Synthesis and cytotoxic activity of novel tetrahydrobenzodifuran–imidazolium salt derivatives

Benzimidazolium Salts Bearing Nitrile Moieties: Synthesis, Enzyme Inhibition Profiling, and Molecular Docking Analysis for Carbonic Anhydrase and Acetylcholinesterase

This report presents the synthesis and characterization of a range of benzimidazolium salts featuring 3-cyanopropyl groups on the 1st nitrogen atom and varied alkyl groups on the 3rd nitrogen atom within the benzimidazole structure. Benzimidazolium salts were synthesized by N-alkylation of 1-alkyl benzimidazole with 3-cyanopropyl-bromide. The new salts were characterized by 1 H and 13 C-NMR, FT-IR spectroscopic and elemental analysis techniques. In this study, the enzyme inhibition abilities of seven nitrile substituted benzimidazolium salts were investigated against acetylcholinesterase (AChE) and carbonic anhydrase isoenzymes I and II (hCA I and hCA II). They showed a highly potent inhibition effect on AChE, hCA I and hCA II (Ki values are in the range of 26.71-119.09 nM for AChE, 19.77 to 133.68 nM for hCA I and 13.09 to 266.38 nM for hCA II). Reflecting the binding mode of the synthesized cyanopropyl series, the importance of the 2,3,5,6-tetramethylbenzyl, 3-methylbenzyl and 3-benzyl groups for optimal interactions with target proteins, evaluated by molecular docking studies. At the same time, the docking findings support the inhibition constants (Ki ) values of the related compounds in this study. Potential compounds were also evaluated by their pharmacokinetic properties were predicted.

Establishment of In Vitro and In Vivo Anticolorectal Cancer Efficacy of Lithocholic Acid-Based Imidazolium Salts

Imidazolium salts (IMSs) are the subject of many studies showing their anticancer activities. In this research, a series of novel imidazolium salts substituted with lithocholic acid (LCA) and alkyl chains of various lengths (S1–S10) were evaluated against colon cancer cells. A significant reduction in the viability and metabolic activity was obtained in vitro for DLD-1 and HT-29 cell lines when treated with tested salts. The results showed that the activities of tested agents are directly related to the alkyl chain length, where S6–S8 compounds were the most cytotoxic against the DLD-1 line and S4–S10 against HT-29. The research performed on the xenograft model of mice demonstrated a lower tendency of tumor growth in the group receiving compound S6, compared with the group receiving 5-fluorouracil (5-FU). Obtained results indicate the activity of S6 in the induction of apoptosis and necrosis in induced colorectal cancer. LCA-based imidazolium salts may be candidates for chemotherapeutic agents against colorectal cancer.

Synthesis and antitumor activity of novel hybrid compounds between 1,4-benzodioxane and imidazolium salts

A series of novel hybrid compounds between 1,4-benzodioxane and imidazolium salts was designed and prepared. The compounds were evaluated in vitro against a panel of human tumor cell lines (K562, SMMC-7721, and A-549). The structure-activity relationship results demonstrated that the 2-methyl-benzimidazole or 5,6-dimethyl-benzimidazole ring and substitution of the imidazolyl-3-position with a 4-phenylphenacyl substituent were critical for promoting cytotoxic activity. Particularly, compound 25 was found to be the most potent compound with IC₅₀ values of 1.06-8.31 μM against the three human tumor cell lines and exhibited higher selectivity to K562 and SMMC-7721 cells with IC₅₀ values 4.5- and 4.7-fold lower than cisplatin. Moreover, compound 25 inhibited cell proliferation by inducing the G0/G1 cell cycle arrest and apoptosis in SMMC-7721 cells.

Coumarin-benzimidazole hybrids: A review of developments in medicinal chemistry

Coumarin and benzimidazole are privileged structures in medicinal chemistry and are widely used in drug discovery and development due to their vast biological properties. The pharmacokinetic and pharmacodynamic properties of the individual scaffolds can be improved by developing coumarin-benzimidazole chimeric molecules via molecular hybridization approach. The three major classes of coumarin-benzimidazole hybrids are merged, fused and spacer-linked hybrids. Depending on the substitution position, fused hybrids and spacer-linked hybrids can be further classified as coumarin-C3 hybrids, coumarin-C4 hybrids and coumarin-C5/6/7/8 hybrids. Most of the coumarin-benzimidazole hybrid molecules exhibited potent anticancer, antiviral, antimicrobial, antitubercular, anthelmintic, anti-inflammatory, antioxidant, anticonvulsant and carbonic anhydrase inhibitory activities. The fused coumarin-C3 hybrid (2), thiomethylene-linked coumarin-C3 hybrid (45), N-glucoside substituted thiomethylene-linked coumarin-C3 hybrid (37c), amide-linked coumarin-C3 hybrid (50a), and sulfonylmethylene-linked coumarin-C4 hybrid (63) were identified as the representative potent anticancer, antimicrobial, antiviral, antioxidant and antitubercular agents respectively. The biological properties of the different classes of coumarin-benzimidazole hybrids with their structure-activity relationship studies and the mechanism of action studies were presented in this review, aiming to help the researchers across the globe to generate future hybrid molecules as potential drug candidates.

