Synthesis and Anticancer Activity Evaluation of 5-[2-Chloro-3-(4-nitrophenyl)-2-propenylidene]-4-thiazolidinones

A series of novel 5-[(Z,2Z)-2-chloro-3-(4-nitrophenyl)-2-propenylidene]-thiazolidinones (Ciminalum–thiazolidinone hybrid molecules) have been synthesized. Anticancer activity screening toward the NCI60 cell lines panel, gastric cancer (AGS), human colon cancer (DLD-1), and breast cancer (MCF-7 and MDA-MB-231) cell lines allowed the identification of 3-{5-[(Z,2Z)-2-chloro-3-(4-nitrophenyl)-2-propenylidene]-4-oxo-2-thioxothiazolidin-3-yl}propanoic acid (2h) with the highest level of antimitotic activity with mean GI₅₀/TGI values of 1.57/13.3 μM and a certain sensitivity profile against leukemia (MOLT-4, SR), colon cancer (SW-620), CNS cancer (SF-539), melanoma (SK-MEL-5), gastric cancer (AGS), human colon cancer (DLD-1), and breast cancers (MCF-7 and MDA-MB-231) cell lines. The hit compounds 2f, 2i, 2j, and 2h have been found to have low toxicity toward normal human blood lymphocytes and a fairly wide therapeutic range. The significant role of the 2-chloro-3-(4-nitrophenyl)prop-2-enylidene (Ciminalum) substituent in the 5 position and the substituent’s nature in the position 3 of core heterocycle in the anticancer cytotoxicity levels of 4-thiazolidinone derivatives have been established     

Total synthesis of (-)-CP2-disorazole C1

The total synthesis of a bis-cyclopropane analog of the antimitotic natural product (-)-disorazole C(1) was accomplished in 23 steps and 1.1% overall yield. A vinyl cyclopropane cross-metathesis reaction generated a key (E)-alkene segment of the target molecule. IC(50) determinations of (-)-CP(2)-disorazole C(1) in human colon cancer cell lines indicated low nanomolar cytotoxic properties. Accordingly, this synthetic bioisostere represents the first biologically active disorazole analog not containing a conjugated diene or polyene substructure element.     

Solar radiation, vitamin D and survival rate of colon cancer in Norway

Solar radiation contributes significantly to the status of serum calcidiol (25-hydroxyvitamin D3, 25-(OH)D3) in humans, even at the high latitudes of northern Norway. Thus, in late summer the serum concentration of calcidiol is roughly 50% larger than that in late winter, when the solar radiation in Norway contains too little ultraviolet radiation to induce any synthesis of vitamin D3 in human skin. This seems to influence the prognosis of colon cancer. We here report that the survival rate of colon cancer in men and women, assessed 18 months after diagnosis, is dependent on the season of diagnosis. A high serum concentration of calcidiol at the time of diagnosis, i.e. at the start of conventional therapy, seems to give an increased survival rate. This agrees with cell and animal experiments reported in the literature, as well as with epidemiological data from some countries relating colon cancer survival with latitude and vitamin D3 synthesis in skin. One possible interpretation of the present data is that, the level of calcidiol, or its derivative calcitriol (1alpha,25-dihydroxyvitamin D3, 1alpha,25-(OH)2D3), may act positively in concert with conventional therapies of colon cancer.     

Deoxycholic Acid Modulates Cell-Junction Gene Expression and Increases Intestinal Barrier Dysfunction

Diet-related obesity is associated with increased intestinal hyperpermeability. High dietary fat intake causes an increase in colonic bile acids (BAs), particularly deoxycholic acid (DCA). We hypothesize that DCA modulates the gene expression of multiple cell junction pathways and increases intestinal permeability. With a human Caco-2 cell intestinal model, we used cell proliferation, PCR array, biochemical, and immunofluorescent assays to examine the impact of DCA on the integrity of the intestinal barrier and gene expression. The Caco-2 cells were grown in monolayers and challenged with DCA at physiological, sub-mM, concentrations. DCA increased transcellular and paracellular permeability (>20%). Similarly, DCA increased intracellular reactive oxidative species production (>100%) and accompanied a decrease (>40%) in extracellular signal-regulated kinase 1/2 (ERK1/2) signaling pathways. Moreover, the mRNA levels of 23 genes related to the epithelial barrier (tight junction, focal adhesion, gap junction, and adherens junction pathways) were decreased (>40%) in (0.25 mM) DCA-treated Caco-2 cells compared to untreated cells. Finally, we demonstrated that DCA decreased (>58%) the protein content of occludin present at the cellular tight junctions and the nucleus of epithelial cells. Collectively, DCA decreases the gene expression of multiple pathways related to cell junctions and increases permeability in a human intestinal barrier model.     

