Cytotoxic Activity and Quantitative Structure Activity Relationships of Arylpropyl Sulfonamides

B13 is a ceramide analogue and apoptosis inducer with potent cytotoxic activity. A series of arylpropyl sulfonamide analogues of B13 were evaluated for their cytotoxicity using MTT assays in prostate cancer PC-3 and leukemia HL-60 cell lines. Some compounds (4, 9, 13, 14, 15, and 20) showed stronger activities than B13 in both tumor cell lines, and compound (15) gave the most potent activity with IC₅₀ values of 29.2 and 20.7 µM, for PC-3and HL-60 cells, respectively. Three-dimensional quantitative structure-activity relationship (3D-QSAR) analysis was performed to build highly reliable and predictive CoMSIA models with cross-validated q² values of 0.816 and 0.702, respectively. Our results suggest that long alkyl chains and a 1R, 2R configuration of the propyl group are important for the cytotoxic activities of arylpropyl sulfonamides. Moreover, the introduction of small hydrophobic groups in the phenyl ring and sulfonamide group could increase biological activity.     

Synthesis and biological evaluation of ceramide analogues with substituted aromatic rings or an allylic fluoride in the sphingoid moiety

The biological activity of synthetic ceramide analogues, having modified sphingoid and N-acyl chains, as well as fluorine substituents in the allylic position, was investigated in hippocampal neurons. Their influence on axonal growth was compared to that of C(6)-N-acyl analogues of natural ceramides. D-erythro-Ceramides with a phenyl group in the sphingoid moiety and a short N-acyl chain were able to reverse the inhibitory effect of fumonisin B(1) (FB(1)), but not of D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (PDMP), on accelerated axonal growth in hippocampal neurons. Moreover, we demonstrated that a ceramide analogue with an aromatic ring in the sphingoid moiety is recognized as a substrate by glucosylceramide synthase, which suggests that the observed biological effects are mediated by activation of the ceramide analogue via glucosylation. Introduction of a methyl, pentyl, fluoro, or methoxy substituent in the para position of the phenyl ring in the sphingoid moiety yielded partly active compounds. Likewise, substitution of the benzene ring for a thienyl group did not abolish the ability to reverse the inhibition of accelerated axonal growth by FB(1). Both D-erythro- and L-threo-ceramide analogues, having an allylic fluorine substituent, partly reversed the FB(1) inhibition.     

Cytotoxic Activity and Structure Activity Relationship of Ceramide Analogues in Caki-2 and HL-60 Cells

B13, a ceramide analogue, is a ceramidase inhibitor and induces apoptosis to give potent anticancer activity. A series of thiourea B13 analogues was evaluated for their in vitro cytotoxic activities against human renal cancer Caki-2 and leukemic cancer HL-60 in the MTT assay. Some compounds (12, 15, and 16) showed stronger cytotoxicity than B13 and C6-ceramide against both tumor cell lines, and compound (12) gave the most potent activity with IC₅₀ values of 36 and 9 µM, respectively. Molecular modeling of thiourea B13 analogues was carried out by comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA). We obtained highly reliable and predictive CoMSIA models with cross-validated q² values of 0.707 and 0.753 and CoMSIA contour maps to show the structural requirements for potent activity. These data suggest that the amide group of B13 could be replaced by thiourea, that the stereochemistry of 1,3-propandiol may not be essential for activity and that long alkyl chains increase cytotoxicity.     

Cytotoxicity of corylifoliae fructus. II. Cytotoxicity of bakuchiol and the analogues

Bakuchiol is a major component of Corylifoliae Fructus (Psoralea corylifolia L.) and has been clarified to have cytotoxic activity. The chemical structure-cytotoxic activity relationship of bakuchiol was investigated by means of cytotoxic activity of synthesized analogues of bakuchiol and phenol. It was proved that an alkyl group was necessary for cytotoxic activity. But the double bonds in the unsaturated hydro-carbon group exerted but little influence on the cytotoxic activity. The cytotoxic activity of bakuchiol was the strongest as compared with that of the analogues examined.     

