Synthesis and biological evaluation of novel derivatives of gambogic acid as anti-hepatocellular carcinoma agents

A series of novel derivatives of gambogic acid (GA) were synthesized and evaluated for their in vitro cytotoxicity against human hepatocellular carcinoma (HCC) cells. All derivatives showed better aqueous solubility than GA, and compounds 3a, 3e, and 3f displayed potent inhibition of HCC cell proliferation (IC(50): 0.045-0.59 μM on Bel-7402 cells and 0.067-0.94 μM on HepG2 cells) superior to GA and taxol. Additionally, the most potent compound 3e did not affect significantly the proliferation of non-tumor liver cells, suggesting that it might selectively inhibit HCC proliferation. Furthermore, 3e induced high frequency of Bel-7402 cell apoptosis. Our findings suggest that these novel GA derivatives may hold a great promise as therapeutic agents for the intervention of human HCC.     

Anticancer activities of novel chalcone and bis-chalcone derivatives

A series of novel chalcones and bis-chalcones containing boronic acid moieties has been synthesized and evaluated for antitumor activity against the human breast cancer MDA-MB-231 (estrogen receptor-negative) and MCF7 (estrogen receptor-positive) cell lines and against two normal breast epithelial cell lines, MCF-10A and MCF-12A. These molecules inhibited the growth of the human breast cancer cell lines at low micromolar to nanomolar concentrations, with five of them (1-4, 9) showing preferential inhibition of the human breast cancer cell lines. Furthermore, bis-chalcone 8 exhibited a more potent inhibition of colon cancer cells expressing wild-type p53 than of an isogenic cell line that was p53-null.     

Antiestrogen action of 2-hydroxyestrone on MCF-7 human breast cancer cells

The estrogen responsive human breast cancer MCF-7 cell culture was examined for its response to 2-hydroxyestrone a principal metabolite of estradiol. Addition of 2-hydroxyestrone to the cell cultures in concentration of 10(-9) - 10(-6) M had no effect on cell growth and proliferation because of rapid O-methylation of the catechol estrogen by catechol O-methyltransferase which is highly active in these cells. In the presence of quinalizarin, a potent catechol O-methyltransferase inhibitor which reduces the O-methylation of the steroid, 10(-7) M and 10(-8) M 2-hydroxyestrone markedly suppresses the growth and proliferation of the cells. The tumor cell growth-inhibitory action of the catechol estrogen was neutralized by the presence of 10(-9) M estradiol. The catechol estrogen inhibition of cell growth is not observed in the estrogen receptor-negative human breast cancer cell lines MDA-MB-231 and MDA-MB-330 providing evidence that the inhibition is specific and is estrogen receptor-mediated. In contrast, the 16 alpha-hydroxylated metabolites of estradiol, estriol and 16 alpha-hydroxyestrone, are effective stimulators of MCF-7 cell proliferation with the latter exhibiting potency in excess of that expected from its estrogen receptor affinity. The present results represent the first observation of a specific receptor-mediated antiestrogenic action of 2-hydroxyestrone and suggest that the physiological regulation of the agonist activity of the primary estrogen may involve in situ generation of catechol estrogen.     

Anti-cancer and immunostimulatory activity of chromones and other constituents from Cassia petersiana