The first synthesis of (-)-asperpentyn and efficient syntheses of (+)-harveynone, (+)-epiepoformin and (-)-theobroxide

A generally applicable strategy for the synthesis of a range of polyoxygenated cyclohexane natural products has been developed. The enantioselective syntheses of (-)-theobroxide, a polyoxygenated cyclohexane natural compound with potent growth inducing properties in potato microtubers has been achieved via a 1,2 O-silyl migration between trans-hydroxyl groups and a remote hydroxyl directed epoxidation of an enone derived from quinic acid. A thus derived alpha-iodoenone was subjected to Stille coupling with tetramethylstannane to afford the first title compound. A similar strategy enabled a route to the complete asymmetric synthesis of the acetylenic phytotoxin (+)-harveynone. By selective reduction of (-)-theobroxide, (+)-epiepoformin was also prepared in enantiopure form and similarly, stereoselective reduction of (+)-harveynone completed the first enantioselective synthesis of (-)-asperpentyn, another natural compound with antimicrobial activity.     

Phage-display selection of a human single-chain fv antibody highly specific for melanoma and breast cancer cells using a chemoenzymatically synthesized G(M3)-carbohydrate antigen

Overexpression of the cell-surface glycosphingolipid G(M3) is associated with a number of different cancers, including those of the skin, colon, breast, and lung. Antibodies against the G(M3) epitope have potential application as therapeutic agents in the treatment of these cancers. We describe the chemoenzymatic synthesis of two G(M3)-derived reagents and their use in the panning of a phage-displayed human single-chain Fv (scFv) antibody library derived from the blood of cancer patients. Three scFv-phage clones, GM3A6, GM3A8, and GM3A15, were selected for recombinant expression and were characterized using BIAcore and flow cytometry. BIAcore measurements using the purified, soluble scFvs yielded dissociation constants (K(d)) ranging from 4.2 x 10(-7) to 2.1 x 10(-5) M. Flow cytometry was used to evaluate the ability of each scFv to discriminate between normal human cells (human dermal fibroblast, HDFa), melanoma cells (HMV-1, M21, and C-8161), and breast cancer cells (BCM-1, BCM-2, and BMS). GM3A6 displayed cross-reactivity with normal cells, as well as tumor cells, and GM3A15 possessed little or no binding activity toward any of the cell lines tested. However, GM3A8 bound to five of the six tumor cell lines and showed no measurable reactivity against the HDFa cells. Hence, we have demonstrated that a synthetic G(M3) panning reagent can be used to isolate a fully human scFv that is highly specific for native G(M3) on the surface of tumor cells. The result is a significant step toward effective immunotherapies for the treatment of cancer.     

Synthesis and Biological Investigation of Bile Acid-Paclitaxel Hybrids

Chenodeoxycholic acid and ursodeoxycholic acid (CDCA and UDCA, respectively) have been conjugated with paclitaxel (PTX) anticancer drugs through a high-yield condensation reaction. Bile acid-PTX hybrids (BA-PTX) have been investigated for their pro-apoptotic activity towards a selection of cancer cell lines as well as healthy fibroblast cells. Chenodeoxycholic-PTX hybrid (CDC-PTX) displayed cytotoxicity and cytoselectivity similar to PTX, whereas ursodeoxycholic-PTX hybrid (UDC-PTX) displayed some anticancer activity only towards HCT116 colon carcinoma cells. Pacific Blue (PB) conjugated derivatives of CDC-PTX and UDC-PTX (CDC-PTX-PB and UDC-PTX-PB, respectively) were also prepared via a multistep synthesis for evaluating their ability to enter tumor cells. CDC-PTX-PB and UDC-PTX-PB flow cytometry clearly showed that both CDCA and UDCA conjugation to PTX improved its incoming into HCT116 cells, allowing the derivatives to enter the cells up to 99.9%, respect to 35% in the case of PTX. Mean fluorescence intensity analysis of cell populations treated with CDC-PTX-PB and UDC-PTX-PB also suggested that CDC-PTX-PB could have a greater ability to pass the plasmatic membrane than UDC-PTX-PB. Both hybrids showed significant lower toxicity with respect to PTX on the NIH-3T3 cell line.     

