Synthesis,Antiproliferative and Cytotoxic Activities,DNA Binding Features and Molecular Docking Study of Novel Enamine Derivatives

Novel enamine derivatives were synthesized from the reaction of lactone and chalcones and their antiproliferative and cytotoxic activities against six cancer cell lines (e. g., HeLa, HT29, A549, MCF7, PC3 and Hep3B) and one normal cell lines (e. g., FL) were investigated along with their mode of interactions with CT‐DNA. Most of the enamine derivatives with IC₅₀ values of 86–168 μM demonstrated much stronger antiproliferative activity than the starting molecules against the cancer cells. While, among the enamine derivatives, four compounds displayed higher cytotoxic potency than the control drugs (5‐fluorouracil and cisplatin) against the Hep3B cell lines, these compounds did not exhibit any significant toxicity against normal cells, FL. The UV/VIS spectral data suggest that eight compounds cause hypochromism with a slight bathochromic shift (～6 nm), indicating that they bind to the DNA by way of an intercalative or minor groove binding mode. The binding constants of the compounds are in the range of 0.1×103 M^?1–2.3×104 M^?1. The antiproliferative activity of studied enamine derivatives could possibly be due to their DNA binding as well as their cytotoxic properties. In addition to these assays, the chalcones and enamine derivatives were investigated by molecular docking to calculate the synergistic effect of antiproliferative activities against six human cancer cell lines.     

Synthesis, anti-inflammatory activity and ulcerogenic liability of novel nitric oxide donating/chalcone hybrids

A group of novel nitric oxide (NO) donating chalcone derivatives was prepared by binding various amino chalcones with different NO donating moieties including; nitrate ester, oximes and furoxans. Most of the prepared compounds showed significant anti-inflammatory activity using carrageenan-induced rat paw edema method compared with indomethacin. The prepared compounds exhibited more protection than indomethacin in regard to gastric toxicity. Histopathological investigation confirmed the beneficial effects of the NO releasing compounds in reducing ulcer formation. The incorporation of the NO-donating group into the parent chalcone derivatives caused a moderate increase in the anti-inflammatory activity with a marked decrease in gastric ulcerations compared to their parent chalcone derivatives.     

Synthesis and biological evaluation of arctigenin ester and ether derivatives as activators of AMPK

A series of new arctigenin and 9-deoxy-arctigenin derivatives bearing different ester and ether side chains at the phenolic hydroxyl positions are designed, synthesized, and evaluated for activating AMPK potency in L6 myoblasts. Initial biological evaluation indicates that some alkyl ester and phenethyl ether arctigenin derivatives display potential activities in AMPK phosphorylation improvement. Further structure–activity relationship analysis shows that arctigenin ester derivatives 3a, 3h and 9-deoxy-arctigenin phenethyl ether derivatives 6a, 6c, 6d activate AMPK more potently than arctigenin. Moreover, the 2-(3,4-dimethoxyphenyl)ethyl ether moiety of 6c has been demonstrated as a potential functional group to improve the effect of AMPK phosphorylation. The structural optimization of arctigenin leads to the identification of 6c as a promising lead compound that exhibits excellent activity in AMPK activation.     

Synthesis and cytotoxicity of dihydroartemisinin ethers containing cyanoarylmethyl group

A new type of ether of dihydroartemisinin containing cyano and aryl groups was prepared and tested for cytotoxicity to A549, P388, L1210 and HT29 cells using the MTT assay. 12k and 12l were the most cytotoxic compounds. 13 lacking the peroxy group showed a 1000-fold less potency than 12l. Similarly, the inactive compound 14 indicated that the position of cyano groups was also important. Flow cytometry data showed that the compounds caused an accumulation of P388 cells in the G(1)-phase of the cell cycle.     

Cytotoxic and apoptotic effects of chalcone derivatives of 2‐acetyl thiophene on human colon adenocarcinoma cells

