Metal-free imidazolium salts inhibit the growth of hepatocellular carcinoma in a mouse model

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.

The anti-tumor effects of imidazolium salts on oral squamous cell carcinoma

BACKGROUND

Imidazolium salts (IS), ionic derivatives of neutral imidazoles, have properties that can be adjusted by structural modifications to their cations and anions, which makes this particular class of compounds a promising option for developing biologically active compounds. The anti-tumor effects of the IS 1-n-butyl-3-methylimidazolium chloride (C₄ MImCl), 1-n-decyl-3-methylimidazolium chloride (C₁₀ MImCl), 1-n-hexadecyl-3-methylimidazolium chloride (C₁₆ MImCl), 1-n-hexadecyl-2,3-dimethylimidazolium chloride (C₁₆ M₂ ImCl), 1-n-octadecyl-3-methylimidazolium chloride (C₁₈ MImCl), 1-n-hexadecyl-3-methylimidazolium methanesulfonate (C₁₆ MImMeS), and 1-n-hexadecyl-2,3- dimethylimidazolium methanesulfonate (C₁₆ M₂ ImMeS) on oral squamous cell carcinoma (OSCC) have been studied here.

METHODS

Oral squamous cell carcinoma cells (CAL27) were incubated with increasing IS doses and then submitted to proliferation (2D), cell death (2D) and spheroid assay (3D).

RESULTS

The IS anti-tumor effect was dependent on both its N-alkyl chain length and anion, whereby C₁₆ MImCl proved to be more effective in combination for inhibiting cell proliferation and cell-cell adhesion, outperforming the methylated C₁₆ M₂ ImCl derivative and, most importantly, the gold standard-cisplatin. In addition, C₁₆ MImCl had little effect on keratinocytes and more pronounced effects on more aggressive tumor cells. It also exhibited similar effects on inducing cell death when compared to Cisplatin. This compound spread to a greater area of the tumor sphere and produced an enhanced number of apoptotic and necrotic cells in the tumor cell line, demonstrating only a small rise in the healthy cells.

CONCLUSION

These data indicate that the effect of C₁₆ MlmCl on OSCC is promising, as it is selective for cancer cells.

Synthesis, Radiolabeling, and Bioevaluation of Bis(Trifluoromethanesulfonyl) Imide

Imidazolium salts have antitumor potential and toxicological effects on various microorganisms. The authors' aim is to synthesize a new imidazolium salt and to assess its pharmacokinetic and antitumor potentials by in vitro and in vivo studies. In this study, bis(trifluoromethanesulfonyl) imide (ITFSI) was synthesized and labeled with (131)I using the iodogen method. The efficiency of radiolabeling was determined with high yield (95.5% ± 3.7%). Pharmacokinetic properties of the compound were investigated in albino Wistar rats using radiolabeled compound. The radiolabeled compound ((131)I-ITFSI) has been stable during a period of 3 hours in human serum. The uptake of (131)I-ITFSI reached maximum in the spleen, liver, and blood at 60 minutes, large intestine and heart at 30 minutes, and ovary at 120 minutes. It is observed that intracellular uptake of the radiolabeled compound is higher in the CaCo-2 (colon adenocarcinoma tumor) cell line than HEK-293 (human epithelial kidney) cell line. In further study, antitumor potential of ITFSI on a colon adenocarcinoma tumor-bearing animal model may be investigated.

Therapeutic effect of a multi-targeted imidazolium compound in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most commonly diagnosed lethal cancers in the world. We previously showed two imidazolium salts (IBN-1 and IBN-9) with a moderate efficacy for HCC. Here we report a more potent imidazolium compound IBN-65 (1-benzyl-2-phenyl-3-(4-isopropyl)-benzyl-imidazolium chloride) and the associated mechanisms of action in a mouse model of HCC. The IC50 of this compound in various liver cancer cell lines was around 5 μm. IBN-65 dose-dependently arrested cell cycle at G1 phase and was associated with the down-regulation of the cyclin-dependent kinase-4, -6, cyclin D1, and cyclin E. In addition, IBN-65 induced apoptosis by down-regulating Survivin, Bcl-2 and up-regulating Bax, leading to sequential activation of Caspase-3, Caspase-9 and the cleavage of poly(ADP-ribose) polymerase (PARP). Dysregulation of the epidermal growth factor receptor (EGFR) signaling network has been frequently reported in HCC. We found that IBN-65 displayed a profound inhibitory effect on the EGFR/Raf/MEK/ERK signaling at the phosphorylation level. In Huh7 or Hep3B cells, pretreatment with IBN-65 attenuated EGF-induced phosphorylation of both EGFR and the downstream p44/42 MAPK. A siRNA knockdown of EGFR also proved that IBN-65 induced apoptosis mostly through inhibiting downstream EGFR pathway signaling, much less at the receptor level. Infrequent administration of IBN-65 (i.p., 5 mg/kg once weekly for four weeks) to mice bearing the Huh7 cells significantly reduced the tumor volume by 65% without affecting the body weight. Critically, many of the anti-tumor signaling features observed in the HCC cell lines were recaptured in the xenografted tissues. Thus, the metal-free imidazolium compound IBN-65 could be a potential candidate towards therapeutic development for HCC.

