Synthetic derivatives of natural cinnamic acids as potential anti-colorectal cancer agents.

Cinnamic acid and its derivatives represent attractive building blocks for the development of pharmacological tools. A series of piperoniloyl and cinnamoyl-based amides (6-9 a-f) have been synthesized and assayed against a wide panel of colorectal cancer (CRC) cells, with the aim of finding promising anticancer agents. Among all twenty-four synthesized molecules, 7a, 7e-f, 9c, and 9f displayed the best antiproliferative activity. The induced G1 cell cycle arrest and the increase in apoptotic cell death was seen in FACS analysis and western Blotting in the colon tumor cell lines HCT116, SW480, LoVo, and HT29, but not in the nontumor cell line HCEC. In particular, 9f overcame the resistance of HT29 cells, which have a mutant p53 and BRAF. Furthermore, 9f, amide of piperonilic acid with the 3,4-dichlorobenzyl substituent upregulated p21, which is involved in cell cycle arrest as well as in apoptosis induction. Cinnamic acid derivatives might be potential anticancer compounds, useful for the development of promising anti-CRC agents.

Pioneering first-in-class FAAH-HDAC inhibitors as potential multitarget neuroprotective agents.

Aiming to simultaneously modulate the endocannabinoid system (ECS) functions and the epigenetic machinery, we selected the fatty acid amide hydrolase (FAAH) and histone deacetylase (HDAC) enzymes as desired targets to develop potential neuroprotective multitarget-directed ligands (MTDLs), expecting to achieve an additive or synergistic therapeutic effect in oxidative stress-related conditions. We herein report the design, synthesis, and biological evaluation of the first-in-class FAAH-HDAC multitarget inhibitors. A pharmacophore merging strategy was applied, yielding 1-phenylpyrrole-based compounds 4a-j. The best-performing compounds (4c, 4f, and 4h) were tested for their neuroprotective properties in oxidative stress models, employing 1321N1 human astrocytoma cells and SHSY5 human neuronal cells. In our preliminary studies, compound 4h stood out, showing a balanced nanomolar inhibitory activity against the selected targets and outperforming the standard antioxidant N-acetylcysteine in vitro. Together with 4f, 4h was also able to protect 1321N1 cells from tert-butyl hydroperoxide or glutamate insult. Our study may provide the basis for the development of novel MTDLs targeting the ECS and epigenetic enzymes.

Development of 1-(2-aminophenyl)pyrrole-based amides acting as human topoisomerase I inhibitors.

Topoisomerases are ubiquitous enzymes in the human body, particularly involved in cancer development and progression. Topoisomerase I (topoI) performs DNA relaxation reactions by "controlled rotation" rather than by "strand passage." The inhibition of topoI has become a useful strategy to control cancer cell proliferation. Nowadays, different compounds have undergone clinical trials, but the search for new molecular entities is necessary and benefits from medicinal chemistry efforts. Pyrrole-based compounds emerged as promising antiproliferative agents, with particular interest in breast cancer therapy and topoI inhibition. Starting from these observations and based on the scaffold-hopping approach, we developed a small library of 1-(2-aminophenyl)pyrrole-based amides (7a-f) as new anticancer agents. Tested on a panel of cancer cell lines, 7a-f displayed the most interesting profile in MDA-MB-231 cells, where the most active compounds, 7d-f, were able to induce death by apoptosis. Direct enzymatic assays and docking simulations on the topoI active site (PDB: 1A35) revealed the inhibitory activity and potential binding site for the newly developed 1-(2-aminophenyl)pyrrole-based amides.

Tetrasubstituted Pyrrole Derivative Mimetics of Protein-Protein Interaction Hot-Spot Residues: A Promising Class of Anticancer Agents Targeting Melanoma Cells.