Recent studies report that chalcones exhibit cytotoxicity to human cancer cell lines. Typically, the form of cell death induced by these compounds is apoptosis. In the context of the discovery of new anticancer agents and in light of the antitumour potential of several chalcone derivatives, in the present study, we synthesized and tested the cytotoxicity of six chalcone derivatives on human colon adenocarcinoma cells. Six derivatives of 3‐phenyl‐1‐(thiophen‐2‐yl) prop‐2‐en‐1‐one were prepared and characterized on the basis of their ¹H and ¹³C NMR spectra. HT‐29 cells were treated with synthesized chalcones on two concentrations by three different incubation times. Cells were evaluated by cell morphology, Tetrazolium dye (MTT) colorimetric assay, live/dead, flow cytometry (annexin V) and gene expression analyses to determine the cytotoxic way. Chalcones 3‐(4‐bromophenyl)‐1‐(thiophen‐2‐yl)prop‐2‐en‐1‐one (C06) and 3‐(2‐nitrophenyl)‐1‐(thiophen‐2‐yl)prop‐2‐en‐1‐one (C09) demonstrated higher cytotoxicity than other chalcones as shown by cell morphology, live/dead and MTT assays. In addition, C06 induced apoptosis on flow cytometry annexin V assay. These data were confirmed by a decreased expression of anti‐apoptotic genes and increased pro‐apoptotic genes. Our findings indicate in summary that the cytotoxic activity of chalcone C06 on colorectal carcinoma cells occurs by apoptosis. Copyright © 2012 John Wiley & Sons, Ltd.     

New luciferin-based probe substrates for human CYP26A1

Activity of human CYP26A1 towards six proluciferin probe substrates and their ester derivatives was monitored. These included three monofluorobenzyl ether isomers and three five-membered heterocycles. Overall, luciferin substrates with a free acid group gave higher activities than the ester compounds. Also, luciferin derivatives with six-ring structures were better metabolized than those with five-rings. The best substrates identified in this study are Luciferin 6′ 3-fluorobenzyl ether (Luciferin-3FBE) and its methyl ester (Luciferin-3FBEME). Taken together, we describe eleven new probe substrates for CYP26A1 and demonstrate for the first time that CYP26A1 does not only accept acid substrates but can also metabolize esters.     

Comparative in vivo sensitizing efficacy of porphyrin and chlorin dimers joined with ester,ether, carbon–carbon or amide bonds

The anti-cancer activity of dimers joined with ether, ester or carbon–carbon bonds by photodynamic therapy (PDT) was compared by using DBA/2 mice transplanted with SMT/F tumors. Dimers with ether and carbon–carbon linkages were found to be more effective than those linked with ester bonds. Variation of the substituents at peripheral positions made a significant difference in in vivo efficacy. Among the ether and carbon–carbon linked dimers, the divinyl analogs were found to be most effective. The preliminary in vivo results also suggest that the position(s) of the hydrophilic substituents in the molecules make a remarkable difference in photosensitizing activity. An unsymmetrical dimer with an amide linkage, obtained from 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a (HPPH) was found to be less effective than HPPH.     

New retinoid derivatives as back-ups of Adarotene

Adarotene belongs to the so-called class of atypical retinoids. The presence of the phenolic hydroxyl group on Adarotene structure allows a rapid O-glucuronidation as a major mechanism of elimination of the drug, favoring a fast excretion of its glucuronide metabolite in the urines. A series of ether, carbamate and ester derivatives was synthesized. All of them were studied and evaluated for their stability at different pH. The cytotoxic activity in vitro on NCI-H460 non-small cell lung carcinoma and A2780 ovarian tumor cell lines was also tested. A potential back-up of Adarotene has been selected to be evaluated in tumor models.     

New derivatives of 11-methyl-6-[2-(dimethylamino)ethyl]-6H-indolo[2,3-b]quinoline as cytotoxic DNA topoisomerase II inhibitors

Novel indolo[2,3-b]quinoline derivatives substituted at N-6 and C-2 or C-9 positions with (dimethylamino)ethyl chains linked to heteroaromatic core by ether, amide or amine bonds, were manufactured and evaluated in vitro for their cytotoxic activity against several cell lines of different origin including multidrug resistant sublines and tested for their ability to influence the cell cycle and inhibit topoisomerase II activity. It was found, that all compounds show cytotoxic activity against cell lines tested, including multidrug resistant LoVo/DX, MES-SA/DX5 and HL-60 sublines. The tested compounds induce the G(2)M phase cell cycle arrest in Jurkat cells, and inhibit topoisomerase II activity.     

Hypocholesterolemic activity of hesperetin derivatives

Hesperetin ester and ether derivatives possessing a long alkyl chain were synthesized for examining their hypocholesterolemic activities in high cholesterol-fed mice. Hesperetin 7-O-lauryl ether (4b) and hesperetin 7-O-oleyl ether (4e) exhibited strong cholesterol-lowering effects.     

