Laura Cipolla

Epitope affinity for MHC class I determines helper requirement for CTL priming

We show here that priming and memory generation of antigen-specific CD8+ cytotoxic T lymphocytes (CTL) does not require help if the immunogen binds major histocompatibility complex (MHC) class I molecules with high affinity. This conclusion was based on the study of three chemically distinct optimal length CTL epitopes with high affinity for the restriction element Kb. In contrast, when two subdominant epitopes with intermediate MHC binding affinity were studied, either a class II MHC–restricted T helper cell epitope or administration of antibody to CD40 was required to obtain significant CTL priming. Depending on the epitope, one source of help was much more efficient than the other.

SYNTHESIS OF AZASUGARS BY GRIGNARD REACTION ON GLYCOSYLAMINES

Abstract Pyrrolidines 5a-b, and piperidines 10a,b and 15, were synthesised by Grignard reaction on a glycosylamine, easily obtained from the parent sugar and a primary amine, followed by cyclization with triflic anhydride.

Pyrrolo(2,1-c)(1,4)benzodiazepine as a Scaffold for the Design and Synthesis of Anti- Tumour Drugs

Compounds that bind in the minor groove of DNA have found use in the experimental treatment of cancer and certain infectious diseases. Furthermore, agents which target and can recognize discrete sequences of DNA have the potential to offer selective therapies by modulating the activity of specific transcription factors or genes. For this reason, a number of sequence-selective DNA binding agents have been evaluated with a range of affinities and recognition fidelities. In this respect, the pyrrolo[2,1-c][1,4]benzodiazepines (PBDs) are of interest as they bind to guanine residues in the minor groove with a preference for Pu-G-Pu sequences. A dramatic increase in cytotoxicity and sequence selectivity has been achieved by linking two PBD units to form PBD dimers as cross-linking agents on opposite DNA strands (e.g., interstrand cross-links). SJG-136 is currently undergoing Phase I evaluation in both the United States (through the NCI) and United Kingdom (through Cancer Research United Kingdom). This review will focus on design, synthesis and structure activity relationship studies of pyrrolobenzodiazepines as anticancer therapeutics reported since 2003.

Novel Tn Antigen-Containing Neoglycopeptides: Synthesis and Evaluation as Anti Tumor Vaccines

The fully unprotected alpha-C-glycosyl analogue of N-acetylgalactosamine 9 was conjugated by a non-natural oxime bond to the segment peptides (328--340)OVA and (327--339)OVA, affording neoglycopeptides 1--2 and 3, having one or two sugar units, respectively. The three neoglycopeptides were tested in vitro in an antigen presentation assay as antitumor vaccines. Neoglycopeptides 1--3 could be presented to and recognized by the T cell receptor; neoglycopeptide 3, bearing two B-epitopes, was presented to the TCR with higher efficiency, compared to neoglycopeptide 2, having only one B-epitope.

Discovery and design of carbohydrate-based therapeutics

Importance of the field: Till now, the importance of carbohydrates has been underscored, if compared with the two other major classes of biopolymers such as oligonucleotides and proteins. Recent advances in glycobiology and glycochemistry have imparted a strong interest in the study of this enormous family of biomolecules. Carbohydrates have been shown to be implicated in recognition processes, such as cell–cell adhesion, cell–extracellular matrix adhesion and cell–intruder recognition phenomena. In addition, carbohydrates are recognized as differentiation markers and as antigenic determinants. Due to their relevant biological role, carbohydrates are promising candidates for drug design and disease treatment. However, the growing number of human disorders known as congenital disorders of glycosylation that are being identified as resulting from abnormalities in glycan structures and protein glycosylation strongly indicates that a fast development of glycobiology, glycochemistry and glycomedicine is highly desirable. Areas covered in this review: The topics give an overview of different approaches that have been used to date for the design of carbohydrate-based therapeutics; this includes the use of native synthetic carbohydrates, the use of carbohydrate mimics designed on the basis of their native counterpart, the use of carbohydrates as scaffolds and finally the design of glyco-fused therapeutics, one of the most recent approaches. The review covers mainly literature that has appeared since 2000, except for a few papers cited for historical reasons. What the reader will gain: The reader will gain an overview of the current strategies applied to the design of carbohydrate-based therapeutics; in particular, the advantages/disadvantages of different approaches are highlighted. The topic is presented in a general, basic manner and will hopefully be a useful resource for all readers who are not familiar with it. In addition, in order to stress the potentialities of carbohydrates, several examples of carbohydrate-based marketed therapeutics are given. Take home message: Carbohydrates are a rich class of natural compounds, possessing an intriguing and still not fully understood biological role. This richness offers several strategies for the design of carbohydrate-based therapeutics.

