SYNTHESIS AND IMMUNOREGULATORY PROPERTIES OF SELECTED 5-AMINO-3-METHYL-4-ISOXAZOLECARBOXYLIC ACID BENZYLAMIDES

The aim of the study was to characterize a series of isoxazole derivatives in several immunological tests in vitro and in vivo, in mouse and human models. The human model included measurement of: viability of peripheral blood mononuclear cells (PBMC), phytohemagglutinin A (PHA)-induced proliferation of PBMC, production of tumor necrosis factor a (TNF a) in whole blood cultures stimulated with lipopolysaccharide (LPS) and growth of SW-948 and L1210 tumor cell lines. Experiments in mice encompassed the following tests: secondary, humoral immune response splenocytes to sheep erythrocytes (SRBC) in vitiv, delayed type hypersensitivity (DTH) to ovalbumin (OVA) and carrageenan-induced foot edema. All compounds were non-toxic against PMBC and displayed differential, dose-dependent suppressive properties in the model of PHA- induced PMBC proliferation. They also exhibited differential, mostly inhibitory effects on TNF a production. The inhibitory actions on growth of tumor cell lines were moderate. M05 (5-amino-3-methyl-N-(4-methyl-benzyl)-4-isoxazolecarboxamide) was most suppressive in the proliferation and TNF a production tests, it was, therefore, selected for in vitro and in vivo studies in the mouse models. The compound inhibited the humoral immune response in vitro, stimulated the inductive phase of DTH in vivo, although it inhibited the eliciting phase of that response. The compound also inhibited the carrageenan skin reaction. M05 combines strong anti-proliferative and anti-inflammatory activities, it is therefore attractive for further studies in more advanced animal models as a potential therapeutic.

SYNTHESIS AND PHARMACOLOGICAL ACTIVITY OF IMIDAZO[2,1- b][1,3,4]THIADIAZOLE DERIVATIVES

In this paper, a series of imidazo[2,l-b][1,3,4]thiadiazoles have been prepared by reacting 2-amino-1,3,4-thiadiazole with various phenacyl bromides in alcohol. The structures of all the derivatives were con- firmed by IR, NMR and mass spectroscopy. All the derivatives have been tested for cytostatic activity against human T-lymphocyte cells (CEM), human cervix carcinoma cells (HeLa), murine leukemia cell line (L1210), and antiviral activity. Among the tested compounds, derivatives 5b, 5c, and 7a were cytostatic between 49-63 mM against Hela and 7g was cytotoxic at 23 mM against L1210 and CEM cell lines. Compounds 5h and 7h emerged as antiviral agents with slight activity against influenza A and B.

[Design, synthesis, antibacterial and anti-cell proliferation activities of [1,2,4]triazino[3,4-h] [1,8]naphthyridine-8-one-7-carboxylic acid derivatives]

To discover novel fluoroquinolone lead compounds as possible anti-infective or/and antitumor chemotherapies, combination principle of pharmacophore-based drug design, a series of novel tricyclic fluoroquinolone title compounds, [1,2,4]triazino[3,4-h][1,8]naphthyridine-8-one-7-carboxylic acid derivatives ( 5a-5p), were designed and synthesized with a fused [1,2,4]-triazine ring unit. Their structures were characterized by spectral data and elemental analysis and the in vitro antibacterial and anti-cell proliferation activities were also evaluated. The results showed that the titled compounds exhibited more significant inhibitory activities against drug-resistant bacteria (Methicillin-resistant Staphylococcus aureus and multi drug-resistant Escherichia coli strains) and three tested cancer cell lines (human hepatoma SMMC-7721, murine leukemia L1210 and human murine leukemia HL60 cells). Interestingly, SAR showed that compounds with electron-donating groups attached to benzene ring had stronger antibacterial activity than antitumor activity, but electron-withdrawing compounds displayed more potential antitumor activity than antibacterial activity, especially antitumor activity of nitro compounds was comparable to comparison doxorubicin. Thus, novel triazine-fused tricyclic fluoroquinolones as potent anti-infective or/and antitumor lead compounds are valuable to pay attention and for further development.

In vitro and in vivo effects of free and chalcones-loaded nanoemulsions: insights and challenges in targeted cancer chemotherapies

Several obstacles are encountered in conventional chemotherapy, such as drug toxicity and poor stability. Nanotechnology is envisioned as a strategy to overcome these effects and to improve anticancer therapy. Nanoemulsions comprise submicron emulsions composed of biocompatible lipids, and present a large surface area revealing interesting physical properties. Chalcones are flavonoid precursors, and have been studied as cytotoxic drugs for leukemia cells that induce cell death by different apoptosis pathways. In this study, we encapsulated chalcones in a nanoemulsion and compared their effect with the respective free compounds in leukemia and in non-tumoral cell lines, as well as in an in vivo model. Free and loaded-nanoemulsion chalcones induced a similar anti-leukemic effect. Free chalcones induced higher toxicity in VERO cells than chalcones-loaded nanoemulsions. Similar results were observed in vivo. Free chalcones induced a reduction in weight gain and liver injuries, evidenced by oxidative stress, as well as an inflammatory response. Considering the high toxicity and the side effects induced generally by all cancer chemotherapies, nanotechnology provides some options for improving patients’ life quality and/or increasing survival rates.

Cell cycle arrest and cell apoptosis induced by Equisetum hyemale extract in murine leukemia L1210 cells

ETHNOPHARMACOLOGICAL RELEVANCE

Equisetum hyemale has been used as a traditional herbal medicine to treat various diseases such as hypertension, inflammatory diseases, acute stroke, bleeding and cancer. The present study aimed to investigate the anti-proliferative effect and the underlying mechanisms of E.hyemale extract on murine leukemia L1210 cells.

MATERIALS AND METHODS

The inhibitory effect of Ehyemale extract on L1210cells was evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. Cell cycle distribution was evaluated with flow cytometry following PI (propidium iodide) staining. Apoptotic cell death was determined by Annexin V-FITC/PI and nuclear DAPI (4'-6-diamidino-2-phenylindole) staining. DNA damage and changes of mitochondrial membrane potential were also detected with flow cytometry analysis.

RESULTS

E.hyemale extract exerted significant antiproliferative effects on L1210 cells in a dose- and time-dependent manner. Flow cytometry analysis showed that E.hyemale extract induced cell cycle arrest at G2/M phase in L1210 cells. Phosphatidylserine exposure, chromatin condensation, DNA damage and loss of mitochondrial membrane potential were observed clearly after treatment with Ehyemale extract.

CONCLUSION

The results in this study indicate that E.hyemale extract could inhibit L1210 cell proliferation through inducing G2/M arrest and cell apoptosis.

Part IV: Design, synthesis and antitumor activity of fluoroquinolone C-3 heterocycles: bis-oxadiazole methylsulfide derivatives derived from ciprofloxacin

To explore an efficient strategy for further development of anticancer fluoroquinolone candidates derived from ciprofloxacin, a heterocyclic ring as the bioisosteric replacement of C3 carboxyl group led to a key intermediate, oxadiazole thiol (5), which was further modified to the bis-oxadiazole methylsulfides (7a-7h) and the corresponding dimethylpiperazinium iodides (8a-8h), respectively. Structures were characterized by elemental analysis and spectra data, and their anticancer activities in vitro against CHO, HL60 and L1210 cancer cells were also evaluated by MTT assay. The preliminary results show that piperazinium compounds (8) possess more potent activity than that of corresponding free bases (7).

