acetylenic derivatives of betulonic and betulinic acids

A series of acetylenic derivatives of betulonic and betulinic acids has been synthesized and characterized by 1H and 13C NMR, IR and MS spectroscopy. The structure of propargyl betulonate 4 and propargyl betulinate-DMF solvate 8A was solved by X-ray diffraction. Thermal properties were examined using a DSC technique. The resulting alkynyl derivatives, as well as betulin 1 and betulinic acid 3, were evaluated in vitro for their cytotoxic activity against human T47D breast cancer, CCRF/CEM leukemia, SW707 colorectal, murine P388 leukemia and BALB3T3 normal fibroblasts cell lines. Several of the obtained compounds have a favorable cytotoxic profile than betulin 1. Propargyl betulinate 8 was the most active derivative, being up to 3-fold more potent than betulin 1 against the human leukemia (CCRF/CEM) cell line, with an IC50 value of 3.9 μg/mL.

New Indole Alkaloids from the Sponge Plakortis sp.

An unprecedented bis-indole 1, a novel indole alkaloid 2, and some known indole-related compounds 3–5 have been isolated from the sponge Plakortis sp. collected from Zampa in Okinawa. Their structures were elucidated by spectroscopic analysis. These metabolites showed cytotoxic activity against P388 leukemia and B16 melanoma cells.

Medicarpin and millepurpan, two flavonoids isolated from Medicago sativa, induce apoptosis and overcome multidrug resistance in leukemia P388 cells

BackgroundHigh consumption of flavonoids has been associated with a decrease risk of cancer. Alfalfa (Medicago sativa) leaves have been widely used in traditional medicine and is currently used as a dietary supplement because of their high nutrient content. We previously reported the cytotoxic activity of alfalfa leaf extracts against several sensitive and multidrug resistant tumor cell lines. Hypothesis/purposeWe aimed to determine whether medicarpin and millepurpan, two isoflavonoids isolated from alfalfa leaves, may have pro-apoptotic effects against drug-sensitive (P388) and multidrug resistant P388 leukemia cells (P388/DOX). Study design/methodsCells were incubated with medicarpin or millepurpan for the appropriate time. Cell viability was assessed by the MTT assay. DNA fragmentation was analyzed by agarose gel electrophoresis. Cell cycle analysis was realized by flow cytometry technics. Caspases 3 and 9 activities were measured using Promega caspACE assay kits. Proteins and genes expression were visualized respectively by western-blot using specific antibodies and RT-PCR assay. ResultsP-glycoprotein-expressing P388/DOX cells did not show resistance to medicarpin (IC50 ≈ 90 µM for P388 and P388/DOX cells) and millepurpan (IC50 = 54 µM and 69 µM for P388 and P388/DOX cells, respectively). Treatment with medicarpin or millepurpan triggered apoptosis in sensitive as well as multidrug resistant P388 cells. These effects were mediated through the mitochondrial pathway by modifying the balance pro/anti-apoptotic proteins. While 3 µM doxorubicin alone could not induce cell death in P388/DOX cells, concomitant treatment with doxorubicin and subtoxic concentration of medicarpin or millepurpan restored the pro-apoptotic cascade. Each compound increased sensitivity of P388/DOX cells to doxorubicin whereas they had no effect in sensitive P388 cells. Vinblastine cytotoxicity was also enhanced in P388/DOX cells (IC50 = 210 nM to 23 and 25 nM with medicarpin and millepurpan, respectively). This improved sensitivity was mediated by an increased uptake of doxorubicin in P388/DOX cells expressing P-gp. P-gp expression was not altered by exposure to medicarpin and millepurpan. ConclusionThese data indicate that medicarpin and millepurpan possess pro-apoptotic properties and potentiate the cytotoxicity of chemotherapy drugs in multidrug resistant P388 leukemia cells by modulating P-gp-mediated efflux of drugs. These flavonoids may be used as chemopreventive agents or as sensitizer to enhance cytotoxicity of chemotherapy drugs in multidrug resistant cancer cells.