Recent developments of metal N-heterocyclic carbenes as anticancer agents

Metal based anticancer drugs have demonstrated their crucial role in preventing all types of cancers whereas their effectiveness is selective with respect to the cancer cells rather than the normal cells. Recently metal N-heterocyclic carbenes have established their selective performance for cancer cells excluding normal healthy cells based on which they are widely utilised for targeting cancer cells specifically which leads to cell death or cell growth inhibition. This is mainly due to their ionic character which helps them to localise in cancer cells with the help of enhanced expression of Organic Cation Transporters (OCT). Also their unique mechanism of action involving DNA binding, less recognizable by DNA repair machinery, mitochondria targeting gives them a new area for anticancer drug development. This review summarises the medicinal as well as pharmacological approach to the anticancer properties of metal NHC complexes.

Imidazolium compounds are active against all stages of Trypanosoma cruzi

Imidazolium salts are best known for their applications in organic synthesis as room-temperature ionic liquids, or as precursors of stable carbenes, but they also show important biological properties such as anti-oxidative effects, induction of mitochondrial membrane permeabilisation and inhibition of the infection cycle of Plasmodium falciparum. For these reasons, and since chemotherapy for Chagas disease is inefficient, the aim of this study was to test the use of imidazolium compounds against the kinetoplastid haemoflagellate aetiological agent for this disease, namely Trypanosoma cruzi. The results show that five of the tested compounds are more effective than the reference drug benznidazole against the epimastigote and trypomastigote forms of T. cruzi. Moreover, intracellular amastigotes were also affected by the compounds, which showed lower toxicity in host cells. Transmission electron microscopy analysis demonstrated that the tested agents induced alterations of the kinetoplast and particularly of the mitochondria, leading to extraordinary swelling of the organelle. These results further demonstrate that the test agents with the best profile are those bearing symmetrical bulky substituents at N(1) and N(3), displaying promising activity against all forms of T. cruzi, interesting selectivity indexes and exceptional activity at low doses. Accordingly, these agents represent promising candidates for the treatment of Chagas disease.

In vitro effects of novel ruthenium complexes in Neospora caninum and Toxoplasma gondii tachyzoites

Upon the screening of 16 antiproliferative compounds against Toxoplasma gondii and Neospora caninum, two hydrolytically stable ruthenium complexes (compounds 16 and 18) exhibited 50% inhibitory concentrations of 18.7 and 41.1 nM (T. gondii) and 6.7 and 11.3 nM (N. caninum). To achieve parasiticidal activity with compound 16, long-term treatment (22 to 27 days at 80 to 160 nM) was required. Transmission electron microscopy demonstrated the rapid impact on and ultrastructural alterations in both parasites. These preliminary findings suggest that the potential of ruthenium-based compounds should thus be further exploited.

Short imidazolium chains effectively clear fungal biofilm in keratitis treatment

Fungal keratitis is a leading cause of ocular morbidity throughout the world. However, current therapies against fungal keratitis are often ineffective. Herein, we have developed the amphiphilic main-chain imidazolium polymer (PIM-45) and oligomer (IBN-1) materials that can efficiently inhibit the growth of fungi with low minimal inhibition concentration (MIC) values and clear the fungal biofilm, while displaying minimal hemolysis. In vivo keratitis treatment indicates that topical solutions of these polyimidazolium salts (PIMSs) are safe and as effective as that of amphotericin B, the most commonly used agent for the treatment of Candida albicans (C. albicans) keratitis. Compared to the costly and unstable amphotericin B and fluconazole, PIM-45 and IBN-1 are easy to prepare, inexpensive and stable. They can be stored in phosphate-buffered saline (PBS) solutions with long shelf life for routine topical use.