An unusual lanostane-type triterpenoid, spiroinonotsuoxodiol, and other triterpenoids from Inonotus obliquus

An unusual lanostane-type triterpenoid, spiroinonotsuoxodiol (1), and two lanostane-type triterpenoids, inonotsudiol A (2) and inonotsuoxodiol A (3), were isolated from the sclerotia of Inonotus obliquus. Their structures were determined to be (3S,7S,9R)-3,7-dihydroxy-7(8-->9)abeo-lanost-24-en-8-one (1), lanosta-8,24-dien-3beta,11beta-diol (2), and (22R)-3beta,22-dihydroxylanosta-8,24-dien-11-one (3) on the basis of NMR spectroscopy, including 1D and 2D ((1)H-(1)H COSY, NOESY, HMQC, HMBC) NMR, and FABMS. Compounds 1-3 showed moderate activity against cultured P388, L1210, HL-60 and KB cells.

Mouse and human mitochondrial nucleoid--detailed structure in relation to function

The independent mitochondrial genetic information is organized in so-called mitochondrial nucleoids that, in vertebrates, typically contain 5-7 genetic units. The total number of nucleoids per cell is several hundred in cultured cells. Mitochondrial nucleoids, similarly to the whole mitochondrial network, have recently been successfully and extensively visualized using fluorescent and confocal microscopy. In the present work, we show high-resolution micrographs of mouse and human mitochondrial nucleoids obtained by transmission electron microscopy. Position in the mitochondria, size, general appearance and other properties of the human nucleoids appear the same as those of mouse nucleoids, and all observations are also in full agreement with the results obtained in different laboratories using different approaches. Most of nucleoids are located inside mitochondrial tubes. However, we show directly that certain part of the nucleoids close to inner membrane is bound to the complex of molecules that crosscut both, the inner and the outer mitochondrial membranes. Nucleoids in cells starving for serum are mostly more dense than those in dividing cells. We discuss the position, appearance and other properties of the nucleoids in relation to functional stage. Other electron-dense structures inside mitochondria that could be erroneously considered to be mitochondrial nucleoids are also described.

[Antisense oligonucleotides as potential drugs for prophylaxis of prion infections]

Prion mRNA translation inhibition by antisense oligodeoxynucleotides (asODN) incorporated into immunoliposomes was investigated. It was shown that asODN complementary to cap region, start-codon region and a part of open reading frame can decrease the prion expression by 80% in L1210 cell line and by 60% in prion-replicating organs of laboratory rats. These results give grounds for further research asODN to be used as a means of prevention and treatment of prion infections.

A low-molecular mass ribonuclease from the brown oyster mushroom

A ribonuclease, with a molecular mass of 9 kDa and an N-terminal sequence resembling the sequence of a fragment of tRNA/rRNA cytosine-C5-methylase and a fragment of a alanyl-tRNA synthetase, was isolated from fresh fruiting bodies of the brown oyster mushroom Pleurotus ostreatus. The ribonuclease was purified using a very simple protocol that comprised ion-exchange chromatography on carboxymethyl (CM)-cellulose and affinity chromatography on Affi-gel blue gel. Subsequent gel filtration by fast protein liquid chromatography on Superdex 75 and sodium dodecyl sulfate (SDS) polyacrylamide gel electrophoresis revealed that the ribonuclease was purified after the first two chromatographic steps. The ribonuclease was adsorbed on CM-cellulose and Affi-gel blue gel. The ribonuclease exhibited the highest activity toward poly A, lower activity toward poly C, slight activity toward poly G, and indiscernible activity toward poly U. The enzyme was stimulated upon exposure to 1 microm Mg2+ and 10 microm Zn2+, but was inhibited by the following ions at 10 mm: Ca2+, Mg2+, Zn2+, Cu2+, Fe2+, Mn2+, and Fe3+. The ribonuclease required a pH of 8.0 and a temperature of 50-70 degrees C to express maximal activity. It had a Km of 60 microm toward yeast tRNA. It lacked mitogenic and HIV-1 reverse transcriptase inhibiting activities, but exerted antiproliferative activity toward leukemia L1210 cells.

beta-Conglycinins among sources of bioactives in hydrolysates of different soybean varieties that inhibit leukemia cells in vitro

Soybean is a complex matrix containing several potentially bioactive components. The objective was to develop a statistical model to predict the in vitro anticancer potential of soybean varieties based on the correlation between protein composition and bioactive components after simulated gastrointestinal enzyme digestion with their effect on leukemia mouse cells. The IC 50 values of the hydrolysates of soy genotypes (NB1-NB7) on L1210 leukemia cells ranged from 3.5 to 6.2 mg/mL. Depending on genotype, each gram of soy hydrolysates contained 2.7-6.6 micromol of total daidzein, 3.0-4.7 micromol of total genistein, 0.5-1.3 micromol of glycitein, 2.1-2.8 micromol of total saponins, 0.1-0.2 micromol of lunasin, and 0.1-0.6 micromol of Bowman-Birk inhibitor (BBI). The IC 50 values calculated from a partial least-squares (PLS) analysis model correlated well with experimental data ( R (2) = 0.99). Isoflavones and beta-conglycinin positively contributed to the cytotoxicity of soy on L1210 leukemia cells. Lunasin and BBI were potent L1210 cell inhibitors (IC 50 = 13.9 and 22.5 microM, respectively), but made modest contributions to the activity of defatted soy flour hydrolysates due to their relatively low concentrations. In conclusion, the data demonstrated that beta-conglycinins are among the major protein components that inhibit leukemia cell growth in vitro. Furthermore, it was feasible to differentiate soybean varieties on the basis of the biological effect of their components using a statistical model and a cell-based assay.

E,E-2-Benzylidene-6-(nitrobenzylidene)cyclohexanones: syntheses, cytotoxicity and an examination of some of their electronic, steric, and hydrophobic properties

Three series of structurally isomeric 2-benzylidene-6-(nitrobenzylidene) cyclohexanones 1-3 were prepared and evaluated against human Molt/C8 and CEM T-lymphocytes as well as murine L1210 cells. The IC(50) values of the majority of compounds are less than 10microM and in some assays, the figures for 1d and 1e are submicromolar. Correlations were discerned between cytotoxic potencies and the atomic charges on one of the olefinic carbon atoms, the torsion angles between an aryl ring, and the adjacent unsaturated group as well as logP values. Three representative compounds were examined for their effect on respiration in rat liver mitochondria.

AMID: new insights on its intracellular localization and expression at apoptosis

AMID (apoptosis-inducing factor (AIF)-like mitochondrion-associated inducer of death) is a poorly studied member of the AIF family; despite the given name AMID, predicting its association with mitochondria, its real cellular localization, as well as its role and changes during apoptosis are currently unclear. By means of MALDI-TOF mass spectrometry, we have identified as AMID (accession number AAH38129, sequence coverage 31%) the protein isolated by Pisum sativum lectin-affinity chromatography from the plasma membrane fraction of apoptotic murine leukemia L1210 cells, lacking in the intact cells. The obtained results suggest its possible glycosylation that was further suggested by finding N-glycosylation sequon in the signal peptide of AMID protein (in silica), and by predicting transmembrane localization of its N-terminal part. Using monoclonal antibodies to AMID, we demonstrated an increased expression of AMID in human leukemia Jurkat T-cells after apoptosis induction. Immunocytochemical study suggested its association to the plasma membrane.