Identification and Bioactivity Studies of Flavonoid Compounds from Macaranga hispida (Blume) Mull.Arg

Two flavonoid compounds, 5,7,3’,4’-tetrahydroxy-6-geranylflavonol (1) and kaempferol 7-O-β-glucose (2) have been isolated from the leaves of Macaranga hispida (Blume) , Mull.Arg. Isolation and purification were conducted by chromatography methods and chemical structure characterization was carried out by spectroscopic methods. The 5,7,3’,4’-tetrahydrxyi-6-geranyl flavonol (1) and kaempferol 7-O-glucose (2) had moderate cytotoxic activity against murine leukemia P-388 cell lines with IC 50 value of 0.22 and 101.5 μg/mL, respectively. The IC 50 for antioxidant activities of (1) and (2) were 2.83 and 13.95 μg/mL, respectively. The LC 50 of (1) and (2) from BSLT were 350 and >1000 μg/mL, respectively.

Abstract 5529: The advanced strategy for novel EGCG derivative modified liposome with high targeting ability to tumor

Abstract Purpose: The aim of this study is increase of antitumor effect and decrease of adverse effect by liposomes which have high affinity with 67 kDa laminin receptor (67LR). It was reported that 67LR is expression specifically on tumor cell membrane. When (-)-epigallocatechin-3-gallate (EGCG) as one of the green tea polyphenol are connected with 67LR, apoptosis is induced on tumor cells. On the other hand, liposome is often used for cancer chemotherapy. Then we have studied about EGCG modified liposome containing antitumor agent as drug delivery system. In this study, important strategies are 3 points. The first point is targets to 67LR on tumor cell by EGCG modification around liposomal membrane. The second point is to induce apoptosis mediated by 67LR. Last point is to increase antitumor effect by antitumor agent loaded into liposome. Based on these strategies, EGCG modified liposome was evaluated in vivo distribution. Methods: Three derivatives were synthesized for EGCG modification on liposomal membrane. The liposome with each EGCG derivative were prepared and assessed by measuring particle sizes and zeta potentials. EGCG was only modified liposome (EL) and both EGCG and polyethyleneglycol (PEG) were modified liposome (EPL). On P388 leukemia cells, cytotoxicity was evaluated by WST-8 assay and shown IC50. In the distribution study, C57BL/6 mice were injected (i.v.) each liposome, and collected blood and removed organs with definite time after injection. Results and Discussion: Synthesized EGCG derivatives with di-palmitoyl base were inserted directly into liposomal membrane. Two structures of other derivatives obtained PEG or is able to connect with PEG. In all liposomes, the particle sizes were from 100 to 200 nm and zeta potentials were negative charge. The cytotoxicity of EL was stronger than EGCG unmodified liposome. Moreover, 50% inhibitory concentration of EPL was smaller than EL, namely the cytotoxicity of EPL was strong. It was suggested that this effect was mediated with 67LR needed gallate base in the structure of EGCG because EPL showed strong effect compared with EL. The EGCG derivative in EL had di-palmitoyl base at gallate base, and its bind was not free. In mice experiment, EL rapidly disappeared from the blood circulation after injection. This concentration was one sixteenth of common PEG modified liposome at 15 min after injection. On the other hand, accumulation levels into liver and spleen as reticuloendothelial system (RES) reached high level immediately after injection. This phenomenon indicated that disappearance of EL depends on RES trap. EPL which had EGCG-PEG was significantly improved blood circulating time. In conclusion, it was expected that EGCG-PEG modified liposome (EPL) maintains long circulation time in blood, and increases targeted ability to tumor cells and antitumor activity. Citation Format: Ikumi Sugiyama, Kunihiro Kaihatsu, Nobuo Kato, Yasuyuki Sadzuka. The advanced strategy for novel EGCG derivative modified liposome with high targeting ability to tumor. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 5529. doi:10.1158/1538-7445.AM2015-5529

PEMISAHAN SENYAWA-SENYAWA YANG BERSIFAT SITOTOKSIK TERHADAP SEL MURIN LEUKEMIA P388 DARI EKSTRAK METANOL KULIT BATANG DIPTEROCARPUS CONFERTUS SLOOT (DIPTEROCARPACEAE)