A new series of tetrasubstituted pyrrole derivatives (TSPs) was synthesized based on a previously developed hypothesis on their ability to mimic hydrophobic protein motifs. The resulting new TSPs were endowed with a significant toxicity against human epithelial melanoma A375 cells, showing IC50 values ranging from 10 to 27 µM, consistent with the IC50 value of the reference compound nutlin-3a (IC50 = 15 µM). In particular, compound 10a (IC50 = 10 µM) resulted as both the most soluble and active among the previous and present TSPs. The biological investigation evidenced that the anticancer activity is related to the activation of apoptotic cell-death pathways, supporting our rational design based on the ability of TSPs to interfere with PPI involved in the cell cycle regulation of cancer cells and, in particular, the p53 pathway. A reinvestigation of the TSP pharmacophore by using DFT calculations showed that the three aromatic substituents on the pyrrole core are able to mimic the hydrophobic side chains of the hot-spot residues of parallel and antiparallel coiled coil structures suggesting a possible molecular mechanism of action. A structure-activity relationship (SAR) analysis which includes solubility studies allows us to rationalize the role of the different substituents on the pyrrole core.

Azetidin-2-one-based small molecules as dual hHDAC6/HDAC8 inhibitors: Investigation of their mechanism of action and impact of dual inhibition profile on cell viability.

The search of new therapeutic tools for the treatment of cancer is being a challenge for medicinal chemists. Due to their role in different pathological conditions, histone deacetylase (HDAC) enzymes are considered valuable therapeutic targets. HDAC6 is a well-investigated HDAC-class IIb enzyme mainly characterized by a cytoplasmic localization; HDAC8 is an epigenetic eraser, unique HDAC-class I member that displays some aminoacidic similarity to HDAC6. New polypharmacological agents for cancer treatment, based on a dual hHDAC6/hHDAC8 inhibition profile were developed. The dual inhibitor design investigated the diphenyl-azetidin-2-one scaffold, typified in three different structural families, that, combined to a slender benzyl linker (6c, 6i, and 6j), displays nanomolar inhibition potency against hHDAC6 and hHDAC8 isoforms. Notably, their selective action was also corroborated by measuring their low inhibitory potency towards hHDAC1 and hHDAC10. Selectivity of these compounds was further demonstrated in human cell-based western blots experiments, by testing the acetylation of the non-histone substrates alpha-tubulin and SMC3. Furthermore, the compounds reduced the proliferation of colorectal HCT116 and leukemia U937 cells, after 48 h of treatment. The toxicity of the compounds was evaluated in rat perfused heart and in zebrafish embryos. In this latter model we also validated the efficacy of the dual hHDAC6/hHDAC8 inhibitors against their common target acetylated-alpha tubulin. Finally, the metabolic stability was verified in rat, mouse, and human liver microsomes.

Extra Virgin Olive Oil Extracts of Indigenous Southern Tuscany Cultivar Act as Anti-Inflammatory and Vasorelaxant Nutraceuticals.

Extra virgin olive oil (EVOO) is the typical source of fats in the Mediterranean diet. While fatty acids are essential for the EVOO nutraceutical properties, multiple biological activities are also due to the presence of polyphenols. In this work, autochthonous Tuscany EVOOs were chemically characterized and selected EVOO samples were extracted to obtain hydroalcoholic phytocomplexes, which were assayed to establish their anti-inflammatory and vasorelaxant properties. The polar extracts were characterized via 1H-NMR and UHPLC-HRMS to investigate the chemical composition and assayed in CaCo-2 cells exposed to glucose oxidase or rat aorta rings contracted by phenylephrine. Apigenin and luteolin were found as representative flavones; other components were pinoresinol, ligstroside, and oleuropein. The extracts showed anti-inflammatory and antioxidant properties via modulation of NF-κB and Nrf2 pathways, respectively, and good vasorelaxant activity, both in the presence and absence of an intact endothelium. In conclusion, this study evaluated the nutraceutical properties of autochthonous Tuscany EVOO cv., which showed promising anti-inflammatory and vasorelaxant effects.

Design and synthesis of multifunctional microtubule targeting agents endowed with dual pro-apoptotic and anti-autophagic efficacy.

