New ionic liquids based on 5-fluorouracil: Tuning of BSA binding and cytotoxicity

Synthesis of versatile fluorescent isoquinolinium salts and their applications

Isoquinolinium salts are well-known N-heterocyclic cationic compounds that have been applied in various research fields, such as materials chemistry and pharmaceutical applications. In particular, isoquinolinium salts with polyaromatic structures have been widely investigated due to their intrinsic photophysical properties, including fluorescence emission maxima, fluorescence lifetime, and quantum yield. Notably, fluorescent isoquinolinium salts have been synthesized via various synthetic strategies, such as alkylation of isoquinoline, oxidation of dihydropyridines, rearrangement reactions, and transition-metal-catalyzed C-H activation. In this review, we summarize the synthetic methodologies for diverse fluorescent isoquinolinium salts and their applications in pharmaceutical applications, materials chemistry, theranostics, DNA binding, fluorescent sensing, and bioimaging.

Interaction between newly synthesized surface-active ionic liquids with pharmaceutically active anion and bovine serum albumin

This work describes the synthesis and properties of new surface active (octyl-, and dodecyl-) imidazolium and choline-based ionic liquids with pharmaceutically active 5-fluorouracil anion (SAAPI-IL). The effect of the novel SAAPI-IL on the secondary and tertiary structure of bovine serum albumin (BSA) was studied using circular dichroism (CD) spectroscopy. The binding constants of BSA with SAAPI-IL were estimated from the fluorescence quenching of BSA. The influence of the length of the alkyl chain SAAPI-IL on the binding constant with BSA was analyzed. The localization of ions on BSA was estimated using the molecular docking method. Also, the effect of alkyl substituent length on the aggregation tendency of SAAPI-IL was studied by dynamic light scattering (DLS). Cytotoxicity and selectivity of SAAPI-ILs on cancer and normal cell lines were compared to molecular 5-fluorouracil and API-IL without the alkyl substituents. Surprisingly, increasing the length of the alkyl substituent did not increase the binding of SAAPI-IL to BSA. On the other hand, [C8Ch][FU] showed selectivity against A 549 cell line, which 5-fluorouracil does not possess.

Tuning of the Anti-Breast Cancer Activity of Betulinic Acid via Its Conversion to Ionic Liquids

Betulinic acid (BA) is a natural pentacyclic triterpene with diverse biological activities. However, its low water solubility limits its pharmaceutical application. The conversion of pharmaceutically active molecules into ionic liquids (ILs) is a promising strategy to improve their physicochemical properties, stability, and/or potency. Here, we report the synthesis and characterization of 15 novel ILs containing a cation ethyl ester of a polar, non-polar, or charged amino acid [AAOEt] and an anion BA. Except for [ValOEt][BA], we observed preserved or up to 2-fold enhanced cytotoxicity toward hormone-dependent breast cancer cells MCF-7. The estimated IC50 (72 h) values within the series varied between 4.8 and 25.7 µM. We found that the most cytotoxic IL, [LysOEt][BA]2, reduced clonogenic efficiency to 20% compared to that of BA. In addition, we evaluated the effect of a 72 h treatment with BA or [LysOEt][BA]2, the most cytotoxic compound, on the thermodynamic behavior of MCF-7 cells. Based on our data, we suggest that the charged amino acid lysine included in the novel ILs provokes cytotoxicity by a mechanism involving alteration in membrane lipid organization, which could be accompanied by modulation of the visco-elastic properties of the cytoplasm.