Rosario Randino

Investigating the Neuroprotective Effects of Turmeric Extract: Structural Interactions of β-Amyloid Peptide with Single Curcuminoids

A broad biophysical analysis was performed to investigate the molecular basis of the neuroprotective action of Curcuma longa extracts in Alzheimer’s disease. By combining circular dichroism and electron paramagnetic resonance experiments with molecular modeling calculations, the minor components of Curcuma longa extracts, such as demethoxycurcumin (2, DMC), bisdemethoxycurcumin (3, BDMC) and cyclocurcumin (4, CYC), were analyzed in a membrane environment mimicking the phospholipid bilayer. Our study provides the first evidence on the relative role of single curcuminoids interacting with Aβ-peptide. When the CYC and curcumin metabolite tetrahydrocurcumin (5, THC) were inserted into an anionic lipid solution, a significant modification of the Aβ CD curves was detected. These data were implemented by EPR experiments, demonstrating that CYC reaches the inner part of the bilayer, while the other curcuminoids are localized close to the membrane interface. Computational studies provided a model for the curcuminoid-Aβ interaction, highlighting the importance of a constrained “semi-folded” conformation to interact with Aβ analogously to the pattern observed in α-helical coiled-coil peptide structures. This combined approach led to a better understanding of the intriguing in vitro and in vivo activity of curcuminoids as anti-Alzheimer agents, paving a new path for the rational design of optimized druggable analogues.

Benzodiazepine Scaffold as Drug-like Molecular Simplification of FR235222: A Chemical Tool for Exploring HDAC Inhibition

BACKGROUND Synthesis, computational study and biological evaluation of peptidomimetic analogues of FR235222 (3), a natural immunosuppressant and HDAC inhibitor, have been reported. These new compounds, bearing α-hydroxyketone moiety, as more stable zinc binding group (ZBG), were evaluated in vitro as HDAC inhibitors against the human HDACs isoforms 1-9 and in cellular antiproliferative assays on U937 human leukemia cell line. The 1,4-benzodiazepin-2,5-dione (BDZ), capping group and the natural ZBG, (S,R)-2-amino-9-hydroxy-8-oxodecanoic acid (Ahoda), were evaluated in order to probe HDAC inhibition and/or paralogue selectivity. Some of the new derivatives showed an interesting activity against a number of HDAC isozymes. The observed activity profile was rationalized by a computational assisted SAR study, in order to understand how the BDZ classes interact with the enzyme into the catalytic pocket. Despite its poor solubility, compound 17b showed significant antiproliferative profile and HDAC inhibition activity. RESULT In order to assess how the solubility issue could have affected the biological outcome, bioassay conditions were reproduced and quantification of precipitated particulate material was evaluated by turbidimetric and NMR studies together with physicochemical descriptors prediction. Thus, BDZ 17b has been chosen to be promising lead compounds for further optimization, in order to elucidate molecule- enzyme surface recognition.

Synthesis and biological evaluation of Santacruzamate-A based analogues

Several derivatives of Santacruzamate-A, a natural product that is structurally related to SAHA, were synthesized to explore the potential of carbamates and oxalylamides as novel biasing element for targeting the catalytic site of zinc-dependent histone deacetylases (HDACs). An additional class of Santacruzamate-A derivatives was synthesized to investigate the influence of the cap group and the linker element on HDAC inhibitory activity. All compounds were evaluated in dose response for their in vitro cytotoxic activity in MTT assay in HCT116 cells. HDAC inhibitory activity was evaluated in vitro by western blot analysis for histone hyperacetylation assay and biochemically for representative human HDACs isoforms. Two novel compounds were identified to exhibit potent time dependent anti proliferative activity. However, unlike hydroxamic acid analogues, the tested Santacruzamate-A derivatives showed no noticeable HDAC inhibitory activity. The ethylcarbamate moiety as unusual zinc-binding group displayed no ability to coordinate the zinc ion and thus, presumably, was not able to reproduce known inhibitor-substrate zinc-binding group interactions with the HDAC catalytic site. This study confirmed that the accommodation of the zinc-binding group is deeply critical of the positioning of the linker and the projection of the cap group toward the different surface pockets of the enzyme.

A highly stereo-controlled protocol to prepare pipecolic acids based on Heck and cyclohydrocarbonylation reactions

A novel synthetic protocol based on an indium-mediated glyoxylate allylation, Heck coupling and Rh-catalysed cyclohydrocarbonylation (CHC) was established to access enantiomerically pure polysubstituted pipecolic acids. The key steps are the Heck reaction, which is performed exclusively using a phenone-oxime derived palladacycle and the domino hydroformylation-cyclisation of a styryl derivative obtained from the Heck coupling. The reaction scheme, proceeding with good stereoselectivity, is also suitable for the preparation of substituted piperidine derivatives.

N-thioalkylcarbazoles derivatives as new anti-proliferative agents: synthesis, characterisation and molecular mechanism evaluation.

Abstract Synthetic or natural carbazole derivatives constitute an interesting class of heterocycles, which showed several pharmaceutical properties and occupied a promising place as antitumour tools in preclinical studies. They target several cellular key-points, e.g. DNA and Topoisomerases I and II. The most studied representative, i.e. Ellipticine, was introduced in the treatment of metastatic breast cancer. However, because of the onset of dramatic side effects, its use was almost dismissed. Many efforts were made in order to design and synthesise new carbazole derivatives with good activity and reduced side effects. The major goal of the present study was to synthesise a series of new N-thioalkylcarbazole derivatives with anti-proliferative effects. Two compounds, 5a and 5c, possess an interesting anti-proliferative activity against breast and uterine cancer cell lines without affecting non-tumoural cell lines viability. The most active compound (5c) induces cancer cells death triggering the intrinsic apoptotic pathway by inhibition of Topoisomerase II. Graphical Abstract