Exploring the role of the 5'-position of TSAO-T. Synthesis and anti-HIV evaluation of novel TSAO-T derivatives

Various analogues of the anti-HIV-1 agent TSAO-T, [1-[2',5'-bis-O-(tert-butyldimethylsilyl)-beta-D-ribofuranosyl]thymine]-3'-spiro-5"-(4"-amino-1",2"-oxathiole-2",2"-dioxide) have been synthesized in which the 5'-TBDMS group has been replaced by alkyl-, alkenyl- or aromatic ether groups, substituted amines, carbamoyl or (thio)acyl groups. The compounds synthesized were evaluated for their inhibitory effect on HIV-1 and HIV-2 replication in cell culture. Replacement of the 5'-TBDMS group by an acyl, aromatic or a cyclic moiety markedly diminish or even eliminate the anti-HIV activity. However, the presence at that position of an alkyl or alkenyl chain, partially retain antiviral activity. These observations suggest that the 5'-TBDMS group of the TSAO molecule plays a crucial role.     

Potential anticancer agents: 5-(N-substituted-aminocarbonyl)- and 5-(N-substituted-aminothiocarbonyl)-5,6,7,8-tetrahydrofolic acids

5-[[N-[(Ethoxycarbonyl)alkyl]amino]carbonyl] (6-9) and the corresponding aminothiocarbonyl (12-15) derivatives of 5,6,7,8-tetrahydrofolic acid were prepared as multisubstrate analogues of the substrate--cofactor adduct in the reactions catalyzed by the folate-mediated one-carbon transfer reactions. Evaluation in vitro showed that 7 (alkyl = hexyl) was cytotoxic to H.Ep.-2 cells (ED50, 4 microM) but noncytotoxic to proliferating L1210 cells. No activity was observed for 7 against the P388 leukemia in mice.     

Synthesis and biological evaluation of spin-labeled alkylphospholipid analogs

Alkylphospholipid analogues of perifosine and miltefosine bearing a nitroxide moiety at different positions on an alkyl chain were synthesized as electron paramagnetic resonance (EPR) probes. Their amphiphilic properties were characterized by determining their critical micelle concentration (cmc) and hemolytic activity on erythrocytes both in free and liposomal form. Spin-labeled analogues as membrane components of large unilamellar liposomes containing cholesterol and dicetyl phosphate or in free solution were evaluated using the MTT assay to determine growth inhibition on MT1, MT3, and MCF7 breast cancer cell lines. 4a (IC50 = 56.4 microM) was found to be significantly more active than the perifosine against the MCF-7 cell line. Its high cmc (194.03 microM) and low hemolytic activity shows that its cytotoxic activity might be more specific; therefore, 4a can be an important molecular tool for further EPR investigations.     

Stereoselective synthesis and structure-activity relationship of novel ceramide trafficking inhibitors. (1R,3R)-N-(3-hydroxy-1-hydroxymethyl-3-phenylpropyl)dodecanamide and its analogues

New ceramide trafficking inhibitors, (1R,3R)-N-(3-hydroxy-1-hydroxymethyl-3-phenylpropyl)dodecanamide (HPA-12) and a series of its analogues, were synthesized in diastereomerically and enantiomerically pure forms, and the structure-activity relationship was investigated. These analogues were stereoselectively synthesized via catalytic enantioselective Mannich-type reactions using a Cu(II)-chiral diamine 4 complex. Analysis of HPA-12 analogues having various lengths of the amide side chain showed that the optimal chain length for the inhibition of sphingomyelin biosynthesis is 13 with an IC(50) of approximately 50 nM. Masking of the hydroxy group at the 2'- or 3-position of HPA-12 was carried out by methylation, and it was revealed that these hydroxy groups were essential for the activity. Installation of another hydroxy group onto HPA-12 at the same position as that in the natural ceramide was also conducted, but no enhancement of the activity was observed.     

