Synthesis, characterization, in vitro SAR study, and preliminary in vivo toxicity evaluation of naphthylmethyl substituted bis-imidazolium salts

A series of novel bis-imidazolium salts was synthesized, characterized, and evaluated in vitro against a panel of non-small cell lung cancer (NSCLC) cells. Two imidazolium cores were connected with alkyl chains of varying lengths to develop a structure activity relationship (SAR). Increasing the length of the connecting alkyl chain was shown to correlate to an increase in the anti-proliferative activity. The National Cancer Institute's NCI-60 human tumor cell line screen confirmed this trend. The compound containing a decyl linker chain, 10, was chosen for further in vivo toxicity studies with C578BL/6 mice. The compound was well tolerated by the mice and all of the animals survived and gained weight over the course of the study.

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.

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 novel N-substituted tetrahydro-β-carboline-imidazolium salt derivatives

The synthesis of a series of novel N-substituted tetrahydro-β-carboline-imidazolium salt derivatives is presented. The biological properties of the compounds were evaluated in vitro against a panel of human tumor cell lines. The results suggest that the benzimidazole ring and 1-(naphthalen-2-yl)ethan-1-one or 2-naphthylmethyl substituent at the imidazolyl-3-position were vital for modulating cytotoxic activity. Compound 41 was observed as a potent derivative with IC₅₀ values of 3.24-8.78 μM and exhibited cytotoxic activity selectively against HL-60, A-549 and MCF-7 cell lines. Meanwhile, high inhibitory activities selectively against HL-60 and MCF-7 cell lines were observed for compound 51. Moreover, compound 51 was able to induce G1 phase cell cycle arrest and apoptosis in MCF-7 cells. The cytotoxicity of compound 51 against human normal lung epithelial cell line BEAS-2B was further evaluated.

Novel 3-substituted N-methylcarbazole-imidazolium salt derivatives: Synthesis and cytotoxic activity

A series of novel 3-substituted N-methylcarbazole-imidazolium salt derivatives has been prepared and evaluated in vitro against a panel of tumor cell lines (Hep G-2, Hela and PC12). The results suggest that the presence of substituted 2-methyl-imidazole or imidazole ring and substitution of the imidazolyl-3-position with a naphthylacyl or 4-bromophenacyl group were important for improving cytotoxic activity. Compounds 17, 18, 27, and 28 with 4-bromophenacyl and naphthylacyl groups displayed good activities with IC₅₀ values of 0.09-7.20 μm against three tumor cell lines investigated and more active than DDP. Compound 35 exhibited cytotoxic activity selectively against Hela cell.

Design, synthesis and in vitro cytotoxicity studies of novel β-carbolinium bromides

A series of novel β-carbolinium bromides has been synthesized from easily accessible β-carbolines and 1-aryl-2-bromoethanones. The newly synthesized compounds were evaluated for their in vitro anticancer activity. Among the synthesized derivatives, compounds 16l, 16o and 16s exhibited potent anticancer activity with IC50 values of <10μM against tested cancer cell lines. The most potent analogue 16l was broadly active against all the tested cancer cell lines (IC50=3.16-7.93μM). In order to test the mechanism of cell death, we exposed castration resistant prostate cancer cell line (C4-2) to compounds 16l and 16s, which resulted in increased levels of cleaved PARP1 and AO/EB staining, indicating that β-carbolinium salts induce apoptosis in these cells. Additionally, the most potent β-carbolines 16l and 16s were found to inhibit tubulin polymerization.

Synthesis, characterization, in vitro SAR and in vivo evaluation of N,N'bisnaphthylmethyl 2-alkyl substituted imidazolium salts against NSCLC

Alkyl- and N,N'-bisnaphthyl-substituted imidazolium salts were tested in vitro for their anti-cancer activity against four non-small cell lung cancer cell lines (NCI-H460, NCI-H1975, HCC827, A549). All compounds had potent anticancer activity with 2 having IC50 values in the nanomolar range for three of the four cell lines, a 17-fold increase in activity against NCI-H1975 cells when compared to cisplatin. Compounds 1-4 also showed high anti-cancer activity against nine NSCLC cell lines in the NCI-60 human tumor cell line screen. In vitro studies performed using the Annexin V and JC-1 assays suggested that NCI-H460 cells treated with 2 undergo an apoptotic cell death pathway and that mitochondria could be the cellular target of 2 with the mechanism of action possibly related to a disruption of the mitochondrial membrane potential. The water solubilities of 1-4 was over 4.4mg/mL using 2-hydroxypropyl-β-cyclodextrin as a chemical excipient, thereby providing sufficient solubility for systemic administration.