Implications of the involvement of the endoplasmic reticulum stress pathway in drug-induced apoptosis

Apoptosis occurs by distinct pathways that involve the cell surface, mitochondria or the endoplasmic reticulum. Previous studies had shown that deoxyadenosine-resistant L1210 cells (Y8) proceeded to apoptosis under conditions in which the parental L1210 cell line (WT) did not undergo an apoptotic response. Combinations of drugs, acting at different molecular targets, markedly potentiated the apoptotic response in the Y8 cells without inducing apoptosis in the WT cells. In the present study, induction of apoptosis by parthenolide and BAY 11-7085, drugs that targeted nuclear factor kappa B activation, was blocked by the presence of N-acetylcysteine (NAC). On the other hand, the levels of apoptosis induced by parthenolide or BAY 11-7085 were increased by pre-treatment of the cells with glutathione lowering L-buthionine-(S,R)-sulfoximine (BSO). Western blot analyses showed that the levels of the stress proteins, Grp 78 and Gadd 153 were reduced in the parthenolide-treated Y8 cells, but not in those co-treated with NAC. Protection of the cells from apoptosis induced by parthenolide or BAY 11-7085 by NAC was relatively specific as the induction of apoptosis in the Y8 cells by MG-132, flavopiridol, Gemcitabine or PRIMA-1 was not decreased by NAC. These data suggest that multiple pathways, one of which is ER-stress induced, may ultimately be involved and interactive in the induction of apoptosis in specific cell lines.

Cytotoxicity of hydroxyapatite, fluorapatite and fluor-hydroxyapatite: a comparative in vitro study

The purpose of this study was to evaluate the cytotoxicity of two formulations of hydroxyapatite (HA), namely fluorapatite (FA) and fluor-hydroxyapatite (FHA). HA is used as carrier material for antibiotics or anticancer drugs during treatment of bone metastasis. Negative control, represented by HA, was included for comparative purposes. Leukemia cells were used as a model cell line, and the effect of eluates of tested biomaterials on cell proliferation/viability and mechanism of antiproliferative activity were assessed. Study design attempted to reveal the toxicity of tested biomaterials with an emphasis to decide if tested biomaterials have promise for further studies in vivo. Results showed that eluates of FA and FHA inhibit the growth of leukemia cells and induce programmed cell death through mitochondrial/caspase-9/caspase-3-dependent pathway. Due to these differences compare to HA, it is concluded that FA and FHA have promise for evaluation of their behaviour in vivo.

Novel substituted 1,4-anthracenediones with antitumor activity directly induce permeability transition in isolated mitochondria

Synthetic analogs of 1,4-anthraquinone (AQ code number), which block nucleoside transport, decrease DNA, RNA and protein syntheses, trigger cytochrome c release without caspase activation, induce apoptotic DNA fragmentation and inhibit the proliferation of wild-type and multidrug resistant tumor cells in the nM range in vitro, rapidly cause the collapse of mitochondrial transmembrane potential in cell and cell-free systems. Because mitochondrial permeability transition (MPT) requires more than depolarization to occur, antitumor AQs were tested for their ability to directly trigger specific markers of MPT in isolated mitochondria. In contrast to a spectrum of conventional anticancer drugs that are inactive, various AQs interact with isolated mitochondria in a concentration- and time-dependent manner to rapidly cause large amplitude swelling and Ca2+ release in relation with their effectiveness against L1210, HL-60 and LL/2 tumor cells in vitro. Indeed, the lead antitumor AQ8, AQ9 and AQ17 are also the most effective inducers of MPT in isolated mitochondria, whereas all AQ derivatives devoid of anti-proliferative activity also fail to trigger mitochondrial swelling and Ca2+ release. Moreover, the ability of 4 microM AQ17 to maximally induce mitochondrial swelling and Ca2+ release within 15 min is similar to that of classic MPT-inducing agents, such as 5 microg/ml alamethicin, 200 microM atractyloside, 5 microM phenylarsine oxide, 100 microM arsenic trioxide and a 100 microM Ca2+ overload. Interestingly, AQ17 requires a priming concentration of 20 microM Ca2+ to trigger mitochondrial swelling and Ca2+ release and these 0.1 microM ruthenium red-sensitive MPT events are abolished by 1 microM cyclosporin A, 2 mM ADP and 20 microM bongkrekic acid, which block components of the permeability transition pore (PTP), and also inhibited by 50-100 microM of various ubiquinones, which interact with the quinone binding site of the PTP and raise the Ca2+ load required for PTP opening. Hence, antitumor AQs that target isolated mitochondria and trigger MPT might directly interact with components of the PTP to induce conformational changes that increase its Ca2+ sensitivity and transition from the closed to the open state.

DNA binding properties and evaluation of cytotoxic activity of 9,10-bis-N-substituted (aminomethyl)anthracenes

The results of DNA binding properties for four selected N-substituted 9,10-bis(aminomethyl)anthracenes are presented. DNA binding affinities were studied using UV-vis and fluorescence spectrophotometric titrations, CD spectroscopy, denaturation transition temperature (Tm) measurements and AM1 quantum chemical calculations. The results obtained indicate that the anthracene products intercalate into the stacked base pairs of DNA with binding constants, K, in the range 1.3-10.9 x 10(5)M(-1) and the binding site size in DNA-base pairs, n, extending over the range 2.4-4.6. Tm values increased in the presence of the anthryl probes, thereby reflecting an increased stability of the calf-thymus (CT) DNA double helix and rendering agreement with the spectrometric titration results. The synthesized compounds were tested against L1210 and HeLa tumor cell lines wherein the HeLa cells appeared to be more sensitive than the L1210 cells. 9,10-Bis{[2-(piperazin-1-yl)ethyl]aminomethyl}anthracene exhibited the highest activity of the tested compounds. Our findings were compared with those of a control drug bisantrene.

Design, synthesis and biological evaluation of substituted dioxodibenzothiazepines and dibenzocycloheptanes as farnesyltransferase inhibitors

A new series of FTase inhibitors containing a tricyclic moiety--dioxodibenzothiazepine or dibenzocycloheptane--has been designed and synthesized. Among them, dioxodibenzothiazepine 18d displayed significant inhibitory FTase activity (IC(50)=17.3 nM) and antiproliferative properties.

Cytotoxic constituents from angelicae sinensis radix

Cytotoxic bioassay-guided fractionation of methanol extract of Angelicae Sinensis Radix led to the isolation of a new dimeric Z-ligustilide, named neodiligustilide (1), together with three known compounds, Z-ligustilide (2), 11(S),16(R)-dihydroxy-octadeca-9Z, 17-dien-12,14-diyn-1-yl acetate (3), and 3(R),8(S)-falcarindiol (4). Among them, 2 showed the strongest cytotoxicity against L1210 and K562 cell lines with IC50 values of 2.27 +/- 0.10 and 4.78 +/- 0.18 microM, respectively, while 1 showed moderate cytotoxicity with IC50 values of 5.45 +/- 0.19 and 9.87 +/- 0.14 microM. Two polyacetylenes, 3 and 4, showed cytotoxicity only against L1210 cell line with IC50 values of 2.60 +/- 0.90 and 2.87 +/- 0.49 microM, respectively.

Farnesyl protein transferase and tumor cell growth inhibitory activities of lipiferolide isolated from Liriodendron tulipifera

The methanolic extract of the leaves of Liriodendron tulipifera was found to show inhibitory activity towards farnesyl protein transferase (FPTase). Bioassay-guided fractionation of the methanolic extract resulted in the isolation of lipiferolide, an inhibitor of FPTase. This compound inhibited the FPTase activity in a dose-dependent manner, and showed cell growth inhibitory activity against several tumor cells.

