Synthesis and in vitro evaluation of quaternary ammonium derivatives of chlorambucil and melphalan, anticancer drugs designed for the chemotherapy of chondrosarcoma

A clickable melphalan for monitoring DNA interstrand crosslink accumulation and detecting ICL repair defects in Fanconi anemia patient cells

Fanconi anemia (FA) is a genetic disorder associated with developmental defects, bone marrow failure and cancer. The FA pathway is crucial for the repair of DNA interstrand crosslinks (ICLs). In this study, we have developed and characterized a new tool to investigate ICL repair: a clickable version of the crosslinking agent melphalan which we name click-melphalan. Our results demonstrate that click-melphalan is as effective as its unmodified counterpart in generating ICLs and associated toxicity. The lesions induced by click-melphalan can be detected in cells by post-labelling with a fluorescent reporter and quantified using flow cytometry. Since click-melphalan induces both ICLs and monoadducts, we generated click-mono-melphalan, which only induces monoadducts, in order to distinguish between the two types of DNA repair. By using both molecules, we show that FANCD2 knock-out cells are deficient in removing click-melphalan-induced lesions. We also found that these cells display a delay in repairing click-mono-melphalan-induced monoadducts. Our data further revealed that the presence of unrepaired ICLs inhibits monoadduct repair. Finally, our study demonstrates that these clickable molecules can differentiate intrinsic DNA repair deficiencies in primary FA patient cells from those in primary xeroderma pigmentosum patient cells. As such, these molecules may have potential for developing diagnostic tests.

Stereoselective synthesis of unnatural α-amino acid derivatives through photoredox catalysis

A protocol for stereoselective C-radical addition to a chiral glyoxylate-derived N-sulfinyl imine was developed through visible light-promoted photoredox catalysis, providing a convenient method for the synthesis of unnatural α-amino acids. The developed protocol allows the use of ubiquitous carboxylic acids as radical precursors without prior derivatization. The protocol utilizes near-stoichiometric amounts of the imine and the acid radical precursor in combination with a catalytic amount of an organic acridinium-based photocatalyst. Alternative mechanisms for the developed transformation are discussed and corroborated by experimental and computational studies.

Biological activity of quaternary ammonium salts and resistance of microorganisms to these compounds

Quaternary ammonium salts (QASs) are ubiquitous in nature, being found in organisms ranging from microorganisms to vertebrates (e.g., glycine betaine, carnitine) where they have important cellular functions. QASs are also obtained by chemical synthesis. These compounds, due to their diverse chemical structure (e.g. monomeric QAS or gemini) and their biological properties, are widely used in medicine (as disinfectants, drugs, and DNA carriers), industry, environmental protection and agriculture (as preservatives, biocides, herbicides and fungicides). Discussed chemical compounds reduce the adhesion of microorganisms to various biotic and abiotic surfaces and cause the eradication of biofilms produced by pathogenic microorganisms. The properties of these chemicals depend on their chemical structure (length of the alkyl chain, linker and counterion), which has a direct impact on the physicochemical and biological activity of these compounds. QASs by incorporation into the membranes, inhibit the activity of proteins (H⁺-ATPase) and disrupt the transport of substances to the cell. Moreover, in the presence of QASs, changes in lipid composition (qualitative and quantitative) of plasma membrane are observed. The widespread use of disinfectants in commercial products can induce resistance in microorganisms to these surfactants and even to antibiotics. In this article we discuss the biological activity of QASs as cationic surfactants against microorganisms and their resistance to these compounds.

Tyrosine-Chlorambucil Conjugates Facilitate Cellular Uptake through L-Type Amino Acid Transporter 1 (LAT1) in Human Breast Cancer Cell Line MCF-7

l-type amino acid transporter 1 (LAT1) is an amino acid transporter that is overexpressed in several types of cancer and, thus, it can be a potential target for chemotherapy. The objectives of this study were to (a) synthesize LAT1-targeted chlorambucil derivatives and (b) evaluate their LAT1-mediated cellular uptake as well as antiproliferative activity in vitro in the human breast cancer MCF-7 cell line. Chlorambucil was conjugated to l-tyrosine—an endogenous LAT1 substrate—via either ester or amide linkage (compounds 1 and 2, respectively). While chlorambucil itself did not bind to LAT1, its derivatives 1 and 2 bound to LAT1 with a similar affinity as with l-tyrosine and their respective cellular uptake was significantly higher than that of chlorambucil in MCF-7. The results of our cellular uptake study are indicative of antiproliferative activity, as a higher intracellular uptake of chlorambucil derivatives resulted in greater cytotoxicity than chlorambucil by itself. LAT1 thus contributes to intracellular uptake of chlorambucil derivatives and, therefore, increases antiproliferative activity. The understanding gained from our research can be used in the development of LAT1-targeted anticancer drugs and prodrugs for site-selective and enhanced chemotherapeutic activity.

