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A previous publication from our laboratory reported the identification of a new class of 2-(1H-imidazo-2-yl)piperazines as potent T. brucei growth inhibitors as potential treatment for Human African Trypanosomiasis (HAT). This work describes the structure–activity relationship (SAR) around the hit compound 1, which led to the identification of the optimized compound 18, a single digit nanomolar inhibitor (EC50 7 nM), not cytotoxic and with optimal in vivo profile that made it a suitable candidate for efficacy studies in a mouse model mimicking the second stage of disease.

The identification of a new series of growth inhibitors of Trypanosoma brucei rhodesiense, causative agent of Human African Trypanosomiasis (HAT), is described. A selection of compounds from our in-house compound collection was screened in vitro against the parasite leading to the identification of compounds with nanomolar inhibition of T. brucei growth. Preliminary SAR on the hit compound led to the identification of compound 34 that shows low nanomolar parasite growth inhibition (T. brucei EC50 5 nM), is not cytotoxic (HeLa CC50 > 25,000 nM) and is selective over other parasites, such as Trypanosoma cruzi and Plasmodium falciparum (T. cruzi EC50 8120 nM, P. falciparum EC50 3624 nM).

The identification of a new series of P. falciparum growth inhibitors is described. Starting from a series of known human class I HDAC inhibitors a SAR exploration based on growth inhibitory activity in parasite and human cells-based assays led to the identification of compounds with submicromolar inhibition of P. falciparum growth (EC50500 nM) and good selectivity over the activity of human HDAC in cells (up to50-fold). Inhibition of parasital HDACs as the mechanism of action of this new class of selective growth inhibitors is supported by hyperacetylation studies.

Oncostatin M is a cytokine that acts as a growth regulator on a wide variety of cells and has diverse biological activities including acute phase protein induction, LDL receptor up-regulation and cell-specific gene expression. In order to gather information about the One M structure, we established a protocol for large scale production and single step purification of this functional cytokine from bacterial cells. The cDNA of human Onc M was cloned by RT-PCR from total RNA of PMA induced U937 cells. After the addition of a six histidine tag at the N-terminus, the coding region of mature Onc M was cloned in the pT7.7 expression vector. Histidine tagged Onc M was overexpressed in bacterial cells and purified to homogeneity in one step on a metal chelating column. We found that recombinant 6xHis-OncM remains fully active in a growth inhibition assay. Structural characterization of the purified protein was performed by electrospray mass spectrometry, automated Edman degradation and peptide mapping by high-pressure liquid chromatography/fast-atom-bombardment mass spectrometry. Thermal and pH stability dependence of Onc M was assessed by circular dichroism spectroscopy; the helical content is about 50%, in agreement with the four helix bundle fold postulated for cytokines that bind haematopoietic receptors of type I.

Two transglutaminase-mediated modifications of the rat epididymal spermatozoon surface were demonstrated in vitro. Transglutaminase was effective in promoting the binding of spermidine to the sperm. Moreover, the enzyme, by reacting with one of the major proteins secreted by the rat seminal vesicle epithelium, produced a modified form of the protein with a higher molecular weight and the capability of binding to the sperm cells. A specific physiological role for the enzyme, bringing about modifications of the rat sperm surface in the seminal fluid environment, is suggested.

Cruciform DNA, a non-double helix form of DNA, can be generated as an intermediate in genetic recombination as well as from palindromic sequences under the effect of supercoiling. Eukaryotic cells are equipped with a DNA-binding protein that selectively recognizes cruciform DNA. Biochemical and immunological data showed that this protein is HMG1, an evolutionarily conserved, essential, and abundant component of the nucleus. The interaction with a ubiquitous protein points to a critical role for cruciform DNA conformations.