A new curcumin derivative, HBC, interferes with the cell cycle progression of colon cancer cells via antagonization of the Ca2+/calmodulin function

HBC (4-[3,5-Bis-[2-(4-hydroxy-3-methoxy-phenyl)-ethyl]-4,5-dihydro-pyrazol-1-yl]-benzoic acid) is a recently developed curcumin derivative which exhibits potent inhibitory activities against the proliferation of several tumor cell lines. In the present study, we identified Ca2+/calmodulin (Ca2+/CaM) as a direct target protein of HBC using phage display biopanning. Ca2+/CaM-expressing phages specifically bound to the immobilized HBC, and the binding was Ca2+ dependent. Moreover, flexible docking modeling demonstrated that HBC is compatible with the binding cavity for a known inhibitor, W7, in the C-terminal hydrophobic pocket of Ca2+/CaM. In biological systems, HBC induced prolonged phosphorylation of ERK1/2 and activated p21(WAF1) expression, resulting in the induction of G0/G1 cell cycle arrest in HCT15 colon cancer cells. These results suggest that HBC inhibits the cell cycle progression of colon cancer cells via antagonizing of Ca2+/CaM functions.     

Total synthesis of ningalin B utilizing a heterocyclic azadiene Diels-Alder reaction and discovery of a new class of potent multidrug resistant (MDR) reversal agents

A concise, efficient approach to the total synthesis of ningalin B (1) based on a heterocyclic azadiene Diels-Alder strategy (1,2,4,5-tetrazine-->1,2,-diazine-->pyrrole) ideally suited for construction of the densely functionalized pyrrole core found in the natural product is detailed. Examination of the natural product and a number of synthetic intermediates revealed that while lacking inherent cytotoxic activity, many reverse the multidrug-resistant (MDR) phenotype, resensitizing a human colon cancer cell line (HCT116/VM46) to vinblastine and doxorubicin at lower doses than the prototypical agent verapamil.     

Synthesis of C-17-functionalized spongiane diterpenes: diastereoselective synthesis of (-)-spongian-16-oxo-17-al, (-)-acetyldendrillol-1, and (-)-aplyroseol-14

The diastereoselective synthesis of spongiane diterpenes (-)-spongian-16-oxo-17-al 2, (-)-acetyldendrillol-1 15, and (-)-aplyroseol-14 16 has been completed efficiently via the common intermediate 14. Compound 14 was prepared in five synthetic steps from (+)-podocarp-8(14)-en-13-one 13, easily available from commercial (-)-abietic acid. The key steps in the syntheses were a regioselective reduction of a 1,4-dialdehyde unit, a one-pot acetalization-acetylation, and a translactonization. The synthesis of 15 and 16 has led us to a revision of the configuration at C-17 for natural (-)-acetyldendrillol-1 and a structural reassignment for aplyroseol-14. Thus, aplyroseol-14 16 presents an unprecedented delta-lactone-based structure for spongiane-type diterpenoids. A theoretical study including a series of ab initio calculations for the mechanism involved in the conversion of ester 22 into natural product 2 has also been carried out.     