Autophagy is a lysosome dependent cell survival mechanism and is central to the maintenance of organismal homeostasis in both physiological and pathological situations. Targeting autophagy in cancer therapy attracted considerable attention in the past as stress-induced autophagy has been demonstrated to contribute to both drug resistance and malignant progression and recently interest in this area has re-emerged. Unlocking the therapeutic potential of autophagy modulation could be a valuable strategy for designing innovative tools for cancer treatment. Microtubule-targeting agents (MTAs) are some of the most successful anti-cancer drugs used in the clinic to date. Scaling up our efforts to develop new anti-cancer agents, we rationally designed multifunctional agents 5a-l with improved potency and safety that combine tubulin depolymerising efficacy with autophagic flux inhibitory activity. Through a combination of computational, biological, biochemical, pharmacokinetic-safety, metabolic studies and SAR analyses we identified the hits 5i,k. These MTAs were characterised as potent pro-apoptotic agents and also demonstrated autophagy inhibition efficacy. To measure their efficacy at inhibiting autophagy, we investigated their effects on basal and starvation-mediated autophagic flux by quantifying the expression of LC3II/LC3I and p62 proteins in oral squamous cell carcinoma and human leukaemia through western blotting and by immunofluorescence study of LC3 and LAMP1 in a cervical carcinoma cell line. Analogues 5i and 5k, endowed with pro-apoptotic activity on a range of hematological cancer cells (including ex-vivo chronic lymphocytic leukaemia (CLL) cells) and several solid tumor cell lines, also behaved as late-stage autophagy inhibitors by impairing autophagosome-lysosome fusion.

Ultrasound-Assisted Extraction, Chemical Characterization, and Impact on Cell Viability of Food Wastes Derived from Southern Italy Autochthonous Citrus Fruits.

Citrus fruits are one of the principal fruits used to produce juices. Over the years, these fruits have been recognized as new health-promoting agents. In this work, food wastes derived from autochthonous citrus fruits of Southern Italy, named Limone di Rocca Imperiale, Arancia Rossa Moro, and Arancia Bionda Tardivo from Trebisacce, were analyzed. After fresh-squeezing juice, peel and pomace were employed to obtain six different extracts using an ultrasound-assisted method in a hydroalcoholic solvent. The extracts were analyzed in terms of qualitative composition, antioxidant properties, and antiproliferative activity on MCF-7, MDA-MB-231, and BJ-hTERT cell lines. GC-MS and LC-ESI-MS analyses showed different compounds: of note, limonin-hexoside, neodiosmin, obacunone glucoside, and diacetyl nomilinic acid glucoside have been identified as limonoid structures present in all the samples, in addition to different polyphenols including naringenin-glucoside, hesperetin-O-hexoside-O-rhamnoside-O-glucoside, diferuloyl-glucaric acid ester, chlorogenic acid, and the presence of fatty acids such as palmitic, myristic, and linoleic acids. These extracts were able to exert antioxidant activity as demonstrated by DPPH and ABTS assays and, although at higher doses, to reduce the cell viability of different solid tumor cell lines, as shown in MTT assays.

Exploring the Photodynamic Properties of Two Antiproliferative Benzodiazopyrrole Derivatives.

The identification of molecules whose biological activity can be properly modulated by light is a promising therapeutic approach aimed to improve drug selectivity and efficacy on the molecular target and to limit the side effects compared to traditional drugs. Recently, two photo-switchable diastereomeric benzodiazopyrrole derivatives 1RR and 1RS have been reported as microtubules targeting agents (MTAs) on human colorectal carcinoma p53 null cell line (HCT 116 p53-/-). Their IC50 was enhanced upon Light Emitting Diode (LED) irradiation at 435 nm and was related to their cis form. Here we have investigated the photo-responsive behavior of the acid derivatives of 1RR and 1RS, namely, d1RR and d1RS, in phosphate buffer solutions at different pH. The comparison of the UV spectra, acquired before and after LED irradiation, indicated that the trans→cis conversion of d1RR and d1RS is affected by the degree of ionization. The apparent rate constants were calculated from the kinetic data by means of fast UV spectroscopy and the conformers of the putative ionic species present in solution (pH range: 5.7-8.0) were modelled. Taken together, our experimental and theoretical results suggest that the photo-conversions of trans d1RR/d1RS into the corresponding cis forms and the thermal decay of cis d1RR/d1RS are dependent on the presence of diazonium form of d1RR/d1RS. Finally, a photo-reaction was detected only for d1RR after prolonged LED irradiation in acidic medium, and the resulting product was characterized by means of Liquid Chromatography coupled to High resolution Mass Spectrometry (LC-HRMS) and Nuclear Magnetic Resonance (NMR) spectroscopy.

