Highly Cytotoxic Copper(II) Mixed-Ligand Quinolinonato Complexes: Pharmacokinetic Properties and Interactions with Drug Metabolizing Cytochromes P450.

The effects of two anticancer active copper(II) mixed-ligand complexes of the type [Cu(qui)(mphen)]Y·H2O, where Hqui = 2-phenyl-3-hydroxy- 1H-quinolin-4-one, mphen = bathophenanthroline, and Y = NO3 (complex 1) or BF4 (complex 2) on the activities of different isoenzymes of cytochrome P450 (CYP) have been evaluated. The screening revealed significant inhibitory effects of the complexes on CYP3A4/5 (IC50 values were 2.46 and 4.88 µM), CYP2C9 (IC50 values were 16.34 and 37.25 µM), and CYP2C19 (IC50 values were 61.21 and 77.07 µM). Further, the analysis of mechanisms of action uncovered a non-competitive type of inhibition for both the studied compounds. Consequent studies of pharmacokinetic properties proved good stability of both the complexes in phosphate buffer saline (>96% stability) and human plasma (>91% stability) after 2 h of incubation. Both compounds are moderately metabolised by human liver microsomes (<30% after 1 h of incubation), and over 90% of the complexes bind to plasma proteins. The obtained results showed the potential of complexes 1 and 2 to interact with major metabolic pathways of drugs and, as a consequence of this finding, their apparent incompatibility in combination therapy with most chemotherapeutic agents.

Triterpenoid pyrazines and pyridines - Synthesis, cytotoxicity, mechanism of action, preparation of prodrugs.

A set of fifteen triterpenoid pyrazines and pyridines was prepared from parent triterpenoid 3-oxoderivatives (betulonic acid, dihydrobetulonic acid, oleanonic acid, moronic acid, ursonic acid, heterobetulonic acid, and allobetulone). Cytotoxicity of all compounds was tested in eight cancer and two non-cancer cell lines. Evaluation of the structure-activity relationships revealed that the triterpenoid core determined whether the final molecule is active or not, while the heterocycle is able to increase the activity and modulate the specificity. Five compounds (1b, 1c, 2b, 2c, and 8) were found to be preferentially and highly cytotoxic (IC50 ≈ 1 µM) against leukemic cancer cell lines (CCRF-CEM, K562, CEM-DNR, or K562-TAX). Surprisingly, compounds 1c, 2b, and 2c are 10-fold more active in multidrug-resistant leukemia cells (CEM-DNR and K562-TAX) than in their non-resistant analogs (CCRF-CEM and K562). Pharmacological parameters were measured for the most promising candidates and two types of prodrugs were synthesized: 1) Sugar-containing conjugates, most of which had improved cell penetration and retained high cytotoxicity in the CCRF-CEM cell line, unfortunately, they lost the selectivity against resistant cells. 2) Medoxomil derivatives, among which compounds 26-28 gained activities of IC50 0.026-0.043 µM against K562 cells. Compounds 1b, 8, 21, 22, 23, and 24 were selected for the evaluation of the mechanism of action based on their highest cytotoxicity against CCRF-CEM cell line. Several experiments showed that the majority of them cause apoptosis via the mitochondrial pathway. Compounds 1b, 8, and 21 inhibit growth and disintegrate spheroid cultures of HCT116 and HeLa cells, which would be important for the treatment of solid tumors. In summary, compounds 1b, 1c, 2b, 2c, 24, and 26-28 are highly and selectively cytotoxic against cancer cell lines and were selected for future in vivo tests and further development of anticancer drugs.

Glyphosate Interaction with eEF1α1 Indicates Altered Protein Synthesis: Evidence for Reduced Spermatogenesis and Cytostatic Effect.

The broad-spectrum herbicide, glyphosate, is considered safe for animals because it selectively affects the shikimate pathway that is specific to plants and microorganisms. We sought a previously unknown mechanism to explain the concerns that glyphosate exposure can negatively affect animals, including humans. Computer modeling showed a probable interaction between glyphosate and eukaryotic translation elongation factor 1 subunit alpha 1 (eEF1α1), which was confirmed by microcalorimetry. Only restricted, nondisrupted spermatogenesis in rats was observed after chronic glyphosate treatments (0.7 and 7 mg/L). Cytostatic and antiproliferative effects of glyphosate in GC-1 and SUP-B15 cells were indicated. Meta-analysis of public health data suggested a possible effect of glyphosate use on sperm count. The in silico, in vitro, and in vivo experimental results as well as the metastatistics indicate side effects of chronic glyphosate exposure. Together, these findings indicate that glyphosate delays protein synthesis through an interaction with eEF1α1, thereby suppressing spermatogenesis and cell growth.