Phytochemical investigation of Cassia petersiana Bolle leaves afforded four new compounds, including two chromone derivatives, 7-acetonyl-5-hydroxy-2-methylchromone (petersinone 1, 1) and 7-(propan-2'-ol-l'-yl)-5-hydroxy-2-methylchromone (petersinone 2, 2), two benzoic acid derivatives, 5-methyl-3-(propan-2'-on-1'-yl) benzoic acid (petersinone 3, 3) and 5-(methoxymethyl)-3-(propan-2'-ol-1'-yl) benzoic acid (petersinone 4, 4), and glyceryl-1-tetracosanoate (6), in addition to the known compound sistosterol-3-beta-D-glycoside (5). The structures of these compounds were determined by comprehensive NMR studies, including DEPT, COSY, HMQC, HMBC, MS and IR. Compounds 1, 2, 5 and 6 were tested for antioxidant, anti-cancer and immunostimulatory properties. The biological investigations indicated that compound 6, among others, possessed the highest anti-cancer activity against hepatocellular carcinoma, immunoproliferative activity via induction of T-lymphocytes and macrophage proliferation, anti-inflammatory activity as indicated by NO inhibition, and antioxidant activity against DPPH radicals. Moreover, compound 5 was the most effective cytotoxic compound against breast carcinoma and stimulated a consistent immunoproliferative effect on lymphocytes and macrophages combined with strong NO inhibitory activity, while compound 1 was promising as immunoproliferative agent and may act as anti-inflammatory agent as a consequence of its NO inhibitory activity.     

Effective chemopreventive activity of genistein against human breast cancer cells

Chemopreventive and cytotoxic effect of genistein against human breast cancer cell lines was investigated. Genistein inhibited cell proliferation in estrogen receptor-positive (MCF-7) and estrogen receptor-negative (MDA-MB-231) human breast carcinoma cell lines. Cytochrome P450 (CYP) 1A1-mediated ethoxyresorufin O-deethylase (EROD)activity was inhibited by genistein in a concentration-dependent manner. Genistein significantly inhibited 12-Otetradecanoylphorbol-13-acetate (TPA)-induced cyclooxygenase-2 activity and protein expression at the concentrations of 10 (p < 0.05), 25 (p < 0.05) and 50 mM (p < 0.01). In addition, ornithine decarboxylase (ODC) activity was reduced to 53.8 % of the control after 6 h treatment with 50 mM genistein in MCF-7 breast cancer cells. These results suggest that genistein could be of therapeutic value in preventing human breast cancer.     

Effect of tamoxifen and 2-methoxyestradiol alone and in combination on human breast cancer cell proliferation

Endocrine therapy is widely accepted for the treatment of hormone receptor-positive breast cancer. However, in many cases eventually resistance will develop and tumor regrows. Combination therapy may be one way to resolve this problem. In the present study we investigated the effect of a combination of the widely used antiestrogen tamoxifen with the endogenous estradiol metabolite 2-methoxyestradiol (2-ME) on the proliferation of human estrogen receptor-positive and receptor-negative breast cancer cells.The receptor-positive cell line MCF-7 and the receptor-negative cell line BM were treated with 4-hydroxytamoxifen (4-OHTam) and 2-methoxyestradiol in the concentration range of 0.8-25 microM alone and equimolar combinations for 4 days. The proliferation of the cells was determined using the ATP-chemosensitivity test.4-Hydroxytamoxifen inhibited proliferation of MCF-7 and BM cells with IC(50) values of 31 and 10 microM, the corresponding figures for 2-methoxyestradiol were 52 and 8 microM. The combination showed IC(50) values of 6 microM and 4 microM.These results indicate that a combination of tamoxifen with 2-methoxyestradiol showed an additive inhibitory effect concerning the proliferation of estrogen receptor-positive and receptor-negative breast cancer cell lines. Thus a combination of these substances may allow ameliorating of adverse events of tamoxifen by reducing its concentrations and probably also drug resistance and should be tested in clinical trials.     

The effects of 2-substituted oestrogen sulphamates on the growth of prostate and ovarian cancer cells