Six compounds, KP-1 up to KP-6 were isolated from the methanol extract of the tree bark of Dipterocarpus confertus Sloot (Dipterocarpaceae). The cytotoxic activities of these compounds were evaluated against murine leukemia P388 cells. Result of these examination indicated that KP-2 compound and KP-1 were very active with each IC 50 value of these compounds were 2.25 and 5.1 μg/mL, respectively. While the others were not active against murine leukemia P388 cells.Keywords: Dipterocarpaceae, Dipterocarpus confertus Sloot, isolated compounds, cytotoxic, and leukemia P-388 cell

Synthesis Methyl Nitrophenyl Acrylate and Cytotoxic Activity Test against P388 Leukemia Cells

Synthesis of methyl nitrophenyl acrylate via modification of methyl trans-cinnamate had been done to improve its biological activity. The reaction of methyl trans-cinnamate with nitrating agent gave methyl 3-(2-nitrophenyl)acrylate and methyl 3-(4-nitrophenyl)acrylate with an ortho/para ratio of 1:8. Its structure was confirmed with 1H-NMR, 13C-NMR, FTIR, GC-MS. Biological activity of methyl 3-(4-nitrophenyl)acrylate and methyl 3-(2-nitrophenyl)acrylate assays was performed on Cancer cells against P388 Murine Leukemia with IC50= 7.98 μg/mL, IC50 = 27.78 μg/mL.

Piceatanol: Anti-Cancer Compound From Gewang Seed Extract

Evaluation of antioxidant, antibacterial, antifungal and cytotoxic effects of Clausena suffruticosa ethanolic root extractMd. Atiar Rahman, Joti Sankhar Chakma, Saiful Islam, Nazim Uddin Ahmed

A New Flavonoid Derivative as Cytotoxic Compound Isolated from Ethyl Acetate Extract of Macaranga gigantifolia Merr. Leaves

A new prenylated flavonoid compound 5,7,3’,4’-tetrahydroxy-3,6-diprenylflavone (1) has been isolated from methanol extract of the leaves of Macaranga gigantifolia Merr. Isolation was performed using chromatography methods and their structures were elucidated based on spectroscopic data. cytotoxic activity against murine leukemia P-388 cell line conducted using MTT method. Compound 1 showed strong cytotoxic activity with IC50 value 6.19μg/mL

Quercetin enhances the anti-leukemic effect of adriamycin

This study was purposed to explore the anti-leukemic mechanism of quercetin (Que) in vivo and it enhancing chemotherapeutic effect of adriamycin (ADR) by establishing the quercetin-treated P388 transplanted nude mouse model. The P388 leukemic cells in logarithmic growth phase were taken and injected subcutaneously into BALB/c nude mice so as to establish the leukemia-transplanted nude mouse model. The model mice were treated by quercetin, ADR and their combination, and the survival changes of model mice were observed, the hemogram and peripheral blood cell count examination were performed regularly; the cell cycle was detected and the influence of quercetin on cell proliferation was analyzed by flow cytometry; the caspase-3 protein expression level was detected by ELISA; the mRNA and protein changes of NF-κB, BCL-2, BAX were measured by real-time quantitative flourascence PCR and Western blot respectively. The results indicated that the quercetin and adriamycin could significantly prolong the survival of P388 leukemia nude mice, and their combination displayed significantly prolonged effect. Quercetin and adriamycin alone or in their combination could reduce the ratio of G0/G1 phase in mice, the cell ratio in S phase and G2/M phase increased, and the effects of the combination group were more significant than that of the single agent groups. Quercetin could activate caspase-3 and promote leukemic cell apoptosis. Meanwhile, quercetin could down-regulate the expression of BCL-2 and NF-κB gene, and up-regulate the expression of BAX gene. It is concluded that through modulating the expression of apoptosis-related genes, the quercetin can inhibit leukemia cell proliferation, promote apoptosis, and enhance the chemotherapeutic effects of adriamycin. These results provide some valuable data for further research and development of quercetin as a new and effective anti-leukemic drug.

