Ippolito Antonini

8-Bromo-9-alkyl adenine derivatives as tools for developing new adenosine A2A and A2B receptors ligands.

Importance of making available selective adenosine receptor antagonists is boosted by recent findings of adenosine involvement in many CNS dysfunctions. In the present work a series of 8-bromo-9-alkyl adenines are prepared and fully characterized in radioligand binding assays or functional cyclase experiments in respect to their interaction with all the four adenosine receptor subtypes. Results show that the presence of the bromine atom in 8-position of 9-substituted adenines promotes in general the interaction with the adenosine receptors, in particular at the A(2A) subtype. The present study also demonstrates that adenine derivatives could be a good starting point to obtain selective adenosine A(2B) receptor antagonists.

Rational design, synthesis and biological evaluation of thiadiazinoacridines: A new class of antitumor agents

A series of potential DNA-binding antitumor agents, 3-[omega-(alkylamino)alkyl]-6-nitro-thiadiazino[3,4,5-kl]acridines 12 and 1,3-di[omega-(alkylamino)alkyl]-6-nitro-thiadiazino[3,4,5-kl]acridines 13, has been prepared by cyclization with SOCl(2) of 1-[[omega-(alkylamino)alkyl]amino]-9-imino-4-nitro-9,10-dihydroacridines 16 or 1-[[omega-(alkylamino)alkyl]amino]-9-[omega-(alkylamino)alkyl]imino-4-nitro-9,10-dihydroacridines 17, respectively. The non-covalent DNA-binding properties of 12, 13 have been examined using a fluorometric technique. In vitro cytotoxic potencies of these derivatives toward six tumor cell lines, including human colon adenocarcinoma (HT29) and human ovarian carcinoma (A2780 sensitive, A2780cisR cisplatin-resistant, CH1, CH1cisR cisplatin-resistant, and SKOV-3) cells, are described and compared to that of reference drugs. In vivo antitumor activity of some selected derivatives, endowed with relevant cytotoxic activity against murine leukemia P388 are reported. The 3-[2-(dimethylamino)ethyl]-6-nitro-2,7-dihydro-3H-2 lambda(4)-thiadiazino[3,4,5-kl]acridin-2-one (12d) has been identified as a new lead in the development of anticancer tetracyclic acridine derivatives.

Design, synthesis, and biological evaluation of new mitonafide derivatives as potential antitumor drugs

A series of potential DNA-binding antitumor agents, 2-[omega-(alkylamino)alkyl]-6-{[omega-(alkylamino)alkyl]amino}-1H-benzo[de]isoquinolin-1,3(2H)-diones and 1,7-bis{6-[(omega-(dimethylamino)alkyl)amino]-1,3-dioxo-1H-benzo[de]isoquinolin-2(3H)-yl}-4-methyl-4-azaheptanes, have been prepared as mitonafide derivatives. Their DNA-binding ability and cytotoxic activity have been evaluated. Some of the target compounds have shown high DNA affinity as well as relevant cytotoxic properties.

Molecular Modeling Studies on the Human Neuropeptide S Receptor and Its Antagonists

Neuropeptide S (NPS) is a 20‐residue peptide of great interest due to its potential involvement in several biological processes such as arousal, anxiety, and food intake. The NPS receptor belongs to the rhodopsin‐like G‐protein‐coupled receptor superfamily, and several polymorphisms and isoforms of this receptor are associated with asthma, allergies, and bronchial hyper‐responsiveness, in particular the Asn 107 Ile mutation. Limited structural information is available for this peptide–receptor system, particularly regarding the NPS receptor structure, its nonpeptide ligands, and the molecular aspects of agonist and antagonist binding processes. In this work, rhodopsin‐based homology models of the NPS receptor and its Asn 107 Ile variant were built and refined in a membrane bilayer model, and binding modes for nonpeptide antagonists were simulated. This study provides the first structural study of the human NPS receptor, and the results provide a starting point for further characterization of the binding modes of its antagonists, and for the rational design of new NPS receptor ligands.

Adenine-based acyclic nucleotides as novel P2X3 receptor ligands.

A new series of acyclic nucleotides based on the adenine skeleton and bearing in 9-position a phosphorylated four carbon chain has been synthesized. Various substituents were introduced in 2-position of the adenine core. The new compounds were evaluated on rat P2X3 receptors, using patch clamp recording from HEK transfected cells and the full P2X3 agonist alpha,beta-meATP as reference compound. The results suggest that certain acyclic nucleotides, in particular compounds 28 and 29, are endowed with modest partial agonism on P2X3 receptors. This is an interesting property that can depress the function of P2X3 receptors, whose activation is believed to be involved in a number of chronic pain conditions including neuropathic pain and migraine. In fact, the new acyclic nucleotides are able to persistently block (by desensitization) P2X3 receptor activity after a brief, modest activation, yet leaving the ability of sensory neurons to mediate responses to standard painful stimuli via a lower level of signaling.

Neuropeptide S receptor: recent updates on nonpeptide antagonist discovery.

Neuropeptide S (NPS) is a 20‐amino acid peptide of great interest due to its possible involvement in several biological processes, including food intake, locomotion, wakefulness, arousal, and anxiety. Structure–activity relationship studies of NPS have identified key points for structural modifications with the goal of modulating NPS receptor (NPSR) agonist activity or achieving antagonism at the same receptor. Only limited information is available for nonpeptide NPSR antagonists. In the last year, several studies have been reported in literature which present various series of small molecules as antagonists of this receptor. The results allow a comparison of the structures and activities of these molecules, leading to the design of new ligands with increased potency and improved pharmacological and pharmacokinetic profiles. This work presents a brief overview of the available information regarding structural features and pharmacological characterization of published nonpeptide NPSR antagonists.

Synthesis and antitumor evaluation of bis aza-anthracene-9,10-diones and bis aza-anthrapyrazole-6-ones

The good results obtained as potential antitumor drugs with aza-anthracenediones and aza-anthrapyrazoles, e.g. pixantrone, 1a, and 1b (Chart 1), prompted us to design and synthesize a series of symmetrical bis derivatives, compounds 7-10 (Chart 1). These compounds are dimers of different aza-anthracenedione and aza-anthrapyrazolone monomers connected by the linker found to be the most appropriate among potential bis intercalators synthesized by us. The DNA-binding properties of bis derivatives 7 and 8 have been examined using fluorometric techniques: these target compounds are excellent DNA ligands, with a clear binding site preference for AT-rich duplexes. In vitro cytotoxic activity of all target compounds 7-10 and of reference compound pixantrone toward human cancer adenocarcinoma cell line HT29 is also described. Two selected compounds have been investigated for their capacity of inducing early apoptosis.

One-Step Synthesis of 4-Alkoxy-1-Ethoxycarbonylmethylazetidin-2-ones

Abstract Stereoselective one-step synthesis of 4-alkoxy-1-ethoxycarbonylmethylazetidin-2-ones from acid chlorides and N-ethoxycarbonylmethylimidates.