L1210 Murine Leukemia Research Articles

Ceratinadin G, a new psammaplysin derivative possessing a cyano group from a sponge of the genus Pseudoceratina.

A new psammaplysin derivative, ceratinadin G (1), was obtained from the Okinawan marine sponge Pseudoceratina sp., and the gross structure was clarified through spectroscopic and spectrometric analyses. The absolute configuration of compound 1 was established by comparing its NMR and ECD data with those of the known psammaplysin derivative, psammaplysin F (2). Ceratinadin G (1) is a rare nitrile containing a cyano group as aminoacetonitrile, and is the first psammaplysin derivative possessing a cyano group. In vitro assays indicated that compound 1 displayed moderate cytotoxicity against L1210 murine leukemia cells and KB epidermoid carcinoma cells.

Ultraviolet Light-Emitting Diode Radiation Kills Leukemia Cells Without Affecting Hematopoiesis of Hematopoietic Stem Cells in Mice.

The eradication of leukemia cells while sparing hematopoietic stem cells in the graft before autologous hematopoietic stem cell transplant is critical to prevention of leukemia relapse. Proliferating cells have been shown to be more prone to apoptosis than differentiated cells in response to ultraviolet radiation; however, whether leukemia cells are more sensitive to ultraviolet LED radiation than hematopoietic stem cells remains unclear. We compared the in vitro responses between murine leukemia L1210 cells and murine hematopoietic stem cells to 280-nm ultraviolet LED radiation. We also investigated the effects of ultraviolet LED radiation on the tumorigenic and metastatic capacity of L1210 cells and hematopoietic stem cell hematopoiesis in a mouse model of hematopoietic stem cell transplant. L1210 cells were more sensitive to ultraviolet LED radiation than hematopoietic stem cells in vitro, as evidenced by significantly reduced colony formation rates and cell proliferation rates, along with remarkably increased apoptosis rates in L1210 cells. Compared with corresponding unirradiated cells, ultraviolet LED-irradiated L1210 cells failed to generate palpable tumors in mice, whereas ultraviolet LED-irradiated bone marrow cells restored hematopoiesis in vivo. Furthermore, transplant with an irradiated mixture of L1210 cells and bone marrow cells showed later onset of leukemia, milder leukemic infiltration, and prolonged survival in mice, compared with unirradiated cell transplant. Our results suggest that ultraviolet LED radiation can suppress the proliferative and tumorigenic abilities of leukemia cells without reducing the hematopoietic reconstitution capacity of hematopoietic stem cells, serving as a promising approach to kill leukemia cells in autograft before autologous hematopoietic stem cell transplant.

Ma'edamines E and F, rare bromotyrosine alkaloids possessing a 1,2,3,5-tetrasubstituted pyridinium moiety from an Okinawan marine sponge Suberea sp.

Two new bromotyrosine alkaloids, ma'edamines E (1) and F (2), were isolated from an Okinawan marine sponge Suberea sp., and their structures were elucidated by the analyses of spectroscopic (UV, IR, and NMR) and spectrometric (MS) data. Ma'edamines E (1) and F (2) are the second and third examples of natural products possessing an N-alkyl-3,5-diethyl-2-propylpyridinium moiety. Ma'edamine F (2) is the first bromotyrosine alkaloid having both pyridinium and quaternary ammonium moieties. Ma'edamines E (1) and F (2) showed moderate cytotoxicity against L1210 murine leukemia cells in vitro.

Application of Multivariate Adaptive Regression Splines (MARSplines) for Predicting Antitumor Activity of Anthrapyrazole Derivatives.

An approach using multivariate adaptive regression splines (MARSplines) was applied for quantitative structure–activity relationship studies of the antitumor activity of anthrapyrazoles. At the first stage, the structures of anthrapyrazole derivatives were subjected to geometrical optimization by the AM1 method using the Polak–Ribiere algorithm. In the next step, a data set of 73 compounds was coded over 2500 calculated molecular descriptors. It was shown that fourteen independent variables appearing in the statistically significant MARS model (i.e., descriptors belonging to 3D-MoRSE, 2D autocorrelations, GETAWAY, burden eigenvalues and RDF descriptors), significantly affect the antitumor activity of anthrapyrazole compounds. The study confirmed the benefit of using a modern machine learning algorithm, since the high predictive power of the obtained model had proven to be useful for the prediction of antitumor activity against murine leukemia L1210. It could certainly be considered as a tool for predicting activity against other cancer cell lines.