Tetra-substituted pyrrole derivatives act as potent activators of p53 in melanoma cells.

Cutaneous melanoma, the most aggressive form of skin cancer, is characterized by activating BRAF mutations. Despite the initial success of selective BRAF inhibitors, only few patients exhibited complete responses, whereas many showed disease progression. Melanoma is one of the few types of cancer in which p53 is not frequently mutated, but p53 inactivation can be indirectly achieved by a stable activation of MDM2 induced by a deletion in CDKN2A (Cyclin Dependent Kinase Inhibitor 2A) locus, encoding for p16INK4A and p14ARF, two tumor suppressor genes. In this study, we tested the efficacy of the previously synthesized tetra-substituted pyrrole derivatives, 8 g, 8 h and 8i, in melanoma cell lines, and we compared the effects of the most active of these, the 8i compound, with that exerted by Nutlin 3, a well-known inhibitor of p53-MDM2 interaction. The obtained results showed that 8i potentiates the inhibitory effect of Nutlin 3 and the combined use of 8i and Nutlin 3 triggers apoptosis and significantly impairs melanoma viability. Finally, the 8i compound reduces p53-MDM2 interaction and induces p53-HSP90 complex formation, suggesting that the observed raise in p53 transcriptional activity could be mediated by HSP90. Because the main feature of melanoma is the resistance to most chemotherapeutics, our studies suggest that the 8i tetra-substituted pyrrole derivative, restoring p53 functions and its transcriptional activities, may have potential application, at least as adjuvant, in the treatment of human melanoma.

Activation of the Wnt Pathway by Small Peptides: Rational Design, Synthesis and Biological Evaluation.

A computational analysis of the X-ray structure of the low-density lipoprotein receptor-related protein 6 (LRP6) with the Dickkopf-1 (DKK1) C-terminal fragment has allowed us to rationally design a small set of decapeptides. These compounds behave as agonists of the canonical Wnt pathway in the micromolar range when tested on a dual luciferase Wnt functional assay in glioblastoma cells. Two of the oligopeptides showed a lack of cytotoxicity in human primary osteoblasts isolated from sponge bone tissue (femoral heads or knees of elderly patients). According to the mechanism of action, the studies revealed a dose- and time-dependent increase in the viability of human osteoblasts. These results may indicate a potential therapeutic application of this class of compounds in the treatment of bone diseases related to aging, such as osteoporosis.

Phosphonium Salt Displays Cytotoxic Effects Against Human Cancer Cell Lines.

Aims/Objective: Phosphonium salts are compounds whose structural characteristics enable them to cross the plasma and mitochondrial membrane with ease. Cancer cells have higher plasma membrane potentials than normal cells; phosphonium salts selectively accumulate in the mitochondria of neoplastic cells and inhibit mitochondrial function. METHOD: In the present work, we investigated the cytotoxic activity of lipophilic phosphonium salt (11- methoxy11-oxo-undecyl) triphenylphosphonium bromide (MUTP) as well as of the two new phosphine oxide salts, 3,3'-(methylphosphoryl) dibenzenaminium chloride (SBAMPO) and 3,3' (phenylphosphoryl) dibenzenaminium chloride (SBAPPO) on the proliferation of breast cancer cell line (MCF-7) and human uterin cervix adenocarcinoma cells (HeLa). RESULT: We showed that only MUTP exhibits antiproliferative effects on both cell lines, without affecting the normal breast epithelial cell proliferation. More specifically, we demonstrated that MUTP treatment of breast cancer cells is associated with impaired cell-cycle progression and metabolically induces mitochondrial damage and triggers apoptotic cell death in MCF-7 and HeLa cells. Taken together, these findings suggest that MUTP may be capable of selectively targeting neoplastic cell growth and therefore has potential applications as anticancer agent.