Studies on panax acetylenes: absolute structure of a new panax acetylene, and inhibitory effects of related acetylenes on the growth of L-1210 cells

A new Panax acetylene, 3-oxo-PQ-1 (1), was isolated from Panax quinquefolium. The absolute configurations of 3-oxo-PQ-1 (1) and PQ-1 (2) were determined to be (9R,10R) and (3R,9R,10R), respectively, by synthesizing 1 and 2 starting from D-(-)-diethyl tartrate, and by synthesizing their stereoisomers from L-(+)-diethyl tartrate. The growth inhibitory effects of Panax acetylenes (1-8) and their stereoisomers against leukemia cells were tested. Unnatural acetylenes having the (3S)-configuration (2, 5, 6, 7, 8; IC(50)=0.01-0.1 microg/ml) were found to be approximately ten times more potent than natural acetylenes (IC(50)=0.1-1.0 microg/ml) with the (3R)-configuration. Potency differences due to the configuration at C-9 and C-10 were unrelated to this stereochemistry. The C(14)-polyacetylenes, PQ-8 (4) and its isomer (IC(50)=1.0-10.0 microg/ml), were found to exhibit weaker cytotoxicity than the C(17)-polyacetylenes.

Antitumor activity of a monoclonal antibody against CD47 in xenograft models of human leukemia

The ligation of CD47 induces the apoptosis of leukemic cells in a caspase-independent manner. We generated a monoclonal antibody against CD47 (mAb-MABL) that possibly induced apoptosis from the ligation of CD47 in CCRF-CEM and JOK-1 cells in vitro. To confirm whether the ligation of CD47 caused cell death in vivo, we examined the antitumor activity of F(ab')2 of mAb-MABL in two xenograft models: The acute lymphoblastic leukemia (CCRF-CEM) and the B-cell chronic lymphocytic leukemia (JOK-1) cell line. Furthermore, in order to clarify the apoptotic activity selective for the tumor cells, we examined F(ab')2 of mAb-MABL apoptotic effects on CD34+ hematopoietic progenitor/stem and human endothelial cells. Male SCID mice were intravenously injected with CCRF-CEM (5 x 10(6) cells/mouse) or JOK-1 cells (5 x 10(6) cells/mouse) and intraperitoneally with JOK-1 cells (2 x 10(7) cells/mice). After the implantation of the cells, the mice were intravenously administered the vehicle or the F(ab')2 fragment of mAb-MABL at several doses and the length of survival was measured. F(ab')2 of mAb-MABL markedly prolonged the survival of mice transplanted with CCRF-CEM and JOK-1. Significantly, 40% of the mice intraperitoneally injected with JOK-1 cells became tumor-free when administered F(ab')2 of mAb-MABL, whereas even a high dose of fludarabine only slightly prolonged the median survival time. On the contrary, F(ab')2 of mAb-MABL showed no apoptotic effect on CD34+ hematopoietic progenitor/stem or human endothelial cells. Thus, monoclonal antibodies that cause cell death from the ligation of CD47 could be novel therapeutic agents for incurable leukemia after further optimization such as humanization or making single chain diabodies.

Comparison of new nitrosoureas esters with modified steroidal nucleus for cytogenetic and antineoplastic activity

Nitrosourea is decomposed under physiological conditions to react with biological macromolecules by two mechanisms: alkylation (with proteins and nucleic acids) and carbamoylation (with proteins but not nucleic acids). It has been suggested that the alkylating action is responsible for the therapeutic effects of nitrosoureas, and that the carbamoylation activity leads to toxicity effects. In order to reduce systemic toxicity and improve specificity and distribution for cancer therapy, 2-haloethyl nitrosourea has been esterified with modified steroids, which are used as biological platforms for transporting the alkylating agent to the tumor site in a specific manner. The cytogenetic and antineoplastic effect were studied of seven newly synthesized esters of N,N-bis(2-chloroethyl)alanyl carboxyl derivatives with a modified steroidal nucleus (compounds 1-7). As a very sensitive indicator of genotoxicity the Sister Chromatid Exchange (SCE) assay was used and as a valuable marker of cytostatic activity the cell Proliferation Rate Index (PRI) in cultures of normal human lymphocytes was used. The order of magnitude of the cytogenetic activity on a molar basis (15, 30, 120 microM) of the compounds was 7>>6>3>5>2>4>1. The most active compound 7 has an enlarged (seven carbon atoms) A ring modified with a lactam group (-NHCO-) with the nitrosourea moiety esterified at position 17 In the group of seven substances a correlation was observed between the magnitude of SCE response and the depression in PRI (r=-O, 65, p<0.001). According to the criterion of activity of National Cancer Institute (NCI), the order of antineoplastic activity of compounds on lymphoid L1210 leukemia is 7>6>2>5>4>3>1 and on lympocytic P388 leukemia cells is 7>2>6>5>4>3>1. The present results are in agreement with previous suggestions that the effectiveness in cytogenetic activity may well be correlated with antitumor effects [T/C: 248% for the compound 7 in 250 mg/kg b.w.; T/C: mean survival time of drug-treated animals (T) (excluding long term survivals) vs. corn-oil-treated controls (C)].

Myriaporones 1-4, cytotoxic metabolites from the Mediterranean bryozoan Myriapora truncata

Four novel polyketide-derived metabolites, myriaporones 1, 2, 3, and 4, have been isolated from the Mediterranean bryozoan Myriapora truncata. Their structures and stereochemistry have been assigned from the analysis of spectroscopic data. The inseparable equilibrium mixture of myriaporones 3 and 4 showed 88% inhibition of L1210 murine leukemia cells at 0.2 microg/mL.

Pharmacokinetic characteristics of L-valyl-ara-C and its implication on the oral delivery of ara-C

AIM

To evaluate the pharmacokinetic characteristics of L-valyl-ara-C, a peptidomimetic prodrug of ara-C.

METHODS

After the synthesis of L-valyl-ara-C, the in vitro stability of L-valyl-ara-C was examined in various biological media. Plasma pharmacokinetic profiles of ara-C and L-valyl-ara-C were also evaluated in rats.

RESULTS

The degradation of L-valyl-ara-C was negligible in fresh plasma and also in the presence of plasmin over a 2 h incubation period. Furthermore, L-valyl-ara-C appeared to be stable in the leukemia cell homogenates, and subsequently, it was far less cytotoxic than the parent, ara-C in AML2 and L1210 cells. The chemical hydrolysis of L-valyl-ara-C was rather accelerated in acidic pH. Following an oral administration of L-valyl-ara-C, the appearance of ara-C was observed in plasma although the systemic exposure of the prodrug was much higher than that of ara-C. The bioavailability of ara-C was about 4% via prodrug administration.

CONCLUSION

The amide bond of L-valyl-ara-C was stable against the enzymatic hydrolysis, and the utility of L-valyl-ara-C as an oral delivery system of ara-C appeared to be limited by its low metabolic conversion to ara-C in rats.

