Bis-chalcone analogues as potent NO production inhibitors and as cytotoxic agents

Bis-chalcones: A review of synthetic methodologies and anti-inflammatory effects

Chalcones are bioactive molecules of natural and synthetic sources, whose physicochemical properties, reactivity, and biological activities are well-known among the scientific community. However, there are many molecules strictly related to chalcones with significantly less recognition like bis-chalcones. Several studies indicated that bis-chalcones have advantages over chalcones in specific bioactivities like anti-inflammatory activity. This review article describes the chemical structure and chemical properties of bis-chalcones, as well as the methods reported in the literature for the synthesis of these compounds highlighting the most recent developments. Finally, the anti-inflammatory activity of bis-chalcones is described, emphasizing the active structures found in literature and their mechanisms of action.

Bis-chalcone polyphenols with potential preventive and therapeutic effects on PD: Design, synthesis and in vitro disaggregation activity against α-synuclein oligomers and fibrils

α-Syn fibrils, which are neurotoxic, play a key role in the development of PD. Maintaining α-Syn proteostasis by suitable molecule ligands is an effective approach to prevent aggregation. Disintegrating the existed oligomers and fibrils into individual α-Syn by small molecular compounds is a more efficient way to treat PD. This work designed and synthesized two series of bis-chalcone polyphenol compounds, which possess a sheet-like conjugated skeleton with stronger H-bonding, π-stacking, and hydrophobic interaction with α-Syn protein residues. Some compounds have shown high α-Syn aggregation inhibitory activities in vitro with IC₅₀ down to 0.64 μM. The inhibition goes throughout the aggregation process from the lag to the stationary phase by stabilizing α-Syn proteostasis conformation and preventing β-sheets aggregation, especially in the lag phase. In addition, the inhibitors present good disintegration abilities against the existed α-Syn oligomers and fibrils. The preliminary mechanism studies suggest that the inhibitors could quickly and randomly bind to the specific site closed to the β-sheet domain in the fibril, resulting in unstable and collapse of the protein fibril and yielding a complex system with aggregates of different sizes and monomers. The inhibitors, which could penetrate the blood-brain barrier, are expected to develop into the drug candidates for PD targeting α-Syn aggregation.

Synthesis and evaluation of the anticancer activity of bischalcone analogs in human lung carcinoma (A549) cell line

Bischalcone has gained much attention because of its wide range of application in pharmaceutical chemistry. This work aims to evaluate the antiproliferation effects and explore the anticancer mechanism of bischalcone analogs on human lung cancer A549 cells. In this study, we synthesized a series of bischalcone analogs via Aldol condensation reaction; MTT method was used to evaluate the antiproliferation effects; the 2',7'-dichlorofluorescein fluorescence assay was used to determine the intracellular reactive oxygen species levels; the glutathione reductase-DTNB recycling assay was used to detect the redox imbalance; determination of thiobarbituric acid-reactive substance was used to evaluate the lipid peroxidation; Rhodamine 123 was used to test the mitochondrial membrane potential (MMP); the FITC/PI kit was used to detect the apoptosis; Western blotting was used to detect the expression of Bax and Caspase 3. After treatment with curcumin and bischalcone analogs, compounds 1d and 1g, the more stabilities compounds than curcumin, exhibited much higher potency in A549 cells than curcumin and other bischalcone analogs. Further mechanism of action studies revealed that 1d and 1g exhibited more stronger reactive oxygen species production abilities than curcumin and accompanied by the redox imbalance, lipid peroxidation, the loss of MMP, the activition of Bax and Caspase 3, and ultimately resulted in apoptosis of A549 cell. These data suggest that enhancing the reactive oxygen species generation ability of bischalcone analogs may be a promising strategy for the treatment of human lung cancer.

Inducible nitric oxide synthase inhibitors: A comprehensive update

Inducible nitric oxide synthase (iNOS), which is expressed in response to bacterial/proinflammatory stimuli, generates nitric oxide (NO) that provides cytoprotection. Overexpression of iNOS increases the levels of NO, and this increased NO level is implicated in pathophysiology of complex multifactorial diseases like Parkinson's disease, Alzheimer's disease, multiple sclerosis, rheumatoid arthritis, and inflammatory bowel disease. Selective inhibition of iNOS is an effective approach in treatment of such complex diseases. l-Arginine, being a substrate for iNOS, is the natural lead to develop iNOS inhibitors. More than 200 research reports on development of nitric oxide synthase inhibitors by different research groups across the globe have appeared in literature so far. The first review on iNOS, in 2002, discussed the iNOS inhibitors under two classes that is, amino acid and non-amino acid derivatives. Other review articles discussing specific chemical classes of iNOS inhibitors also appeared during last decade. In the present review, all reports on both natural and synthetic iNOS inhibitors, published 2002 onwards, are studied, classified, and discussed to provide comprehensive information on iNOS inhibitors. The synthetic inhibitors are broadly classified into two categories that is, arginine and non-arginine analogs. The latter are further classified into amidines, five- or six-membered heterocyclics, fused cyclics, steroidal type, and chalcones analogs. Structures of the most/significantly potent compounds from each report are provided to know the functional groups important for incurring iNOS inhibitory activity and selectivity. This review is aimed to provide a comprehensive view to the medicinal chemists for rational designing of novel and potent iNOS inhibitors.