Biological activity of glycine and alanine derivatives of quaternary ammonium salts (QASs) against micro-organisms

Quaternary ammonium salts (QASs) are commonly used in medicine, agriculture and industry and their wide usage caused the development of microbial resistance, thus there is still a need for new effective antimicrobial agents. Present work describes the biological activity of alanine- (DMALM-n) and glycine-derived (DMGM-n) QASs against planktonic and biofilm forms of micro-organisms. The antimicrobial activity was dependent mainly on the hydrocarbon chain length and surfactants with 12-16 atoms of carbon in the alkyl chain were the most active ones. The lowest MIC value was determined for DMALM-14 against Rhodotorula rubra and Saccharomyces cerevisiae (2·5 µmol l^{- 1} ). Generally, alanine derivatives showed stronger effects against micro-organisms than glycine-derived QASs. Alanine-derived surfactants with 12-16 carbons in the alkyl chain had antiadhesive properties on the polystyrene surface, preventing cell attachment (about 70% of inhibition for C. albicans and 40% for S. epidermidis). Strong adhesion reduction was also observed on the stainless steel surface and the highest reduction was observed for C. albicans cells incubated on surface pretreated with DMGM-16. Moreover, DMGM-16 and DMALM-16 prevented C. albicans filamentation, one of the determinants of cell adhesion. Surfactants with C₁₆ alkyl chain (DMGM-16 and DMALM-16) eradicated bacterial and yeast biofilm (from 60 to 90% of reduction observed after incubation of the previously grown biofilm in the presence of the highest tested concentration of the surfactant - 400 µmol l^{- 1} ) and reduced its viability. Strong antimicrobial activity as well as antiadhesive properties make alanine- and glycine-derived QASs the potential candidates for future application as disinfectants. SIGNIFICANCE AND IMPACT OF THE STUDY: Cationic surfactants are used in many fields, among others in medicine, cosmetic and pharmaceutical industry. Their usage on a large scale caused the development of microbial resistance mechanisms to such compounds. Thus, there is a need to synthesize new surfactants with potential application as effective disinfectants to combat both planktonic and biofilm forms of micro-organisms. Present work focuses on the antimicrobial activity of chosen quaternary ammonium salts.

Quaternary ammonium salt N-(dodecyloxycarboxymethyl)-N,N,N-trimethyl ammonium chloride induced alterations in Saccharomyces cerevisiae physiology

We investigated the influence of the quaternary ammonium salt (QAS) called IM (N-(dodecyloxycarboxymethyl)- N,N,N-trimethyl ammonium chloride) on yeast cells of the parental strain and the IM-resistant mutant (EO25 IMR) growth. The phenotype of this mutant was pleiotropic. The IMR mutant exhibited resistance to ethanol, osmotic shock and oxidative stress, as well as increased sensitivity to UV. Moreover, it was noted that mutant EO25 appears to have an increased resistance to clotrimazole, ketoconazole, fluconazole, nystatin and cycloheximide. It also tolerated growth in the presence of crystal violet, DTT and metals (selenium, tin, arsenic). It was shown that the presence of IM decreased ergosterol level in mutant plasma membrane and increased its unsaturation. These results indicate changes in the cell lipid composition. Western blot analysis showed the induction of Pma1 level by IM. RT-PCR revealed an increased PMA1 expression after IM treatment.

Antibacterial, cytotoxic and genotoxic activity of nitrogenated and haloid derivatives of C50-C60 and C70-C120 polyprenol homologs

Background

Polyprenol is an important lipid with many bioactive effects. The study on differences in bioactive effects of polyprenol derivatives having different isoprene units are seldom reported and it is helpful to find out which type of polyprenol derivatives are effective for treating A549/HepG2 cells and E. coli /S. aureus.

Methods

All tested polyprenol derivatives were measured with inhibition halos by Oxford cup assays. MIC values were assessed by the broth dilution method. Time-killing curve studies were conducted in duplicate on separate days. Cytotoxicity study was measured by the MTT assay and genotoxic study was evaluated by comet assay.