Synthesis and Biological Activities of Simplified Analogs of the Natural PKC Ligands,Bryostatin‐1 and Aplysiatoxin

Protein kinase C (PKC) isozymes play central roles in signal transduction on the cell surface and could serve as promising therapeutic targets of intractable diseases like cancer, Alzheimer's disease, and acquired immunodeficiency syndrome (AIDS). Although natural PKC ligands like phorbol esters, ingenol esters, and teleocidins have the potential to become therapeutic leads, most of them are potent tumor promoters in mouse skin. By contrast, bryostatin‐1 (bryo‐1) isolated from marine bryozoan is a potent PKC activator with little tumor‐promoting activity. Numerous investigations have suggested bryo‐1 to be a promising therapeutic candidate for the above intractable diseases. However, there is a supply problem of bryo‐1 both from natural sources and by organic synthesis. Recent approaches on the synthesis of bryo‐1 have focused on its simplification, without decreasing the ability to activate PKC isozymes, to develop new medicinal leads. Another approach is to use the skeleton of natural PKC ligands to develop bryo‐1 surrogates. We have recently identified 10‐methyl‐aplog‐1 ( 26 ), a simplified analog of tumor‐promoting aplysiatoxin (ATX), as a possible therapeutic lead for cancer. This review summarizes recent investigations on the simplification of natural PKC ligands, bryo‐1 and ATX, to develop potential medicinal leads.     

A review of analytical methods for the determination of trichloroethylene and its major metabolites chloral hydrate, trichloroacetic acid and dichloroacetic acid

Trichloroethylene (TCE) and some of its metabolites are potentially carcinogenic compounds that the general population is commonly exposed to in drinking water. Concentrations of TCE, dichloroacetic acid (DCA) and trichloroacetic acid (TCA) given to laboratory animals in cancer bioassays are high, whereas drinking water levels of the compounds are very low. It is not clear whether the trace amounts of TCE, DCA and TCA in drinking water pose a cancer risk to humans. The accuracy of pharmacokinetic studies relies on the analytical method from which blood and tissue concentration data are obtained. Models that extrapolate cancer risks of TCE and its metabolites from laboratory animals to humans, in turn, rely on the results of pharmacokinetic studies. Therefore, it is essential to have reliable analytical methods for the analysis of TCE and its metabolites. This paper reviews the methods currently in the literature for the analysis of TCE, DCA, TCA and, to a lesser extent, chloral hydrate (CH). Additional aspects of analytical methods such as method validation, species preservation and future directions in the analysis of TCE and its metabolites are also discussed.     

in vitro biological evaluation of folate-functionalized block copolymer micelles for selective anti-cancer drug delivery

The main objective of this study was to evaluate the ability of folic acid-functionalized diblock copolymer micelles to improve the delivery and uptake of two poorly water-soluble anti-tumor drugs, tamoxifen and paclitaxel, to cancer cells through folate receptor targeting. The diblock copolymer used in this study comprised a hydrophilic poly[2-(methacryloyloxy)ethyl phosphorylcholine] (MPC) block, carrying at the chain end the folate targeting moiety, and a pH-sensitive hydrophobic poly[2-(diisopropylamino)ethyl methacrylate] (DPA) block (FA-MPC-DPA). The drug-loading capacities of tamoxifen- and paclitaxel-loaded micelles were determined by high performance liquid chromatography and the micelle dimensions were determined by dynamic light scattering and transmission electron microscopy. Cell viability studies were carried out on human chronic myelogenous leukaemia (K-562) and colon carcinoma cell lines (Caco-2) in order to demonstrate that drug-loaded FA-MPC-DPA micelles exhibited higher cytotoxicities toward cancer cells than unfunctionalized MPC-DPA micelles. Uptake studies confirmed that folate-conjugated micelles led to increased drug uptake within cancer cells, demonstrating the expected selectivity toward these tumor cells.     

