Rosaleen Anderson

Antibacterial Agents: Chemistry, Mode of Action, Mechanisms of Resistance, and Clinical Applications

Antibacterial agents act against bacterial infection either by killing the bacterium or by arresting its growth. They do this by targeting bacterial DNA and its associated processes, attacking bacterial metabolic processes including protein synthesis, or interfering with bacterial cell wall synthesis and function. Antibacterial Agents is an essential guide to this important class of chemotherapeutic drugs. Compounds are organised according to their target, which helps the reader understand the mechanism of action of these drugs and how resistance can arise. The book uses an integrated “lab-to-clinic” approach which covers drug discovery, source or synthesis, mode of action, mechanisms of resistance, clinical aspects (including links to current guidelines, significant drug interactions, cautions and contraindications), prodrugs and future improvements. Agents covered include: • agents targeting DNA - quinolone, rifamycin, and nitroimidazole antibacterial agents • agents targeting metabolic processes - sulfonamide antibacterial agents and trimethoprim • agents targeting protein synthesis - aminoglycoside, macrolide and tetracycline antibiotics, chloramphenicol, and oxazolidinones • agents targeting cell wall synthesis - β-Lactam and glycopeptide antibiotics, cycloserine, isonaizid, and daptomycin Antibacterial Agents will find a place on the bookshelves of students of pharmacy, pharmacology, pharmaceutical sciences, drug design/discovery, and medicinal chemistry, and as a bench reference for pharmacists and pharmaceutical researchers in academia and industry.

Identification of indolyl-3-acryloylglycine in the urine of people with autism.

HPLC analysis of the urine of autistic subjects indicated the presence of an unidentified component in greatly increased concentrations. We have reported the isolation of this component by HPLC and its identification. Mass spectrometry, NMR and UV spectroscopy identified the peak as corresponding to indolyl‐3‐acryloylglycine (IAG, 3), and this has been confirmed by an independent synthesis.

Synthesis and evaluation of fluorogenic 2-amino-1,8-naphthyridine derivatives for the detection of bacteria

Several novel fluorogenic N-aminoacylnaphthyridine substrates were synthesized in good yield and tested for their ability to detect pathogenic bacteria in agar-based cell culture. Simple 2-N-(β-alanyl)amino-5,7-dialkylnaphthyridine substrates were selectively hydrolysed by β-alanylaminopeptidase expressing bacteria, but were subject to diffusion in the agar medium. Diffusion was reduced in the 2-N-(β-alanyl)amino-7-alkylnaphthyridine substrates with longer alkyl chains, but inhibition of growth was increased. 2-N-(β-Alanyl)amino-7-octylnaphthyridine inhibited the growth of all species tested, except for strains resistant to colistin/polymyxin, providing a rationale for the development of substrates for the selective detection of drug resistant species in clinical samples.

The generation and reactivity of N-substituted, stabilised α,β:γ,δ-unsaturated azomethine ylides

Abstract The generation of N-substituted, stabilised azomethine ylides in the presence of N-phenylmaleimide gave the bicyclo[3.3.0] octane-3-carboxylate cycloadducts. In the absence of a dipolarophile, these azomethine ylides gave novel piperazine-6-carboxylates.

Evaluation of a Range of Anti-Proliferative Assays for the Preclinical Screening of Anti-Psoriatic Drugs: A Comparison of Colorimetric and Fluorimetric Assays with the Thymidine Incorporation Assay

Established treatments for psoriasis are generally based on antiproliferative, anti-inflammatory, or differentiation-modifying activity, or a combination of these effects. New agents for the treatment of psoriasis could be identified by high-throughput screening (HTS) of large compound libraries using keratinocyte proliferation models. Although several new proliferation assays have been developed, the radioactive [(3)H]-thymidine incorporation assay is still considered to be the gold standard for the evaluation of keratinocyte proliferation in vitro. In this study, we compare a number of simple, and reliable, colorimetric (MTT, NRU, SRB, and CVS), and fluorimetric (CAM and AB) methods with the [(3)H]-thymidine incorporation assay for the measurement of keratinocyte proliferation in the exponential growth phase in 96-well formats. The concentrations that induced 50% growth inhibition (GI(50)) were determined by each assay for the established antipsoriatics, dithranol, and methotrexate. Strong correlations were observed between the percentage growth inhibitions determined by the radioactive and the colorimetric assays, with no significant differences (P > 0.05) between their GI(50) values. The colorimetric assays are thus suitable alternatives to the radioactive assay for quantifying keratinocyte growth inhibition. We have also validated the use of the HaCaT cell line as a representative of the hyperproliferative psoriatic epidermis, in the preclinical screening of experimental anti-psoriatic agents.

An investigation of the effects of dithranol-induced apoptosis in a human keratinocyte cell line

Dithranol, one of the most successful topical agents for the treatment of psoriasis, has been shown to exert its therapeutic effect by inducing keratinocyte apoptosis. To gain further insights into dithranol‐induced apoptotic events in vitro, a detailed investigation of its time‐ and dose‐dependent effects has been performed through the evaluation of selected apoptotic markers, using a human keratinocyte cell line (HaCaT) as a model.

Potential transition state phosphoramidate inhibitors of β-tubulin as antifilarial agents

Transition state phosphoramidate inhibitors of β‐tubulin were designed as potential antifilarial agents.

Synthesis of diacylated γ-glutamyl-cysteamine prodrugs, and in vitro evaluation of their cytotoxicity and intracellular delivery of cysteamine

To overcome the major disadvantages of cysteamine, the only registered treatment for the rare genetic disease cystinosis, nine prodrugs of γ-glutamyl-cysteamine (4) were synthesized for evaluation. Esterification of the thiol conferred oxidative stability, while sufficient lipophilicity for oral bioavailability was achieved by acylation of the α-carboxyl group of γ-glutamyl-cysteamine (4). Low cytotoxicity was observed in cultured HaCaT keratinocytes using the MTT assay, with EC50 values higher than or similar to that of cysteamine. Successful uptake of the esterified prodrugs and the subsequent release of cysteamine into cultured human proximal tubule epithelial cells were demonstrated using CMQT derivatisation and HPLC with UV detection. These prodrugs show potential as novel delivery vehicles of cysteamine to improve the treatment of the genetic disorder nephropathic cystinosis.

A novel synthesis of imidazoles via the cycloaddition of nitrile ylides to their imidoyl chloride precursors

Generation of nitrile ylides, 4 and 22, via the base-catalysed 1,3-dehydrochlorination of imidoyl chlorides, 3 and 21, gives the imidazoles, 13, 23 and 24. These imidazoles are formed by the cycloaddition of the nitrile ylides, 4 and 22, to their precursor imidoyl chlorides, 3 and 21, and the observed regiochemistry of this cycloaddition has been rationalised by energy calculations on the frontier molecular orbitals of these reactants using semi-empirical (MOPAC PM3) methods.

Synthesis of Mono- and Bis-substituted Anthraquinones as Inhibitors of Human Telomerase

A number of anthraquinone derivatives have been synthesized in good yield and tested for their ability to inhibit the enzymes telomerase and Taq polymerase using a modified telomeric repeat amplification protocol. In addition, all the synthesized compounds were screened against a panel of ovarian carcinoma cell lines (A2780, CH1 and SKOV-3) to determine their cytotoxicity. All compounds tested inhibited telomerase at a concentration of 10 μM, but showed negligible inhibition of Taq polymerase. None of the compounds tested displayed significant general cell toxicity in ovarian cancer cell lines. The synthesized compounds are potential selective inhibitors of human telomerase.