Oxidation and Acetylation of Ursolic and Oleanolic Acids Isolated from <i>Fragraea fragrans</i> fruits; Antiproliferation of P388 Leukemia Cells

An interesting natural product chemistry aspect of Fragraea fragrans is that their fruits are richness with ursolic acid and its isomer oleanolic acid (3.05% of dried powder). As our continuous work on these inseparable structural isomeric triterpenes, this paper reports that 51.0% of inseparable 3-oxo-ursolic[3-oxo-oleanolic] acids and 48.6% of inseparable 3-acethyl-ursolic [3-acethyl-oleanolic] acids have already been made from those triterpenes as starting materials of the oxidized and acetylated compounds and evaluated their activity against P388 leukemia cells. The activity of 3-oxo-ursolic [3-oxo-oleanolic] acids with IC50 = 18.6 µg/mL exhibited three-fold more potent against P388 leukemia cell proliferations compared to ursolic [oleanolic] acids with IC50 = 53.5 µg/mL; while the 3-acethyl-ursolic [3-acethyl-oleanolic] acids with IC50 = 37.9 µg/mL showed two-fold more potent then their parent triterpenes (IC50 = 53.5 µg/mL) in the inhibition of P388 leukemia cell growth.

Abstract 5408: Liposomal doxorubicin with modified EGCG increased antitumor activity by topical targeting efficiency into tumor

Abstract Purpose: The aim of this study is increase of antitumor activity using novel liposome with (-)-epigallocatechin-3-gallate (EGCG) as one of the green tea components. Liposome has been known as a one of useful drug carriers for delivering drug into targeting site. Moreover, some ligand is able to modify around liposomal membrane by a simple method. On the other hand, it was reported that surface of high grade tumor cell expresses 67kDa laminin receptor (67LR) which intermediates of cytostatic effect of EGCG, and EGCG is able to induce apoptosis selectively. Our strategy was to prepare liposomal doxorubicin with EGCG as carrier ligand for getting antitumor activity by both apoptosis and doxorubicin at tumor site. In this study, we tried to prepare EGCG-modified liposome and evaluated the antitumor activity in vitro. Methods: The liposomal doxorubicin was prepared by L-α-distearoylphosphatidylcholine, cholesterol, L-α-distearoylphosphatidyl-DL-glycerol and doxorubicin (100:100:60:18 μmol). Doxorubicin included EGCG-modified liposome (EL-DOX) was prepared to add EGCG-dipalmitate. Amount of EGCG modification on liposomal membrane was determined using DPPH assay. On P388 leukemia cells and M5076 ovarian sarcoma cells, cytotoxicity was evaluated by WST-8 assay and shown IC50. DOX uptake into tumor cells was evaluated in vitro. The concentration of doxorubicin into tumor cells was determined with a fluorescence spectrophotometer at an excitation wavelength of 500 nm and an emission wavelength of 550 nm. Results and Discussion: Particle sizes of EL-DOX were 147 nm on average, zeta potential was -33.1 mV and encapsulated ratio of doxorubicin was 96.5 %. These data of sizes and zeta potentials were better for intravenous administration of liposomes. EGCG ratio on liposomal membrane (71.0 %) was enough to show its ability. In the study of doxorubicin uptake into tumor cells, EL-DOX group was increased amount of doxorubicin for 30 min. The doxorubicin level of EL-DOX was significantly higher compared with that of unmodified liposomal doxorubicin (p<0.05). At cytotoxicity, EL-DOX was stronger than unmodified liposomal doxorubicin. It was provided that IC50 of EL-DOX was also 125 times higher than EGCG solution which was reported to have been antitumor activity. Furthermore, co-incubation of EGCG solution and liposomal doxorubicin was not shown the enhancement effect both doxorubicin uptake into cells and the cytotoxicity. It was suggested that superior effect were shown in modification of EGCG around liposomal membrane, not mixture of EGCG and liposome. In conclusion, EL-DOX exhibited strong antitumor activity efficiently. Citation Format: Ikumi Sugiyama, Kunihiro Kaihatsu, Nobuo Kato, Yasuyuki Sadzuka. Liposomal doxorubicin with modified EGCG increased antitumor activity by topical targeting efficiency into tumor. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5408. doi:10.1158/1538-7445.AM2014-5408

