Appended Aromatic Moieties in Flexible Bis-3-chloropiperidines Confer Tropism against Pancreatic Cancer Cells.

Nitrogen mustards (NMs) are an old but still largely diffused class of anticancer drugs. However, spreading mechanisms of resistance undermine their efficacy and therapeutic applicability. To expand their antitumour value, we developed bis-3-chloropiperidines (B-CePs), a new class of mustard-based alkylating agent, and we recently reported the striking selectivity for BxPC-3 pancreatic tumour cells of B-CePs bearing aromatic moieties embedded in the linker. In this study, we demonstrate that such tropism is shared by bis-3-chloropiperidines bearing appended aromatic groups in flexible linkers, whereas esters substituted by aliphatic groups or by efficient DNA-interacting groups are potent but nonselective cytotoxic agents. Besides, we describe how the critical balance between water stability and DNA reactivity can affect the properties of bis-3-chloropiperidines. Together, these findings support the exploitation of B-CePs as potential antitumour clinical candidates.

Direct and Topoisomerase†II Mediated DNA Damage by Bis-3-chloropiperidines: The Importance of Being an Earnest G.

Bis-3-chloropiperidines are a new class of DNA-active compounds capable of alkylating nucleobases and inducing strand cleavage. In this study, we investigated the reactivity of these mustard-based agents with both single- and double-stranded DNA constructs. Polyacrylamide gel electrophoresis (PAGE) and electrospray ionization mass spectrometry (ESI-MS) were used to obtain valuable insight into their mechanism at the molecular level and to investigate their time- and concentration-dependent activity. The results revealed the preferential formation of mono- and bifunctional adducts at nucleophilic guanine sites. In a stepwise fashion, alkylation was followed by depurination and subsequent strand scission at the ensuing apurinic site. We demonstrated that the covalent modifications introduced by this new class of compounds can inhibit the activity of essential DNA-processing proteins, such as topoisomerase IIα, thereby suggesting that bis-3-chloropiperidines may have excellent anticancer potential.

Synthesis and evaluation of a bis-3-chloropiperidine derivative incorporating an anthraquinone pharmacophore.

With the aim to attain an alkylating agent with enhanced DNA-affinity, we have successfully synthesised lysine-linked bis-3-chloropiperidine 1 bearing an anthraquinone moiety known to bind double-stranded DNA. Consistent with our expectations, compound 1 appears to intercalate into the DNA double helix, which can be observed by conformational changes of plasmid DNA suggesting alkylation and intercalation-induced DNA unwinding. The results of this work can provide a meaningful starting point for investigating the molecular mechanism of action of this novel DNA alkylating conjugate 1 with improved affinity for DNA.

Bis-3-chloropiperidines containing bridging lysine linkers: Influence of side chain structure on DNA alkylating activity.

A series of bis-3-chloropiperidines containing lysine linkers was synthesised as DNA alkylating model compounds by using a bidirectional synthetic strategy. These novel piperidine mustard based agents have been evaluated for their alkylating properties towards nucleic acids and were shown to alkylate and cleave DNA with strong preference for guanine residues. Our studies reveal that the introduction of aromatic groups in the side chain of the lysine linker has an impact on DNA alkylating activity. Analysis by ESI mass spectrometry enabled the verification of the reactive aziridinium ion formation. Overall, the results confirm our recently proposed reaction mechanism of bis-3-chloropiperidines.

Synthesis and DNA cleavage activity of Bis-3-chloropiperidines as alkylating agents.

Nitrogen mustards are an important class of bifunctional alkylating agents routinely used in chemotherapy. They react with DNA as electrophiles through the formation of highly reactive aziridinium ion intermediates. The antibiotic 593A, with potential antitumor activity, can be considered a naturally occurring piperidine mustard containing a unique 3-chloropiperidine ring. However, the total synthesis of this antibiotic proved to be rather challenging. With the aim of designing simplified analogues of this natural product, we developed an efficient bidirectional synthetic route to bis-3-chloropiperidines joined by flexible, conformationally restricted, or rigid diamine linkers. The key step involves an iodide-catalyzed double cyclization of unsaturated bis-N-chloroamines to simultaneously generate both piperidine rings. Herein we describe the synthesis and subsequent evaluation of a series of novel nitrogen-bridged bis-3-chloropiperidines, enabling the study of the impact of the linker structure on DNA alkylation properties. Our studies reveal that the synthesized compounds possess DNA alkylating abilities and induce strand cleavage, with a strong preference for guanine residues.