Synthesis and evaluation of 5-arylated 2(5H)-furanones and 2-arylated pyridazin-3(2H)-ones as anti-cancer agents

Bis-cyclic butenolides, 5-arylated 2(5H)-furanones 6a-c, 7a, b and the 3(2H)-pyridazones 9a-d were prepared by using the aldehyde form of muco halogen acids in electrophilic substitution reactions and in an aldol-like condensation reaction. The cytotoxicity of these simple and bis-cyclic butenolides have been evaluated in tissue culture studies on MAC 13 and MAC 16 murine colon cancer cell lines. The butyl furanone 3 displayed the highest cytotoxicity of 3 μM, as one selected example of a series of dichlorinated pseudoesters. The 5-arylated 2(5H)-furanones 6 and 7 did not show a structure-activity relationship (SAR) depending on the substitution pattern of the aromatic system. An IC50 (concentration inhibiting growth by 50%) was found within a range of 30-50 and 40-50 μM for the MAC 13 and MAC 16 cell lines, respectively. The pyridazine series 9 showed a maximum in-vitro activity for the p-methoxydrivative 9b, having an IC50 of 17 in MAC 13 and 11 μM in MAC 16 cell lines. Selected examples of each series and further novel 2(5H)-furanones such as the hydrazone 5 and the hydantoin 8 have been screened in-vivo in mice and the data are presented. For the pyridazines 9a-d, the in-vitro cytotoxicity correlated with an in-vivo inhibition of tumour growth. The ring expansion of the 5-membered 2(5H)-furanone ring system such as 6a into the 6-membered 3(2H)-pyridazone 9b led to an agent with improved antineoplastic properties. On the resistant MAC 16 cell line the pyridazone 9b displayed 52% tumour inhibition in mice at a dose of 50 mg kg-1 compared with 27% for the 5-FU standard.

Synthesis and biological evaluation of potential anti-cancer agents

The new technology of combinational chemistry has been introduced to pharmaceutical companies, improving and making more efficient the process of drug discovery. Automated combinatorial chemistry in the solution-phase has been used to prepare a large number of compounds of anti-cancer screening. A library of caffeic acid derivatives has been prepared by the Knoevenagel condensation of aldehyde and active methylene reagents. These products have been screened against two murine adenocarcinoma cell lines (MAC) which are generally refractive to standard cytotoxic agents. The target of anti-proliferative action was the 12- and 15-lipoxygenase enzymes upon which these tumour cell lines have been shown to be dependent for proliferation and metastasis. Compounds were compared to a standard lipoxygenase inhibitor and if found to be active anti-proliferative agents were tested for their general cytotoxicity and lipoxygenase inhibition. A solid-phase bound catalyst, piperazinomethyl polystyrene, was devised and prepared for the improved generation of Knoevenagel condensation products. This piperazinomethyl polystyrene was compared to the traditional liquid catalyst, piperidine, and was found to reduce the amount of by-products formed during reaction and had the advantage of easy removal from the reaction. 13C NMR has been used to determine the E/Z stereochemistry of Knoevenagel condensation products. Soluble polymers have been prepared containing different building blocks pendant to the polymer backbone. Aldehyde building blocks incorporated into the polymer structure have been subjected to the Knoevenagel condensation. Cleavage of the resultant pendant molecules has proved that soluble linear polymers have the potential to generate combinatorial mixtures of known composition for biological testing. Novel catechol derivatives have been prepared by traditional solution-phase chemistry with the intention of transferring their synthesis to a solid-phase support. Catechol derivatives prepared were found to be active inhibitors of lipoxygenase. Soluble linear supports for the preparation of these active compounds were designed and tested. The aim was to develop a support suitable for the automated synthesis of libraries of catechol derivatives for biological screening.

