Daniele Passarella

Microtubule Alterations Occur Early in Experimental Parkinsonism and The Microtubule Stabilizer Epothilone D Is Neuroprotective

The role of microtubule (MT) dysfunction in Parkinsons disease is emerging. It is still unknown whether it is a cause or a consequence of neurodegeneration. Our objective was to assess whether alterations of MT stability precede or follow axonal transport impairment and neurite degeneration in experimental parkinsonism induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in C57Bl mice. MPTP induced a time- and dose-dependent increase in fibres with altered mitochondria distribution, and early changes in cytoskeletal proteins and MT stability. Indeed, we observed significant increases in neuron-specific βIII tubulin and enrichment of deTyr tubulin in dopaminergic neurons. Finally, we showed that repeated daily administrations of the MT stabilizer Epothilone D rescued MT defects and attenuated nigrostriatal degeneration induced by MPTP. These data suggest that alteration of ΜΤs is an early event specifically associated with dopaminergic neuron degeneration. Pharmacological stabilization of MTs may be a viable strategy for the management of parkinsonism.

Chemical approaches to targeting drug resistance in cancer stem cells.

Cancer stem cells (CSCs) are a subpopulation of cancer cells with high clonogenic capacity and ability to reform parental tumors upon transplantation. Resistance to therapy has been shown for several types of CSC and, therefore, they have been proposed as the cause of tumor relapse. Consequently, much effort has been made to design molecules that can target CSCs specifically and sensitize them to therapy. In this review, we summarize the mechanisms underlying CSC resistance, the potential biological targets to overcome resistance and the chemical compounds showing activity against different types of CSC. The chemical compounds discussed here have been divided according to their origin: natural, natural-derived and synthetic compounds.

Inhibitors of tubulin polymerization: synthesis and biological evaluation of hybrids of vindoline, anhydrovinblastine and vinorelbine with thiocolchicine, podophyllotoxin and baccatin III.

A series of novel hybrid compounds obtained by the attachment of anhydrovinblastine, vinorelbine, and vindoline to thiocolchicine, podophyllotoxin, and baccatin III are described. Two types of diacyl spacers are introduced. The influence of the hybrid compounds on tubulin polymerization is reported. The results highlight the importance of the length of the spacer. Immunofluorescence microscopy and flow cytometry measurements that compound with the best in vitro activity could disrupt microtubule networks in cell and prevent the formation of the proper spindle apparatus, thereby causing cell cycle arrest in the G2/M phase. The newly synthesized compounds were tested in the human lung cancer cell line A549.

Synthesis and biological evaluation of novel thiocolchicine–podophyllotoxin conjugates

The synthesis and biological evaluation of 9 dimeric compounds obtained by condensation of thiocolchicine and/or podophyllotoxin with 6 different dicarboxylic acids is described. In particular, tubulin assembly assay and immunofluorescence analysis results are reported. The biological data highlighted three compounds as being more active than the others, having a marked ability to inhibit the polymerization of tubulin in vitro and causing significant disruption to the microtubule network in vivo. The spacer unit was found to have a significant effect on biological activity, reinforcing the importance of the design of conjugate compounds to create new biologically active molecules in which the spacer could be useful to improve the solubility and to modulate the efficacy of well known anticancer drugs.

Synthesis and biological evaluation of imidazolo[2,1-b]benzothiazole derivatives, as potential p53 inhibitors

Since activation of p53 in response to cytotoxic stress may have proapoptotic or protective effects depending on the nature of the injury, inhibitors of p53 may have therapeutic interest as modulators of chemotherapy toxicity or efficacy. In an attempt to identify novel p53 inhibitors, a quality collection of compounds structurally related to pifithrin-β were designed and synthesized as potential inhibitors of p53. The biochemical and biological evaluations supported that compounds of the tetrahydrobenzothiazole series were inhibitors of the p53 transcriptional activity and were effective in enhancing paclitaxel-induced apoptosis. In contrast, in spite of the increased cytotoxic potency, selected compounds of the benzothiazole series were not able to modulate the transcriptional activity of p53, as indicated by lack of change of p21 expression. The therapeutic interest of the compounds of the former series in combination with taxanes was confirmed in a human tumor xenograft model.

Efficient continuous flow synthesis of hydroxamic acids and suberoylanilide hydroxamic acid preparation.

A continuous flow tubing reactor can be used to readily transform methyl or ethyl carboxylic esters into the corresponding hydroxamic acids. Flow rate, reactor volume, and temperature were optimized for the preparation of a small collection of hydroxamic acids. Synthetic advantages were identified as an increased reaction rate and higher product purity. This method was also successfully applied to the multistep preparation of suberoylanilide hydroxamic acid, a potent HDAC inhibitor used in anticancer therapy.

Enzymatic Kinetic Resolution of 2-Piperidineethanol for the Enantioselective Targeted and Diversity Oriented Synthesis †

2-Piperidineethanol (1) and its corresponding N-protected aldehyde (2) were used for the synthesis of several natural and synthetic compounds. The existence of a stereocenter at position 2 of the piperidine skeleton and the presence of an easily-functionalized group, such as the alcohol, set 1 as a valuable starting material for enantioselective synthesis. Herein, are presented both synthetic and enzymatic methods for the resolution of the racemic 1, as well as an overview of synthesized natural products starting from the enantiopure 1.

Synthesis of (+)‐Dumetorine and Congeners by Using Flow Chemistry Technologies

An efficient total synthesis of the natural alkaloid (+)-dumetorine by using flow technology is described. The process entailed five separate steps starting from the enantiopure (S)-2-(piperidin-2-yl)ethanol 4 with 29% overall yield. Most of the reactions were carried out by exploiting solvent superheating and by using packed columns of immobilized reagents or scavengers to minimize handling. New protocols for performing classical reactions under continuous flow are disclosed: the ring-closing metathesis reaction with a novel polyethylene glycol-supported Hoveyda catalyst and the unprecedented flow deprotection/Eschweiler-Clarke methylation sequence. The new protocols developed for the synthesis of (+)-dumetorine were applied to the synthesis of its simplified natural congeners (-)-sedamine and (+)-sedridine.

Synthesis of enantiopure diamine ligands related to sparteine, via scandium triflate-catalyzed imino Diels–Alder reactions

Imino Diels–Alder reactions have been investigated as a new route to sparteine analogues. The first enantioselective synthesis of two diastereoisomeric tricyclic diamines, structurally equivalent to the ABC and BCD rings of the naturally occurring alkaloid, is reported, starting from enantiopure intermediates. The effectiveness of the diamines in the lithiation of N-Boc-pyrrolidine is discussed.

Application of the Pd-catalyzed heteroarylation to the synthesis of 5-(indol-2′-yl)pyridin-2-one and 5-(indol-2′-yl)pyran-2-one

Abstract The synthesis of 5-(indol-2′-yl)pyridin-2-ones and 5-(indol-2′-yl)pyran-2-one by Pd-catalyzed reactions is described. The best results are obtained using 2-indolylstannanes or 2-indolylzinc halides to be coupled with 5-bromopyridin-2-ones or 5-bromopyran-2-one in the presence of Pd(PPh3)4 as catalyst. Other Pd-catalyzed reactions are discussed.