The human endogenous metabolite 2-methoxyoestradiol (2-MeOE2) has been shown to inhibit the proliferation of breast cancer cells. We have previously shown that sulphamoylation of a series of 2-substituted oestrogens greatly enhances their ability to inhibit breast cancer cell proliferation and induce apoptosis. In this study, we have investigated the ability of a number of 2-substituted oestrogens and their sulphamoylated derivatives to inhibit the proliferation of two prostate cancer cell lines, an ovarian cancer cell line and its drug-resistant derivatives. 2-Methoxyoestrone, 2-ethyloestrone and 2-ethyloestradiol had little effect on the growth of the cell lines tested (IC(50)>10 microM). 2-MeOE2 did inhibit the growth of the cells (IC(50)<10 microM), but to a lesser extent than any of the sulphamoylated derivatives tested (IC(50)<1.0 microM). Cells treated with the sulphamoylated derivatives became detached and rounded, displaying a characteristic apoptotic appearance. FACS analysis revealed induced G(2)/M cell cycle arrest. Treatment of cells and subsequent drug removal indicated that the effects of the drugs on the cells were irreversible. Immunoblot analysis indicated that apoptosis may be induced by phosphorylation of BCL-2. From these studies, 2-substituted oestrogen sulphamates are emerging as a potent new class of drug that may be effective against AR+/AR- prostate and ovarian tumours, and against tumours that are resistant to conventional chemotherapeutic regimens.     

Synthesis and evaluation of novel 4-[(3H,3aH,6aH)-3-phenyl)-4,6-dioxo-2-phenyldihydro-2H-pyrrolo[3,4-d]isoxazol-5(3H,6H,6aH)-yl]benzoic acid derivatives as potent acetylcholinesterase inhibitors and anti-amnestic agents

The present study was designed to synthesize and evaluate pyrrolo-isoxazole benzoic acid derivatives as potential acetylcholinesterase (AChE) inhibitors for the management of Alzheimer's disease. The synthesis of pyrrolo-isoxazole benzoic acid derivatives involved ring opening cyclization of p-aminobenzoic acid with maleic anhydride to yield maleanilic acid, which in turn afforded N-arylmaleimide via ring closed cyclization. Azomethine-N-oxides were obtained by condensation of N-arylhydroxylamine with differently substituted benzaldehydes followed by refluxing of N-arylmaleimide with differently substituted azomethine-N-oxides to pyrrolo-isoxazole benzoic acid derivatives as cis- and trans-stereoisomers. The synthesized compounds were evaluated in vitro for AChE inhibitory activity in rat brain homogenate with donepezil as standard AChE inhibitor. Thereafter, the most potent test compound was evaluated for in vitro butyrylcholinesterase inhibitory activity and in vivo memory evaluation in scopolamine (0.4mg/kg)-induced amnesia in mice by employing Morris water maze test. All pyrrolo-isoxazole benzoic acid derivatives demonstrated potent AChE inhibitory activity. Most of compounds exhibited similar activity to donepezil and four of them (7h, 7i, 8i, and 8h, IC(50)=19.1±1.9-17.5±1.5nM) displayed higher inhibitory activity as compared to donepezil (21.5±3.2nM) with compound 8ia (IC(50)=17.5±1.5nM) being the most active one. The test compound 8ia also ameliorated scopolamine-induced amnesia in mice in terms of restoration of time spent in target quadrant (TSTQ) and escape latency time (ELT). It may be concluded that pyrrolo-isoxazole benzoic acid derivatives may be employed as potential AChE inhibitors.     

Characterization of Catecholestrogen Membrane Binding Sites in Estrogen Receptor Positive and Negative Human Breast Cancer Cell-Lines

Abstract

A specific membrane-binding of an estradiol metabolite, the catecholestrogen (CE) 2 hydroxyestrone (2OH-E1), was demonstrated in two receptor-positive (MCF7 and VHB1) and one receptor-negative (MDA-MB-231) human mammary carcinoma cell lines. The three cell lines were found to be able to synthesise and inactivate CE. Solubilization of membrane bound CE results in a high molecular weight component whose specificity differs from that of the classical estrogen receptor. Apparent dissociation constants were 6-10. 10^?9 M and binding capacities were higher in the receptor positive cell lines than in the receptor-negative one. Since CE are susceptible to rapid degradation, the presence of such a site may be relevant in the protection and concentration of 2OH-E1 which has been shown to have “in vitro” anti-estrogenic properties in MCF7 breast tumor cells.     