Epoxide Opening versus Silica Condensation during Sol–Gel Hybrid Biomaterial Synthesis

Hybrid organic-inorganic solids represent an important class of engineering materials, usually prepared by sol-gel processes by cross-reaction between organic and inorganic precursors. The choice of the two components and control of the reaction conditions (especially pH value) allow the synthesis of hybrid materials with novel properties and functionalities. 3-Glycidoxypropyltrimethoxysilane (GPTMS) is one of the most commonly used organic silanes for hybrid-material fabrication. Herein, the reactivity of GPTMS in water at different pH values (pH 2-11) was deeply investigated for the first time by solution-state multinuclear NMR spectroscopic and mass spectrometric analysis. The extent of the different and competing reactions that take place as a function of the pH value was elucidated. The NMR spectroscopic and mass spectrometric data clearly indicate that the pH value determines the kinetics of epoxide hydrolysis versus silicon condensation. Under slighly acidic conditions, the epoxy-ring hydrolysis is kinetically more favourable than the formation of the silica network. In contrast, under basic conditions, silicon condensation is the main reaction that takes place. Full characterisation of the formed intermediates was carried out by using NMR spectroscopic and mass spectrometric analysis. These results indicate that strict control of the pH values allows tuning of the reactivity of the organic and inorganic moities, thus laying the foundations for the design and synthesis of sol-gel hybrid biomaterials with tuneable properties.

Glycoconjugates in Cancer Therapy

This review focuses on recent efforts in glycoconjugate construction for the creation and evaluation of vaccines based on carbohydrate cancer-associated antigens. This therapeutic approach takes advantage from the known tendency of transformed cells to express selective carbohydrate motifs otherwise hidden in normal cells. The immunological response is elicited by the association in the same molecule a carbohydrate, as B-cell antigen, and a peptide, or an entire protein, as T-cell epitope. We will review on the synthesis and the immunological investigation of various glycoconjugates presenting tumor-associated carbohydrate antigens. Different approaches including the use of clustered glycoconjugates such as multiple antigenic glycopeptides (MAG), and glyconanoparticles as potential anti-tumour therapeutics will be considered.

Kdo: a critical monosaccharide for bacteria viability

Covering: 2000 to 2010 Kdo belongs to the 3-deoxysugar ‘family’ and is a critical monosaccharidic component of lipopolysaccharides (LPSs) in Gram-negative bacteria. The incorporation of Kdo into LPSs is a vital step in the assembly of the protective outer membrane of Gram-negative bacteria. This review intends to present recent advances on structural/biocatalytic knowledge on the four enzymes involved in Kdo metabolism, and on the synthesis and biological activity of analogues of biosynthetic intermediates, highlighting the potential of this pathway for the discovery of new antibacterials – a pressing need due to the emergence of new classes of antibiotic-resistant bacteria.

Casuarine-6-O-α-D-glucoside and its analogues are tight binding inhibitors of insect and bacterial trehalases

Two novel casuarine-6-alpha-D-glucoside analogues, as well as the parent compound, were synthesized and tested as inhibitors towards Chironomus riparius, mammalian pig kidney and Escherichia coli trehalases. Their potent and selective activity is promising for the development of new insecticides.

Carbohydrate mimetics and scaffolds: sweet spots in medicinal chemistry

Several glycoprocessing enzymes and glycoreceptors have been recognized as important targets for therapeutic intervention. This concept has inspired the development of important classes of therapeutics, such as anti-influenza drugs inhibiting influenza virus neuraminidase, anti-inflammatory drugs targeting lectin-sialyl-Lewis X interaction and glycosidase inhibitors against HIV, Gauchers disease, hepatitis and cancer. These therapeutics are mainly carbohydrate mimics in which proper modifications permit stronger interactions with the target protein, higher stability, better pharmacokinetic properties and easier synthesis. Furthermore, the conformational rigidity and polyfunctionality of carbohydrates stimulate their use as scaffolds for the generation of libraries by combinatorial decoration with different pharmacophores. This mini-review will present examples of how to exploit carbohydrates mimics and scaffolds in drug research.