Total synthesis and evaluation of cytostatin, its C10-C11 diastereomers, and additional key analogues: impact on PP2A inhibition

The total synthesis of cytostatin, an antitumor agent belonging to the fostriecin family of natural products, is described in full detail. The convergent approach relied on a key epoxide-opening reaction to join the two stereotriad units and a single-step late-stage stereoselective installation of the sensitive (Z,Z,E)-triene through a beta-chelation-controlled nucleophilic addition. The synthetic route provided rapid access to the C4-C6 stereoisomers of the cytostatin lactone, which were prepared and used to define the C4-C6 relative stereochemistry of the natural product. In addition to the natural product, each of the C10-C11 diastereomers of cytostatin was divergently prepared (11 steps from key convergence step) by this route and used to unequivocally confirm the relative and absolute stereochemistry of cytostatin. Each of the cytostatin diastereomers exhibited a reduced activity toward inhibition of PP2A (>100-fold), demonstrating the importance of the presence and stereochemistry of the C10-methyl and C11-hydroxy groups for potent PP2A inhibition. Extensions of the studies provided dephosphocytostatin, sulfocytostatin (a key analogue related to the natural product sultriecin), 11-deshydroxycytostatin, and an analogue lacking the entire C12-C18 (Z,Z,E)-triene segment, which were used to define the magnitude of the C9-phosphate (>4000-fold), C11-alcohol (250-fold), and triene (220-fold) contribution to PP2A inhibition. A model of cytostatin bound to the active site of PP2A is presented, compared to that of fostriecin, which is also presented in detail for the first time, and used to provide insights into the role of the key substituents. Notably, the alpha,beta unsaturated lactone of cytostatin, like that of fostriecin, is projected to serve as a key electrophile, providing a covalent adduct with Cys269 unique to PP2A, contributing to its potency (> or =200-fold for fostriecin) and accounting for its selectivity.

Comparative studies on the mechanism of cytotoxic action of novel platinum II complexes with pyrazole ligands

In search for new platinum-based anticancer drugs, four cisplatin analogues, which contain pyrazole rings as non-leaving ligands, have been synthesized: cis-PtCl(2)(3,5-DM HMPz)(2), cis-PtCl(2)(Pz)(2), cis-PtCl(2)(ClMPz)(2), and cis-PtCl(2)(HMPz)(2), where Pz=pyrazole, H=hydroxyl, M=methyl. We tested their cytotoxicity, apoptosis induction ability, DNA damaging and modification properties comparing them in respect to the parent compound. The cytotoxic activity of these platinum pyrazole complexes toward the murine leukemia cell line was 2.9-3.8 times lower than actvity of cisplatin. The tested compounds varied in their mechanism of action by producing different DNA lesions. The most interesting compound seems to be the complex with chloromethyl groups at N1 of pyrazole rings, which exhibited the highest ability to form bifunctional adducts with DNA in vitro.

Mode of action of the chloroethylating and carbamoylating moieties of the prodrug cloretazine

Cloretazine is an antitumor sulfonylhydrazine prodrug that generates both chloroethylating and carbamoylating species. The cytotoxic potency of these species was analyzed in L1210 leukemia cells using analogues with chloroethylating or carbamoylating function only. Clonogenic assays showed that the chloroethylating-only agent 1,2-bis(methylsulfonyl)-1-(2-chloroethyl)hydrazine (90CE) produced marked differential cytotoxicity against wild-type and O6-alkylguanine-DNA alkyltransferase-transfected L1210 cells (LC10, 1.4 versus 31 micromol/L), indicating that a large portion of the cytotoxicity was due to alkylation of DNA at the O-6 position of guanine. Consistent with the concept that O-6 chloroethylation of DNA guanine progresses to interstrand cross-links, the comet assay, in which DNA cross-links were measured by a reduction in DNA migration induced by strand breaks, showed that cloretazine and 90CE, but not the carbamoylating-only agent 1,2-bis(methylsulfonyl)-1-[(methylamino)carbonyl]hydrazine (101MDCE), produced DNA cross-links and that cloretazine caused more DNA cross-links than 90CE at equimolar concentrations. Cell cycle analyses showed that 90CE and 101MDCE at concentrations of 5 and 80 micromol/L, respectively, produced similar degrees of G2-M arrest. 90CE produced selective inhibition of DNA synthesis after overnight incubation, whereas 101MDCE caused rapid and nonselective inhibition of RNA, DNA, and protein syntheses. Both 90CE and 101MDCE induced phosphorylation of histone H2AX, albeit with distinct kinetics. These results indicate that (a) differential expression of O6-alkylguanine-DNA alkyltransferase in tumor and host cells seems to be responsible for tumor selectivity exerted by cloretazine; (b) 101MDCE enhances DNA cross-linking activity; and (c) 90CE induces cell death at concentrations lower than those causing alterations in the cell cycle and macromolecular syntheses.

Tumor escape mutants develop within an immune-privileged environment in the absence of T cell selection

The establishment of tumor escape mutants, which can be driven by innate and/or adaptive immune effector cells, presents a significant obstacle in the development of successful tumor immunotherapies. Our study documents that tumors growing within an immune-privileged site within the eye develop a tumor escape phenotype in the absence of selective T cell pressure. P815 tumor cells that are recovered from progressively growing tumors within the anterior chamber of the eye escape elimination when injected into the flanks of a second group of syngeneic DBA/2 mice that were previously immunized against P815 tumor cells. The escape phenotype of eye-derived P815 tumors was stable and permanent when the tumor cells were cultured in vitro. Eye-derived tumor cells recovered from the anterior chamber of CB-17 SCID mice also escaped elimination when injected into the flanks of immunized mice, demonstrating that selective pressure by tumor Ag-specific T cells did not contribute to the development of the escape phenotype. In vitro studies demonstrated that eye-derived tumor cells were not lysed by specific CTL and were unable to restimulate primed Ag-specific T cells. Immune escape of eye-derived tumor cells was not due to down-regulation of either MHC class I or ICAM-1. Our data demonstrate that the immune-privileged environment within the eye induces a tumor escape phenotype that is not driven by selective T cell pressure. We predict that immune escape within the eye is driven by the unique ocular environment that permanently alters gene expression in eye-derived tumor cells.

Purification and characterization of a galactose-specific lectin with mitogenic activity from pinto beans

A galactose-specific dimeric lectin from pinto beans was purified using a procedure that involved affinity chromatography on Affi-gel blue gel, anion exchange chromatography on Q-Sepharose, fast protein liquid chromatography (FPLC)-ion exchange chromatography on Mono S, and FPLC-gel filtration on Superdex 200. The molecular mass of this homodimeric lectin was 62 kDa and that of each of its subunits was 31 kDa. The hemagglutinating activity of pinto bean lectin was stable within the pH range of 3-12 and the temperature range of 0-70 degrees C. By using the [3H-methyl]-thymidine incorporation assay, it was shown that the lectin had the ability to evoke a mitogenic response from murine splenocytes but it did not inhibit proliferation of L1210 leukemia cells. The pinto bean lectin inhibited HIV-1 reverse transcriptase with an IC50 of 3 microM.

Involvement of glutathione in the cytotoxicity of 9-isothiocyanatoacridine

Isothiocyanates (ITCs) are phytochemicals with promising cancer-preventive potential. To elucidate the mechanism of cytotoxicity of ITCs, their accumulation by cells and the role of intracellular glutathione, fluorescent 9-isothiocyanatoacridine (AcITC) was synthesized. The kinetic parameters for the reactions of AcITC with thiols were estimated and the influence of AcITC on human chronic myeloid leukemia cell line (K562) in regard to intracellular glutathione was studied. Cytotoxicity was evaluated by MTT assay, IC(50)=29.2 +/- 2.5 microM (48 h incubation). This acridine derivative was able to induce apoptosis of cells (morphological changes of cells and DNA fragmentation were observed) at least within certain dose that only decreased the level of intracellular glutathione, excessive doses (completely depleted intracellular pool of glutathione) induced necrosis rather than apoptosis. Our results indicated that apoptosis of leukemia cells induced by ITC is possible only if intracellular glutathione is not entirely depleted.