Synthesis and cytotoxic evaluation of novel spirohydantoin derivatives of the dihydrothieno[2,3-b]naphtho-4,9-dione system

The synthesis and cytotoxic evaluation of 3-(alkyl)(alkyl-substituted)spiro[(dihydroimidazo-2,4-dione)-5,3'-(2',3'-dihydrothieno[2,3-b]naphtho-4',9'-dione)]derivatives are described. Evaluation of these analogues against the MCF-7 human breast carcinoma and SW 620 human colon carcinoma cell lines uncovered for most of the compounds a cytotoxic potency comparable to or greater than that of doxorubicin. Compound 15 exhibited remarkable cytotoxic activity against several other human solid tumor cell lines. Interestingly, only a partial cross-resistance to compound 15 in selected tumor cell sublines known to be resistant to doxorubicin (MCF-7/Dx and A2780/Dx) was observed, whereas a total absence of cross-resistance in a tumor cell subline selected for resistance to cisplatin was found (A2780/DDP).     

(2,6-Methano-3-benzazocin-11 beta-yl)alkanones. 1. Alkylalkanones: a new series of N-methyl derivatives with novel opiate activity profiles.

A general stereospecific synthesis of (N-methyl-2,6-methano-3-benzazocin-11 beta-yl)alkanones is described and applied to the preparation of a series of alkyl ketones wherein the alkyl group is a straight or terminally branched chain containing from one to six carbon atoms. Several compounds with methoxy groups in the aromatic ring are in the morphine range of potency; they are uniformly inactive as phenazocine antagonists. Phenolic analogues range up to 100 times as potent as morphine. Those containing five or six carbon atoms in the alkyl group exhibit phenazocine antagonist activity, in one case equivalent to naloxone. This compound (3e) is selective for phenazocine in its antagonist action.     

Synthesis and antitumor activity of conjugates of muramyldipeptide, normuramyldipeptide, and desmuramylpeptides with acridine/acridone derivatives

The synthesis of two groups (Chart 1, types A and B) of conjugates of MDP (muramyldipeptide) and nor-MDP (normuramyldipeptide) with acridine/acridone derivatives and the synthesis of analogues of desmuramylpeptides (Chart 1, types C and D) containing acridine/ acridone derivatives have been described. In type A conjugates, the hydroxyl group at C6 of the sugar moiety was acylated with acridine/acridone N-substituted omega-aminoalkanocarboxylic acids (Scheme 1), whereas the conjugates of type B (Table 2) and three analogues of type C or D (Scheme 2) have an amide bond formed between the carboxylic group of isoglutamine and the amine function of the respective acridine/acridone derivatives. The preliminary screening data indicate that the analogues of groups A, C, and D exhibit small cytotoxic activity, whereas several analogues of type B, 4b, 4c, 4e, 4g, 4h, 4i, and 4l, exhibiting potent in vitro cytotoxic activity against a panel of human cell lines (Table 4), have been selected by the National Cancer Institute (NCI) Evaluation Committee for further testing. Analogues 4b and 4h were active in the in vivo hollow fiber assay (Table 5). Analogue 3a shows an immunostimulating effect on the cytotoxic activity of the NK cells obtained from the spleen of healthy and Ab melanoma bearing animals.     

Further naphthylcombretastatins. An investigation on the role of the naphthalene moiety

By synthesis and biological studies of new naphthalene analogues of combretastatins, we have found that the naphthalene is a good surrogate for the isovanillin moiety (3-hydroxy-4-methoxyphenyl) of combretastatin A-4, always generating highly cytotoxic analogues when combined with the 3,4,5-trimethoxyphenyl or related systems. On the other hand, when the naphthalene replaces the 3,4,5-trimethoxyphenyl moiety, the cytotoxic activity is largely decreased. The most cytotoxic naphthalene analogues of combretastatins, which also produce inhibition of tubulin polymerization, exerted their antimitotic effects through microtubule network disruption and subsequent G(2)/M arrest of the cell cycle in human cancer cells.     