Results

With regard to antibacterial activity, the sensitivities to the quaternary polyprenyl ammonium salt derivatives GAS and MAS were 31.3 μg/mL and 15.6–31.3 μg/mL, respectively. GAS and MAS exhibited cytotoxic activity toward HepG2 cells (IC₅₀ of 10.1–11.6 μg/mL), which was stronger than that exhibited toward A549 cells (IC₅₀ of 13.8–13.9 μg/mL). The bactericidal activity of MAS was stronger than that of GAS at the same concentration at least 48 h. The DNA damage in A549 and HepG2 cells exposed to all 10, 20 and 40 μg/mL MAS was statistically significant in comparison to the control. Our results indicate a dose-dependent increment in DNA damage in A549 and HepG2 cells exposed to 10, 20 and 40 μg/mL MAS for both the percentage of DNA in the tail and tail moment.

Conclusion

The quaternary ammonium salt derivatives GAS and MAS exhibited higher antibacterial (E. coli and S. aureus) and cytotoxic activity (A549 and HepG2 cells) than the other derivatives evaluated in this study. The DNA damage in HepG2 cells suggests that MAS induced A549 and HepG2 cells death via apoptotic pathway. Our results provide new evidence supporting the medical use of polyprenol derivatives against bacterial and tumor diseases.

Functional vesicles formed by anticancer drug assembly

In this Letter, a new type of nitrogen mustard conjugate vesicles is developed to improve the stability and efficiency of anticancer drug. Benzoic acid nitrogen mustard-peptide (AAAK) conjugate was designed and synthesized, which was found to self-assemble into vesicles in water. The formation of the vesicles was confirmed by dynamic light scattering (DLS), transmission electron microscopy (TEM) and circular dichroism (CD). The degradation data revealed that the benzoic acid nitrogen mustard peptide (AAAK) conjugate vesicles are more stable than the parent drug in aqueous solution. Furthermore, MTT assay revealed that the free drug conjugate has similar antitumor activity against MCF-7, Hela, HepG-2 cell lines compared with the parent drug. The benzoic acid nitrogen mustard-peptide conjugate vesicles may have potential in the treatment of cancers.

A facile method to prepare composite and porous polyphosphazene membranes and investigation of their properties

Polyphosphazene/SiO₂ composite membranes and porous polyphosphazene membranes were prepared and their properties were studied in detail.

An anticancer drug delivery system based on surfactant-templated mesoporous silica nanoparticles

Three types of surfactant-templated mesoporous silica nanoparticles (Surf@MSNs) of 150-660 nm in diameter were developed as anticancer drug delivery systems. The Surf@MSNs exhibit the high drug (surfactant) loading capacities, the sustained drug (surfactant) release profiles and the high and long-term anticancer efficacy. The effects of the Surf@MSNs concentration, the type of the contained surfactants and the incubation time on the cytotoxicity and proliferative activity of MCF-7 cells were evaluated. A common anticancer drug CPT-11 was also loaded into surfactant-free MSNs (CPT@MSNs) and used as a reference for estimating the anticancer efficacies of Surf@MSNs. Surfactant-extracted MSNs exhibited neglectable cytotoxicity to MCF-7 cell, and free surfactants exhibited higher cytotoxicity than free CPT-11 at the same concentration. The endocytosis enhanced the drug uptake by MCF-7 cells and the anticancer efficacies of Surf@MSNs and CPT@MSNs, and more surfactants would be released in a longer term, which led to the more significant enhancement of the cytotoxicity, than CPT-11 with the process of incubation. Among the investigated Surf@MSNs, CTAB-contained MSNs (CTAB@MSNs) show remarkably higher long-term anticancer efficacy than CPT-11-loaded surfactant-free MSNs (CPT@MSNs), even at very low concentrations of 2-15 microg mL(-1).

Intra-articular depot formulation principles: role in the management of postoperative pain and arthritic disorders

The joint cavity constitutes a discrete anatomical compartment that allows for local drug action after intra-articular injection. Drug delivery systems providing local prolonged drug action are warranted in the management of postoperative pain and not least arthritic disorders such as osteoarthritis. The present review surveys various themes related to the accomplishment of the correct timing of the events leading to optimal drug action in the joint space over a desired time period. This includes a brief account on (patho)physiological conditions and novel potential drug targets (and their location within the synovial space). Particular emphasis is paid to (i) the potential feasibility of various depot formulation principles for the intra-articular route of administration including their manufacture, drug release characteristics and in vivo fate, and (ii) how release, mass transfer and equilibrium processes may affect the intra-articular residence time and concentration of the active species at the ultimate receptor site.