Development of a Novel Anti-Mouse CCR2 Monoclonal Antibody (C2Mab-6) by N-Terminal Peptide Immunization.

The CC chemokine receptor type-2 (CCR2) belongs to the G-protein-coupled receptor superfamily, expressed on the cell surface of immune cells and tumors. CCR2 binds to the CC motif chemokine 2/monocyte chemoattractant protein-1, a CC chemokine, which is produced by various cells, including immune-related cells and tumors. Therefore, the development of sensitive monoclonal antibodies (mAbs) for CCR2 has been desired for treatment and diagnosis. This study established a novel, specific, and sensitive anti-mouse CCR2 (mCCR2) mAb; C2Mab-6 (rat IgG1, kappa), using the mCCR2 synthetic peptide immunization method. C2Mab-6 reacted with mCCR2-overexpressed Chinese hamster ovary-K1 cells and L1210 (murine leukemia) cells, which express endogenous mCCR2 in flow cytometry. Furthermore, C2Mab-6 showed a high binding affinity for both cells. Hence, C2Mab-6 can be a useful tool for analyzing mCCR2-related biological responses, using flow cytometry.

Isolation and Structure Elucidation of New Cytotoxic Macrolides Halosmysins B and C from the Fungus Halosphaeriaceae sp. Associated with a Marine Alga.

Two new cytotoxic metabolites, halosmysins B and C, have been isolated from the fungus Halosphaeriaceae sp. OUPS-135D-4 separated from the marine alga Sargassum thunbergii. These chemical structures have been elucidated by 1D and 2D NMR, and HRFABMS spectral analyses. The new compounds had the same 14-membered macrodiolide skeleton as halosmysin A, which was isolated from this fungal strain previously. As the unique structural feature, a diketopiperazine derivative and a sugar are conjugated to the 14-membered ring of halosmysins B and C, respectively. The absolute stereostructures of them were elucidated by the chemical derivatization such as a hydrolysis, the comparison with the known compounds (6R,11R,12R,14R)-colletodiol and halosmysin A, and a HPLC analysis of sugar. In addition, their cytotoxicities were assessed using murine P388 leukemia, human HL-60 leukemia, and murine L1210 leukemia cell lines. Halosmysin B was shown to be potent against all of them, with IC50 values ranging from 8.2 ± 1.8 to 20.5 ± 3.6 μM, though these values were slightly higher than those of halosmysin A.

Synthesis, molecular docking, and preliminary cytotoxicity study of some novel 2-(naphthalen-1-yl)-methylimidazo[2,1-b][1,3,4]thiadiazoles

A series of 2-(naphthalen-1-yl)-methyl-6-arylimidazo[2,1-b][1,3,4]thiadiazole derivatives was prepared and studied for cytotoxicity against murine leukemia L1210, human cervix carcinoma HeLa, and human T-lymphocyte CEM cell lines. The preliminary study showed that compounds 5g, 6g, 7a-c, 7e, and 8e were more potent among the tested compounds. The pharmacokinetic properties of all compounds were then investigated with FAF-Drugs, a tool for prediction of ADME and toxicity. Finally, in order to support in vitro studies, molecular docking studies were performed by using AutoDock Vina with a Lamarckian genetic algorithm to determine whether or not the synthesized compounds could be used as inhibitors for the protein structure 1m17 (EGFR). The docking scores of many compounds were found to be higher than [6,7-bis(2-methoxy-ethoxy)quinazoline-4-yl]-(3-ethynyl phenyl)amine, an inhibitor of the 1m17 EGFR receptor. Among the selected compounds 7b, 7c, 7e, 7f, 7g, and 8g showed better stability in the molecular dynamics simulation study.

Halosmysin A, a Novel 14-Membered Macrodiolide Isolated from the Marine-Algae-Derived Fungus Halosphaeriaceae sp.

Halosmysin A, a new 14-membered macrodiolide with an unprecedented skeleton, was isolated from the fungus Halosphaeriaceae sp. OUPS-135D-4, which, in turn, was obtained from the marine algae Sargassum thunbergii. The chemical structure of the macrodiolide was elucidated using 1D and 2D NMR, as well as high resolution fast atom bombardment mass (HRFABMS) spectral analysis. The absolute stereochemistry was determined via chemical derivatization and comparison with a known compound, (6R,11R,12R,14R)-colletodiol. Additionally, halosmysin A was shown to be very potent against murine P388 leukemia, human HL-60 leukemia, and murine L1210 leukemia cell lines, with IC50 values ranging from 2.2 ± 3.1 to 11.7 ± 2.8 μM.

