(E)-4-aryl-4-oxo-2-butenoic acid amides, chalcone-aroylacrylic acid chimeras: design, antiproliferative activity and inhibition of tubulin polymerization

Chalcones: Promising therapeutic agents targeting key players and signaling pathways regulating the hallmarks of cancer

The need for innovative anticancer treatments with high effectiveness and low toxicity is urgent due to the development of malignancies that are resistant to chemotherapeutic agents and the poor specificity of existing anticancer treatments. Chalcones are 1,3-diaryl-2-propen-1-ones, which are the precursors for flavonoids and isoflavonoids. Chalcones are readily available from a wide range of natural resources and consist of very basic chemical scaffolds. Because the ease with which the synthesis it allows for the production of several chalcone derivatives. Various in-vitro and in-vivo studies indicate that naturally occurring and synthetic chalcone derivatives exhibit promising biological activities against cancer hallmarks such as proliferation, angiogenesis, invasion, metastasis, inflammation, stemness, and regulation of cancer epigenetics. According to their structure and functional groups, chalcones derivatives and their hybrid compounds exert a broad range of biological activities through targeting key elements and signaling molecules relevant to cancer progression. This review will provide valuable insights into the latest updates of chalcone groups as anticancer agents and extensively discuss their underlying molecular mechanisms of action.

Microwave-assisted synthesis of 4-oxo-2-butenoic acids by aldol-condensation of glyoxylic acid

4-Oxobutenoic acids are useful as biologically active species and as versatile intermediates for further derivatisation. Currently, routes to their synthesis can be problematic and lack generality. Reaction conditions for the synthesis of 4-oxo-2-butenoic acid by microwave-assisted aldol-condensation between methyl ketone derivatives and glyoxylic acid have been developed. They provide the desired products in moderate to excellent yields for a wide range of substrates, by applying a simple procedure to accessible starting materials. The investigation revealed different conditions are required depending on the nature of the methylketone substituent, with aryl derivatives proceeding best using tosic acid and aliphatic substrates reacting best with pyrrolidine and acetic acid. This substituent effect is rationalised by frontier orbital calculations. Overall, this work provides methods for synthesis of 4-oxo-butenoic acids across a broad range of substrates.

Novel Polymethoxylated Chalcones as Potential Compounds Against KRAS-Mutant Colorectal Cancers

BACKGROUND/OBJECTIVE

KRAS-mutant colorectal cancers (CRC) are tumors that are associated with poor prognosis. However, no effective treatments are available to target them. Therefore, we designed and synthesized novel chalcone analogs, small organic molecules, to investigate their effects on KRAS-mutant CRC cells.

METHODS

Fourteen new chalcone analogs were synthesized, optimized, characterized, and tested against two KRAS-mutant CRC cell lines (HCT-116 and LoVo), one p-53 and BRAF mutant CRC cell line (HT-29) and one normal immortalized colon cells (NCE-1 E6/E7). Effects on cell viability, apoptosis, cell cycle, migration, colony formation, EMT, and angiogenesis were investigated.

RESULTS

Compounds 3 and 14 were the most effective. Compound 3 showed potent activity against HCT-116 and LoVo cell lines (GI50 of 6.10 μM and 7.00 μM, respectively). While compound 14 showed GI50 of 8.60 μM and 8.80 μM on HCT-116 and LoVo cell lines, respectively. Both compounds were approximately 2-3 times more selective toward cancer cells rather than normal colon cells. Compound 3 was effective in inducing apoptosis in HCT-116 cells via Bax upregulation and Bcl-2 downregulation. Invasion and metastasis of KRAS-mutant cells were modulated by compounds 3 and 14 through significant inhibition of cell migration and the prevention of colony formation. In addition, they reversed EMT by downregulation of EMT markers (vimentin, fascin, and β- catenin) and upregulation of cell-cell adhesion marker, E-cadherin. Furthermore, compounds 3 and 14 had significantly inhibited angiogenesis in ovo.

CONCLUSION

Compounds 3 and 14 represent potent and selective leads for KRAS-mutant CRC cells, thus, further in vitro and in vivo studies are necessary to confirm their effect on KRAS-mutant CRCs.

Design, synthesis and biological evaluation of 3,4-diaryl-1,2,5-oxadiazole-2/5-oxides as highly potent inhibitors of tubulin polymerization

Structure-activity relationships for rigid analogues of combretastatin A-4 (CA-4) were investigated, leading to the discovery of a series of 3,4-diaryl-1,2,5-oxadiazole-N-oxides. Among them, 7n' and 7n'' showed remarkable antiproliferative activities against three cancer cell lines in nanomolar concentrations. Interestingly, 7n' inhibited tubulin polymerization much more efficiently than CA-4. Cellular mechanism investigation elucidated 7n' disrupted the cellular microtubule structure, arrested cell cycle at G₂/M phase and induces apoptosis. Molecular modeling study revealed 1,2,5-oxadiazole-N-oxide ring could increase a hydrogen bond interaction with the binding site. These results provide impetus and further guidance for the development of new CA-4 analogues.