First dual AK/GSK-3ß inhibitors endowed with antioxidant properties as multifunctional, potential neuroprotective agents.

The manuscript deals with the design, synthesis and biological evaluation of novel benzoxazinone-based and indole-based compounds as multifunctional neuroprotective agents. These compounds inhibit human adenosine kinase (hAK) and human glycogen synthase kinase 3 beta (hGSK-3ß) enzymes. Computational analysis based on a molecular docking approach underlined the potential structural requirements for simultaneously targeting both proteins' allosteric sites. In silico hints drove the synthesis of appropriately decorated benzoxazinones and indoles (5a-s, and 6a-c) and biochemical analysis revealed their behavior as allosteric inhibitors of hGSK-3ß. For both our hit 4 and the best compounds of the series (5c,l and 6b) the potential antioxidant profile was assessed in human neuroblastoma cell lines (IMR 32, undifferentiated and neuronal differentiated), by evaluating the protective effect of selected compounds against H2O2 cytotoxicity and reactive oxygen species (ROS) production. Results showed a strong efficacy of the tested compounds, even at the lower doses, in counteracting the induced oxidative stress (50 µM of H2O2) and in preventing ROS formation. In addition, the tested compounds did not show any cytotoxic effect determined by the LDH release, at the concentration range analyzed (from 0.1 to 50 µM). This study allowed the identification of compound 5l, as the first dual hAK/hGSK-3ß inhibitor reported to date. Compound 5l, which behaves as an effective antioxidant, holds promise for the development of new series of potential therapeutic agents for the treatment of neurodegenerative diseases characterized by an innovative pharmacological profile.

Anti-Inflammatory, Antioxidant and Crystallographic Studies of N-Palmitoyl-ethanol Amine (PEA) Derivatives.

N-Palmitoyl-ethanolamine (PEA) is an anti-inflammatory component of egg yolk that is usually employed for the prevention of respiratory apparatus virus infection and then frequently used for its efficient anti-inflammatory and analgesic effects in experimental models of visceral, neuropathic, and inflammatory diseases. Nevertheless, data of its use in animal or human therapy are still scarce and further studies are needed. Herein, we report the biological evaluation of a small library of N-palmitoyl-ethanolamine analogues or derivatives, characterized by a protected acid function (either as palmitoyl amides or hexadecyl esters), useful to decrease their hydrolysis rate in vitro and prolong their biological activity. Two of these compounds-namely phenyl-carbamic acid hexadecyl ester (4) and 2-methyl-pentadecanoic acid (4-nitro-phenyl)-amide (5)-have shown good anti-inflammatory and antioxidant properties, without affecting the viability of J774A.1 macrophages. Finally, crystals suitable for X-ray analysis of compound 4 have been obtained, and its solved crystal structure is here reported. Our outcomes may be helpful for a rational drug design based on new PEA analogues/derivatives with improved biological properties.

Inhibition of human topoisomerase I and II and anti-proliferative effects on MCF-7 cells by new titanocene complexes.

The antitumor activity shown by many platinum complexes has produced a strong interest in research of new organometallic compounds having anticancer action. Among the many metal compounds synthesized and tested, those based on titanium have received considerable attention because of their cytotoxic activity against solid tumors. Particularly, new titanocene compounds containing aromatic groups linked to the Cp (cyclopentadienyl ring, C5H5) have been synthetized, such as the titanocene Y (bis-[(p-methoxybenzyl)cyclopentadienyl]titanium dichloride) that displayed promising medium-high cytotoxic activity on breast cancer cell lines. Other titanocene complexes recently synthesized, obtained by replacing the substituent methoxy-aryl of cyclopentadienes of titanocene Y with ethenyl-methoxide or ethenyl-phenoxide, showed increased cytotoxic activity on breast cancer cell lines being more stable compounds. In this paper, we report that new titanocene complexes holding lipophilic groups, for instance a methyl group on benzyl carbon, exhibit improved antiproliferative effect on breast cancer cell line MCF-7. Similar results have been obtained introducing a 5-methoxy naphthyl group to further stabilize the titanocene complexes. These inhibitory effects on breast cancer cells have been ascribed to human topoisomerase I and II inhibition as demonstrated by specific enzymatic assays.