Automated synthesis and evaluation of potential new anti-microbial agents

A series of N1-benzylideneheteroarylcarboxamidrazones was prepared in an automated fashion, and tested against Mycobacterium fortuitum in a rapid screen for antimycobacterial activity. Many of the compounds from this series were also tested against Mycobacterium tuberculosis, and the usefulness as M.fortuitum as a rapid, initial screen for anti-tubercular activity evaluated. Various deletions were made to the N1-benzylideneheteroarylcarboxamidrazone structure in order to establish the minimum structural requirements for activity. The N1-benzylideneheteroarylcarbox-amidrazones were then subjected to molecular modelling studies and their activities against M.fortuitum and M.tuberculosis were analysed using quantitative structure-analysis relationship (QSAR) techniques in the computational package TSAR (Oxford Molecular Ltd.). A set of equations predictive of antimycobacterial activity was hereby obtained. The series of N1-benzylidenehetero-arylcarboxamidrazones was also tested against a multidrug-resistant strain of Staphylococcus aureus (MRSA), followed by a panel of Gram-positive and Gram-negative bacteria, if activity was observed for MRSA. A set of antimycobacterial N1-benzylideneheteroarylcarboxamidrazones was hereby discovered, the best of which had MICs against m. fortuitum in the range 4-8μgml-1 and displayed 94% inhibition of M.tuberculosis at a concentration of 6.25μgml-1. The antimycobacterial activity of these compounds appeared to be specific, since the same compounds were shown to be inactive against other classes of organisms. Compounds which were found to be sufficiently active in any screen were also tested for their toxicity against human mononuclear leucocytes. Polyethylene glycol (PEG) was used as a soluble polymeric support for the synthesis of some fatty acid derivatives, containing an isoxazoline group, which may inhibit mycolic acid synthesis in mycobacteria. Both the PEG-bound products and the cleaved, isolated products themselves were tested against M.fortuitum and some low levels of antimycobacterial activity were observed, which may serve as lead compounds for further studies.

Formulation of topical non-steroidal anti-inflammatory agents

Reversed-pahse high-performance liquid chromatographic (HPLC) methods were developed for the assay of indomethacin, its decomposition products, ibuprofen and its (tetrahydro-2-furanyl)methyl-, (tetrahydro-2-(2H)pyranyl)methyl- and cyclohexylmethyl esters. The development and application of these HPLC systems were studied. A number of physico-chemical parameters that affect percutaneous absorption were investigated. The pKa values of indomethacin and ibuprofen were determined using the solubility method. Potentiometric titration and the Taft equation were also used for ibuprofen. The incorporation of ethanol or propylene glycol in the solvent resulted in an improvement in the aqueous solubility of these compounds. The partition coefficients were evaluated in order to establish the affinity of these drugs towards the stratum corneum. The stability of indomethacin and of ibuprofen esters were investigated and the effect of temperature and pH on the decomposition rates were studied. The effect of cetyltrimethylammonium bromide on the alkaline degradation of indomethacin was also followed. In the presence of alcohol, indomethacin alcoholysis was observed and the kinetics of decomposition were subjected to non-linear regression analysis and the rate constants for the various pathways were quantified. The non-isothermal, sufactant non-isoconcentration and non-isopH degradation of indomethacin were investigated. The analysis of the data was undertaken using NONISO, a BASIC computer program. The degradation profiles obtained from both non-iso and iso-kinetic studies show that there is close concordance in the results. The metabolic biotransformation of ibuprofen esters was followed using esterases from hog liver and rat skin homogenates. The results showed that the esters were very labile under these conditions. The presence of propylene glycol affected the rates of enzymic hydrolysis of the ester. The hydrolysis is modelled using an equation involving the dielectric constant of the medium. The percutaneous absorption of indomethacin and of ibuprofen and its esters was followed from solutions using an in vitro excised human skin model. The absorption profiles followed first order kinetics. The diffusion process was related to their solubility and to the human skin/solvent partition coefficient. The percutaneous absorption of two ibuprofen esters from suspensions in 20% propylene glycol-water were also followed through rat skin with only ibuprofen being detected in the receiver phase. The sensitivity of ibuprofen esters to enzymic hydrolysis compared to the chemical hydrolysis may prove valuable in the formulation of topical delivery systems.

The biochemical pharmacology and toxicology of anti-parasitic agents

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In vitro toxicity and bioactivity of some pyrimethamine derivatives as anti-tuberculosis agents

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A bio-adhesive formulation for the delivery of anti-fungal agents to the oesophagus

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Total synthesis of furospongolide and related furanolipid analogues as potential anti-tumour agents

