Synthesis and evaluation of 2,5-di(4-aryloylaryloxymethyl)-1,3,4-oxadiazoles as anti-cancer agents

A series of 2,5-di(4-aryloylaryloxymethyl)-1,3,4-oxadiazoles 9a-j were obtained via multistep synthesis from hydroxybenzophenones 4a-e. The cytotoxicity of compounds 9a-j was evaluated against human leukemia cell lilies (K562 and CEM). The compounds exhibited moderate to good anti-cancer activity with compounds 9b and 9i having a chloro group exhibiting the best activity (IC50 = 10 mu M). Compound 9i exhibited activity against both the cell lines and 9b only exhibited activity against CEM. Further, a lactate dehydrogenase (LDH) assay and DNA fragmentation studies of the compounds 9a-j were also performed. (C) 2013 Elsevier Masson SAS. All rights reserved.

A comparative phase 1 clinical trial to identify anti-infective mechanisms of vitamin D in people with HIV infection

Objectives:To determine if there is a biological mechanism that explains the association between HIV disease progression and increased mortality with low circulating vitamin D levels; specifically, to determine if restoring vitamin D levels induced T-cell functional changes important for antiviral immunity.Design:This was a pilot, open-label, three-arm prospective phase 1 study.Methods:We recruited 28 patients with low plasma vitamin D (<50nmol/l 25-hydroxyvitamin D3), comprising 17 HIV+ patients (11 on HAART, six treatment-naive) and 11 healthy controls, who received a single dose of 200000IU oral cholecalciferol. Advanced T-cell flow cytometry methods measured CD4(+) T-cell function associated with viral control in blood samples at baseline and 1-month after vitamin D supplementation.Results:One month of vitamin D supplementation restored plasma levels to sufficiency (>75nmol/l) in 27 of 28 patients, with no safety issues. The most striking change was in HIV+ HAART+ patients, where increased frequencies of antigen-specific T cells expressing macrophage inflammatory protein (MIP)-1 - an important anti-HIV blocking chemokine - were observed, with a concomitant increase in plasma MIP-1, both of which correlated significantly with vitamin D levels. In addition, plasma cathelicidin - a vitamin D response gene with broad antimicrobial activity - was enhanced.Conclusion:Vitamin D supplementation modulates disease-relevant T-cell functions in HIV-infected patients, and may represent a useful adjunct to HAART therapy. Copyright (C) 2015 Wolters Kluwer Health, Inc. All rights reserved.

Synthesis of analogues of flazin, in particular, flazinamide, as promising Anti-HIV agents

Flazin isolated from the fruiting bodies of Suillus granulatus was found to possess weak anti-HIV activity (EC50=2.36 mu m, TI= 12.1). To establish a SAR study, 46 flazin analogues were synthesized, and their anti-HIV activities were evaluated in vitro. A

Design, synthesis and development of novel indolocarbazole derivatives as potential anti-cancer agents

This thesis describes work carried out on the design of new routes to a range of bisindolylmaleimide and indolo[2,3-a]carbazole analogs, and investigation of their potential as successful anti-cancer agents. Following initial investigation of classical routes to indolo[2,3-a]pyrrolo[3,4-c]carbazole aglycons, a new strategy employing base-mediated condensation of thiourea and guanidine with a bisindolyl β-ketoester intermediate afforded novel 5,6-bisindolylpyrimidin-4(3H)-ones in moderate yields. Chemical diversity within this H-bonding scaffold was then studied by substitution with a panel of biologically relevant electrophiles, and by reductive desulfurisation. Optimisation of difficult heterogeneous literature conditions for oxidative desulfurisation of thiouracils was also accomplished, enabling a mild route to a novel 5,6-bisindolyluracil pharmacophore to be developed within this work. The oxidative cyclisation of selected acyclic bisindolyl systems to form a new planar class of indolo[2,3-a]pyrimido[5,4-c]carbazoles was also investigated. Successful conditions for this transformation, as well as the limitations currently prevailing for this approach are discussed. Synthesis of 3,4-bisindolyl-5-aminopyrazole as a potential isostere of bisindolylmaleimide agents was encountered, along with a comprehensive derivatisation study, in order to probe the chemical space for potential protein backbone H-bonding interactions. Synthesis of a related 3,4-arylindolyl-5-aminopyrazole series was also undertaken, based on identification of potent kinase inhibition within a closely related heterocyclic template. Following synthesis of approximately 50 novel compounds with a diversity of H-bonding enzyme-interacting potential within these classes, biological studies confirmed that significant topo II inhibition was present for 9 lead compounds, in previously unseen pyrazolo[1,5-a]pyrimidine, indolo[2,3-c]carbazole and branched S,N-disubstituted thiouracil derivative series. NCI-60 cancer cell line growth inhibition data for 6 representative compounds also revealed interesting selectivity differences between each compound class, while a new pyrimido[5,4-c]carbazole agent strongly inhibited cancer cell division at 10 µM, with appreciable cytotoxic activity observed across several tumour types.

