Krystyna Dzierzbicka

Natural and synthetic acridines/acridones as antitumor agents: their biological activities and methods of synthesis

Acridine derivatives constitute a class of compounds that are being intensively studied as potential anticancer drugs. Acridines are well-known for their high cytotoxic activity; however, their clinical application is limited or even excluded because of side effects. Numerous synthetic methods are focused on the preparation of target acridine skeletons or modifications of naturally occurring compounds, such as acridone alkaloids, that exhibit promising anticancer activities. They have been examined in vitro and in vivo to test their importance for cancer treatment and to establish the mechanism of action at both the molecular and cellular level, which is necessary for the optimization of their properties so that they are suitable in chemotherapy. In this article, we review natural and synthetic acridine/acridone analogs, their application as anticancer drugs and methods for their preparation.

Therapeutic potential of adenosine analogues and conjugates

This review summarizes current knowledge of adenosine analogues and conjugates with promising therapeutic properties. Adenosine is a signaling molecule that triggers numerous physiological responses. It acts through the adenosine receptors (ARs), belonging to the family of G-protein-coupled receptors and widely distributed throughout the body. Moreover, adenosine is involved in key biochemical processes as a part of ATP, the universal energy currency. Thus, compounds that are analogues of adenosine and its conjugates have been extensively studied as potential therapeutics. Many inhibitors of ARs are in clinical trials as promising agents in treatment of inflammation, type 2 diabetes, arrhythmia and as vasodilators used in the myocardial perfusion imaging (MPI) stress test. Furthermore, adenosine analogues revealed high efficacy as enzyme inhibitors, tested for antitrypanosomal action and as bivalent ligands and adenosine-oligoarginine conjugates as inhibitors of protein kinases.

Analogues of muramyl dipeptide (MDP) and tuftsin limit infection and inflammation in murine model of sepsis.

Pharmacological manipulation of the balance between pro- and anti-inflammatory mediators emerges as a key aspect of a successful treatment of sepsis. A murine model of septic shock was developed and chosen conjugates (1a, 1b, 8a, 8c) and analogs (T2) of muramyl dipeptide and tuftsin were tested in this model as prospective anti-bacterial drugs or adjuvants. The phagocytic activity of monocytes/macrophages was determined (flow cytometry, bacterial clearance from vital organs). To evaluate cytokines levels (TNFalpha, IFNgamma, IL6, IL10) we used real-time PCR. The most promising immunomodulatory properties were displayed by the analogue T2 and two conjugates: 8a, 8c.

Synthesis and biological activity of mycophenolic acid-amino acid derivatives

In search of new immunosuppressants we synthesized 11 amino acids derivatives of MPA as methyl esters 10a-k using EDCI/DMAP and their corresponding amino acid derivatives in free acid form 11a-k by hydrolysis of ester group with LiOH/MeOH. New analogs were evaluated as growth inhibitors of lymphoid cell line (Jurkat) and human peripheral blood mononuclear cells (PBMC) from healthy donors. According to obtained results recovering of free carboxylic group increased their activity. Additionally, the cytotoxic properties depends on the substituent and configuration at chiral center in amino acid unit. The compounds 10j, 11e and 11h exhibited higher potency than MPA 1 in vitro.

Recent Developments in the Synthesis and Biological Activity of Muramylpeptides

Derivatives of muramyl dipeptide (MDP) are considered as immunostimulants and adjuvants in the immunotherapy of cancer and infections. The interest in these compounds is mainly related to a high variety of their structure and biological properties. Here, we describe the synthesis and biological activity of several recently developed classes of MDP analogues. We also report potential of these analogues in the treatment of cancer and infectious diseases in experimental systems and cancer patients.

Synthesis and biological activity of novel mycophenolic acid conjugates containing nitro-acridine/acridone derivatives

Hybrid pharmacophore anti-proliferative compounds, comprised of mycophenolic acid (MPA) and 1-nitroacridine/4-nitroacridone derivative have been synthesized and evaluated as inhibitors of five different leukemia cell lines (Jurkat, Molt-4, HL-60, CCRF-CEM, L1210) and human peripheral blood mononuclear cells from healthy donors. These conjugates possess different length of the linker between MPA and heterocyclic units. The type of heterocyclic part influenced their cytotoxic and anti-proliferative properties. Coupling of MPA 1 with 9-(ω-aminoalkyl)amino-1-nitroacridines 2 and 1-[(ω-aminoalkyl)-4-nitro-9(10H)]-acridones 3 was tested. Although all tested conjugates were active, compounds 4a-e exhibited the highest potency. Preliminary experiments with GMP suggested that the tested compounds acted as IMPDH inhibitors.