Analysis of dichloroacetic acid in rat blood and tissues by hydrophilic interaction liquid chromatography with tandem mass spectrometry

Dichloroacetic acid (DCA) is a compound found in chlorinated drinking water. In addition, the compound is a metabolite of several halogenated solvents, including trichloroethylene (TCE) and perchloroethylene (PCE). Exposure to DCA is of concern because high doses of the compound have been shown to cause cancer in laboratory animals. Dosages of TCE administered to animals in cancer studies are designed to elicit maximal DCA formation in vivo, whereas levels of DCA to which individuals are exposed in drinking water are very low. Analysis of DCA in biological samples has been quite challenging. Derivatizing reagents commonly used to convert DCA into a more volatile form for analysis by gas chromatography (GC) have been found to convert trichloroacetic acid (TCA), a major metabolite of TCE and PCE, into DCA. High-performance liquid chromatography (HPLC) analysis does not require derivatization of DCA and can thus avoid this problem. However, the most popular stationary phases in HPLC columns do not retain small, polar compounds such as DCA well. The liquid chromatography/tandem mass spectrometry (LC/MS/MS) method described in this paper uses hydrophilic interaction liquid chromatography (HILIC), a type of chromatography that is able to retain these small, polar compounds. Method validation was performed using the United States Food and Drug Administration (USFDA) and International Conference on Harmonziation (ICH) Guidance for Industry: Bioanalytical Method Validation as a guide. Levels of DCA found in rats dosed with 2 g/kg TCE were 17.2 ng/mL (liver), 262.4 ng/mL (kidney), 175.1 ng/mL (lung), and 39.5 ng/mL (blood).     

Colon targeted drug delivery of branch-chained disulphide cross-linked polymers: design,synthesis, and characterisation studies

Drug delivery directly to the colon is a very useful approach for treating localised colonic diseases such as inflammatory bowel disease, ulcerative colitis, and Crohn’s disease. The use of disulphide cross-linked polymers in colon targeted drug delivery systems has received much attention because these polymers are redox sensitive, and the disulphide bonds are only cleaved by the low redox potential environment in the colon. The goal of this study was to synthesise tricarballylic acid-based trithiol monomers for polymerisation into branch-chained disulphide polymers. The monomer was synthesised via the amide coupling reaction between tricarballylic acid and (triphenylmethyl) thioethylamine using two synthesis steps. The disulphide cross-linked polymers which were synthesised using the air oxidation method were completely reduced after 1 h of reduction with different thiol concentrations detected for the different disulphide polymers. In simulated gastric and intestinal conditions, all polymers had low thiol concentrations compared to the thiol concentrations in the simulated colon condition with Bacteroides fragilis present. Degradation was more pronounced in polymers with loose polymeric networks, as biodegradability relies on the swelling ability of polymers in an aqueous environment. Polymer P15 which has the loosest polymeric networks showed highest degradation.     

Apoptosis of Human Gastric Carcinoma SGC-7901 Induced by Deoxycholic Acid via the Mitochondrial-Dependent Pathway

The study aimed to evaluate the effects of deoxycholic acid (DCA) on human gastric carcinoma cell lines and to explore its mechanisms. In the present study, effects of DCA on SGC-7901 cell growth, cell cycle, and apoptosis were investigated by MTT assay, inverted microscopy, fluorescence microscopy, PI single- and FITC/PI double-staining flow cytometry, and western blotting. The study have revealed that DCA significantly inhibited the growth of SGC-7901 cells in a dose- and time-dependent manner and arrested cell cycle at G0/G1 phase. SGC-7901 cells showed typical apoptotic morphological changes after treated with DCA for 48 h. The intensity of typical apoptosis pattern- “ladders” formed by DNA in fragments of multiples of 200 base pairs was also observed. Apoptosis of SGC-7901 cells induced by DCA were associated with collapse of the mitochondrial membrane potential. DCA treatment could also increase the ratio of Bax to Bcl-2 in SGC-7901 cells. Meanwhile, the expression of p53, cyclinD1, and c-Myc were changed after DCA treatment. These results suggest that DCA induces apoptosis of gastric carcinoma cells through an intrinsic mitochondrial-dependent pathway, and the increase in the Bax/Bcl-2 ratio and collapse of the mitochondrial membrane potential may play important roles in DCA-induced apoptosis of gastric carcinoma cells.     

