Mini Reviews in Medicinal Chemistry - Volume 3, Issue 2, 2003

The hydroxy group in 9-hydroxyellipticines increases the apparent affinity for DNA, stabilisation of toposiomerase II-DNA cleavable complex, oxidation to reactive quinone-imine intermediates, phosphorylation of p53 suppressor proteins and cytotoxicity relative to the parent ellipticines. Recent studies have focused on the mechanism of inhibition of phosphorylation of the mutant type of p53 protein, structural characterisation of the drug-DNA complex, the synthesis of carbohydrate derivatives and calculations of physical parameters, including dipole moments, as potential screens to allow identification of new active derivatives. Derivatisation at the 2- and 9-positions has lead to significant improvements in the in vivo activity of the 9- hydroxyellipticine derivatives and has provided important insights into the mechanism of action of these compounds.

The present review discusses the synthetic strategies of new ligands exhibiting mainly 5-HT1A binding affinities. Specifically we focused our attention in the synthesis of compounds structurally related to arylpiperazine, 2-aminotetralin, and benzopyran derivatives.

The recent advances in the chemistry of carbocyclic nucleosides focused on different synthetic approaches that lead to optically pure products as well as a comprehensive overview of their biological properties are discussed. In the latter aspect, molecular recognition of enzymes of pharmacological importance such as: reverse transcriptase, adenosine deaminase, thymidine kinase, DNA cytosine-C5 methyl transferase, Sadenosylhomocysteine hydrolase, etc are considered. The role of conformation and puckering of the glycon moiety in modulating the biological activity and also the use of carbanucleosides as building blocks to prepare oligonucleotides are carefully illustrated.

Bacterial biosynthesis of lysine has come under increased scrutiny as a target for novel antibacterial agents as it provides both lysine for protein synthesis and meso-diaminopimelate for construction of the bacterial peptidoglycan cell wall. Recent studies of the enzymes of the lysine biosynthetic pathway, development of inhibitors and investigations of their antibacterial properties are discussed.

Monoamine oxidase (MAO) inhibitors were developed as antidepressants but many drugs, including the novel oxazolidinone antibacterial agents, share similar molecular properties and have MAO inhibitory activity. Factors important for binding antidepressants and modifications to decrease binding of oxazolidinones to avoid undesirable vascular effects are discussed.

Buprenorphine is a partial agonist at the μ-opioid receptor with long duration of action and also exhibits delayed antagonist activity. Buprenorphine is finding increasing use as a treatment agent for opioid abuse, though its low efficacy is not well tolerated by all addicts. There is interest in developing a higher efficacy version of buprenorphine and in this mini-review some of the ligands recently discovered, that share with buprenorphine a profile of agonism followed by delayed antagonism, are discussed.

ADP plays a crucial role in haemostasis and thrombosis and its receptors are potential target for antithrombotic drugs.The knowledge of the ADP-receptors has been amplified by recent discoveries. This review highlights the ADP-receptors models and their antagonists described in the recent literature, mainly the thienopyridine derivatives.

Epothilones are naturally occurring 16-membered macrolides with the ability to promote tubulin polymerization in vitro and to stabilize preformed microtubules against Ca2+- or cold-induced depolymerization. In contrast to paclitaxel (Taxol) epothilones are also active in vitro against multidrugresistant cancer cell lines as well as cell lines whose paclitaxel-resistance is derived from specific β-tubulin mutations. Based on their attractive in vitro biological profile epothilones have turned into important lead structures in anticancer drug discovery and hundreds of analogs and derivatives of epothilone A and B have been prepared and biologically characterized over the past four years. A number of compounds, including natural epothilone B, deoxyepothilone B, and epothilone B lactam (BMS-247550) have also been reported to exhibit profound in vivo antitumor activity in animal models. Apart from providing a brief summary of the SAR that has emerged from the above in vitro studies, this minireview will largely focus on the biology and chemistry of those analogs for which in vivo antitumor activity has been reported in the literature. Two of these compounds, natural epothilone B and epothilone B lactam (BMS-247550) have advanced to clinical studies in humans.

New natural peroxides that have potent biological activities with novel diverse structures are reviewed with classification as secondary metabolites such as terpenes, polyketides, phenolics, and hydroperoxides. These compounds, isolated mainly from medicinal plants and marine sponges, are valuable sources in the drug discovery for particularly antitumor and antimalarial agents.