Lipid hydroperoxy and hydroxy derivatives in copper-catalyzed oxidation of low density lipoprotein

Oxidation of low density lipoprotein (LDL) causes changes in the biological properties of LDL that may be important in atherogenesis. That LDL oxidation is accompanied by lipid peroxidation has been demonstrated, but previous analyses of the products of LDL oxidation have not included measurement of specific lipid hydroperoxy and hydroxy derivatives. In this study, LDL was isolated from plasma of normal volunteers and exposed to oxygenated buffer and 5 microM CuSO4 for 24 h. Oxidized LDL showed decreased linoleate (18:2) and arachidonate (20:4) content with increased concentrations of thiobarbituric acid reactive substances (TBARS) and hydroxy and hydroperoxy 18:2 and 20:4. The electrophoretic mobility of the LDL protein also was increased by oxidation. After reduction, the hydroxy fatty acids were characterized by gas chromatography-mass spectrometric analysis of the trimethylsilyl ether methyl ester derivatives. The hydroperoxy and hydroxy derivatives accounted for approximately 70% of the linoleate consumed during LDL oxidation and represented 45-fold more product than was measured by TBARS analysis. Numerous biological properties, including cytotoxic and chemoattractant activities of hydroperoxy and hydroxy fatty acids, have been reported, but the manner in which they may contribute to atherogenesis requires further study.     

Synthesis and antitumor activity of novel C-8 ester derivatives of leinamycin

A novel series of C-8 ester derivatives of leinamycin are described. Condensation of N-substituted amino acids or carboxylic acids containing polyether moiety with leinamycin resulted in the C-8 ester derivatives with good antitumor activity in several experimental models. Among these derivatives, compound 4e, which has five ethylene glycol ether units in the C-8 acyl group, showed potent antitumor activity against human tumor xenograft. Combination with the modification of the dithiolanone moiety was applied to these C-8 ester derivatives and some of them also showed good antitumor activity.     

Uptake of photofrin II,a photosensitizer used in photodynamic therapy,by tumour cells in vitro

Photosensitizing dyes are used in fluorescence diagnostics and photodynamic therapy (PDT). These usually hematoporphyrin derivatives (HpD) accumulate preferentially within neoplastic tissues. HpD is a mixture of ether and ester linked porphyrins. Its partially purified form is known under the commercial name of photofrin II (PII). PII emission spectra were studied in a hydrophilic (PBS) and a lipophilic (PC liposomes) environment. Red shift was observed in their emission maxima from 615 nm in buffer solution to 635 nm in lipid. Identical red shift was obtained when the intracellular fluorescence of two cancer cell lines, MCF 7 and Jurkat, incubated with PII was investigated. Thus, intramembrane localization of PII may be suggested. As determined from the total fluorescence intensity, the uptake of PII was only slightly higher for Jurkat than for MCF 7 cells. Nevertheless the kinetics of the uptake was found to be different for both cell lines.     

Heme Mediates Cytotoxicity from Artemisinin and Serves as a General Anti-Proliferation Target

Heme (Fe2+ protoporphyrin IX) is an essential molecule that has been implicated the potent antimalarial action of artemisinin and its derivatives, although the source and nature of the heme remain controversial. Artemisinins also exhibit selective cytotoxicity against cancer cells in vitro and in vivo. We demonstrate that intracellular heme is the physiologically relevant mediator of the cytotoxic effects of artemisinins. Increasing intracellular heme synthesis through the addition of aminolevulinic acid, protoporphyrin IX, or transferrin-bound iron increased the cytotoxicity of dihydroartemisinin, while decreasing heme synthesis through the addition of succinyl acetone decreased its cytotoxic activity. A simple and robust high throughput assay was developed to screen chemical compounds that were capable of interacting with heme. A natural products library was screened which identified the compound coralyne, in addition to artemisinin, as a heme interacting compound with heme synthesis dependent cytotoxic activity. These results indicate that cellular heme may serve a general target for the development of both anti-parasitic and anti-cancer therapeutics.     

Introduction of a carboxyl group through an acetal as a new route to carboxylic acid derivatives of sugars.

A new class of carboxylic acid derivatives of sugars is described. Acetalation of mono- and disaccharides with a functionalized vinylic ether or a diethoxybutanoate afforded mono- and diacetals bearing an ester group. Their saponification led to the corresponding carboxylic acid acetals in which the length of the acetal side chain can be modulated.     