Cytotoxic effects of methionine alkyl esters and amides in normal and neoplastic cell lines

Homologous series of L-methionine alkyl ester hydrochlorides and tosylates were synthesized and evaluated for in vitro growth inhibitory activity in Meth A sarcoma. Cytotoxicity, as determined by [3H]thymidine incorporation, was found to be directly proportional to alkyl chain length and surface tension lowering activity. L-Methionine decyl and dodecyl ester hydrochlorides possessed optimum cytotoxic activity (IC50 = 29, 28 microM) which was not reversible by the addition of L-methionine. Surface tension of a 50 microM solution of the decyl and dodecyl ester hydrochlorides were 35.4 and 32.7 dyn/cm, respectively. The corresponding decyl and dodecyl ester tosylates and amide hydrochlorides were less active. The N-t-butoxycarbonyl analogues were essentially inactive, demonstrating the necessity of an unsubstituted and/or potentially cationic amino group. Methionine dependence characteristics and cytotoxicity were also determined for three human (IMR-90, LX-1, MCF7) and four additional murine (L1210, L5178Y, 3T3, SV-T2) cell lines. The human cell lines Meth A, LX-1, and SV-T2 were found to be methionine independent. The LX-1 tumor cell line and the SV-T2 transformed line exhibited two to four times more sensitivity to the cytotoxic and cytolytic properties of the decyl and dodecyl ester hydrochlorides than their normal counterparts. The dodecyl amide hydrochloride derivative demonstrated enhanced cytotoxic activity in vivo relative to the corresponding ester, possibly due to decreased metabolic hydrolysis.     

Synthesis and cytotoxicity of new 3-alkyl-1-(1-methyl-2-phenylethyl)ureas related to ceramide

A series of new 3-alkyl-1-(1-methyl-2-phenylethyl)ureas related to ceramide was synthesized and evaluated for their in vitro cytotoxic activity against five human tumor cell lines. The urea analogue (2b) of B13 showed comparable or slightly more potent cytotoxic activity as compared to B13, indicating that urea does appear to serve as a bioisostere of amide.     

Synthesis and antihypertensive activity of 4-(substituted-carbonylamino)-2H-1-benzopyrans

The synthesis and antihypertensive activity of a series of novel 4-(substituted-carbonylamino)-2H-1-benzopyran-3-ols, administered orally to conscious spontaneously hypertensive rats, are described. Optimum activity was observed for compounds with alkyl, amino, or aryl groups flanking the carbonyl group. Of the alkyl and amino series the most potent compounds contained the methyl and methylamino groups, respectively. Several analogues have been compared with cromakalim (1) for their effects on potassium ion efflux in the rabbit mesenteric artery using rubidium-86 as a marker. The ability of each compound to enhance rubidium-86 efflux is approximately parallelled by its blood pressure lowering activity, and thus these analogues, like compound (1), belong to the series of drugs which have been classified as potassium-channel activators.     

Synthesis, in vitro anti-breast cancer activity, and intracellular decomposition of amino acid methyl ester and alkyl amide phosphoramidate monoesters of 3'-azido-3'-deoxythymidine (AZT)

We report the synthesis and anticancer activity of a series of AZT phosphoramidate monoesters containing amino acid methyl ester (3a-11a) and N-alkyl amide (3b-11b, 9c-9f) moieties. The aromatic amino acid methyl esters were found to be more cytotoxic than the aliphatic analogues toward MCF-7 cells (human pleural effusion breast adenocarcinoma cell line). A marked stereochemical preference for the L-amino acid stereochemistry was also observed in MCF-7 cells. There was no consistent enhancement of cytotoxicity of the methyl amides over the corresponding methyl esters. AZT and the two AZT aromatic amino acid methyl ester phosphoramidates 8a and 9a were found to be more cytotoxic toward MCF-7 cells than to CEM cells (human T-cell lymphoblastic leukemia). The selective cytotoxicity toward MCF-7 cells may be associated with greater intracellular levels of phosphoramidate monoester and/or phosphorylated AZT.     

Design, synthesis, and characterization of the antitumor activity of novel ceramide analogues.