Pilicides inhibit the FGL chaperone/usher assisted biogenesis of the Dr fimbrial polyadhesin from uropathogenic Escherichia coli

BackgroundThe global spread of bacterial resistance has given rise to a growing interest in new anti-bacterial agents with a new strategy of action. Pilicides are derivatives of ring-fused 2-pyridones which block the formation of the pili/fimbriae crucial to bacterial pathogenesis. They impair by means of a chaperone-usher pathway conserved in the Gram-negative bacteria of adhesive structures biogenesis. Pili/fimbriae of this type belong to two subfamilies, FGS and FGL, which differ in the details of their assembly mechanism. The data published to date have shown that pilicides inhibit biogenesis of type 1 and P pili of the FGS type which are encoded by uropathogenic E. coli strains.ResultsWe evaluated the anti-bacterial activity of literature pilicides as blockers of the assembly of a model example of FGL-type adhesive structures, – the Dr fimbriae encoded by a dra gene cluster of uropathogenic Escherichia coli strains. In comparison to the strain grown without pilicide, the Dr+ bacteria cultivated in the presence of the 3.5 mM concentration of pilicides resulted in a reduction of 75 to 87% in the adherence properties to CHO cells expressing Dr fimbrial DAF receptor protein. Using quantitative assays, we determined the amount of Dr fimbriae in the bacteria cultivated in the presence of 3.5 mM of pilicides to be reduced by 75 to 81%. The inhibition effect of pilicides is concentration dependent, which is a crucial property for their use as potential anti-bacterial agents. The data presented in this article indicate that pilicides in mM concentration effectively inhibit the adherence of Dr+ bacteria to the host cells, – the crucial, initial step in bacterial pathogenesis.ConclusionsStructural analysis of the DraB chaperone clearly showed it to be a model of the FGL subfamily of chaperones. This permits us to conclude that analyzed pilicides in mM concentration are effective inhibitors of the assembly of adhesins belonging to the Dr family, and more speculatively, of other FGL-type adhesive organelles. The presented data and those published so far permit to speculate that based on the conservation of chaperone-usher pathway in Gram-negative bacteria , the pilicides are potential anti-bacterial agents with activity against numerous pathogens, the virulence of which is dependent on the adhesive structures of the chaperone-usher type.

The Chemistry of Mycophenolic Acid - Synthesis and Modifications Towards Desired Biological Activity

Mycophenolic acid (MPA) is a basis for the immunosuppressive drugs used in clinic against rejection in solid organs transplantations. Since its physiological activity is very promising, numerous studies have been performed to establish mechanism of action, structure - activity relationship (SAR), synthesis of MPA derivatives to improve or extent its clinical use to anticancer one, especially. The reported methods for preparation of MPA analogues have been achieved by semi-synthetic approaches or total synthesis and accomplished by in vitro or / and in vivo evaluations. In this review we would like to bring together chemical aspects of these compounds and their implementations within biological activity, their synthesis and structural modifications referred to the structure-activity relationship (SAR).

Recent developments in the synthesis and biological activity of acridine/acridone analogues

Many people in the world struggle with cancer or bacterial, parasitic, viral, Alzheimers and other diseases. Therefore, many scientists seek new, more effective, more selective and less toxic drugs. Acridine/acridone derivatives constitute a class of compounds with a broad spectrum of biological activity and are of great interest to scientists. To date, many acridine/acridone analogues have been obtained, which, inter alia, exhibit antitumour (e.g., (1–5)), antimicrobial (e.g., (59)), and antiviral (e.g., (61)) activities and are applicable in the treatment of Alzheimers disease (e.g., (26)). However, in many cases, their clinical application is limited and excluded because of side effects. In this survey, we describe acridine and acridone derivatives reported since 2013, methods of their synthesis and their potential clinical applications.

Solid phase synthesis and biological activity of tuftsin conjugates.

New tuftsin/retro-tuftsin conjugates were designed and synthesized using a classical fluorenylmethoxycarbonyl (Fmoc) solid phase procedure. All the peptide conjugates were divided into three series: 1,4-dihydroxyanthraquinone (type A), 1-nitroacridine (type B), and 4-carboxyacridone (type C) derivatives. In type A conjugates, the N-terminal group of the peptide chain is directly connected to the anthraquinone ring at C1 (Scheme 1), whereas types B and C conjugates possess an amide bond formed between the carboxyl group of heterocyclic molecule and the N-termini of the tuftsin chain. The in vitro cytotoxic activity of the tuftsin conjugates and their precursors using two human tumor cell lines (lung adenocarcinoma (A549) and myeloblastic leukemia (HL-60)) was investigated. The analogues from groups A and C exhibited low cytotoxic activity, whereas several compounds of type B showed a potent and selective cytotoxic activity against tested tumor cell lines. None of the examined tuftsin conjugates demonstrated any significant effect on the catalytic activity of types I and II DNA topoisomerases.