Synthesis, characterization, and in vitro SAR evaluation of N,N'-bis(arylmethyl)-C2-alkyl substituted imidazolium salts

A series of C2-alkyl substituted N,N'-bis(arylmethyl)imidazolium salts were synthesized, characterized, and tested for their in vitro anti-cancer activity against multiple non-small cell lung cancer cell lines by our group and the National Cancer Institute's-60 human tumor cell line screen to establish a structure-activity relationship. Compounds are related to previously published N,N'-bis(arylmethyl)imidazolium salts but utilize the historical quinoline motif and anion effects to increase the aqueous solubility. Multiple derivatives displayed high anti-cancer activity with IC50 values in the nanomolar to low micromolar range against a panel of non-small cell lung cancer cell lines. Several of these derivatives have high aqueous solubilities with potent anti-proliferative properties and are ideal candidates for future in vivo xenograft studies and have high potential to progress into clinic use.

Influence of the Headgroup of Azolium-Based Lipids on Their Biophysical Properties and Cytotoxicity

A series of (un-)charged NHC derivatives bearing two pentadecyl chains in the backbone was studied in detail to find cooperative effects between the membrane and the NHC derivative. The tendency to show lipid-like behavior is dependent on the properties of the NHC derivative headgroup, which can be modified on demand. The surface activity was investigated by film balance measurements, epifluorescence microscopy, and differential scanning calorimetry. Additionally the cytotoxicity was evaluated against different cell lines such as eukaryotic tumor cell lines. These novel lipid-like NHC derivatives offer a broad spectrum for biological applications.

Synthesis, anti-proliferative activity, SAR study, and preliminary in vivo toxicity study of substituted N,N'-bis(arylmethyl)benzimidazolium salts against a panel of non-small cell lung cancer cell lines

A series of N,N'-bis(arylmethyl)benzimidazolium salts have been synthesized and evaluated for their in vitro anti-cancer activity against select non-small cell lung cancer cell lines to create a structure activity relationship profile. The results indicate that hydrophobic substituents on the salts increase the overall anti-proliferative activity. Our data confirms that naphthylmethyl substituents at the nitrogen atoms (N¹(N³)) and highly lipophilic substituents at the carbon atoms (C² and C⁵(C⁶)) can generate benzimidazolium salts with anti-proliferative activity that is comparable to that of cisplatin. The National Cancer Institute's Developmental Therapeutics Program tested 1, 3-5, 10, 11, 13-18, 20-25, and 28-30 in their 60 human tumor cell line screen. Results were supportive of data observed in our lab. Compounds with hydrophobic substituents have higher anti-cancer activity than compounds with hydrophilic substituents.

Synthesis and antitumor activity of novel 2-substituted indoline imidazolium salt derivatives

A series of novel 2-substituted indoline imidazolium salt derivatives has been prepared and evaluated in vitro against a panel of human tumor cell lines. The results suggest that the existence of a substituted benzimidazole ring and substitution of the imidazolyl-3-position with a naphthylacyl or 2-naphthylmethyl group were vital for modulating the cytotoxic activity. Compound 25 was found to be the most potent derivative with IC50 values of 0.24-1.18 μM, and exhibited cytotoxic activity selectively against MCF-7, SW480, SMMC-7721 and HL-60 cell lines, while compound 26 showed powerful inhibitory activities selectively against SMMC-7721 and A549 cell lines. Compound 25 can induce G2/M phase cell cycle arrest and apoptosis in SMMC-7721 cells.

Synthesis and antitumor activity of novel N-substituted carbazole imidazolium salt derivatives

A series of novel N-substituted carbazole imidazolium salt derivatives has been prepared and investigated for their cytotoxic activity against five human tumor cell lines by MTS assay. The results indicated that the existence of 5,6-dimethyl-benzimidazole ring, substitution of the imidazolyl-3-position with a 2-bromobenzyl or naphthylacyl group, as well as alkyl chain length between carbazole and imidazole ring were important for the antitumor activity. Compound 61, bearing a 2-bromobenzyl substituent at position-3 of the 5,6-dimethyl-benzimidazole, showed powerful inhibitory activities and was more selective to HL-60, SMMC-7721, MCF-7 and SW480 cell lines with IC50 values 0.51-2.48 μM. Mechanism of action studies revealed that this new compound could remarkably induce cell cycle arrest and apoptosis in SMMC-7721 cells. This work provides alternative novel way for future drug development based on carbazole and imidazolium salt scaffolds.

Novel 3-substituted fluorine imidazolium/triazolium salt derivatives: synthesis and antitumor activity

A series of novel (±)-3-substituted fluorene–imidazolium/triazolium salt derivatives were synthesized and their antitumor structure–activity relationship studies were reported.