Cytoprotective activities of kinetin purine isosteres.

Kinetin (N6-furfuryladenine), a plant growth substance of the cytokinin family, has been shown to modulate aging and various age-related conditions in animal models. Here we report the synthesis of kinetin isosteres with the purine ring replaced by other bicyclic heterocycles, and the biological evaluation of their activity in several in vitro models related to neurodegenerative diseases. Our findings indicate that kinetin isosteres protect Friedreich́s ataxia patient-derived fibroblasts against glutathione depletion, protect neuron-like SH-SY5Y cells from glutamate-induced oxidative damage, and correct aberrant splicing of the ELP1 gene in fibroblasts derived from a familial dysautonomia patient. Although the mechanism of action of kinetin derivatives remains unclear, our data suggest that the cytoprotective activity of some purine isosteres is mediated by their ability to reduce oxidative stress. Further, the studies of permeation across artificial membrane and model gut and blood-brain barriers indicate that the compounds are orally available and can reach central nervous system. Overall, our data demonstrate that isosteric replacement of the kinetin purine scaffold is a fruitful strategy for improving known biological activities of kinetin and discovering novel therapeutic opportunities.

Iodinated Choline Transport-Targeted Tracers.

We present a novel series of radioiodinated tracers and potential theranostics for diseases accompanied by pathological function of proteins involved in choline transport. Unlike choline analogues labeled with 11C or 18F that are currently used in the clinic, the iodinated compounds described herein are applicable in positron emission tomography, single-photon emission computed tomography, and potentially in therapy, depending on the iodine isotope selection. Moreover, favorable half-lives of iodine isotopes result in much less challenging synthesis by isotope exchange reaction. Six of the described compounds were nanomolar ligands, and the best compound possessed an affinity 100-fold greater than that of choline. Biodistribution data of 125I-labeled ligands in human prostate carcinoma bearing (PC-3) mice revealed two compounds with a biodistribution profile superior to that of [18F]fluorocholine.

Sulfonamido carboranes as highly selective inhibitors of cancer-specific carbonic anhydrase IX.

Carbonic anhydrase IX (CA IX) is a transmembrane enzyme overexpressed in hypoxic tumors, where it plays an important role in tumor progression. Specific CA IX inhibitors potentially could serve as anti-cancer drugs. We designed a series of sulfonamide inhibitors containing carborane clusters based on prior structural knowledge of carborane binding into the enzyme active site. Two types of carborane clusters, 12-vertex dicarba-closo-dodecaborane and 11-vertex 7,8-dicarba-nido-undecaborate (dicarbollide), were connected to a sulfonamide moiety via aliphatic linkers of varying lengths (1-4 carbon atoms; n = 1-4). In vitro testing of CA inhibitory potencies revealed that the optimal linker length for selective inhibition of CA IX was n = 3. A 1-sulfamidopropyl-1,2-dicarba-closo-dodecaborane (3) emerged as the strongest CA IX inhibitor from this series, with a Ki value of 0.5 nM and roughly 1230-fold selectivity towards CA IX over CA II. X-ray studies of 3 yielded structural insights into their binding modes within the CA IX active site. Compound 3 exhibited moderate cytotoxicity against cancer cell lines and primary cell lines in 2D cultures. Cytotoxicity towards multicellular spheroids was also observed. Moreover, 3 significantly lowered the amount of CA IX on the cell surface both in 2D cultures and spheroids and facilitated penetration of doxorubicin. Although 3 had only a moderate effect on tumor size in mice, we observed favorable ADME properties and pharmacokinetics in mice, and preferential presence in brain over serum.

Synthesis and Cytotoxic and Antiviral Activity Profiling of All-Four Isomeric Series of Pyrido-Fused 7-Deazapurine Ribonucleosides.

