Quantitative parameters of complexes of tris(1-alkylindol-3-yl)methylium salts with serum albumin: Relevance for the design of drug candidates

Evaluation of New Antimicrobial Agents Based on tris(1H-Indol-3-yl)methylium Salts: Activity, Toxicity, Suppression of Experimental Sepsis in Mice

The antimicrobial activity and toxicity of three novel synthetic antibacterial agents containing tris(1H-indol-3-yl)methylium fragment were studied in vitro and in vivo. All compounds in vitro revealed high activity (minimal inhibitory concentration (MIC) 0.13–1.0 µg/mL) against bacteria that were either sensitive or resistant to antibiotics, including multidrug-resistant clinical isolates. The derivatives combining high antimicrobial activity with relatively low cytotoxicity against human donor fibroblasts HPF-hTERT were subjected to further testing on mice. In vivo they revealed fairly good tolerance and relatively low toxicity. Acute toxicity was evaluated, and the main indicators of toxicity, including LD₅₀ and LD₁₀, were determined. A study of compounds in vivo showed their efficiency in the model of staphylococcal sepsis in mice. The efficiency of compounds may be due to the ability of indolylmethylium salts to form pores in the cytoplasmic membrane of microbial cells and thereby facilitate the penetration of molecules into the pathogen.

N-(Hydroxyalkyl) Derivatives of tris(1H-indol-3-yl)methylium Salts as Promising Antibacterial Agents: Synthesis and Biological Evaluation

The wide spread of pathogens resistance requires the development of new antimicrobial agents capable of overcoming drug resistance. The main objective of the study is to elucidate the effect of substitutions in tris(1H-indol-3-yl)methylium derivatives on their antibacterial activity and toxicity to human cells. A series of new compounds were synthesized and tested. Their antibacterial activity in vitro was performed on 12 bacterial strains, including drug resistant strains, that were clinical isolates or collection strains. The cytotoxic effect of the compounds was determined using an test with HPF-hTERT (human postnatal fibroblasts, immortalized with hTERT) cells. The activity of the obtained compounds depended on the carbon chain length. Derivatives with C5–C6 chains were more active. The minimum inhibitory concentration (MIC) of the most active compound on Gram-positive bacteria, including MRSA, was 0.5 μg/mL. Compounds with C5–C6 chains also revealed high activity against Staphylococcus epidermidis (1.0 and 0.5 μg/mL, respectively) and moderate activity against Gram-negative bacteria Escherichia coli (8 μg/mL) and Klebsiella pneumonia (2 and 8 μg/mL, respectively). However, they have no activity against Salmonella cholerasuis and Pseudomonas aeruginosa. The most active compounds revealed higher antibacterial activity on MRSA than the reference drug levofloxacin, and their ratio between antibacterial and cytotoxic activity exceeded 10 times. The data obtained provide a basis for further study of this promising group of substances.

Synthesis and antibacterial activity of novel arylbis(indol-3-yl)methane derivatives

A series of new compounds-arylbis(indol-3-yl)methylium derivatives-were synthesized and their antimicrobial activity was evaluated. All the compounds turned out to be highly active, with MIC depending on their structure and the length of N-alkyl residues. The parent triarylmethane compounds possess weaker activity.

Spectroscopic investigation of the anticancer alkaloid piperlongumine binding to human serum albumin from the viewpoint of drug delivery

Piperlongumine (PL) is a very promising natural agent with a high potential for cancer treatment. To overcome the poor water solubility of PL, there is a need to develop a novel water-soluble formulation in which PL is non-covalently bound to human serum albumin (HSA). PL binding to HSA was studied by various spectroscopic techniques under simulated physiological conditions. Spectroscopic evidence showed that the interaction of PL with HSA could form a PL-HSA complex. The binding constant (Ka ) values increased with increasing temperature, and a similar dependence was observed for the number of binding sites (n) values. The number of PL molecules bound to HSA reached 8.1 when the temperature was raised to 308 K. Thermodynamic calculation results suggested that the binding reaction occurred spontaneously but was an entropy-driven process, and hydrophobic forces played a major role in stabilizing the complex. Furthermore, PL binding induced conformational and microenvironmental changes in HSA. Displacement studies indicated that PL and warfarin had separate binding regions in site I. Therefore, it would be possible to develop a novel water-soluble formulation involving PL and HSA. This study may provide some valuable information in terms of improving the poor water solubility of PL.