Novel hybrids derived from aspirin and chalcones potently suppress colorectal cancer in vitro and in vivo

Colorectal cancer (CRC) remains the fourth leading cause of cancer deaths around the world despite the availability of many approved small molecules for treatment. The issues lie in the potency, selectivity and targeting of these compounds. Therefore, new strategies and targets are needed to optimize and develop novel treatments for CRC. Here, a group of novel hybrids derived from aspirin and chalcones were designed and synthesized based on recent reports of their individual benefits to CRC targeting and selectivity. The most active compound 7h inhibited proliferation of CRC cell lines with better potency compared to 5-fluorouracil, a currently used therapeutic agent for CRC. Importantly, 7h had 8-fold less inhibitory activity against non-cancer CCD841 cells. In addition, 7h inhibited CRC growth via the inhibition of the cell cycle in the G1 phase. Furthermore, 7h induced apoptosis by activating caspase 3 and PARP cleavage, as well as increasing ROS in CRC cells. Finally, 7h significantly retarded the CRC cell growth in a mouse xenograft model. These findings suggest that 7h may have potential to treat CRC.

Design and in vitro biological evaluation of substituted chalcones synthesized from nitrogen mustards as potent microtubule targeted anticancer agents

Six chalcones were synthesized and their structures determined by single crystal X-ray diffraction studies. They exhibited enhanced anticancer activity and tubulin inhibition.

Recent advances of cytotoxic chalconoids targeting tubulin polymerization: Synthesis and biological activity

Since microtubules have an important role in mitosis and other vital cellular functions, tubulin-targeting chemotherapy has been received growing attention in anticancer drug design and development. It was found that a number of naturally occurring compounds including distinct chalcones exert their effect by inhibition of tubulin polymerization. After the identification of tubulin polymerization as potential target for chalcone-type compounds, extensive researches have been made to design and synthesis of new anti-tubulin chalconoids. Although diverse chalcones have found to be potent anticancer agents but in the present review, we focused on the recently reported tubulin polymerization inhibitors from chalcone origin and related synthetic compounds, and their detailed synthetic methods and biological activities.

Synthesis and Regioselective Reaction of Some Unsymmetrical Heterocyclic Chalcone Derivatives and Spiro Heterocyclic Compounds as Antibacterial Agents

A number of novel heterocyclic chalcone derivatives can be synthesized by thermal and microwave tools. Treatment of 4-(4-Acetylamino- and/or 4-bromo-phenyl)-4-oxobut-2-enoic acids with hydrogen peroxide in alkaline medium were afforded oxirane derivatives 2. Reaction of the epoxide 2 with 2-amino-5-aryl-1,3,4-thiadiazole derivatives yielded chalcone of imidazo[2,1-b]thiadiazole derivative 4 via two thermal routes. In one pot reaction of 4-bromoacetophenone, diethyloxalate, and 2-amino-5-aryl-1,3,4-thiadiazole derivatives in MW irradiation (W 250 and T 150 °C) under eco-friendly conditions afforded an unsuitable yield of the desired chalcone 4d. The chalcone derivatives 4 were used as a key starting material to synthesize some new spiroheterocyclic compounds via Michael and aza-Michael adducts. The chalcone 4f was similar to the aryl-oxo-vinylamide derivatives for the inhibition of tyrosine kinase and cancer cell growth. The electron-withdrawing substituents, such as halogens, and 2-amino-1,3,4-thiadiazole moeity decreasing the electron density, thereby decreasing the energy of HOMO, and the presence of imidazothiadiazole moiety should improve the antibacterial activity. Thus, the newly synthesized compounds were evaluated for their anti-bacterial activity against (ATCC 25923), (ATCC 10987), (ATCC 274,) and (SM514). The structure of the newly synthesized compounds was confirmed by elemental analysis and spectroscopic data.

Molecular targeted approaches to cancer therapy and prevention using chalcones

There is an emerging paradigm shift in oncology that seeks to emphasize molecularly targeted approaches for cancer prevention and therapy. Chalcones (1,3-diphenyl-2-propen-1-ones), naturally-occurring compounds with widespread distribution in spices, tea, beer, fruits and vegetables, consist of open-chain flavonoids in which the two aromatic rings are joined by a three-carbon α, β-unsaturated carbonyl system. Due to their structural diversity, relative ease of chemical manipulation and reaction of α, β-unsaturated carbonyl moiety with cysteine residues in proteins, some lead chalcones from both natural products and synthesis have been identified in a variety of screening assays for modulating important pathways or molecular targets in cancers. These pathways and targets that are affected by chalcones include MDM2/p53, tubulin, proteasome, NF-kappa B, TRIAL/death receptors and mitochondria mediated apoptotic pathways, cell cycle, STAT3, AP-1, NRF2, AR, ER, PPAR-γ and β-catenin/Wnt. Compared to current cancer targeted therapeutic drugs, chalcones have the advantages of being inexpensive, easily available and less toxic; the ease of synthesis of chalcones from substituted benzaldehydes and acetophenones also makes them an attractive drug scaffold. Therefore, this review is focused on molecular targets of chalcones and their potential implications in cancer prevention and therapy.