This thesis details the design, development and execution of innovative methodology in the total synthesis of the terpene-derived marine natural product, furospongolide. It also outlines the synthetic routes used to prepare a novel range of furanolipids derivatives and subsequent evaluation of their potential as antitumour agents. The first chapter is a review of the literature describing efforts undertaken towards the synthesis of biologically active furanosesterterpenoid marine natural products. A brief discussion on the sources and biological activity exhibited by furan natural products is also provided. In addition, a concise account of the role of hypoxia in cancer, and the increasing interest in HIF-1 inhibition as a target for chemotherapeutics is examined. The second chapter discusses the concise synthesis of the marine HIF-1 inhibitor furospongolide, which was achieved in five linear steps from (E,E)-farnesyl acetate. The synthetic strategy features a selective oxidation reaction, a Schlosser sp3-sp3 cross-coupling, a Wittig cross-coupling and an elaborate one-pot selective reduction, lactonisation and isomerization reaction to install the butenolide ring. The structure-activity relationship of furospongolide was also investigated. This involved the design and synthesis of a library of structurally modified analogues sharing the same C1-C13 subunit. This was achieved by exploiting the brevity and high level of convergence of our synthetic route together with the readily amenable structure of our target molecule. Exploiting the Schlosser cross-coupling allowed for replacement of furan with other heterocycles in the preparation of various furanolipid and thiophenolipid derivatives. The employment of reductive amination and Wittig chemistry further added to our novel library of structural derivatives. The third chapter discusses the results obtained from the NCI from biological evaluation From a collection of 28 novel compounds evaluated against the NCI-60 cancer cell array, six drug candidates were successfully selected for further biological evaluation on the basis of antitumour activity. COMPARE analysis revealed a strong correlation between some of our design analogues and the blockbuster anticancer agent tamoxifen, further supporting the potential of furanolipids in the treatment of breast cancer. The fourth chapter, details the full experimental procedures, including spectroscopic and analytical data for all the compounds prepared during this research.

Synthesis and evaluation of novel ellipticines as potential anti-cancer agents

Ellipticine is a natural product which possesses multimodal anti-cancer activity. This thesis encompasses the synthesis and biological evaluation of novel ellipticine and isoellipticine derivatives as anti-cancer agents. Expanding on previous work within the group utilising vinylmagnesium bromide, derivatisation of the C5 position of ellipticine was accomplished by reaction of a key ketolactam intermediate with Grignard reagents. Corresponding attempts to introduce diverse substitution at the C11 position were unsuccessful, although one novel C11 derivative was produced using an alkyllithium reagent. A panel of novel ellipticinium salts encompassing a range of substitutions at the N2, C9 and N6 positions were prepared. Extensive derivatisation of the N10 position of isoellipticine was undertaken for the first time. Novel substitution in the form of acid and methyl ester functionalities were introduced at the C7 position of isoellipticine while novel C7 aldehyde and alcohol derivatives were synthesised. A large panel of isoellipticinium salts were prepared with conditions adjusted for the reactivity of the alkyl halide. Novel coupling reactions to increase the yield of isoellipticine were attempted but proved unsuccessful. A panel of 54 novel derivatives was prepared and a multimodal analysis of their anti-cancer activity was conducted. The NCI 60-human tumour cell lines screen was a primary source of information on the in vitro activity of compounds with derivatives found to exert potent anticancer effects, with mean GI50 values as low as 1.01 μM across the full range of cancer types and as low as 16 nM in individual cell lines. A second in vitro screen in collaboration with researchers in the University of Nantes identified derivatives which could potently inhibit growth in a p53 mutant NSCLC cell line. The cell cycle effects of a selected panel of isoellipticines were studied in leukaemia cell lines by researchers in the Department of Biochemistry and Cell Biology, UCC. Emerging from this, the therapeutic potential of one of the derivatives in AML was then assessed in vivo in an AML xenograft mouse model, with tumour weight reduced by a factor of 7 in treated mice relative to control.

Safety and Efficacy of Oral Fexofenadine in Children with Seasonal Allergic Rhinitis - a Pooled Analysis of Three Studies

Allergic rhinitis is one of the most common clinical conditions in children; however, data regarding the safety of antihistamines in children with seasonal allergic rhinitis are limiting. To evaluate the safety and efficacy of fexofenadine in children with seasonal allergic rhinitis, data were pooled from three, double-blind, randomized, placebo-controlled, parallel-group, 2-week trials in children (6-11 year) with seasonal allergic rhinitis. All studies assessed fexofenadine HCl 30 mg b.i.d.; two studies included fexofenadine HCl at 15 and 60 mg b.i.d. Patients (and investigators) reported any adverse events during the trial. Physical examinations, including measurements of vital signs and laboratory tests, were performed. Efficacy assessments (total symptom score and individual symptom scores) were evaluated. Exposure to fexofenadine HCl 30 mg b.i.d. and to any fexofenadine dose exceeded 10,000 and 17,000 patient days, respectively. Incidences of adverse events, and discontinuations because of adverse events, were low and similar across treatment groups. In the placebo group, 24.4% of subjects reported adverse events compared with 24.1% for fexofenadine HCl 30 mg b.i.d., and 28.4% for all fexofenadine-treated groups. The most common adverse event overall was headache (4.3% placebo; 5.8% fexofenadine HCl 30 mg b.i.d.; and 7.2% any fexofenadine doses). Treatment-related adverse events were similar across treatment groups with no sedative effects. Fexofenadine HCl 30 mg b.i.d. was significantly superior to placebo in reducing the total symptom score and all individual seasonal allergic rhinitis symptoms, including nasal congestion (p < 0.05). Fexofenadine, at doses of up to 60 mg b.i.d., is safe and non-sedating, and fexofenadine HCl 30 mg b.i.d. effectively reduces all seasonal allergic rhinitis symptoms in children aged 6-11 years.