Overexpression of GRP78/BiP in P-Glycoprotein-Positive L1210 Cells is Responsible for Altered Response of Cells to Tunicamycin as a Stressor of the Endoplasmic Reticulum.

P-glycoprotein (P-gp, ABCB1 member of the ABC (ATP-binding cassette) transporter family) localized in leukemia cell plasma membranes is known to reduce cell sensitivity to a large but well-defined group of chemicals known as P-gp substrates. However, we found previously that P-gp-positive sublines of L1210 murine leukemia cells (R and T) but not parental P-gp-negative parental cells (S) are resistant to the endoplasmic reticulum (ER) stressor tunicamycin (an N-glycosylation inhibitor). Here, we elucidated the mechanism of tunicamycin resistance in P-gp-positive cells. We found that tunicamycin at a sublethal concentration of 0.1 µM induced retention of the cells in the G1 phase of the cell cycle only in the P-gp negative variant of L1210 cells. P-gp-positive L1210 cell variants had higher expression of the ER stress chaperone GRP78/BiP compared to that of P-gp-negative cells, in which tunicamycin induced larger upregulation of CHOP (C/EBP homologous protein). Transfection of the sensitive P-gp-negative cells with plasmids containing GRP78/BiP antagonized tunicamycin-induced CHOP expression and reduced tunicamycin-induced arrest of cells in the G1 phase of the cell cycle. Taken together, these data suggest that the resistance of P-gp-positive cells to tunicamycin is due to increased levels of GRP78/BiP, which is overexpressed in both resistant variants of L1210 cells.

Activity Trends in Desoxy Anthrapyrazoles: The Influence of Molar Volume, Polarizability and Lipophilicity of N<sub>2</sub> C<sub>5</sub> Side Chains on Their Anticancer Response

QSAR methodology was used to assess the effects of lipophilicity (logP), molar volume (MV) and polarizability (pl) of the side chains at N2 and C5 of 20 known desoxy anthrapyrazoles on their in vitro anticancer activity expressed as the negative logarithm of the inhibitory concentration of 50% of L1210 murine leukemia cell line (1/logIC50). The main data set shows poor correlations between biological response and the descriptors with exception of MV of the C5 side chain, where a moderate correlation was discerned ( =0.60, n = 18, two outliers). To extract more information regarding mechanism, the main data set was visually classified to three clusters depending on N2 side chain. Cluster 1 containing six 5-substituted 2-[(2-hydroxyethyl) amino] ethyl anthrapyrazoles; cluster 2 contains ten 5-subsitutes 2-(diethyl amino) ethyl anthrapyrazoles and cluster 3 contains four anthrapyrazoles with miscellaneous substituents at both N2 and C5. For cluster 1, MV and pl of C5 show high correlation with biological response (R2’s = 0.75 and 0.72 respectively) while logP gives a weak correlation (R2 = 0.44). For cluster 2, the correlations of logP and pl of C2side chain are higher (=0.66 and 0.62 respectively) compared with MV (=0.16). Cluster 3 shows very poor correlation with all descriptors (~0.3). This indicates mechanistic distinction between the three clusters. Derived descriptors which represent the difference between the descriptors of N2 and C5 side chains where used to explore the presence of interplay between these descriptors in affecting variability of the biological response.

Altercrasins A⁻E, Decalin Derivatives, from a Sea-Urchin-Derived Alternaria sp.: Isolation and Structural Analysis Including Stereochemistry.

In order to find out the seeds of antitumor agents, we focused on potential bioactive materials from marine-derived microorganisms. Marine products include a number of compounds with unique structures, some of which may exhibit unusual bioactivities. As a part of this study, we studied metabolites of a strain of Alternaria sp. OUPS-117D-1 originally derived from the sea urchin Anthocidaris crassispina, and isolated five new decalin derivatives, altercrasins A–E (1–5). The absolute stereostructure of altercrasins A (1) had been decided by chemical transformation and the modified Mosher’s method. In this study, four decalin derivatives, altercrasins B–E (2–5) were purified by silica gel chromatography, and reversed phase high-performance liquid chromatography (RP HPLC), and their structures were elucidated on the basis of 1D and 2D nuclear magnetic resonance (NMR) spectroscopic analyses. The absolute configuration of them were deduced by the comparison with 1 in the NMR chemical shifts, NOESY correlations, and electronic circular dichroism (ECD) spectral analyses. As a result, we found out that compound pairs of 1/2 and 4/5 were respective stereoisomers. In addition, their cytotoxic activities using murine P388 leukemia, human HL-60 leukemia, and murine L1210 leukemia cell lines showed that 4 and 5 exhibit potent cytotoxicity, in especially, the activity of 4 was equal to that of 5-fluorouracil.