Synthesis and cytotoxic activity of 17-carboxylic acid modified 23-hydroxy betulinic acid ester derivatives

New 17-carboxylic acid modified 23-hydroxy betulinic acid ester derivatives were prepared and tested for cytotoxic activity on five cancer cell lines in vitro: all tested compounds showed stronger cytotoxic activity than 23-hydroxy betulinic acid and betulinic acid. In addition, compound 5a was tested for anti-tumor activity in vivo: it had much better anti-tumor activity than 23-OH betulinic acid and had similar anti-tumor activity with cyclophosphamide and 5-fluorouracil.     

Pharmacokinetic and -dynamic investigations on HL60 cells with a new protoporphyrin dimethyl ester hematoporphyrin dimer

Pharmacokinetic and -dynamic studies using a novel porphyrin dimer were performed in human line HL60 promyelocytic leukemia cells. Uptake of the dimer into leukemic cells was observed to occur at substantially lower concentrations in comparison to a previously described monomeric dihematoporphyrin ether-free hematoporphyrin derivative. Both dimer and monomer derivatives could be demonstrated to inhibit cell growth, with no remarkable quantitative differences being found in cell proliferation studies regarding [3H]-thymidine incorporation and assay for colony formation. Structurally, the new compound represents an unsymmetrically substituted diethyl ether having protoporphyrin dimethyl ester and hematoporphyrin as substituents. For this reason the compound was designated as protoporphyrin dimethyl ester hematoporphyrin ether.     

Evidence for the involvement of carbon-centered radicals in the induction of apoptotic cell death by artemisinin compounds

Artemisinin and its derivatives are currently recommended as first-line antimalarials in regions where Plasmodium falciparum is resistant to traditional drugs. The cytotoxic activity of these endoperoxides toward rapidly dividing human carcinoma cells and cell lines has been reported, and it is hypothesized that activation of the endoperoxide bridge by an iron(II) species, to form C-centered radicals, is essential for cytotoxicity. The studies described here have utilized artemisinin derivatives, dihydroartemisinin, 10beta-(p-bromophenoxy)dihydroartemisinin, and 10beta-(p-fluorophenoxy)dihydroartemisinin, to determine the chemistry of endoperoxide bridge activation to reactive intermediates responsible for initiating cell death and to elucidate the molecular mechanism of cell death. These studies have demonstrated the selective cytotoxic activity of the endoperoxides toward leukemia cell lines (HL-60 and Jurkat) over quiescent peripheral blood mononuclear cells. Deoxy-10beta-(p-fluorophenoxy)dihydroartemisinin, which lacks the endoperoxide bridge, was 50- and 130-fold less active in HL-60 and Jurkat cells, respectively, confirming the importance of this functional group for cytotoxicity. We have shown that chemical activation is responsible for cytotoxicity by using liquid chromatography-mass spectrometry analysis to monitor endoperoxide activation by measurement of a stable rearrangement product of endoperoxide-derived radicals, which was formed in sensitive HL-60 cells but not in insensitive peripheral blood mononuclear cells. In HL-60 cells the endoperoxides induce caspase-dependent apoptotic cell death characterized by concentration- and time-dependent mitochondrial membrane depolarization, activation of caspases-3 and -7, sub-G(0)/G(1) DNA formation, and attenuation by benzyloxycarbonyl-VAD-fluoromethyl ketone, a caspase inhibitor. Overall, these results indicate that endoperoxide-induced cell death is a consequence of activation of the endoperoxide bridge to radical species, which triggers caspase-dependent apoptosis.     

A novel strategy for unambiguous determination of inner esterification sites of ganglioside lactones

A method is described which is suitable for protection of all free hydroxyl groups of a glycosphingolipid under conditions which will not cleave ester linkages, including inner ester linkages characteristic of ganglioside lactones. The protecting methoxyethoxymethyl group is stable in alkaline media, surviving permethylation procedures which introduce a methyl ether at all sites previously acylated. Hydrolysis, reduction, and acetylation then yield alditol acetate derivatives which can be analyzed by conventional GC-MS to locate the methyl ether groups. The method is used to locate the inner esterification site of GM3 lactone.     

Synthesis and antiangiogenic activity of exo-olefinated deoxoartemisinin derivatives

10-exo-Bromoalkylidene and benzylidene deoxoartemisinin derivatives with antiangiogenic activity were synthesized from corresponding 10-alkanesulfonyl dihydroartemisinin and 10-phenylmethanesulfonyl dihydroartemisinin using a highly efficient, mild, and simple Ramberg-B?cklund rearrangement.