A deficiency in apoptosis is one of the key events in the proliferation and resistance of malignant cells to antitumor agents; for these reasons, the search for apoptosis-inducing drugs represents a valuable approach for the development of novel anticancer therapies. In this study we report the first example of conformationally restrained analogues of ceramide (compounds 1-4), where the polar portion of the molecule has been replaced by a thiouracil (1, 3) or uracil (2, 4) ring. The evaluation of their biologic activity on CCRF-CEM human leukemia cells demonstrated that the most active was compound 1 followed by compound 2 (mean 50% inhibition of cell proliferation [IC(50)] 1.7 and 7.9 microM, respectively), while compounds 3 and 4 were inactive, as were uracil, thiouracil, and 5,6-dimethyluracil, the pyrimidine moieties of compounds 1-4. For comparison, the IC(50) of the reference substance, the cell-permeable C2-ceramide, was 31.6 microM. Compounds 1 and 2 and C2-ceramide were able to trigger apoptosis, as shown by the occurrence of DNA and nuclear fragmentation, and to release cytochrome c from treated cells. The treatment of female CD-1 nu/nu athymic mice bearing a WiDr human colon xenograft with the most active compound 1 at 2, 10, 50, and 200 mg/kg ip daily for 10 days resulted in an antitumor effect that was equivalent at 50 mg/kg or superior (200 mg/kg) to that of cyclophosphamide, 20 mg/kg ip daily, delivered on the same schedule, with markedly lower systemic toxicity. In conclusion, the present study demonstrates that the new ceramide analogues 1 and 2 are characterized by in vitro and in vivo antitumor activity and low toxicity.     

DNA-binding properties and cytotoxicity of extended aromatic bisamidines in breast cancer MCF-7 cells.

The DNA binding properties of three novel extended aromatic bisamidines (1-3) possessing different dicationic terminal side chains were studied. Data from the ethidium displacement assay showed that bisamidines 1-3 have significant affinity for DNA. We studied the cytotoxic activity of bisamidines 1-3 and Hoechst 33258 in the cultured breast cancer MCF-7 cells. These data show that in broad terms the cytotoxic potency of bisamidines 1-3 in the cultured breast cancer MCF-7 cells decreases with the size of the alkyl group substituent (cyclopropyl > isopropyl > cyclopentyl), in accord with their increases in DNA affinity, as shown by the binding constant values. The bisamidines 1-3 showed comparable antitumor activity to Hoechst 33258.     

The role of substituents ofar-turmerone for its anticancer activity

For the evaluation of the role of substituents ofar-turmerone for its anticancer activity, ar-turmerone (1a) and its analogs like 2-methyl-6-(4′-methyphenyl)-2-octen-4-one (1b), 2-methyl-6-phenyl-2-hepten-4-one (1c), 2-methyl-6-phenyl-2-octen-4-one, (1d), and 2-methyl-6-(trans-4′-methylcyclohexyl)-2-hepten-4-one (1e) were prepared and their cytotoxic activities against L₁₂₁₀ cell were determined. Omission of methyl group atpara-position dose not variate the cytotoxicity of ar-turmerone. Elongation of alkyl group at 6-position decreases ED₅₀ value. Saturation of aromatic ring of ar-turmerone markedly decreases the cytotoxicity. Therefore the smaller size of alkyl group at 6-position and aromatic ring of ar-turmerone should be essential for exhibiting its anticancer activity.     

3'-Hydroxyesorubicin halogenated at C-2'.

New 3'-deamino-3'-hydroxy-2'-iodoesorubicin analogues were synthesized using optically active 4,6-dideoxyhex-1-enitol (7) as starting material. Direct coupling of daunomycinone (8) and 14-O-tert-butyldimethylsilyladriamycinone (9) with glycal 7 in the presence of N-iodosuccinimide gave 2'-iodo analogues 10 and 12. Deprotection of compounds 10 and 12 led to compounds 11 and 14, the 2'-iodinated, fully unblocked 4'-deoxy-3'-hydroxy congeners of daunorubicin (2) and doxorubicin (1). 2'-Iodo-3'-hydroxyesorubicin (14) showed cytotoxic activity similar to that of doxorubicin in vitro and higher antitumor activity against L-1210 leukemia than doxorubicin in vivo.