Synthesis and Antimicrobial,Anticancer and Anti-Oxidant Activities of Novel 2,3-Dihydropyrido[2,3-d]pyrimidine-4-one and Pyrrolo[2,1-b][1,3]benzothiazole Derivatives via Microwave-Assisted Synthesis

In our attempt towards the synthesis and development of effective antimicrobial, anticancer and antioxidant agents, a novel series of 2,3-dihydropyrido[2,3-d]pyrimidin-4-one 7a–e and pyrrolo[2,1-b][1,3]benzothiazoles 9a–e were synthesized. The synthesis of 2-(1,3-benzo thiazol-2-yl)-3-(aryl)prop-2-enenitrile (5a–e) as the key intermediate was accomplished by a microwave efficient method. Via a new variety oriented synthetic microwave pathway, these highly functionalized building blocks allowed access to numerous fused heteroaromatic such as 7-amino-6-(1,3-benzo thiazol-2-yl)-5-(aryl)-2-thioxo-2,3dihydropyrido [2,3-d]pyrimidin-4(1H)-one 7a–e and 1-amino-2-(aryl)pyrrolo[2,1-b][1,3]benzothiazole-3-carbonitrile derivatives 9a–e in order to study their antimicrobial and anticancer activity. The present investigation offers effective and rapid new procedures for the synthesis of the newly polycondensed heterocyclic ring systems. All the newly synthesized compounds were evaluated for antimicrobial, anticancer and antioxidant activity. Compounds 7a,d, and 9a,d showed higher antimicrobial activity than cefotaxime and fluconazole while the remaining compounds exhibited good to moderate activity against bacteria and fungi. An anticancer evaluation of the newly synthesized compounds against the three tumor cell lines (lung cell NCI-H460, liver cancer HepG2 and colon cancer HCT-116) exhibited that compounds 7a, d, and 9a,d have higher cytotoxicity against the three human cell lines compared to doxorubicin as a reference drug. These compounds also exhibited higher antioxidant activity and a great ability to protect DNA from damage induced by bleomycin.     

Erythrolic acids A-E, meroterpenoids from a marine-derived Erythrobacter sp

Erythrolic acids A-E (1-5) are five unusual meroterpenoids isolated from the bacterium Erythrobacter sp. derived from a marine sediment sample collected in Galveston, TX. The structures were elucidated by means of detailed spectroscopic analysis and chemical derivatization. The erythrolic acids contain a 4-hydroxybenzoic acid appended with a modified terpene side chain. The side-chain modifications include oxidation of a terminal methyl substituent and in the case of 1-4 addition of a two-carbon unit to give terpene side chains of unusual length: C22 for 1 and 2, C17 for 3, and C12 for 4. The relative and absolute configurations of the meroterpenoids were determined by coupling constant, NOE, and Mosher's analysis. In vitro cytotoxicity toward a number of nonsmall cell lung cancer (NSCLC) cell lines revealed only modest activity for erythrolic acid D (4) (2.5 μM against HCC44). The discovery of these unusual diterpenes, along with the previously reported erythrazoles, demonstrates the natural product potential of a previously unstudied group of bacteria for drug discovery. The unusual nature of the terpene side chain, we believe, involves an oxidation of a terminal methyl group to a carboxylic acid and subsequent Claisen condensation with acetyl-CoA.     

Uses of ethyl benzoyl acetate for the synthesis of thiophene,pyran, and pyridine derivatives with antitumor activities

The N-(arly)propanamide derivatives 3a,b were used for a series of heterocyclization reactions to give thiophene, pyran, and pyridine derivatives. Thus, these compounds underwent the Gewald's thiophene synthesis through their reactions with either malononitrile or ethyl cyanoacetate and elemental sulfur to afford compounds 6a-f , respectively. In addition, they were subjected through a series of multicomponent reactions (MCRs) to give pyran and fused derivatives. The reactions of 3a,b with either malononitrile or ethyl cyanoacetate gave pyridine derivatives 14a-d , respectively. The latter compounds afforded arylhydrazone derivatives 15a-m through their reactions with any of the aromatic diazonium salts 15a-c . The antitumor of the synthesized compounds against A549 (nonsmall cell lung cancer), H460 (human lung cancer), HT-29 (human colon cancer), and MKN-45 (human gastric cancer cancer) cancer cell lines together with foretinib as the positive control by a MTT assay was measured, and the results obtained showed that many compounds exhibited high potency against the six cancer cell lines.