Effects of dose and route on the disposition and kinetics of 1-butyl-1-methylpyrrolidinium chloride in male F-344 rats

Mechanisms of Biological Effects of Ionic Liquids: From Single Cells to Multicellular Organisms

The review presents a detailed discussion of the evolving field studying interactions between ionic liquids (ILs) and biological systems. Originating from molten salt electrolytes to present multiapplication substances, ILs have found usage across various fields due to their exceptional physicochemical properties, including excellent tunability. However, their interactions with biological systems and potential influence on living organisms remain largely unexplored. This review examines the cytotoxic effects of ILs on cell cultures, biomolecules, and vertebrate and invertebrate organisms. Our understanding of IL toxicity, while growing in recent years, is yet nascent. The established findings include correlations between harmful effects of ILs and their ability to disturb cellular membranes, their potential to trigger oxidative stress in cells, and their ability to cause cell death via apoptosis. Future research directions proposed in the review include studying the distribution of various ILs within cellular compartments and organelles, investigating metabolic transformations of ILs in cells and organisms, detailed analysis of IL effects on proteins involved in oxidative stress and apoptosis, correlation studies between IL doses, exposure times and resulting adverse effects, and examination of effects of subtoxic concentrations of ILs on various biological objects. This review aims to serve as a critical analysis of the current body of knowledge on IL-related toxicity mechanisms. Furthermore, it can guide researchers toward the design of less toxic ILs and the informed use of ILs in drug development and medicine.

Biological Activity of Ionic Liquids and Their Application in Pharmaceutics and Medicine

Ionic liquids are remarkable chemical compounds, which find applications in many areas of modern science. Because of their highly tunable nature and exceptional properties, ionic liquids have become essential players in the fields of synthesis and catalysis, extraction, electrochemistry, analytics, biotechnology, etc. Apart from physical and chemical features of ionic liquids, their high biological activity has been attracting significant attention from biochemists, ecologists, and medical scientists. This Review is dedicated to biological activities of ionic liquids, with a special emphasis on their potential employment in pharmaceutics and medicine. The accumulated data on the biological activity of ionic liquids, including their antimicrobial and cytotoxic properties, are discussed in view of possible applications in drug synthesis and drug delivery systems. Dedicated attention is given to a novel active pharmaceutical ingredient-ionic liquid (API-IL) concept, which suggests using traditional drugs in the form of ionic liquid species. The main aim of this Review is to attract a broad audience of chemical, biological, and medical scientists to study advantages of ionic liquid pharmaceutics. Overall, the discussed data highlight the importance of the research direction defined as "Ioliomics", studies of ions in liquids in modern chemistry, biology, and medicine.

Sulfasalazine in ionic liquid form with improved solubility and exposure

An ionic liquid form of sulfasalazine demonstrates improved solubility (4000×), bioavailability (2.5×), andin vivoexposure over the neutral drug.

Toxicity of ionic liquids: eco(cyto)activity as complicated, but unavoidable parameter for task-specific optimization

Rapid progress in the field of ionic liquids in recent decades led to the development of many outstanding energy-conversion processes, catalytic systems, synthetic procedures, and important practical applications. Task-specific optimization emerged as a sharpening stone for the fine-tuning of structure of ionic liquids, which resulted in unprecedented efficiency at the molecular level. Ionic-liquid systems showed promising opportunities in the development of green and sustainable technologies; however, the chemical nature of ionic liquids is not intrinsically green. Many ionic liquids were found to be toxic or even highly toxic towards cells and living organisms. In this Review, we show that biological activity and cytotoxicity of ionic liquids dramatically depend on the nature of a biological system. An ionic liquid may be not toxic for particular cells or organisms, but may demonstrate high toxicity towards another target present in the environment. Thus, a careful selection of biological activity data is a must for the correct assessment of chemical technologies involving ionic liquids. In addition to the direct biological activity (immediate response), several indirect effects and aftereffects are of primary importance. The following principal factors were revealed to modulate toxicity of ionic liquids: i) length of an alkyl chain in the cation; ii) degree of functionalization in the side chain of the cation; iii) anion nature; iv) cation nature; and v) mutual influence of anion and cation.