Synthesis and biological activity of new bisbenzofuran-imidazolium salts

A series of novel bisbenzofuran-imidazolium salts were designed and prepared. The in vitro antitumor activity of these derivatives was evaluated against a panel of human tumor cell lines (A549, HL-60, MCF-7, SMMC-7721 and SW480). Results demonstrated that 2-methyl-benzimidazole ring and substitution of the imidazolyl-3-position with a 4-methoxyphenacyl or 2-naphthylacyl substituent were important for promoting cytotoxic activity. Notably, compound 23 was found to be the most potent compound with IC₅₀ values of 0.64-1.47 μM against five human tumor cell lines, and exhibited higher selectivity to MCF-7 and SW-480 cell lines with IC₅₀ values 15.3-fold and 9.1-fold lower than DDP.

Synthesis and biological evaluation of novel 3-benzylcoumarin-imidazolium salts

A series of novel 3-benzylcoumarin-imidazolium salts were prepared and evaluated in vitro against a panel of human tumor cell lines. The results showed that the existence of 5,6-dimethyl-benzimidazole ring and substitution of the imidazolyl-3-position with a naphthylacyl group were vital for modulating cytotoxic activity. Notably, compound 38 was found to be the most potent derivative with IC₅₀ values of 2.04-4.51 μM against five human tumor cell lines, while compound 34 were more selective to SW-480 cell lines with IC₅₀ value 40.0-fold lower than DDP. Mechanism of action studies indicated that compound 38 can cause the G0/G1 phase cell cycle arrest and apoptosis in SMMC-7721 cell lines.

Design, Synthesis, and Anticancer Activity of Novel Trimethoxyphenyl-Derived Chalcone-Benzimidazolium Salts

A series of novel trimethoxyphenyl-derived chalcone-benzimidazolium salts were synthesized. The biological properties of the compounds were screened in vitro against five different human tumor cell lines. The results suggest that the 5,6-dimethyl-benzimidazole or 2-methyl-benzimidazole ring as well as the 2-naphthylmethyl, 4-methylbenzyl, or 2-naphthylacyl substituent at position-3 of the benzimidazole ring was important to the cytotoxic activity. Notably, (E)-5,6-dimethyl-3-(naphthalen-2-ylmethyl)-1-(3-(4-(3-(3,4,5-trimethoxyphenyl)acryloyl)phenoxy)propyl)-1H-benzo[d]imidazol-3-ium bromide (7f) was more selective to HL-60, MCF-7, and SW-480 cell lines with IC₅₀ values 8.0-, 11.1-, and 5.8-fold lower than DDP. Studies of the antitumor mechanism of action showed that compound 7f could induce cell-cycle G1 phase arrest and apoptosis in SMMC-7721 cells.

Synthesis and antitumor activity of aza-brazilan derivatives containing imidazolium salt pharmacophores

The synthesis of a series of novel aza-brazilan derivatives containing imidazolium salt pharmacophores is presented. The biological activity of such imidazolium salts was further evaluated in vitro against a panel of human tumor cell lines. The results suggest that the electron-withdrawing group on the aza-brazilan moiety, substituted 5,6-dimethyl-benzimidazole ring and substitution of the imidazolyl-3-position with a 4-methylbenzyl group were essential for modulating the cytotoxic activity. Compounds 55 and 39, bearing a 4-methylbenzyl substituent at position-3 of 5,6-dimethyl-benzimidazole, were found to be the most potent compounds with IC₅₀ values of 0.52-1.30 μM and 0.56-1.51 μM against four human tumor cell lines investigated. Particularly, compound 57 exhibited inhibitory activity against the MCF-7 cell line with an IC₅₀ value of 0.35 μM and was 56-fold more sensitive than DDP. Moreover, compound 55 inhibited cell proliferation through inducing G0/G1 cell cycle arrest and apoptosis in SMMC-7721 cells.

Chemoselective synthesis of aryl(pyridinyl)methanol derivatives through Ni-NIXANTPHOS catalyzed α-arylation and tandem arylation/rearrangement of pyridylmethyl ethers

An efficient synthesis of aryl(pyridyl)-methanol derivatives using Ni-NIXANTPHOS catalyzed α-arylation and tandem arylation/rearrangement is described.

Transition-Metal-Free Radical C(sp3)-C(sp2) and C(sp3)-C(sp3) Coupling Enabled by 2-Azaallyls as Super-Electron-Donors and Coupling-Partners

The past decade has witnessed the rapid development of radical generation strategies and their applications in C-C bond-forming reactions. Most of these processes require initiators, transition metal catalysts, or organometallic reagents. Herein, we report the discovery of a simple organic system (2-azaallyl anions) that enables radical coupling reactions under transition-metal-free conditions. Deprotonation of N-benzyl ketimines generates semistabilized 2-azaallyl anions that behave as "super-electron-donors" (SEDs) and reduce aryl iodides and alkyl halides to aryl and alkyl radicals. The SET process converts the 2-azaallyl anions into persistent 2-azaallyl radicals, which capture the aryl and alkyl radicals to form C-C bonds. The radical coupling of aryl and alkyl radicals with 2-azaallyl radicals makes possible the synthesis of functionalized amine derivatives without the use of exogenous radical initiators or transition metal catalysts. Radical clock studies and 2-azaallyl anion coupling studies provide mechanistic insight for this unique reactivity.

Arylation of Azaarylmethylamines with Aryl Chlorides and a NiBr2/NIXANTPHOS-based Catalyst

A nickel-catalyzed coupling of azaarylmethylamines with aryl chlorides has been achieved. NIXANTPHOS together with low cost NiBr₂ was successfully developed and optimized to exhibit high reactivity at 2.5 mol % loading. Under optimized reaction conditions, aryl(azaaryl)methylamine products were afforded in good to excellent yields (22 examples, up to 98% yield).