Comparison of drug retention rates and causes of drug discontinuation between anti-tumor necrosis factor agents in rheumatoid arthritis

OBJECTIVE: Tumor necrosis factor (TNF) inhibitors have revolutionized the treatment of severe rheumatoid arthritis (RA), yet drug discontinuation is common. The aim of this study was to compare treatment retention rates and specific causes of anti-TNF discontinuation in a population-based RA cohort. METHODS: All patients treated with etanercept, infliximab, or adalimumab within the Swiss Clinical Quality Management RA cohort between 1997 and 2006 were included in the study. Causes of treatment discontinuation were broadly categorized as adverse events (AEs) or nontoxic causes, and further subdivided into specific categories. Specific causes of treatment interruption were analyzed using a Cox proportional hazards model and adjusted for potential confounders. RESULTS: A total of 2,364 anti-TNF treatment courses met the inclusion criteria. Treatment discontinuation was reported 803 times: 309 with etanercept, 249 with infliximab, and 245 with adalimumab. Drug inefficacy represented the largest single cause of treatment discontinuation (55.8% of cases). The median time of receiving anti-TNF therapy was 37 months, but discontinuation rates differed between the 3 anti-TNF agents (P < 0.001), with shorter retention rates for infliximab (hazard ratio [HR] 1.24, 99% confidence interval [99% CI] 1.01-1.51). The specific causes of treatment discontinuation revealed an increased risk of AEs with infliximab (HR 1.4, 99% CI 1.003-1.96), mostly due to an increased risk of infusion or allergic reactions (HR 2.11, 99% CI 1.23-3.62). Other discontinuation causes were equally distributed between the anti-TNF agents. CONCLUSION: In this population, infliximab was associated with higher overall discontinuation rates compared with etanercept and adalimumab, which is mainly due to an increased risk of infusion or allergic reactions.

Reativação da retocolite ulcerativa com o uso de droga anti-inflamatória não esteróide: relato de caso e revisão da literatura

The case of a patient with ulcerative colitis and isolated sacro-ileitis is presented. She suffered reactivation of the intestinal disease with diclofenac. The patient was allergic to sulfasalazine and was using fish oil fatty acid. The possible mechanisms of reactivation of the inflammatory bowel disease with non-steroidal anti-inflammatory drugs are discussed. It is suggested when necessary the utilization of non-steroidal anti-inflammatory drugs that inhibits the lipoxygenase in these patients.

A review of non-pharmacological and pharmacological management of seasonal and perennial allergic conjunctivitis

Allergic eye disease encompasses a group of hypersensitivity disorders which primarily affect the conjunctiva and its prevalence is increasing. It is estimated to affect 8% of patients attending optometric practice but is poorly managed and rarely involves ophthalmic assessment. Seasonal allergic conjunctivitis (SAC) is the most common form of allergic eye disease (90%), followed by perennial allergic conjunctivitis (PAC; 5%). Both are type 1 IgE mediated hypersensitivity reactions where mast cells play an important role in pathophysiology. The signs and symptoms are similar but SAC occurs periodically whereas PAC occurs year round. Despite being a relatively mild condition, the effects on the quality of life can be profound and therefore they demand attention. Primary management of SAC and PAC involves avoidance strategies depending on the responsible allergen(s) to prevent the hypersensitivity reaction. Cooled tear supplements and cold compresses may help bring relief. Pharmacological agents may become necessary as it is not possible to completely avoid the allergen(s). There are a wide range of anti-allergic medications available, such as mast cell stabilisers, antihistamines and dual-action agents. Severe cases refractory to conventional treatment require anti-inflammatories, immunomodulators or immunotherapy. Additional qualifications are required to gain access to these medications, but entry-level optometrists must offer advice and supportive therapy. Based on current evidence, the efficacy of anti-allergic medications appears equivocal so prescribing should relate to patient preference, dosing and cost. More studies with standardised methodologies are necessary elicit the most effective anti-allergic medications but those with dual-actions are likely to be first line agents.