Design, synthesis and evaluation of novel ellipticine derivatives and analogues as anti-cancer agents

This thesis describes work carried out on the synthesis of novel 5- and 11-substituted ellipticines and derivatives of the ellipticine analogues, isoellipticine and deazaellipticine, followed by investigation of their potential as anti-cancer agents. Preparation of the key 5- and 11-substituted ellipticine targets involved the development of regiospecific, sequential alkylation reactions with alkenyllithium and Grignard reagents. Investigation of these novel reactions resulted in a new route towards 5-substituted ellipticines via Grignard reaction with vinylmagnesium bromide. These novel 5-vinylellipticine derivatives were further functionalised in an ozonolysis reaction, followed by oxidation to give a range of novel 5-substituted ellipticines. Less success was encountered in the 11-substituted ellipticine series, however preparation of these derivatives using a previously published route was accomplished, and the resulting 11-formylellipticine was further derivatised to give a panel of novel 9- and 11-substituted ellipticines, incorporating amide, carboxylate, imine and amine functionality. The successful route towards 5-substituted ellipticines was applied to the preparation of a range of novel 11-substituted isoellipticines and 6-substituted deazaellipticines, the first time substantial synthesis has been undertaken with these analogues. In addition to this, the first preparation of isoellipticinium salts is described, and a panel of novel isoellipticinium, 7 formylisoellipticinium and 7-hydroxyisoellipticinium salts were synthesised in good yields. Biological evaluation of a panel of 43 novel ellipticine, isoellipticine and deazaellipticine derivatives was accomplished with a topoisomerase II decatenation assay and submission to the NCI 60-cell line screen. Four novel isoellipticine topoisomerase II inhibitors were identified from the decatenation assay, with strong activity at 10 μM. In addition to this, NCI screening identified five highly cytotoxic ellipticine and isoellipticine compounds with remarkable selectivity profiles for different cancer types. These novel lead compounds represent new templates for further research and synthesis.

Synthesis and evaluation of novel quinolines and quinazolinediones as potential anti-cancer agents

This thesis outlines the design and effectuation of novel chemical routes towards a nascent class of functionalised quinoline-5,8-diones and the expansion of a series of contemporary quinazolinediones towards an innovative family of pyridinoquinazolinetetrone derivatives. This fragment based approach is envisaged to lead to advancements in the three scaffolds, expanding the SAR pool of both quinolines and quinazolinediones with subsequent evaluation of chemotherapeutic potential as well as furnishing a new class of tricycle for biological investigation. Development of novel quinoline-5,8-diones is provided for by expanding on existing methodology. Using a variety of nucleophiles on a critical intermediate, a broad range of novel compounds was afforded allowing chemotherapeutic potential to be assessed, while also serving as intermediates for accomplishing novel pyridinoquinazolinetetrone congeners. In order to incorporate functionality into our quinazolinedione template, an efficient synthetic strategy was constructed which provided a robust route to effectuate a highly derivatised pyrimidinedione ring. As derivatisation of this template is unreported our chief priority was to synthesise a range of diverse quinazolinediones. The application of annulation methodology using functionalised precursors provided a library of N-3 derivatised quinazolinedione analogues. These, along with their N-1 functionalised derivatives provide a wide scope from which to construct a series of pyridinoquinazolinetetrone derivatives while also serving as a unique class of molecules whose biological potential is uncharted. Although the actualisation of the pyridinoquinazolinetetrone was ultimately unsuccessful, our work has led to the development of novel quinoline-5,8-diones which were found to possess excellent anti-cancer activity when assessed by the NCI screen. Of the quinazolinediones synthesised eight compounds were accepted for screening by the NCI. Results from the single-dose tests however indicated that these compounds possessed little cytotoxic activity at 10 μM. The development of this novel template in conjunction with the highly active quinolinediones serves as an excellent rostrum for future synthetic endeavours.