Substrate-dependent inhibition of human MATE1 by cationic ionic liquids

The multidrug and toxin extruders 1- and 2-K (MATE1 and MATE2-K) are expressed in the luminal membrane of renal proximal tubule cells and provide the active step in the secretion of molecules that carry a net positive charge at physiologic pH, so-called organic cations. The present study tested whether structurally distinct MATE substrates can display different quantitative profiles of inhibition when interacting with structurally distinct ligands. The tested ligands were three structurally similar cationic ionic liquids (ILs, salts in the liquid state: N-butylpyridinium, NBuPy; 1-methyl-3-butylimidazolium, Bmim; and N-butyl-N-methylpyrrolidinium, BmPy). Uptake was measured using Chinese hamster ovary cells that stably expressed MATE1 or MATE2-K. By trans-stimulation, all three ILs were transported by both MATE transporters. The three ILs also inhibited uptake of three structurally distinct MATE substrates: 1-methyl-4-phenylpyridinium (MPP), triethylmethylammonium (TEMA), and N,N,N-trimethyl-2-[methyl(7-nitrobenzo[c][1,2,5]oxadiazol-4-yl)amino]ethanaminium (NBD-MTMA). MATE1 displayed a higher affinity for the pyridinium-based NBuPy (IC50 values, 2-4 µM) than for either the pyrrolidinium- (BmPy; 20-70 µM) or imidazolium-based ILs (Bmim; 15-60 µM). Inhibition of MPP, TEMA, and NBD-MTMA transport by NBuPy was competitive, with comparable Ki values against all substrates. Bmim also competitively blocked the three substrates but with Ki values that differed significantly (20 µM against MPP and 30 µM against NBD-MTMA versus 60 µM against TEMA). Together, these data indicate that renal secretion of ILs by the human kidney involves MATE transporters and suggest that the mechanism of transport inhibition is ligand-dependent, supporting the hypothesis that the binding of substrates to MATE transporters involves interaction with a binding surface with multiple binding sites.

Characterization of the inhibitory effects of N-butylpyridinium chloride and structurally related ionic liquids on organic cation transporters 1/2 and human toxic extrusion transporters 1/2-k in vitro and in vivo

Ionic liquids (ILs) are a class of salts that are expected to be used as a new source of solvents and for many other applications. Our previous studies revealed that selected ILs, structurally related organic cations, are eliminated exclusively in urine as the parent compound, partially mediated by renal transporters. This study investigated the inhibitory effects of N-butylpyridinium chloride (NBuPy-Cl) and structurally related ILs on organic cation transporters (OCTs) and multidrug and toxic extrusion transporters (MATEs) in vitro and in vivo. After Chinese hamster ovary cells expressing rat (r) OCT1, rOCT2, human (h) OCT2, hMATE1, or hMATE2-K were constructed, the ability of NBuPy-Cl, 1-methyl-3-butylimidazolium chloride (Bmim-Cl), N-butyl-N-methylpyrrolidinium chloride (BmPy-Cl), and alkyl substituted pyridinium ILs to inhibit these transporters was determined in vitro. NBuPy-Cl (0, 0.5, or 2 mg/kg per hour) was also infused into rats to assess its effect on the pharmacokinetics of metformin, a substrate of OCTs and MATEs. NBuPy-Cl, Bmim-Cl, and BmPy-Cl displayed strong inhibitory effects on these transporters (IC(50) = 0.2-8.5 μM). In addition, the inhibitory effects of alkyl-substituted pyridinium ILs on OCTs increased dramatically as the length of the alkyl chain increased. The IC(50) values were 0.1, 3.8, 14, and 671 μM (hexyl-, butyl-, and ethyl-pyridinium and pyridinium chloride) for rOCT2-mediated metformin transport. Similar structurally related inhibitory kinetics were also observed for rOCT1 and hOCT2. The in vivo coadministration study revealed that NBuPy-Cl reduced the renal clearance of metformin in rats. These results demonstrate that ILs compete with other substrates of OCTs and MATEs and could alter the in vivo pharmacokinetics of such substrates.

A comparison of the effects of prenatal exposure of CD-1 mice to three imidazolium-based ionic liquids

BACKGROUND

Ionic liquids (ILs; salts with melting points below 100 degrees C) exhibit wide liquid ranges, non-flammability, and thermal stability among other properties. These unique salts are best known as "green" alternatives to traditional volatile organic solvents, which are utilized in both academia and industry. Our current study compares the developmental toxicity potential of three representative ionic liquids, with various chain lengths: 1-ethyl-3-methylimidazolium chloride ([C(2)mim]Cl), 1-butyl-3-methylimidazolium chloride ([C(4)mim]Cl), and 1-decyl-3methylimidazolium chloride ([C(10)mim]Cl).

METHODS

From gestation days (GD) 6-16, mated CD-1 mice were orally dosed with one of the following: 1,000, 2,000, or 3,000 mg/kg/day [C(2)mim]Cl; 113, 169, or 225 mg/kg/day [C(4)mim]Cl; 50, 75, or 100 mg/kg/day [C(10)mim]Cl; or the vehicle only. Dams were sacrificed on GD 17, and their litters were examined for adverse effects.

RESULTS

Fetal weight was significantly decreased in the two highest dosage groups exposed to [C(4)mim]Cl and [C(10)mim]Cl in comparison with their controls, but the [C(2)mim]Cl treated groups were not affected. An apparent teratogenic effect was associated with both [C(4)mim]Cl and [C(10)mim]Cl, as the offspring exhibited certain uncommon morphological defects. However, the incidences of malformations were low and no correlation between incidence and dosage could be made. No morphological defects were observed in any of the [C(2)mim]Cl-treated groups, despite maternal morbidity at the highest dosage level.

CONCLUSIONS

This study indicates that [C(4)mim]Cl and [C(10)mim]Cl may have adverse effects on development at high maternal exposures and strongly supports the supposition that the toxicity of imidazolium-based ILs is influenced by alkyl chain length.