Contrasting Chemistry of cis- and trans-Platinum(II) Diamine Anticancer Compounds: Hydrolysis Studies of Picoline Complexes

cis-[PtCl2(NH3)(2-picoline)] (AMD473) is currently on clinical trials as an anticancer drug. The trans isomer, AMD443 (1), is also cytotoxic in a variety of cancer cell lines. The X-ray crystal structure of the trans isomer (1) shows that the pyridine ring is tilted by 69 degrees with respect to the platinum square-plane in contrast to the cis isomer in which it is almost perpendicular (103 degrees ). In the 3-picoline (2) and 4-picoline (3) trans isomers, the ring is tilted by 58 degrees /60 degrees (2 molecules/unit cell) and by 56 degrees , respectively. Hydrolysis may be an important step in the intracellular activation and anticancer mechanism of action of these complexes. The first hydrolysis step is relatively fast even at 277 K, with rate constants (determined by 1H,15N NMR) of k1 = 2.6 x 10(-5) s(-1), 12.7 x 10(-5) s(-1), and 5.2 x 10(-5) s(-1) (I = 0.1 M) for formation of the monoaqua complexes of 1-3, respectively. Although the hydrolysis of 3 is slower than 2, it is hydrolyzed to a greater extent. No formation of the diaqua complex was observed for any of the three complexes at 277 K, and it accounts for <3% of the platinum species at 310 K. In general the extent of hydrolysis of the trans complexes is much less than for their cis analogues. The pK(a) values for the monoaqua adducts of 1-3 were determined to be 5.55, 5.35, and 5.39, respectively, suggesting that they would exist largely as the monohydroxo complex at physiological pH. The pKa values for the diaqua adducts were determined to be 4.03 and 7.01 for 1, 3.97 and 6.78 for 2, and 3.94 and 6.88 for 3, the first pK(a) being >1 unit lower than for related cis complexes.

Cytotoxic saponins from the root ofDipsacus asper wall

Cytotoxic activitiy of seven hederagenin saponins isolated from the root of Dipsacus asper were investigated in vitro against L1210, HL-60 and SK-OV-3 tumor cell lines by the MTT method. 3-O-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl hederagenin (2), 3-O-beta-D-xylopyranosyl-(1-->3)-alpha-L-Rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl hederagenin (6) and 3-O-beta-D-glucopyranosyl-(1-->3)-alpha-L-rhamnopyranosyl-(1-->2)-alpha-L-arabinopyranosyl hederagenin (7) exhibited the potent cytotoxicity against the three tumor cell lines with IC50 values ranging from 4.7 to 8.7 microg/mL, with the exception of compound 7, which exhibited weak cytotoxic activity against SK-OV-3 (IC50 22.5 microg/mL). Other compounds did not exhibit any cytotoxic activity (IC50 > 30 microg/mL).

Enforced adhesion of hematopoietic cells to culture dish induces endomitosis and polyploidy

Cells of epithelial or endothelial lineage when forced to grow in suspension undergo the detachment-induced death termed "anoikis". In the present study we explored the reverse situation namely the effect of enforcement of hematopoietic lineage cells that are normally maintained in suspension to grow attached. Towards this end murine L1210 or human HL-60 and Jurkat leukemia cells were cultured in slide chambers coated with poly-L- or poly-D- lysine, or with compound 48/80, the polycations attracting them electrostatically. Within minutes after the transfer L1210 cells strongly adhered to bottom surface of the dish and shortly thereafter binuclear-, and later on, polynuclear-cells become apparent. The frequency of nuclei per cell was increasing with time and polykaryons with up to 16 nuclei and high DNA ploidy (DI = 16.0) were apparent after 48 h. After 4 days the size (volume) of some polykaryons exceeded by over 340-fold the volume of mononuclear cells. The presence of mitotic figures and abnormal mitotic spindles in adhering polykaryons provided evidence of the impeded cytokinesis that led to endomitosis. Most polykaryons excluded trypan blue, had balanced growth (unchanged protein/DNA ratio compared to monokaryons), and showed no evidence of apoptosis. Individual nuclei within each polykaryon replicated DNA in synchrony. The strong cell attachment and aborted cytokinesis were cell line specific since no significant endomitosis was observed in Jurkat- or HL-60- cells which did not strongly attach to polycation-coated surfaces. Defective cytokinesis and induction of polyploidy by this mechanism, if occurs in vivo (e.g., mediated by integrins), may lead to aneuploidy and therefore have tumorigenic consequences. The phenomenon offers novel experimental model for induction of polyploidy and provides alternative to cytocholasin B to prevent cytokinesis in the mutagenicity cytokinesis-blocked micronucleus (CBMN) assay.

Differential inhibition of cellular glutathione reductase activity by isocyanates generated from the antitumor prodrugs Cloretazine™ and BCNU

The antitumor, DNA-alkylating agent 1,3-bis[2-chloroethyl]-2-nitrosourea (BCNU; Carmustine), which generates 2-chloroethyl isocyanate upon decomposition in situ, inhibits cellular glutathione reductase (GR; EC 1.8.1.7) activity by up to 90% at pharmacological doses. GR is susceptible to attack from exogenous electrophiles, particularly carbamoylation from alkyl isocyanates, rendering the enzyme unable to catalyze the reduction of oxidized glutathione. Evidence implicates inhibition of GR as a cause of the pulmonary toxicity often seen in high-dose BCNU-treated animals and human cancer patients. Herein we demonstrate that the prodrug Cloretazine (1,2-bis[methylsulfonyl]-1-[2-chloroethyl]-2-[(methylamino)carbonyl]hydrazine; VNP40101M), which yields methyl isocyanate and chloroethylating species upon activation, did not produce similar inhibition of cellular GR activity, despite BCNU and Cloretazine being equally potent inhibitors of purified human GR (IC(50) values of 55.5 microM and 54.6 microM, respectively). Human erythrocytes, following exposure to 50 microM BCNU for 1h at 37 degrees C, had an 84% decrease in GR activity, whereas 50 microM Cloretazine caused less than 1% inhibition under the same conditions. Similar results were found using L1210 murine leukemia cells. The disparity between these compounds remained when cells were lysed prior to drug exposure and were partially recapitulated using purified enzyme when 1mM reduced glutathione was included during the drug exposure. The superior antineoplastic potential of Cloretazine compared to BCNU in animal models could be attributed in part to the contribution of the methyl isocyanate, which is synergistic with the co-generated cytotoxic alkylating species, while at the same time unable to significantly inhibit cellular GR.

Cytotoxicity, cellular uptake and DNA damage by daunorubicin and its new analogues with modified daunosamine moiety

Daunorubicin (DRB) and its two analogues containing a trisubstituted amidino group at the C-3' position of the daunosamine moiety have been compared regarding their cytotoxic activity, cellular uptake, subcellular localization and DNA damaging properties. An analogue containing in the amidino group a morpholine moiety (DRBM) as well as an analogue with a hexamethyleneimine moiety (DRBH), tested against cultured L1210 cells, exhibited lower cytotoxicity then DRB. The decrease of cytotoxic activity was not related to cellular uptake and subcellular localization of drugs. Although all tested drugs were active in the induction of DNA breaks and DNA-protein crosslinks, they differed in the mechanism of induction of DNA lesions. DRB produced DNA breaks mediated solely by topoisomerase II, whereas DRBM and DRBH induced two types of DNA breaks by two separate processes. The first is related to the inhibition of topoisomerase II and the second presumably reflects a covalent binding of drug metabolites to DNA. It is hypothesized that the replacement of the primary amino group (-NH(2)) at the C-3' position of the daunosamine moiety by a trisubstituted amidino group (-N=CH-NRR) may be a route to the synthesis of anthracycline derivatives with enhanced ability to form covalent adducts to DNA.