Isolation and structural elucidation of cytotoxic compounds from the root bark of Diospyros quercina (Baill.) endemic to Madagascar

To isolate and characterize the cytotoxic compounds from Diospyros quercina (Baill.) G.E. Schatz & Lowry (Ebenaceae). An ethno-botanical survey was conducted in the south of Madagascar from July to August 2010. Bio-guided fractionation assay was carried out on the root bark of Diospyros quercina, using cytotoxicity bioassay on murine P388 leukemia cell lines as model. The structures of the cytotoxic compounds were elucidated by 1D and 2D NMR spectroscopy and mass spectrometry. Biological experiments resulted in the isolation of three bioactive pure compounds (named TR-21, TR-22, and TR-23) which exhibited very good in vitro cytotoxic activities with the IC50 values of (0.017 5±0.0060) µg/mL, (0.089±0.005) µg/mL and (1.027±0.070) µg/mL respectively. Thus, they support the claims of traditional healers and suggest the possible correlation between the chemical composition of this plant and its wide use in Malagasy folk medicine to treat cancer. The ability of isolated compounds in this study to inhibit cell growth may represent a rational explanation for the use of Diospyros quercina root bark in treating cancer by Malagasy traditional healers. Further studies are, therefore, necessary to evaluate the in vivo anti-neoplastic activity of these cytotoxic compounds as effective anticancer drugs.

Disruption of a methyltransferase gene in actinomycin G gene cluster inStreptomyces iakyrusincreases the production of phenazinomycin

Phenazinomycin is a hybrid natural product consisting of two chemical entities, a phenazine and a cyclic terpenoid. Phenazinomycin exhibits potent activity against murine tumors and adriamycin-resistant P388 leukemia cells. Streptomyces iakyrus DSM 41873 is known to produce five actinomycin G2 -G6 . In the previous study, we identified the gene cluster directing the biosynthesis of actinomycin G2 -G4 . Inactivation of acmG5' gene in the actinomycin G gene cluster in S.iakyrus completely abolished the production of actinomycin G. Metabolic profiling, chemical isolation, and structural elucidation of the resulting mutant SIAΔacmG5' showed a previously unnoticed metabolite phenazinomycin in S.iakyrus. In silico analysis identified a hybrid biosynthetic gene cluster in the genome of S.iakyrus that could be responsible for the biosynthesis of phenazinomycin. It is proposed that the perturbation of actinomycin G to enhance the phenazinomycin production in the mutant may result from the lifted competition of chorismate, the common precursor of the biosynthetic pathways of these two structurally unrelated natural products.

Synthesis of Methyl 2-Cinnamamido-3-Hydroxy Propanoate Having Activity against P388 Leukemia Cells

Cinnamic acid derivative compound was investigated for the anti-cancer inhibitory activity. To be able to obtain compounds that have bioactivity as above, it is needed to study quantitative structure-activity relationship (QSAR) which is the process by which the chemical structure is quantitatively correlated with biological activity/chemical reactivity. Chemical methods used in synthesizing the chemical of methyl trans-cinnamate derivatives are tailored to match their targeted bioactivities. Here, we investigated the anti-cancer inhibitor compound with the method amidation of cinnamic acid derivative compounds. In this reaction we use two steps to get the target product. Firstly, we hydrolize of methyl trans-cinnamate to cinnamic acid. That reaction has a yield 85.5 % and secondly, we amidate of cinnamic acid to metil 2-cinnamamido-3-hydroxy propanoate has a yield of 51.5%. The compound of metil 2-cinnamamido-3-hydroxy propanoate showed against P388 leukemia cells inhibitory activity with IC50 = 10.78 µg/mL.

Resveratrol oligomers from the tree bark ofShorea accuminatissima: Their properties and significance

This study was aimed to isolate and structure elucidate the resveratrol oligomers from the acetone extract of the tree bark of S. accuminatissima. Five resveratrol oligomers, namely vaticanol-A, davidiol-A, α-viniferin, hopeaphenol and hemsleyanol-D have been isolated for the first time from this plant. The structures of these compounds were established based on the spectroscopic data evidence, including UV, IR, 1H NMR, and 13C NMR spectra, and compared to their reported data. Hopeaphenol showed cytotoxicity and strongly inhibited murine leukemia P-388 cells.