Anti-cancer chalcones: Structural and molecular target perspectives

Chalcone or (E)-1,3-diphenyl-2-propene-1-one scaffold remained a fascination among researchers in the 21st century due to its simple chemistry, ease of synthesis and a wide variety of promising biological activities. Several natural and (semi) synthetic chalcones have shown anti-cancer activity due to their inhibitory potential against various targets namely ABCG2/P-gp/BCRP, 5α-reductase, aromatase, 17-β-hydroxysteroid dehydrogenase, HDAC/Situin-1, proteasome, VEGF, VEGFR-2 kinase, MMP-2/9, JAK/STAT signaling pathways, CDC25B, tubulin, cathepsin-K, topoisomerase-II, Wnt, NF-κB, B-Raf and mTOR etc. In this review, a comprehensive study on molecular targets/pathways involved in carcinogenesis, mechanism of actions (MOAs), structure activity relationships (SARs) and patents granted have been highlighted. With the knowledge of molecular targets, structural insights and SARs, this review may be helpful for (medicinal) chemists to design more potent, safe, selective and cost effective anti-cancer chalcones.

Recent developments in biological activities of chalcones: a mini review

Chalcones represent key structural motif in the plethora of biologically active molecules including synthetic and natural products. Synthetic manipulations of chalcones or their isolation from natural sources are being investigated worldwide for the development of more potent and efficient drugs for the treatment of several dreadful diseases such as cancer, diabetes, HIV, tuberculosis, malaria etc. Over the past few years, a large volume of research papers and review articles highlighting the significance of chalcone derivatives has been compiled in the literature. The present review article focuses on the recent developments (2010-2014) on various pharmacological and medicinal aspects of chalcones and their analogues.

Tubulin inhibitors: pharmacophore modeling, virtual screening and molecular docking

AIM

To construct a quantitative pharmacophore model of tubulin inhibitors and to discovery new leads with potent antitumor activities.

METHODS

Ligand-based pharmacophore modeling was used to identify the chemical features responsible for inhibiting tubulin polymerization. A set of 26 training compounds was used to generate hypothetical pharmacophores using the HypoGen algorithm. The structures were further validated using the test set, Fischer randomization method, leave-one-out method and a decoy set, and the best model was chosen to screen the Specs database. Hit compounds were subjected to molecular docking study using a Molecular Operating Environment (MOE) software and to biological evaluation in vitro.

RESULTS

Hypo1 was demonstrated to be the best pharmacophore model that exhibited the highest correlation coefficient (0.9582), largest cost difference (70.905) and lowest RMSD value (0.6977). Hypo1 consisted of one hydrogen-bond acceptor, a hydrogen-bond donor, a hydrophobic feature, a ring aromatic feature and three excluded volumes. Hypo1 was validated with four different methods and had a goodness-of-hit score of 0.81. When Hypo1 was used in virtual screening of the Specs database, 952 drug-like compounds were revealed. After docking into the colchicine-binding site of tubulin, 5 drug-like compounds with the required interaction with the critical amino acid residues and the binding free energies < -4 kcal/mol were selected as representative leads. Compounds 1 and 3 exhibited inhibitory activity against MCF-7 human breast cancer cells in vitro.

CONCLUSION

Hypo1 is a quantitative pharmacophore model for tubulin inhibitors, which not only provides a better understanding of their interaction with tubulin, but also assists in discovering new potential leads with antitumor activities.

Antiproliferative activity of the Michael adducts of aroylacrylic acids and cyclic amines

Antiproliferative activity of twenty one Michael adducts of aroylacrylic acids and cyclic amines (N-Me-piperazine, imidazole, 2-Me-imidazole, and indole) was tested toward five human tumor cell lines (HeLa, LS174, K562, FemX, MDA-MB-361) in vitro. Compounds exerted antiproliferative activity in the high to the single-digit micromolar concentrations, causing increase of the cell population fraction in S phase and apoptosis. N-Me-piperazine and imidazole derivatives of aroylacrylic acids substituted with bulky alkyl substituents (2,4-di-i-Pr-Ph-, 2,4,6-tri-Et-Ph-, or β-tetrahydronaphthyl-) showed the best potency, while indole adducts were proved as the inferior antiproliferative agents. Few compounds showed significant selectivity, tumor versus healthy cells, with selectivity index ~60 for the most selective congener. An unbiased in silico distinction between more and less potent compounds was obtained from 3D QSAR models derived by alignment-independent GRIND-2 descriptors.