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Novel 1,4-dioxane compounds structurally related to WB 4101 (1) were prepared in order to investigate the possibility that the quite planar 1,4-benzodioxane template of 1 might be replaced by the less conformationally constrained 1,4-dioxane ring. The biological profiles of the new compounds were assessed using binding assays at human cloned alpha 1-adrenoreceptor (alpha 1-AR) subtypes and 5-HT 1A receptors, expressed in Chinese hamster ovary and HeLa cell membranes, respectively, and by functional experiments in isolated rat vas deferens (alpha 1A), spleen (alpha 1B), and aorta (alpha 1D). Moreover, the cytotoxic effects of the novel compounds were determined in PC-3 prostate cancer cells. The results showed that the properly substituted 1,4-dioxane nucleus proved to be a suitable scaffold for selective alpha 1D-AR antagonists (compound 14), potential anticancer agents (compound 13), and full 5-HT 1A receptor agonists (compound 15). In particular, compound 15 may represent a novel lead in the development of highly potent 5-HT 1A receptor full agonists useful as antidepressant and neuroprotective agents.

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.

The good results obtained in the past decade with various types of potential bisintercalating agents, e.g., LU 79553, DMP 840, BisBFI, MCI3335, WMC-26, BisAC, BisPA, and the asymmetrical derivative WMC-79 (Chart 1), prompted us to investigate a new series of asymmetrical bisintercalators, compounds 1a-t (Chart 2), which can combine the potentiality of bisintercalation with a possible different mechanism of action due to two diverse chromophores. The DNA-binding properties of these compounds have been examined using fluorometric techniques: target compounds are excellent DNA ligands, with a clear preference for binding to AT-rich duplexes. In vitro cytotoxicity of these derivatives toward human hormone-refractory prostate adenocarcinoma cell line (PC-3) is described. Apoptosis assays of four selected compounds are also reported. Very potent cytotoxic compounds, some of them capable of inducing early apoptosis, have been identified.

A series of new alpha1-adrenoreceptor antagonists (5-18) was prepared by introducing various substituents (Topliss approach) into the ortho, meta, and para positions of the benzyloxy function of the phendioxan open analogue 4 ("openphendioxan"). All the compounds synthesized were potent antagonists and generally displayed, similarly to 4, the highest affinity values at alpha1D- with respect to alpha1A- and alpha1B-AR subtypes and 5-HT1A subtype. By sulforhodamine B (SRB) assay on human PC-3 prostate cancer cells, the new compounds showed antitumor activity (estimated on the basis of three parameters GI50, TGI, LC50), at low micromolar concentration, with 7 ("clopenphendioxan") exhibiting the highest efficacy. Moreover, this study highlighted for the first time alpha1D- and alpha1B-AR expression in PC3 cells and also demonstrated the involvement of these subtypes in the modulation of apoptosis and cell proliferation. A significant reduction of alpha1D- and alpha1B-AR expression in PC3 cells was associated with the apoptosis induced by 7. This depletion was completely reversed by norepinephrine.