Resveratrol 1 (3,4',5-trihydroxy-trans-stilbene), a phytoalexin present in grapes and other food products, has recently been suggested as a potential cancer chemopreventive agent based on its striking inhibitory effects on cellular events associated with cancer initiation, promotion, and progression. This triphenolic stilbene has also displayed in vitro growth inhibition in a number of human cancer cell lines. In this context, a series of cis- and trans-stilbene-based resveratrols were prepared with the aim of discovering new lead compounds with clinical potential. All the synthesized compounds were tested in vitro for cell growth inhibition and the ability to induce apoptosis in HL60 promyelocytic leukemia cells. The tested trans-stilbene derivatives were less potent than their corresponding cis isomers, except for trans-resveratrol, whose cis isomer was less active. The best results were obtained with compounds 11b and 7b, the cis-3,5-dimethoxy derivatives of rhapontigenin 10a (3,5,3'-trihydroxy-4'methoxy-trans-stilbene) and its 3'-amino derivative 10b, respectively, which showed apoptotic activity at nanomolar concentrations. The corresponding trans isomers 12b and 8b were less active both as antiproliferative and as apoptosis-inducing agents. Of interest, 11b and 7b were active toward resistant HL60R cells and their activity was higher than that of several classic chemotherapeutic agents. The flow cytometry assay showed that at 50 nM compounds 7b or 11b were able to recruit almost all cells in the apoptotic sub-G(0)-G(1) peek, thus suggesting that the main mechanism of cytotoxicity of these compounds could be the activation of apoptosis. These data indicate unambiguously that structural alteration of the stilbene motif of resveratrol can be extremely effective in producing potent apoptosis-inducing agents.

The expression of acid ceramidase (AC) – a cysteine amidase that hydrolyses the proapoptotic lipid ceramide – is abnormally high in several human tumors, which is suggestive of a role in chemoresistance. Available AC inhibitors lack, however, the potency and drug-likeness necessary to test this idea. Here we show that the antineoplastic drug carmofur, which is used in the clinic to treat colorectal cancers, is a potent AC inhibitor and that this property is essential to its anti-proliferative effects. Modifications in the chemical scaffold of carmofur yield new AC inhibitors that act synergistically with standard antitumoral drugs to prevent cancer cell proliferation. These findings identify AC as an unexpected target for carmofur, and suggest that this molecule can be used as starting point for the design of novel chemosensitizing agents.

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Herein we report on a novel series of multitargeted compounds obtained by linking together galantamine and memantine. The compounds were designed by taking advantage of the crystal structures of acetylcholinesterase (AChE) in complex with galantamine derivatives. Sixteen novel derivatives were synthesized, using spacers of different lengths and chemical composition. The molecules were then tested as inhibitors of AChE and as binders of the N-methyl-D-aspartate (NMDA) receptor (NMDAR). Some of the new compounds were nanomolar inhibitors of AChE and showed micromolar affinities for NMDAR. All compounds were also tested for selectivity toward NMDAR containing the 2B subunit (NR2B). Some of the new derivatives showed a micromolar affinity for NR2B. Finally, selected compounds were tested using a cellbased assay to measure their neuroprotective activity. Three of them showed a remarkable neuroprotective profile, inhibiting the NMDAinduced neurotoxicity at subnanomolar concentrations (e.g., 5, named memagal, IC 50 = 0.28 nM).

Cumulative evidence strongly supports that the amyloid and tau hypotheses are not mutually exclusive, but concomitantly contribute to neurodegeneration in Alzheimer's disease (AD). Thus, the development of multitarget drugs which are involved in both pathways might represent a promising therapeutic strategy. Accordingly, reported here in is the discovery of 6-amino-4-phenyl-3,4-dihydro-1,3,5-triazin-2(1H)-ones as the first class of molecules able to simultaneously modulate BACE-1 and GSK-3β. Notably, one triazinone showed well-balanced in vitro potencies against the two enzymes (IC50 of (18.03±0.01) μM and (14.67±0.78) μM for BACE-1 and GSK-3β, respectively). In cell-based assays, it displayed effective neuroprotective and neurogenic activities and no neurotoxicity. It also showed good brain permeability in a preliminary pharmacokinetic assessment in mice. Overall, triazinones might represent a promising starting point towards high quality lead compounds with an AD-modifying potential.

Acid ceramidase (AC) is an intracellular cysteine amidase that catalyzes the hydrolysis of the lipid messenger ceramide. By regulating ceramide levels in cells, AC may contribute to the regulation of cancer cell proliferation and senescence and to the response to cancer therapy. We recently identified the antitumoral agent carmofur (4a) as the first nanomolar inhibitor of intracellular AC activity (rat AC, IC 50 = 0.029 μM). In the present work, we expanded our initial structure−activity relationship (SAR) studies around 4a by synthesizing and testing a series of 2,4-dioxopyrimidine-1-carboxamides. Our investigations provided a first elucidation of the structural features of uracil derivatives that are critical for AC inhibition and led us to identify the first single-digit nanomolar inhibitors of this enzyme. The present results confirm that substituted 2,4-dioxopyrimidine-1-carboxamides are a novel class of potent inhibitors of AC. Selected compounds of this class may represent useful probes to further characterize the functional roles of AC.

To further explore the SAR of resveratrol-related trans-stilbene derivatives, here we describe the synthesis of (a) a series of 3,5-dimethoxy analogues in which a variety of substituents were introduced at positions 2', 3', 4', and 5' of the stilbene scaffold and (b) a second group of derivatives (2-phenylnaphthalenes and terphenyls) that incorporate a phenyl ring as a bioisosteric replacement of the stilbene alkenyl bridge. We thoroughly characterized all of the new compounds with respect to their apoptosis-inducing activity and their effects on the cell cycle. One of the new derivatives, 13g, behaved differently from the others, as it was able to block the cell cycle in the G(0)-G(1) phase and also to induce differentiation in acute myelogenous leukemia HL60 cells. Compared to resveratrol, the synthetic terphenyl 13g showed a more potent apoptotic and differentiating activity. Moreover, it was active on both multidrug resistance and Bcr-Abl-expressing cells that were resistant to resveratrol.

Solubility optimization is a crucial step to obtaining oral PROTACs. Here we measured the thermodynamic solubilities (log S) of 21 commercial PROTACs. Next, we measured BRlogD and log k w IAM (lipophilicity), EPSA, and Δ log k w IAM (polarity) and showed that lipophilicity plays a major role in governing log S, but a contribution of polarity cannot be neglected. Two-/three-dimensional descriptors calculated on conformers arising from conformational sampling and steered molecular dynamics failed in modeling solubility. Infographic tools were used to identify a privileged region of soluble PROTACs in a chemical space defined by BRlogD, log k w IAM and topological polar surface area, while machine learning provided a log S classification model. Finally, for three pairs of PROTACs we measured the solubility, lipophilicity, and polarity of the building blocks and identified the limits of estimating PROTAC solubility from the synthetic components. Overall, this paper provides promising guidelines for optimizing PROTAC solubility in early drug discovery programs.