FLAVANONES FROM THE WOOD OF <i>Morus nigra</i> WITH CYTOTOXIC ACTIVITY

Two flavanone derivatives, norartocarpanone (1) and euchrenone a7 (2) had been isolated for the first time from the methanol extract of the wood of Morus nigra. The structures of these compounds were determined base on spectral evidence, including UV, IR, and NMR. The first compound also confirmed by comparison with the reported data. Cytotoxic properties of these compounds were evaluated against murine leukemia P-388 cells. Euchrenone a7 (2) was found more cytotoxic than norartocarpanone (1) with their IC50 7.8 and 12.7 mg/mL respectively.

Sialyl-glycoconjugates in cholesterol-rich microdomains of P388 cells are the triggers for apoptosis induced by Rana catesbeiana oocyte ribonuclease

SBL/RC-RNase was originally isolated from frog (Rana catesbeiana) oocytes and purified as a novel sialic acid-binding lectin (SBL) that displayed strong anti-cancer activity. SBL was later shown to be identical to a ribonuclease (RC-RNase) from oocytes of the same species. The administration of SBL/RC-RNase induced apoptosis (with nuclear condensation and DNA fragmentation) in mouse leukemia P388 cells but did not kill umbilical vein endothelial or fibroblast cells derived from normal tissues. The cytotoxic activity of SBL/RC-RNase was inhibited by desialylation of P388 cells and/or the co-presence of free bovine submaxillary mucin. FACS analysis showed that SBL/RC-RNase was incorporated into cells after attachment to cholesterol-rich microdomains. Addition of the cholesterol remover methyl-β-cyclodextrin reduced SBL/RC-RNase-induced apoptosis. Apoptosis occurred through the caspase-3 pathway following activation of caspase-8 by SBL/RC-RNase. A heat shock cognate protein (Hsc70) and a heat shock protein (Hsp70) (each 70 kDa) on the cell membrane were shown to bind to SBL/RC-RNase by mass spectrometric and flow cytometric analyses. Quercetin, an inhibitor of Hsc70 and Hsp70, significantly reduced SBL/RC-RNase-induced apoptosis. Taken together, our findings suggest that sialyl-glycoconjugates present in cholesterol-rich microdomains form complexes with Hsc70 or Hsp70 that act as triggers for SBL/RC-RNase to induce apoptosis through a pathway involving the activation of caspase-3 and caspase-8.

Antiplasmodial, cytotoxic activities and characterization of a new naturally occurring quinone methide pentacyclic triterpenoid derivative isolated from Salacia leptoclada Tul. (Celastraceae) originated from Madagascar

ObjectiveTo validate scientifically the traditional use of Salacia leptoclada Tul. (Celastraceae) (S. leptoclada) and to isolate and elucidate the structure of the biologically active compound. MethodsBioassay-guided fractionation of the acetonic extract of the stem barks of S. leptoclada was carried out by a combination of chromatography technique and biological experiments in viro using Plasmodium falciparum and P388 leukemia cell lines as models. The structure of the biologically active pure compound was elucidated by 1D and 2D NMR spectroscopy and mass spectrometry. ResultsBiological screening of S. leptoclada extracts resulted in the isolation of a pentacyclic triterpenic quinone methide. The pure compound exhibited both in vitro a cytotoxic effect on murine P388 leukemia cells with IC50 value of (0.041±0.020) μg/mL and an antiplasmodial activity against the chloroquine-resistant strain FC29 of Plasmodium falciparum with an IC50 value of (0.052±0.030) μg/mL. Despite this interesting anti-malarial property of the lead compound, the therapeutic index was weak (0.788). In the best of our knowledge, the quinone methide pentacyclic triterpenoid derivative compound is reported for the first time in S. leptoclada. ConclusionsThe results suggest that furthers studies involving antineoplastic activity is needed for the development of this lead compound as anticancer drug.