Modified norcantharidins; synthesis, protein phosphatases 1 and 2A inhibition, and anticancer activity

Fourteen modified norcantharidin analogues have been synthesised and screened for their ability to inhibit the serine/threonine protein phosphatases 1 and 2A. The most potent compounds found were 10 (PP1 IC(50)=13+/-5 microM; PP2A IC(50)=7+/-3 microM) and 16 (PP1 IC(50)=18+/-8 microM; PP2A IC(50)=3.2+/-0.4 microM). Overall, only analogues possessing at least one acidic residue at the former anhydride warhead displayed any PP1 or PP2A inhibitory action. The ability of these analogues to inhibit PP1 and PP2A correlates well with their observed anti-cancer activity against a panel of five cancer cell lines: A2780 (human ovarian carcinoma), G401 (human kidney carcinoma), HT29 (human colorectal carcinoma), H460 (human lung carcinoma) and L1210 (murine leukemia).     

Molecular Design,Synthesis and Docking Study of Alkyl and Benzyl Derivatives of Robustic Acid as Topoisomerase I Inhibitors

Robustic acid is reported to be a bioactive compound, isolated from the medicinal plant Dalbergia benthamii Prain . Ten alkyl and benzyl derivatives ( 2a – 2j ) of robustic acid were designed and synthesized based on molecular docking approaches. The biological activities of most of the synthesized compounds (such as 2g , 2h , and 2i ) were closely consistent with the docking results. In particular, 4‐O‐phenylpropyl substituted compound 2g displayed potent topoisomerase I inhibitory activity as well as cytotoxicity against SMMC‐7721, HepG2, and HeLa cell lines. Further biological testing suggests that compound 2g acted mainly by an arrest of the tumor cells in G1 phase of the cell cycle and suppressed cell proliferation by inducing apoptosis. The findings of this study are encouraging with respect to potential utilization of these compounds as new topoisomerase I inhibitors.     

Chemopreventive activity of Cnidii Rhizoma for breast cancer

Chemopreventive potential for human breast cancer was assessed in vitro with Cnidii Rhizoma extract. Cnidii Rhizoma inhibited cell proliferation in estrogen receptor-positive (MCF-7) and estrogen receptor-negative (MDA-MB-231) human breast carcinoma cell lines. Cytochrome P450 (CYP) 1A1-mediated ethoxyresorufin O-deethylase (EROD) activity was inhibited by Cnidii Rhizoma in a concentration-dependent manner. In addition, Cnidii Rhizoma extract caused inhibition of microsomal aromatase (estrogen synthase) activity. Ornithine decarboxylase (ODC) activity was reduced to 40.3% of the control after 6 h treatment with Cnidii Rhizoma (5 mg/mL) in MCF-7 breast cancer cells. Cnidii Rhizoma extract markedly reduced 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated matrix metalloproteinase (MMP)-9 activity. These results suggest that Cnidii Rhizoma could be of therapeutic value in preventing human breast cancer.     

A natural propenoic acid derivative activates peroxisome proliferator-activated receptor-β/δ (PPARβ/δ)

AimsPrevious studies showed that natural prenyloxyphenylpropanoid derivatives have potent biological properties in vivo. Given the structural similarities between these compounds and known peroxisome proliferator-activated receptor (PPAR) agonists, the present study examined the hypothesis that propenoic acid derivatives activate PPARs.Main methodsChimeric reporter assays were performed to identify propenoic acid derivates that could activate PPARs. Quantitative polymerase chain reaction (qPCR) analysis of wild-type and Pparβ/δ-null mouse primary keratinocytes was performed to determine if a test compound could specifically activate PPARβ/δ. A human epithelial carcinoma cell line and primary mouse keratinocytes were used to determine the effect of the compound on cell proliferation.Key findingsThree of the propenoic acid derivatives activated PPARs, with the greatest efficacy being observed with prenyloxycinnamic acid derivatives 4′-geranyloxyferulic acid (compound 1) for PPARβ/δ. Compound 1 increased expression of a known PPARβ/δ target gene through a mechanism that requires PPARβ/δ. Inhibition of cell proliferation by compound 1 was found in a human epithelial carcinoma cell line.SignificanceResults from these studies demonstrate that compound 1 can activate PPARβ/δ and inhibit cell proliferation of a human skin cancer cell line, suggesting that the biological effects of 4′-geranyloxyferulic acid may be mediated in part by activating this PPAR isoform.     

