Synthesis of Bio-Inspired 1,3-Diarylpropene Derivatives via Heck Cross-Coupling and Cytotoxic Evaluation on Breast Cancer Cells

The Heck cross-coupling reaction is a well-established chemical tool for the synthesis of unsaturated compounds by formation of a new C-C bond. In this study, 1,3-diarylpropene derivatives, designed as structural analogues of stilbenoids and dihydrostilbenoids, were synthesised by the palladium-catalysed reactions of 2-amidoiodobenzene derivatives with either estragole or eugenol. The products were obtained with high (E) stereoselectivity but as two regioisomers. The ratios of isomers were found to be dependent on the nature of the allylbenzene partner and were rationalised by electronic effects exercising a determining influence in the β-hydride elimination step. In addition, the cytotoxic effects of all the Heck reaction products were evaluated against MCF-7 and MDA-MB-231 human breast cancer cells, with unpromising results. Among all, compound 7d exhibited weak cytotoxic activity towards MCF-7 cell lines with IC50 values of 47.92 µM in comparison with tamoxifen and was considered to have general toxicity (SI value < 2).

(E)-N-(2-(3, 5-Dimethoxystyryl) phenyl) furan-2-carboxamide (BK3C231) induces cytoprotection in CCD18-Co human colon fibroblast cells through Nrf2/ARE pathway activation

Cytoprotection involving the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant response element (ARE) signaling pathway is an important preventive strategy for normal cells against carcinogenesis. In our previous study, the chemopreventive potential of (E)-N-(2-(3, 5-Dimethoxystyryl) phenyl) furan-2-carboxamide (BK3C231) has been elucidated through its cytoprotective effects against DNA and mitochondrial damages in the human colon fibroblast CCD-18Co cell model. Therefore this study aimed to investigate the molecular mechanisms underlying BK3C231-induced cytoprotection and the involvement of the Nrf2/ARE pathway. The cells were pretreated with BK3C231 before exposure to carcinogen 4-nitroquinoline N-oxide (4NQO). BK3C231 increased the protein expression and activity of cytoprotective enzymes namely NAD(P)H:quinone oxidoreductase 1 (NQO1), glutathione S-transferase (GST) and heme oxygenase-1 (HO-1), as well as restoring the expression of glutamate-cysteine ligase catalytic subunit (GCLC) back to the basal level. Furthermore, dissociation of Nrf2 from its inhibitory protein, Keap1, and ARE promoter activity were upregulated in cells pretreated with BK3C231. Taken together, our findings suggest that BK3C231 exerts cytoprotection by activating the Nrf2 signaling pathway which leads to ARE-mediated upregulation of cytoprotective proteins. This study provides new mechanistic insights into BK3C231 chemopreventive activities and highlights the importance of stilbene derivatives upon development as a potential chemopreventive agent.

Cytoprotective effects of (E)-N-(2-(3, 5-dimethoxystyryl) phenyl) furan-2-carboxamide (BK3C231) against 4-nitroquinoline 1-oxide-induced damage in CCD-18Co human colon fibroblast cells

Stilbenes are a group of chemicals characterized with the presence of 1,2-diphenylethylene. Previously, our group has demonstrated that synthesized (E)-N-(2-(3, 5-dimethoxystyryl) phenyl) furan-2-carboxamide (BK3C231) possesses potential chemopreventive activity specifically inducing NAD(P)H:quinone oxidoreductase 1 (NQO1) protein expression and activity. In this study, the cytoprotective effects of BK3C231 on cellular DNA and mitochondria were investigated in normal human colon fibroblast, CCD-18Co cells. The cells were pretreated with BK3C231 prior to exposure to the carcinogen 4-nitroquinoline 1-oxide (4NQO). BK3C231 was able to inhibit 4NQO-induced cytotoxicity. Cells treated with 4NQO alone caused high level of DNA and mitochondrial damages. However, pretreatment with BK3C231 protected against these damages by reducing DNA strand breaks and micronucleus formation as well as decreasing losses of mitochondrial membrane potential (ΔΨm) and cardiolipin. Interestingly, our study has demonstrated that nitrosative stress instead of oxidative stress was involved in 4NQO-induced DNA and mitochondrial damages. Inhibition of 4NQO-induced nitrosative stress by BK3C231 was observed through a decrease in nitric oxide (NO) level and an increase in glutathione (GSH) level. These new findings elucidate the cytoprotective potential of BK3C231 in human colon fibroblast CCD-18Co cell model which warrants further investigation into its chemopreventive role.

The synthesis of some novel stilbene dimers incorporating diamide tethers: studies in single electron transfer oxidation (FeCl3)

Investigation of the oxidation of the stilbene succinamide dimer 72 (FeCl₃/CH₂Cl₂) appears, on the basis of spectroscopic evidence, to have produced the bridged macrocyclic indoline 73.

TRPA1 channels as targets for resveratrol and related stilbenoids

A series of twenty resveratrol analogues was synthesized and tested on TRPA1 and TRPV1 channels. None was able to significantly modulate TRPV1 channels. Conversely, most of them exhibited remarkably higher TRPA1 modulating activity than resveratrol. Optimal potency was observed with ortho monoxygenated stilbenes 6 and 17.

Design, synthesis and cytotoxic evaluation of o-carboxamido stilbene analogues

Resveratrol, a natural stilbene found in grapes and wines exhibits a wide range of pharmacological properties. Resveratrol is also known as a good chemopreventive agent for inhibiting carcinogenesis processes that target kinases, cyclooxygenases, ribonucleotide reductase and DNA polymerases. A total of 19 analogues with an amide moiety were synthesized and the cytotoxic effects of the analogues on a series of human cancer cell lines are reported. Three compounds 6d, 6i and 6n showed potent cytotoxicity against prostate cancer DU-145 (IC50=16.68 µM), colon cancer HT-29 (IC50=7.51 µM) and breast cancer MCF-7 (IC50=21.24 µM), respectively, which are comparable with vinblastine. The resveratrol analogues were synthesized using the Heck method.

Cyclization vs. cyclization/dimerization in o-amidostilbene radical cation cascade reactions: the amide question

The n-butyramido, isobutyramido, benzamido, and furancarboxamido functions profoundly modulate the electronics of the stilbene olefinic and NH groups and the corresponding radical cations in ways that influence the efficiency of the cyclization due presumably to conformational and stereoelectronic factors. For example, isobutyramido- stilbene undergoes FeCl₃ promoted cyclization to produce only indoline, while n-butyramidostilbene, under the same conditions, produces both indoline and bisindoline.