Brasilibactin A, a cytotoxic compound from actinomycete Nocardia brasiliensis

A new cytotoxic compound, brasilibactin A (1), has been isolated from the actinomycete Nocardia brasiliensis IFM 0995, and the structure was elucidated on the basis of spectroscopic data and chemical means.

Synthesis and evaluation of antitumor activity of 2- and 6-[(1,3-benzothiazol-2-yl)aminomethyl]-5,8-dimethoxy-1,4-naphthoquinone derivatives

2- or 6-substituted BZT-N derivatives were synthesized, and their cytotoxic activity against cancer L1210 and SNU-1 cells was examined. The antitumor action was also assessed in mice bearing S-180 cells in peritoneal cavity. In a comparison, it was found that 6-substituted BZT-N derivatives exhibited higher potencies in both bioactivities than 2-substituted BZT-N derivatives against L1210 cells in in vitro and S-180 in vitro tests exception of compound 36. Interestingly, it was observed that 2-substituted compound 36, which has methyl group at R1 position, exhibited a better antitumor activity than 6-substituted compounds against L1210 and SNU-1 in vitro. The ED50 value of 2-substituted compound 36 against L1210 was found to be comparable to the ED50 value of adriamycin and was even better against the solid cancer cell line SNU-1. It was also observed that 2-substituted compound 36 showed better antitumor activity in mice bearing S-180 cells in the peritoneal cavity. The T/C (%) value of 2-substituted compound 36 was similar to that of adriamycin. Quantitative structure-activity relationship (QSAR) tests reveal that the experimental ED50 values against SNU-1 closely correlate with both the calculated HOMO energies (E(HOMO)) and the measured 1H-NMR chemical shift of 3-H (deltaH). The results suggests that a compound having higher E(HOMO) and deltaH values usually should have a lower ED50 (SNU-1) value.

Retro Hydrazino-azapeptoids as Peptidomimetics of Proteasome Inhibitors

Several groups of proteasome inhibitors are widely used to study the role of the ubiquin proteasome pathway in various cellular processes or as anticancer drugs. Peptidomimetics have been developed to circumvent problems inherent in peptides such as poor bioavailability and protease-mediated degradation, while retaining biological activity. In this study, we introduce new pseudopeptides, the retro hydrazino-azapeptoids, designed as proteasome inhibitor peptidomimetics. Their proteasome inhibitory activity and antiproliferative properties are reported here.

Self-Reactive T Cell Receptor-Reactive CD8+ T Cells Inhibit T Cell Lymphoma Growth In Vivo

Syngenic C57BL/6 mice (H-2(b)) vaccinated with mitomycin C-treated L12R4 T lymphoma cells develop protective immunity toward the MHC class II-negative tumor cells. In the present study, we characterize the nature, mode of function, and specificity of the effector cells in this immunity. These cells are TCR-specific CD8(+) T lymphocytes with effector function in vitro as well as in vivo upon transfer to naive mice. They produce high levels of IFN-gamma and TNF-alpha, but little or no IL-4. By means of TCRbeta-negative variant L12R4 cells, P3.3, and TCR-Vbeta2 cDNA-transfected and TCR-Vbeta2-expressing P3.3 lymphoma cells, we found that a significant part of the effector T cells are specific for the Vbeta12 region. The growth inhibition of L12R4 cells in vitro was inhibited by anti-H-2, anti-K(b), and anti-D(b) mAb. Furthermore, vaccination with Vbeta12 peptide p67-78, which binds to both K(b) and D(b) MHC class I molecules, induces partial protection against L12R4 T lymphoma cells. Thus, self-reactive TCR-Vbeta-specific, K(b)-, or D(b)-restricted CD8(+) T cells mediate inhibition of T cell lymphoma growth in vitro and in vivo.

Resistance-modifying agents. 11.(1) Pyrimido[5,4-d]pyrimidine modulators of antitumor drug activity. Synthesis and structure-activity relationships for nucleoside transport inhibition and binding to alpha1-acid glycoprotein

The cardiovascular and antithrombotic agent dipyridamole (DP) has potential therapeutic utility as a modulator of the activity of antimetabolite antitumor agents by virtue of its inhibition of nucleoside transport. However, the activity of DP can be compromised by binding to the acute phase serum protein, alpha(1)-acid glycoprotein (AGP). Analogues of DP were synthesized and evaluated as inhibitors of (3)H-thymidine uptake into L1210 leukamia cells in the presence and absence of 5 mg/mL AGP. Compounds with potency similar to that of DP were identified where the piperidino substituents at the 4,8-positions were replaced by 4'-methoxybenzylamino, 3',4'-dimethoxybenzylamino, or piperonylamino groups. Replacement of the diethanolamino groups at the 2,6-positions of DP by alkylamino or alkoxy substituents was tolerated, although at least one oxygen-bearing function (hydroxyl or alkoxy) was required in the side chain for activity comparable to that of DP. Whereas AGP completely ablated the activity of DP, the majority of the newer compounds synthesized retained significant activity in the presence of excess AGP, although replacement of the piperidino groups at the 4,8-positions by N-methylbenzylamino substituents did, in some cases, restore susceptibility to AGP. Selected compounds have been demonstrated to prevent rescue from antifolate cytotoxicity, mediated by nucleoside salvage.

Cytotoxic and anticonvulsant aryloxyaryl Mannich bases and related compounds

A series of 1-(4-aryloxyphenyl)-3-diethylamino-1-propanone hydrochlorides 3a-3e and related compounds 3f, 3g and 4a-4d were synthesised. In addition, a group of 4-(4-aryloxyphenyl)-3-(4-aryloxyphenylcarbonyl)-1-ethyl-4-piperidinol hydrochlorides 6a-6e were prepared which incorporated most of the structural features of 3a-3e. All of these compounds displayed cytotoxic properties towards murine L1210 cells as well as human Molt 4/C8 and CEM T-lymphocytes. A number of these compounds possessed noteworthy potencies towards seven human colon cancer cell lines. Some correlations were noted between the IC(50) values generated in the different screens and the sigma, pi and molar refractivity constants of the aryl substituents as well as with the volumes and solvent accessible surface areas of various basic groups. Molecular modelling of representative compounds revealed structural features, which may have contributed to the varying potencies noted. In general, the compounds in series 6 were well tolerated when administered to mice. Anticonvulsant properties were demonstrated by a number of compounds in the maximal electroshock (MES) screen when administered intraperitoneally to mice while 4c and 6e afforded protection in the MES test when given orally to rats.

1-Methyl-3-nitropyridine: an efficient oxidant of NADH in non-enzymatic and enzyme-mediated processes

It is shown that NADH can be effectively oxidized by 1-methyl-3-nitropyridine in non-enzymatic and enzyme-mediated processes. Mechanistic issues of these reactions are discussed. These processes seem to contribute to the observed cytotoxicity of 1-methyl-3-nitropyridine. A key role of 1-methyl-3-nitropyridinyl radical formed in the enzyme-mediated processes is emphasized.