Synthesis and Evaluation of Piperazine-Tethered Derivatives of Alepterolic Acid as Anticancer Agents

Alepterolic acid is a natural diterpenoid isolated from Aleuritopteris argentea with potential anti-cancer activity. In this study, alepterolic acid was modified to construct a series of arylformyl piperazinyl derivatives ( 3a – 3p ). The synthesized derivatives were fully characterized with HRMS, NMR, and IR. Four compounds with inhibition rate higher than 30 % at 10 μM ( 3f , 3n , 3g and 3k ) were further measured to obtain the IC₅₀ values against four cancer cell lines, including hepatoma cell lines HepG2, lung cancer cell lines A549, estrogen receptor-positive cell lines MCF7, and triple-negative breast cancer (TNBC) cell lines MDA-MB-231 by MTT assay. It was found that these compounds were more effective to HepG2 and MDA-MB-231 cells, while less toxic to A549 and MCF7 cells, and compound 3n as the most toxic derivatve against MDA-MB-231 cell lines, with IC₅₀ value of 5.55±0.56 μM. Trypan blue staining and colony formation assay showed that compound 3n inhibited the growth of MDA-MB-231 cells and prevented colony formation. Hoechst staining, flow cytometry and western blot analysis revealed that compound 3n induced caspase-dependent apoptosis in MDA-MB-231 cells. Conclusively, compound 3n was demonstrated to be a potential anti-cancer lead compound for further investigation.     

Synthesis and antitumor activity of new retinobenzoic acids

New retinobenzoic acid derivatives have been synthesized starting from 1,2,3,4-tetrahydro-1,1,2,4,4,6-hexamethylnaphthalene and 1,1,2,3,3-pentamethylindane. Four of the synthetic compounds displayed potent cytotoxic activities in vitro against human breast cancer and leukemic cell lines. Thus, these molecules can be further evaluated for the treatment of human leukemia and breast cancer.     

Novel pyrazole derivatives: Synthesis and evaluation of anti-angiogenic activity

The synthesis of a series of novel trisubstituted pyrazole derivatives and their PIFA-mediated conversion to molecules bearing the fused pyrazolo[4,3-c]quinoline ring system is reported. The anti-angiogenic activity of these compounds was evaluated by using in vitro assays for endothelial cell proliferation and migration, and in the chicken chorioallantoic membrane (CAM) assay. Compounds containing the fused pyrazolo[4,3-c]quinoline motifs emerged as potent anti-angiogenic compounds, which also had the ability to inhibit the growth of human breast (MCF-7) and cervical (Hela) carcinoma cells in vitro.     

Photochemical synthesis and anticancer activity of barbituric acid,thiobarbituric acid,thiosemicarbazide, and isoniazid linked to 2-phenyl indole derivatives

2-Phenyl-1H-indole-3-carbaldehyde-based barbituric acid, thiobarbituric acid, thiosemicarbazide, isoniazid, and malononitrile derivatives were synthesized under photochemical conditions. The antitumor activities of the synthesized compounds were evaluated on three different human cancer cell lines representing prostate cancer cell line DU145, Dwivedi (DWD) cancer cell lines, and breast cancer cell line MCF7. All the screened compounds possessed moderate anticancer activity, and out of all the screened compounds, 5-{1[2-(4-chloro-phenyl)2-oxo-ethyl]-2-phenyl-1H-indole-3-ylmethylene}-2-thioxo-dihydro-pyrimidine-4,6-dione (2b) and 5-{1[2-(4-methoxy-phenyl)2-oxo-ethyl]-2-phenyl-1H-indole-3-ylmethylene}-2-thioxo-dihydro-pyrimidine-4,6-dione (2d) exhibited marked antitumor activity against used cell lines. Additionally, barbituric acid derivatives were selective to inhibit cell line DWD and breast cancer cell lines.     