Evaluation of antioxidant and antiproliferative activities of 1,2-bis (p-amino-phenoxy) ethane derivative Schiff bases and metal complexes.

In this study, the effects of the two Schiff base derivatives and their metal complexes were tested for MDA concentration, which is an indicator of lipid peroxidation, antioxidant vitamin A, vitamin E, and vitamin C levels in cell culture. A comparison was performed among the groups and it was observed that MDA, vitamin A, vitamin E, and vitamin C concentrations were statistically changed. According to the results, all compounds caused a significant oxidative stress without Zn complexes. Moreover, Mn(II), Cu(II), Zn(II), and Ni(II) complexes of Schiff bases derived from a condensation of 1,2-bis (p-aminophenoxy) ethane with naphthaldehydes and 4-methoxy benzaldehyde were examined in terms of antitumor activity against MCF-7 human breast cancer and L1210 murine leukemia cells. Furthermore, the derivatives were tested for antioxidative and prooxidative effects on MCF-7 breast cancer cells. The compounds which were tested revealed that there was an antitumor activity for MCF-7 and L 1210 cancer cells. Also, some of the compounds induced oxidative harmful.

Ishigadine A, a new canthin-6-one alkaloid from an Okinawan marine sponge Hyrtios sp.

A new indole alkaloid with the canthin-6-one skeleton, ishigadine A, has been isolated from an Okinawan marine sponge Hyrtios sp. The structure of ishigadine A was elucidated on the basis of spectroscopic analyses. Ishigadine A is a new canthin-6-one alkaloid possessing a hydroxy group, a 1,3-dimethyl-4-methylthioimidazolium, and a 1-propylguanidine. Ishigadine A is the third canthin-6-one alkaloid from sponges. Ishigadine A might be generated from l-arginine, l-histidine, and l-tryptophan. Ishigadine A exhibited moderate cytotoxicity against L1210 murine leukemia cells.

PO-458 The role of functional groups in the antitumor properties of antrafuran

IntroductionRecently we have discovered a promising anticancer agent Anthrafuran (LCTA-2034, (S)−3-(3-aminopyrrolidine-1-carbonyl)−4,11-dihydroxy-2-methylanthra [2,3-b]furan-5,10-dione methanesulfonate) which targeted topoisomerases (Top) 1, 2 and protein kinases Aur B, Aur C, Pim-1 and Pim-3 important for tumour cell biology. LCTA-2034 demonstrated an outstanding antitumor efficacy in vivo that makes this class attractive for anticancer drug development [Treshalina E.M. et al. Eur. J. Pharm. Sci., 2017] To evaluate the role of the key functional groups and investigate structure-activity relationships within this class, we next have synthesised a series of new analogues of LCTA-2034 using anthra[2,3-b]furan scaffold.Material and methodsTo prepare new derivatives of anthra[2,3-b]furan several synthetic schemes were developed and used for pointed modifications of LCTA-2034. Comparison of antiproliferative activity (IC50) of LCTA-2034 and its new analogues was performed on a murine leukaemia L1210 cell line. Cells were incubated for 48 hour at 37°C in a humidified CO2-controlled atmosphere, counted in a Coulter counter, and IC50 values were calculated.Results and discussionsReplacement of the methyl group at the position 2 of LCTA-2034 by hydrogen led to a slight decrease of antiproliferative potency of new analogues. The congeners bearing different diamines in the carboxamide moiety potently inhibited tumour cell growth at low micromolar to submicromolar concentrations. Introduction of the trifluoromethyl group at the position 2 decreased the potency of the corresponded analogue. Substitution of hydroxy groups in the core structure for amino, methoxy groups or chlorine atoms also significantly reduced cytotoxicity compared to the parent LCTA-2034. Transformation of the carboxamide group in LCTA-2034 into the aminomethyl spacer linked to 3-aminopyrrolidine residue also dramatically increased IC50 value. These data were in agreement with results of molecular modelling of binding of LCTA-2034 and its analogues with intracellular targets Aur B and DNA duplex.ConclusionOur results strongly suggest that the carboxamide group, as well as 4,11-hydroxy groups, are critical for the cytotoxic efficacy of LCTA-2034 and shown perspective direction for further drug development studies in this class of anticancer compounds. The study was partially supported by RFBR (17-53-45105) and DST (INT/RUS/RFBR/P-291).

