NMR for screening and a biochemical assay: Identification of new FPPS inhibitors exerting anticancer activity.

Farnesyl pyrophosphate synthase (FPPS) is a crucial enzyme for the synthesis of isoprenoids and the key target of nitrogen-containing bisphosphonates (N-BPs). N-BPs are potent and selective FPPS inhibitors that are used in the treatment of bone-related diseases, but have poor pharmacokinetic properties. Given the key role played by FPPS in many cancer-related pathways and the pharmacokinetic limits of N-BPs, hundreds of molecules have been screened to identify new FPPS inhibitors characterized by improved drug-like properties that are useful for broader therapeutic applications in solid, non-skeletal tumours. We have previously shown that N6-isopentenyladenosine (i6A) and its related compound N6-benzyladenosine (2) exert anti-glioma activity by interfering with the mevalonate pathway and inhibiting FPPS. Here, we report the design and synthesis of a panel of N6-benzyladenosine derivatives (compounds 2a-m) incorporating different chemical moieties on the benzyl ring. Compounds 2a-m show in vitro antiproliferative activity in U87MG glioma cells and, analogous to the bisphosphonate FPPS inhibitors, exhibit immunogenic properties in ex vivo γδ T cells from stimulated peripheral blood mononuclear cells (PBMCs). Using saturation transfer difference (STD) and quantitative 1H nuclear magnetic resonance (NMR) experiments, we found that 2f, the N6-benzyladenosine analogue that includes a tertbutyl moiety in the para position of the benzyl ring, is endowed with increased FPPS binding and inhibition compared to the parent compounds i6A and 2. N6-benzyladenosine derivatives, characterized by structural features that are significantly different from those of N-BPs, have been confirmed to be promising chemical scaffolds for the development of non N-BP FPPS inhibitors, exerting combined cytotoxic and immunostimulatory activities.

Investigating the Neuroprotective Effects of Turmeric Extract: Structural Interactions of ß-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 Aß-peptide. When the CYC and curcumin metabolite tetrahydrocurcumin (5, THC) were inserted into an anionic lipid solution, a significant modification of the Aß 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-Aß interaction, highlighting the importance of a constrained "semi-folded" conformation to interact with Aß 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.