Anti-AIDS agents 81. Design, synthesis, and structure-activity relationship study of betulinic acid and moronic acid derivatives as potent HIV maturation inhibitors.

In our continuing study of triterpene derivatives as potent anti-HIV agents, different C-3 conformationally restricted betulinic acid (BA, 1) derivatives were designed and synthesized in order to explore the conformational space of the C-3 pharmacophore. 3-O-Monomethylsuccinyl-betulinic acid (MSB) analogues were also designed to better understand the contribution of the C-3' dimethyl group of bevirimat (2), the first-in-class HIV maturation inhibitor, which is currently in phase IIb clinical trials. In addition, another triterpene skeleton, moronic acid (MA, 3), was also employed to study the influence of the backbone and the C-3 modification toward the anti-HIV activity of this compound class. This study enabled us to better understand the structure-activity relationships (SAR) of triterpene-derived anti-HIV agents and led to the design and synthesis of compound 12 (EC(50): 0.0006 microM), which displayed slightly better activity than 2 as a HIV-1 maturation inhibitor.

High-throughput identification of chemical inhibitors of E. coli Group 2 capsule biogenesis as anti-virulence agents.

Rising antibiotic resistance among Escherichia coli, the leading cause of urinary tract infections (UTIs), has placed a new focus on molecular pathogenesis studies, aiming to identify new therapeutic targets. Anti-virulence agents are attractive as chemotherapeutics to attenuate an organism during disease but not necessarily during benign commensalism, thus decreasing the stress on beneficial microbial communities and lessening the emergence of resistance. We and others have demonstrated that the K antigen capsule of E. coli is a preeminent virulence determinant during UTI and more invasive diseases. Components of assembly and export are highly conserved among the major K antigen capsular types associated with UTI-causing E. coli and are distinct from the capsule biogenesis machinery of many commensal E. coli, making these attractive therapeutic targets. We conducted a screen for anti-capsular small molecules and identified an agent designated "C7" that blocks the production of K1 and K5 capsules, unrelated polysaccharide types among the Group 2-3 capsules. Herein lies proof-of-concept that this screen may be implemented with larger chemical libraries to identify second-generation small-molecule inhibitors of capsule biogenesis. These inhibitors will lead to a better understanding of capsule biogenesis and may represent a new class of therapeutics.

Anti-infective photodynamic biomaterials for the prevention of intraocular lens-associated infectious endophthalmitis

Bacterial attachment onto intraocular lenses (IOLs) during cataract extraction and IOL implantation is a prominent aetiological factor in the pathogenesis of infectious endophthalmitis. Photodynamic therapy (PDT) and photodynamic antimicrobial chemotherapy (PACT) have shown that photosensitizers are effective treatments for cancer, and in the photoinactivation of bacteria, viruses, fungi and parasites, in the presence of light. To date, no method of localizing the photocytotoxic effect of a photosensitizer at a biomaterial surface has been demonstrated. Here we show a method for concentrating this effect at a material surface to prevent bacterial colonization by attaching a porphyrin photosensitizer at, or near to, that surface, and demonstrate the principle using IOL biomaterials. Anionic hydrogel copolymers were shown to permanently bind a cationic porphyrin through electrostatic interactions as a thin surface layer. The mechanical and thermal properties of the materials showed that the porphyrin acts as a surface cross-linking agent, and renders surfaces more hydrophilic. Importantly, Staphylococcus epidermidis adherence was reduced by up to 99.0 ± 0.42% relative to the control in intense light conditions and 91.7± 5.99% in the dark. The ability to concentrate the photocytotoxic effect at a surface, together with a significant dark effect, provides a platform for a range of light-activated anti-infective biomaterial technologies.