Luminescent SiO2 nanoparticles for cell labelling: Combined water dispersion polymerization and 3D condensation controlled by oligoperoxide surfactant-initiator

Hybrid polymer coated silica nanoparticles (NPs) were synthesized using low temperature graft (co)polymerization of trimethoxysilane propyl methacrylate (MPTS) initiated by surface-active oligoperoxide metal complex (OMC) in aqueous media. These NPs were characterized by means of kinetic, solid-state NMR, TEM and FTIR techniques. Two processes, namely the radical graft-copolymerization due to presence of double bonds and 3D polycondensation provided by the intra- or/and intermolecular interaction of organosilicic fragments, occurred simultaneously. The relative contribution of the reactions depending on initiator concentration and pH value leading to the formation of low cured polydisperse microparticles or OMC coated SiO2 NPs of controlled curing degree was studied. The availability of free-radical forming peroxide fragments on the surface of SiO2 NPs provides an opportunity for seeded polymerization leading to the formation of the functional polymer coated NPs with controlled particle structure, size, and functionality. Encapsulation of the luminescent dye (Rhodamine 6G) in SiO2 core of functionalized NPs provided a noticeable increase in their resistance to photo-bleaching and improved biocompatibility. These luminescent NPs were not only attached to murine leukemia L1210 cells but also tolerated by the mammalian cells. Their potential use for labeling of the mammalian cells is considered.

Rice protein prolamin promotes anti-leukemia immunity and inhibits leukemia growth in vivo

Prolamin is a heat-stable storage protein of rice (Oryza sativa). This study aimed to examine the effect of prolamin on anti-tumor immune response in vitro and leukemia growth in vivo. The prolamin-enriched rice fractions were prepared to stimulate peripheral blood mononuclear cells (MNC) from mice spleen. The MNC-conditioned medium (MNC-CM) was collected to treat leukemia L1210 cells. Human MNC-CM was prepared to treat Jurkat acute T cell leukemia cells. Purified prolamin was orally administered to syngeneic L1210-bearing DBA/2 mice to assess weights of tumor, liver and spleen, liver histopathology, peripheral blood neutrophil count and cytokine levels. Prolamin-prepared MNC-CM inhibited the viability of murine leukemia L1210 cells and human leukemia Jurkat cells, indicating an immunomodulatory effect. In syngeneic L1210-bearing DBA/2 mice, oral administration of purified prolamin dose-dependently decreased the tumor weight and attenuated the leukemia-induced reduction of liver and spleen weights. Prolamin inhibited the increase of peripheral blood leukocyte count. The levels of tumor necrosis factor-α and interferon-γ in MNC-CM and mice serum were significantly increased by prolamin treatment. No significant change in body weight, serum alanine aminotransferase and creatinine levels was noted by prolamin treatment. Rice prolamin could effectively promote anti-tumor immunity and inhibit leukemia growth without significant toxicity.

PH-dependent general base catalyzed activation rather than isocyanate liberation may explain the superior anticancer efficacy of laromustine compared to related 1,2-bis(methylsulfonyl)-1-(2-chloroethyl)hydrazine prodrugs.

Laromustine (also known as cloretazine, onrigin, VNP40101M, 101M) is a prodrug of 90CE, a short-lived chloroethylating agent with anticancer activity. The short half-life of 90CE necessitates the use of latentiated prodrug forms for in vivo treatments. Alkylaminocarbonyl-based prodrugs such as laromustine exhibit significantly superior in vivo activity in several murine tumor models compared to analogs utilizing acyl, and alkoxycarbonyl latentiating groups. The alkylaminocarbonyl prodrugs possess two exclusive characteristics: (i) They are primarily unmasked by spontaneous base catalyzed elimination; and (ii) they liberate a reactive carbamoylating species. Previous speculations as to the therapeutic superiority of laromustine have focused upon the inhibition of enzymes by carbamoylation. We have investigated the therapeutic interactions of analogs with segregated chloroethylating and carbamoylating activities (singly and in combination) in the in vivo murine L1210 leukemia model. The combined treatment with chloroethylating and carbamoylating prodrugs failed to result in any synergism and produced a reduction in the therapeutic efficacy compared to the chloroethylating prodrug alone. Evidence supporting an alternative explanation for the superior tumor selectivity of laromustine is presented that is centered upon the high pH sensitivity of its base catalyzed activation, and the more alkaline intracellular pH values commonly found within tumor cells.