SAR study on N2,N4-disubstituted pyrimidine-2,4-diamines as effective CDK2/CDK9 inhibitors and antiproliferative agents

Cyclin-dependent kinases (CDKs) are pivotal kinases in cell cycle transition and gene transcription. A series of N2,N4-diphenylpyrimidine-2,4-diamines were previously identified as potent CDK2/CDK9 inhibitors. To explore the SAR of this structural prototype, twenty-four novel N2,N4-disubstituted pyrimidine-2,4-diamines were designed and synthesized. Among them, twenty-one compounds exhibited potent inhibitory activities against both CDK2/cyclin A and CDK9/cyclin T1 systems, and the most potent CDK2 and CDK9 inhibitors, 3g and 3c, showed IC50 values of 83 nM and 65 nM respectively. Most of these compounds displayed significant inhibition against the tested tumor cell lines in the SRB assay, and in particular, remained active against the triple-negative breast cancer (TNBC) cell line MDA-MB-231. Flow cytometer analysis of compounds 2a, 2d and 3b in MDA-MB-231 cells indicated that these compounds induced cell cycle arrest in G2/M phase. Docking studies on compound 3g were performed, which provided conducive clues for further molecular optimization.

Inhibition of pro-inflammatory mediators in RAW264.7 cells by 7-hydroxyflavone and 7,8-dihydroxyflavone

OBJECTIVES

Flavonoids are a class of compounds that having the benzo-γ-pyrone skeleton, which possess anti-inflammatory properties in vitro and in vivo. The aim of this study was to investigate the inhibition of two flavonoids 7-hydroxyflavone (HF) and 7,8-dihydroxyflavone (DHF) on the production of pro-inflammatory mediators in RAW264.7 cells activated by lipopolysaccharides (LPS).

METHODS

For this purpose, we selected four pro-inflammatory mediators including nitric oxide (NO), prostaglandin E₂ (PGE₂ ), tumour necrosis factor-α (TNF-α) and interleukin-6 (IL-6) as markers to evaluate the anti-inflammatory activity of HF and DHF.

KEY FINDINGS

In this regard, we showed that HF and DHF dose-dependently reduced the production of NO, PGE₂ , TNF-α and IL-6 through downregulating mRNA expression of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX2), TNF-α and IL-6, respectively. Moreover, DHF generally possesses more efficient than HF in reducing these markers secretion in this study.

CONCLUSIONS

Consider together, these findings suggest that DHF and HF can inhibit LPS-induced inflammation via attenuating the production of NO, PGE₂ , TNF-α and IL-6, indicating that they may be lead compounds for developing anti-inflammatory agent.

Analogues of xanthones--Chalcones and bis-chalcones as α-glucosidase inhibitors and anti-diabetes candidates

Two series of compounds (chalcones and bis-chalcones) were designed, synthesized, and evaluated as α-glucosidase inhibitors (AGIs) with 1-deoxynojirimycin as positive control in vitro. Most of the compounds with two or four hydroxyl groups showed better inhibitory activities than 1-deoxynojirimycin towards α-glucosidase with noncompetitive mechanism. Moreover, most of the hydroxy bis-chalcones exhibit good α-glucosidase inhibitory activities in enzyme test. Inspiringly, bis-chalcones 2g (at 1 μM concentration) has stronger effect than 1-deoxynojirimycin on reducing the glucose level in HepG-2 cells (human liver cancer cell line).

Microwave-assisted synthesis of bis(N-substituted thiazol-2-amine) derivatives and their biological activities

New 4,4′-(4,6-dimethoxy-1,3-phenylene)-bis(

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.

Discovery of novel 5-fluoro-N2,N4-diphenylpyrimidine-2,4-diamines as potent inhibitors against CDK2 and CDK9

Based on a 3D-QSAR pharmacophore derived from a diverse set of known cyclin-dependent kinase 9 (CDK9) inhibitors and a composite pharmacophore extracted from the complex structure of flavopiridol (FVP)-CDK9, thirty novel 5-fluoro-N²,N⁴-diphenylpyrimidine-2,4-diamine derivatives were designed and synthesized. Initial tests against four tumor cell lines with the sulforhodamine B (SRB) assay identified a series of potent compounds with GI₅₀ values at lower micromolar or submicromolar level. Most of the highly cytotoxic compounds exhibited potent inhibitory activities against both CDK2/cyclin E1 and CDK9/cyclin T1. Notably, inhibitions against the two enzymes were generally correlated well with the cytotoxicity of these compounds. Appreciable inhibition was also observed for selected compounds in the anti-HIV-1 assay. Docking studies on compounds 6d and 9g provided conducive clues to further structural optimization.

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.