Novel 1,4-benzodiazepine derivatives with antiproliferative properties on tumor cell lines

Novel 1,4-benzodiazepine compounds were synthesized and evaluated for their ability to inhibit the proliferation of tumor cells. Some compounds revealed activities in the micromolar range and were more efficient than reference compound Ro 5-4864. Preliminary SAR helped to identify critical motifs for antiproliferative activity and led to the discovery of a compound selective for a melanoma cell line, known for its resistance to chemotherapy.     

Evaluation of a luciferase-based reporter assay as a screen for inhibitors of estrogen-ERα-induced proliferation of breast cancer cells

Estrogens, acting through estrogen receptor α (ERα), stimulate breast cancer proliferation, making ERα an attractive drug target. Since 384-well format screens for inhibitors of proliferation can be challenging for some cells, inhibition of luciferase-based reporters is often used as a surrogate end point. To identify novel small-molecule inhibitors of 17β-estradiol (E(2))-ERα-stimulated cell proliferation, we established a cell-based screen for inhibitors of E(2)-ERα induction of an estrogen response element (ERE)(3)-luciferase reporter. Seventy-five "hits" were evaluated in tiered follow-up assays to identify where hits failed to progress and evaluate their effectiveness as inhibitors of E(2)-ERα-induced proliferation of breast cancer cells. Only 8 of 75 hits from the luciferase screen inhibited estrogen-induced proliferation of ERα-positive MCF-7 and T47D cells but not control ERα-negative MDA-MB-231 cells. Although 12% of compounds inhibited E(2)-ERα-stimulated proliferation in only one of the ERα-positive cell lines, 40% of compounds were toxic and inhibited growth of all the cell lines, and ~37% exhibited little or no ability to inhibit E(2)-ERα-stimulated cell proliferation. Representative compounds were evaluated in more detail, and a lead ERα inhibitor was identified.     

Modulation of cholinephosphotransferase activity in breast cancer cell lines by Ro5-4864, a peripheral benzodiazepine receptor agonist

Changes in phospholipid and fatty acid profile are hallmarks of cancer progression. Increase in peripheral benzodiazepine receptor expression has been implicated in breast cancer. The benzodiazepine, Ro5-4864, increases cell proliferation in some breast cancer cell lines. Biosynthesis of phosphatidylcholine (PC) has been identified as a marker for cells proliferating at high rates. Cholinephosphotransferase (CPT) is the terminal enzyme for the de novo biosynthesis of PC. We have addressed here whether Ro5-4864 facilitates some cancer causing mechanisms in breast cancer. We report that cell proliferation increases exponentially in aggressive breast cancer cell lines 11-9-1-4 and BT-549 when treated with nanomolar concentrations of Ro5-4864. This increase is seen within 24 h of treatment, consistent with the cell doubling time in these cells. Ro5-4864 also upregulates c-fos expression in breast cancer cell lines 11-9-1-4 and BT-549, while expression in non-tumorigenic cell line MCF-12A was either basal or slightly downregulated. We further examined the expression of the CPT gene in breast cancer (11-9-1-4, BT-549) and non-tumorigenic cell lines (MCF-12A, MCF-12F). We found that the CPT gene is overexpressed in breast cancer cell lines compared to the non-tumorigenic cell lines. Furthermore, the activity of CPT in forming PC is increased in the breast cancer cell lines cultured for 24 h. Additionally, we examined the CPT activity in the presence of nanomolar concentrations of Ro5-4864. Biosynthesis of PC was increased in breast cancer cell lines upon treatment. We therefore propose that Ro5-4864 facilitates PC formation, a process important in membrane biogenesis for proliferating cells.