6-Benzylidene-2-[4-(pyridin-3-ylcarboxy)benzylidene]cyclohexanones: A novel cluster of tumour-selective cytotoxins

Novel cytotoxins 3–5 containing the 1,5-diaryl-3-oxo-1,4-pentadienyl pharmacophore are disclosed. The compounds in series 3 and 5 have the potential to liberate niacin which may reduce some of the side effects of antineoplastic compounds. 3a-c emerged as the most potent cytotoxic compounds with IC50 values in the low micromolar range against human Molt4/C8 and CEM CD4+ T-lymphocytes as well as murine L1210 leukemia cells. QSAR studies revealed that cytotoxic potencies were negatively correlated with the magnitude of the Hammett sigma values of the aryl substituents. The compounds 3a-e displayed tumour-selective toxicity against human HL-60, HSC-2, HSC-3 and HSC-4 neoplasms as compared to human HGF, HPC and HPLF nonmalignant cells. A representative potent compound 3a caused PARP1 cleavage and G0/G1 cell cycle arrest in HSC-2 cells. These compounds are well tolerated in mice at doses up to and including 300mg/kg of the compounds and no mortalities were noted after 4h. The stability studies undertaken did not reveal that a representative compound 3a underwent hydrolysis to the related phenol 2a. Some guidelines for further analog development of the novel esters 3 were made.

Involvement of mitochondrial dynamics in the antineoplastic activity of cisplatin in murine leukemia L1210 cells.

Leukemia is a type of hematopoietic stem cell malignant cloned disease with high mortality. Cisplatin-based chemotherapy is one of the most common treatments for leukemia. Similar to other chemotherapeutic agents, cisplatin resistance has become a serious issue in cancer therapy. In the present study, we investigated the role of mitochondrial dynamics in the antineoplastic activity of cisplatin in murine leukemia L1210 cells. Firstly, the L1210 cell line resistant to cisplatin (L1210/DDP) was established. Compared to its parental cell line, the IC50 value of cisplatin in the L1210/DDP cells was increased 10-fold. Mitofusins (Mfn1 and Mfn2), mitochondrial outer membrane fusion proteins, were markedly upregulated in the L1210/DDP cells, whereas the expression of fission protein Drp1 and inner membrane fusion protein OPA1 were not significantly altered. In addition, mitofusins were also upregulated in the parental L1210 cells subjected to cisplatin stress. To investigate the role of mitochondrial dynamics in the antineoplastic activity of cisplatin, the effect of mitochondrial division inhibitor (Mdivi)-1 on cisplatin‑induced cell death, caspase-3 cleavage and ROS production was examined in L1210 cells. We found that 5µM of Mdivi-1 efficiently attenuated cisplatin-induced cell death, caspase activation and intracellular ROS increase in L1210 cells. Our data indicated that mitochondrial dynamics play an important role in the antineoplastic activity of cisplatin, and mitofusin-mediated mitochondrial fusion may be involved in the process of cisplatin resistance in leukemia cells. Therefore, the present study revealed that mitochondrial dynamics may be a potential target used to improve the antineoplastic activity of cisplatin in leukemia in the future.

Niacin esters of chalcones with tumor-selective properties

Novel series of niacin esters of chalcones 2, 4 and 6 were designed as antineoplastic agents that have the potential to release the chemoprotectant niacin. These enones are cytotoxic to human CD4+ T-lymphocyte Molt 4/C8 and CEM and murine leukemia L1210 cells. Quantitative structure–activity relationship (QSAR) studies of the biodata in series 4 revealed that cytotoxic potency was enhanced by placing electron-repelling groups in one of the aryl rings. The compounds are lethal to HL-60, HSC-2, HSC-3 and HSC-4 neoplasms but less toxic to nonmalignant hepatocyte growth factor, hematopoietic progenitor cell and human periodontal ligament fibroblast cells. Hence, the compounds display tumor-selective toxicity. These chalcones are well tolerated in mice and no overt toxicity was noted. The results establish that in general the compounds in series 2, 4 and 6 have positive characteristics which warrant further studies.