Synthesis and in vitro evaluation of targeted tetracycline derivatives: Effects on inhibition of matrix metalloproteinases

Among other non-antibiotic properties, tetracyclines inhibit matrix metalloproteinases and are currently under study for the treatment of osteoarthritis. Quaternary ammonium conjugates of tetracyclines were synthesized by direct alkylation of the amine function at the 4-position with methyl iodide. When tested in vitro, they inhibited cytokine-induced MMP expression to a lesser extent than parent tetracyclines. This was compensated by an improved inhibition of MMP catalytic activity. Since inhibition of collagen degradation was maintained these derivatives could be potent drug candidates for cartilage-targeted chondroprotective treatment.

Novel class of cyclophosphamide prodrug: Cyclophosphamide spiropiperaziniums (CPSP)

A novel class of cyclophosphamide spiropiperaziniums was synthesized and evaluated for their in vivo anti-cancer activities against S180 and H22. Most of them exhibited definite activities. Especially, compounds 8b and 8k showed good anti-cancer activities, meanwhile, 8k also showed much lower toxicity than CP. Several interesting structure-activity relationships were revealed.

Alkylating benzamides with melanoma cytotoxicity

Radioiodinated N-(2-(diethylamino)ethyl)benzamides have recently been discovered as selective agents for melanotic melanoma and are used for scintigraphic imaging in nuclear medicine. Owing to the high binding capacity, benzamide derivatives conjugated with alkylating cytostatics were synthesized and tested for their potential for targeted drug delivery. Conjugates of chlorambucil with procainamide (1), diethylaminoethylamine (2) and 2-pyrrolidin-1-yl-ethylamine (3), as well as 4-(bis(2-chloroethyl)amino)- (6,7) and 4-(N,N-diethyltriazeno)-substituted (8-10) benzamides, were synthesized. Cell uptake studies with B16 melanoma cells revealed high uptake of radioiodinated 1 and 2, while radiolabelled chlorambucil was found to lack this characteristic. These results were confirmed by biodistribution studies in a mouse melanoma model. Viability measurements revealed that all chlorambucil-benzamide derivatives showed higher toxicity against B16 melanoma and SK-MEL-28 cells than did the parent chlorambucil itself, and that the triazene derivatives were more potent than dacarbazine, which is currently used as a standard cytostatic drug in melanoma therapy. Of all the compounds tested in this series, the triazenes 9 and 10 showed the most promising targeting effect. The toxicity of these compounds against hepatoma cells (MH3924A) and, to a lesser extent, against mouse fibroblast (NIH 3T3) and cervix carcinoma (HeLa) cells was also enhanced, but they were not as toxic as dacarbazine (HeLa). These findings support the concept of a selective, benzamide-mediated in vivo delivery of cytostatics in melanoma cells, leading to enhanced efficacy.

Synthesis and pharmacokinetic profile of a quaternary ammonium derivative of chlorambucil, a potential anticancer drug for the chemotherapy of chondrosarcoma

As a part of our targeting program based on the affinity of the quaternary ammonium moiety for cartilage, our objective was to develop more selective anticancer drugs towards chondrosarcoma that would concentrate in this malignant cartilaginous tissue and so improve the therapeutic index through a reduction of side effects. For this purpose we have synthesized and labeled with 14C a quaternary ammonium (QA) derivative of chlorambucil. Biological studies performed in rats showed that [14C]-CQA and [14C]-chlorambucil exhibited different pharmacokinetic profiles. The blood elimination of [14C]-CQA was faster than that of parent compound. [14C]-CQA was principally excreted by the fecal way. However, until 15 min after administration, levels of radioactivity were measured in cartilaginous tissues of rats given [14C]-CQA which was not the case for the rats which had received [14C]-chlorambucil. Although rates of radioactivity were quantified only during 15 min, these results prove that the functionalization of chlorambucil by a quaternary ammonium group allows the molecule to be carried selectively to cartilaginous tissues.

Enhanced hydrolytic stability and water solubility of an aromatic nitrogen mustard by conjugation with molecular umbrellas

Chlorambucil, an aromatic nitrogen mustard, has been conjugated to putrescine- and spermidine-based scaffolds bearing one, two, and four persulfated cholic acid units. Those conjugates bearing two or four sterols show improved hydrolytic stability and water solubility relative to chlorambucil. A similar conjugate that contained only one sterol unit shows negligible improvement in hydrolytic stability but a significant increase in water solubility. Qualitatively, the hydrolytic stability within this series of conjugates parallels the shielding effects that have previously been found for related conjugates bearing a pendant, hydrophobic fluorescent probe. In vitro studies indicate that these conjugates possess modest to moderate activity against certain human lymphoblastic leukemia and human colon carcinoma cells.