Total Syntheses of (+)-Chloropuupehenone and (+)-Chloropuupehenol and Their Analogues and Evaluation of Their Bioactivities

Tetracyclic pyrans (+)-chloropuupehenone (1) and (+)-chloropuupehenol (5) and its C8-R-isomer (+)-3 were synthesized via a one-pot condensation of 1-chloro-2-lithio-3,5,6-tris(tert-butyldimethylsilyloxy)benzene (8) with (4aS,8aS)-3,4,4a,5,6,7,8,8a-octahydro-2,5,5,8a-tetramethylnaphthalene-1-carboxaldehyde (7). The major condensation product, (4aS,6aR,12bS)-2H-9,10-bis(tert-butyldimethylsilyloxy)-11-chloro-1,3,4,4a,5,6,6a,12b-octahydro-4,4,6a,12b-tetramethyl-benzo[a]xanthene (4), after desilylation provided tetracyclic pyran (+)-(4aS,6aR,12bS)-2H-11-chloro-1,3,4,4a,5,6,6a,12b-octahydro-4,4,6a,12b-tetramethyl-benzo[a]xanthene-9,10-diol (3). At a dosage of 42 mg/rat over 8 h, pyran diol 3 inhibited the intestinal absorption of cholesterol by 71% in rats. Tetracyclic pyran 4 was also converted to o-quinone 28, which inhibited cholesteryl ester transfer protein (CETP) activity and L1210 leukemic cell viability with IC(50) values of 31 and 2.4 microM, respectively. Diol (+)-5 inhibited CETP activity with an IC(50) value of 16 microM. The minor condensation product, (4aS,6aS,12bS)-2H-9,10-bis(tert-butyldimethylsilyloxy)-11-chloro-1,3,4,4a,5,6,6a,12b-octahydro-4,4,6a,12b-tetramethyl-benzo[a]xanthene (6), was transformed into (+)-5 and (+)-1. A stepwise stereoselective synthesis of (+)-1 was also developed utilizing an oxyselenylation ring-closure reaction. The synthetic sequence also produced four biologically active naturally occurring drimanic sesquiterpenes, (+)-drimane-8alpha,11-diol (34), (-)-drimenol (38), (+)-albicanol (39), and (-)-albicanal (31) as intermediates.

Lipids as cofactors in protein folding: stereo-specific lipid-protein interactions are required to form HAMLET (human alpha-lactalbumin made lethal to tumor cells)

Proteins can adjust their structure and function in response to shifting environments. Functional diversity is created not only by the sequence but by changes in tertiary structure. Here we present evidence that lipid cofactors may enable otherwise unstable protein folding variants to maintain their conformation and to form novel, biologically active complexes. We have identified unsaturated C18 fatty acids in the cis conformation as the cofactors that bind apo alpha-lactalbumin and form HAMLET (human alpha-lactalbumin made lethal to tumor cells). The complexes were formed on an ion exchange column, were stable in a molten globule-like conformation, and had attained the novel biological activity. The protein-fatty acid interaction was specific, as saturated C18 fatty acids, or unsaturated C18:1trans conformers were unable to form complexes with apo alpha-lactalbumin, as were fatty acids with shorter or longer carbon chains. Unsaturated cis fatty acids other than C18:1:9cis were able to form stable complexes, but these were not active in the apoptosis assay. The results demonstrate that stereo-specific lipid-protein interactions can stabilize partially unfolded conformations and form molecular complexes with novel biological activity. The results offer a new mechanism for the functional diversity of proteins, by exploiting lipids as essential, tissue-specific cofactors in this process.

Synthesis and antileukemic activity of new 3-(5-methylisoxazol-3-yl) and 3-(pyrimidin-2-yl)-2-styrylquinazolin-4(3H)-ones

3-(3-Methylisoxazol-5-yl) and 3-(pyrimidin-2-yl)-2-styrylquinazolin-4(3H)-ones 8a-l and 9a,c-e,h-l were synthesized by refluxing in acetic acid the corresponding 2-methylquinazolinones 6 and 8 with the opportune benzoic aldehyde for 12 h. The synthesized styrylquinazolinones 8a-l and 9a,c-e,h-l were tested in vitro for their antileukemic activity against L-1210 (murine leukemia), K-562 (human chronic myelogenous leukemia) and HL-60 (human leukemia) cell lines showing in some cases good activity.

Effects of Germinated Brown Rice Extracts with Enhanced Levels of GABA on Cancer Cell Proliferation and Apoptosis

In the present work we investigated the effects of brown rice extracts on proliferation and apoptosis of cancer cells. Brown rice extracts were prepared using nongerminated brown rice versus germinated brown rices. Mouse leukemia L1210 cells, human acute lymphoblastic leukemia Molt4 cells, and human cervical cancer HeLa cells were treated with either nongerminated brown rice extract (N ex), water-germinated extract (W ex), chitosan-germinated extract (C ex), glutamic acid-germinated brown rice extract (G ex), or chitosan/glutamic acid-germinated brown rice extract (CG ex). The concentrations of gamma-aminobutyric acid (GABA) in the G ex and CG ex were three and 3.3 times higher than the GABA concentration in the N ex, respectively. The G ex and CG ex retarded significantly the proliferation rates of L1210 and Molt4 cells, and the highest retardation rate was with CG ex. In addition, the G ex and CG ex enhanced significantly apoptosis of the cultured L1210 cells, but no significant apoptosis was seen with the other extracts, which have lower concentrations of GABA than G ex and CG ex. These results show that brown rice extracts with enhanced levels of GABA have an inhibitory action on leukemia cell proliferation and have a stimulatory action on the cancer cell apoptosis.

Tirucallane-type triterpenes from Juliania adstringens

Five tirucallane-type triterpenes were isolated along with nine known triterpenes from the bark of Juliania adstringens. The structures of the five triterpenes were determined by analysis of their 1H and 13C NMR and mass spectral data, and each compound exhibited growth inhibitory activity against leukemia cells (L-1210).

New diterpenes from Croton insularis

Two new diterpenes (1 and 2) have been isolated from the aerial parts of Croton insularis. Their structures have been established by NMR and mass spectral data, and the absolute configuration of 1 and related trachylobane diterpenes was determined through a series of chemical correlations.

Reversal of P-glycoprotein mediated vincristine resistance of L1210/VCR cells by analogues of pentoxifylline

In our previous papers we described the ability of methylxanthine pentoxifylline (PTX) to depress the P-glycoprotein (P-gp) mediated multidrug resistance (MDR) of the mouse leukemic cell line L1210/VCR. Other methylxanthines like caffeine and theophylline were found to be ineffective in this respect. In the present paper we have analysed the capability of 25 methylxanthines to depress MDR of L1210/VCR cells. These methylxanthines structurally differ in substituents located in positions N1, N3, N7 and C8. The results indicate that for an effective reversal of P-gp mediated MDR of our cells the existence of a longer polar substituent in the position N1 plays a crucial role. The elongation of the substituent in the positions N3 and N7 (from methyl to propyl) increases and in the position C8 (from H to propyl) decreases the efficacy of xanthines to reverse the vincristine resistance of L1210/VCR cells. The multiple linear regression for effectiveness of methylxanthines in reversal of P-gp mediated MDR of L1210/VCR cells (expressed as respective IC(50r) values) has been computed, with molar weight: M(w), molar volume: V(M), molar refractivity: R(M), crystal density: d and partition coefficient n-octanol/water: logP as descriptors. A high intercorrelation of M(W), V(M) and R(M) was found for the tested group of methylxanthines indicating that only one of these parameters is necessary for testing a potential correlation. The best fit in the multiple linear regression was obtained for R(M) applied together with d and logP and resulted in a QSAR model given by the following equation: IC(50r)=-[(32.3+/-7.2)x10(-3)xR(M)]+[(10.1+/-2.3)xd]+[(0.74+/-0.10)xlogP]-[10.5+/-3.2]. Model revealed that: (i) the molar refractivity influences the effectiveness of xanthine positively; (ii) the crystal density and partition coefficient influence the MDR reversal effectiveness of xanthine negatively.