All four isomeric series of novel 4-substituted pyrido-fused 7-deazapurine ribonucleosides possessing the pyridine nitrogen atom at different positions were designed and synthesized. The total synthesis of each isomeric fused heterocycle through multistep heterocyclization was followed by glycosylation and derivatization at position 4 by cross-coupling reactions or nucleophilic substitutions. All compounds were tested for cytostatic and antiviral activity. The most active were pyrido[4',3':4,5]pyrimidine nucleosides bearing MeO, NH2 , MeS, or CH3 groups at position 4, which showed submicromolar cytotoxic effects and good selectivity for cancer cells. The mechanism involved activation by phosphorylation and incorporation to DNA where the presence of the modified ribonucleosides causes double-strand breaks and apoptosis.

Synthesis and biological evaluation of triterpenoid thiazoles derived from betulonic acid, dihydrobetulonic acid, and ursonic acid.

In this work, 35 new derivatives of betulonic, dihydrobetulonic and ursonic acid were prepared including 30 aminothiazoles and all of them were tested for their in vitro cytotoxic activity in eight cancer cell lines and two non-cancer fibroblasts. Compounds with the IC50 below 5 µM in CCRF-CEM cells and low toxicity in non-cancer fibroblasts (4m, 5c, 5m, 6c, 6m, 7b, and 7c) were further subjected to tests of pharmacological parameters yielding the final set for advanced biological evaluation (4m, 5m, 6m, and 7b). It was proved by several methods, that all of them trigger apoptosis via the intrinsic pathway and derivatives 5m and 7b are the most effective (IC50 2.4 µM and 3.6 µM). They are the best candidates to become potentially new anticancer drugs and will be subjected to in vivo tests in mice. In addition, compounds 6b and 6c deserve more attention because their activity is not limited only to chemosensitive CCRF-CEM cell line. Specifically, compound 6b is highly active against K562 leukemic cell line (0.7 µM) and its IC50 activity in colon cancer HCT116 cell line is 1.0 µM. Compound 6c is active in both normal K562 and resistant K562-TAX cell lines (IC50 3.4 µM and 5.4 µM) and both colon cancer cell lines (HCT116 and HCT116p53-/-, IC50 3.5 µM and 3.4 µM).

Metallacarborane Sulfamides: Unconventional, Specific, and Highly Selective Inhibitors of Carbonic Anhydrase IX.

Carbonic anhydrase IX (CAIX) is a transmembrane enzyme that regulates pH in hypoxic tumors and promotes tumor cell survival. Its expression is associated with the occurrence of metastases and poor prognosis. Here, we present nine derivatives of the cobalt bis(dicarbollide)(1-) anion substituted at the boron or carbon sites by alkysulfamide group(s) as highly specific and selective inhibitors of CAIX. Interactions of these compounds with the active site of CAIX were explored on the atomic level using protein crystallography. Two selected derivatives display subnanomolar or picomolar inhibition constants and high selectivity for the tumor-specific CAIX over cytosolic isoform CAII. Both derivatives had a time-dependent effect on the growth of multicellular spheroids of HT-29 and HCT116 colorectal cancer cells, facilitated penetration and/or accumulation of doxorubicin into spheroids, and displayed low toxicity and showed promising pharmacokinetics and a significant inhibitory effect on tumor growth in syngenic breast 4T1 and colorectal HT-29 cancer xenotransplants.

Identification of Eukaryotic Translation Elongation Factor 1-α 1 Gamendazole-Binding Site for Binding of 3-Hydroxy-4(1 H)-quinolinones as Novel Ligands with Anticancer Activity.

Here, we have identified the interaction site of the contraceptive drug gamendazole using computational modeling. The drug was previously described as a ligand for eukaryotic translation elongation factor 1-α 1 (eEF1A1) and found to be a potential target site for derivatives of 2-phenyl-3-hydroxy-4(1 H)-quinolinones (3-HQs), which exhibit anticancer activity. The interaction of this class of derivatives of 3-HQs with eEF1A1 inside cancer cells was confirmed via pull-down assay. We designed and synthesized a new family of 3-HQs and subsequently applied isothermal titration calorimetry to show that these compounds strongly bind to eEF1A1. Further, we found that some of these derivatives possess significant in vitro anticancer activity.