New anticancer agents mimicking protein recognition motifs.

The novel tetrasubstituted pyrrole derivatives 8g, 8h, and 8i showed selective cytotoxicity against M14 melanoma cells at low micromolar concentration. Structure-activity relationships (SARs) indicated the presence of three aromatic substituents on the pyrrole core as necessary for biological activity. Computational studies strongly suggest that the peculiar 3D orientation of these substituents is able to reproduce the hydrophobic side chains in LxxLL-like protein recognition motifs. Biological results showed altered p53 expression and nuclear translocation in cells sensitive to the compounds, suggesting p53 involvement in their anticancer mechanism of action. Unfortunately, because of poor solubility of the active analogues, it was not possible to perform further investigation by NMR techniques. Pharmacophore models were generated and used to perform 3D searches in molecular databases. Results indicated that two compounds share the same pharmacological profile and the same pharmacophoric features with our new derivatives, and one of them inhibited MDM2-MDM4 heterodimer formation.

Progresses in the pursuit of aldose reductase inhibitors: the structure-based lead optimization step.

Aldose reductase (ALR2) is a crucial enzyme in the development of the major complications of diabetes mellitus. Very recently it has been demonstrated that the ARL2 inhibitor, fidarestat, significantly prevents inflammatory signals (TNF-α, LPS) that cause cancer (colon, breast, prostate and lung), metastasis, asthma, and other inflammatory diseases. Currently, fidarestat is in phase III clinical trial for diabetic neuropathy and was found to be safe. Thus the finding of novel, potent ARL2 inhibitors is today more than in the past in great demand as they can pave the way for a novel therapeutic approach for a number of diseases besides the diabetes. Herein, starting from the virtual screening-derived ALR2 inhibitor S12728 (1), a rational receptor-based lead optimization has been undertaken. The design and synthetic efforts here reported led to the discovery of several new compounds endowed with low micromolar/submicromolar activities.

Interaction between Alzheimer's Abeta(25-35) peptide and phospholipid bilayers: the role of cholesterol.

There is mounting evidence that the lipid matrix of neuronal cell membranes plays an important role in the accumulation of beta-amyloid peptides into senile plaques, one of the hallmarks of Alzheimer's disease (AD). With the aim to clarify the molecular basis of the interaction between amyloid peptides and cellular membranes, we investigated the interaction between a cytotoxic fragment of Abeta(1-42), i.e., Abeta(25-35), and phospholipid bilayer membranes. These systems were studied by Electron Paramagnetic Resonance (EPR) spectroscopy, using phospholipids spin-labeled on the acyl chain. The effect of inclusion of charged phospholipids or/and cholesterol in the bilayer composition was considered in relation to the peptide/membrane interaction. The results show that Abeta(25-35) inserts in bilayers formed by the zwitterionic phospholipid dilauroyl phosphatidylcholine (DLPC), positioning between the outer part of the hydrophobic core and the external hydrophilic layer. This process is not significantly influenced by the inclusion of the anionic phospholipid phosphatidylglycerol (DLPG) in the bilayer, indicating the peptide insertion to be driven by hydrophobic rather than electrostatic interactions. Cholesterol plays a fundamental role in regulating the peptide/membrane association, inducing a membrane transition from a fluid-disordered to a fluid-ordered phase. At low cholesterol content, in the fluid-disordered phase, the insertion of the peptide in the membrane causes a displacement of cholesterol towards the more external part of the membrane. The crowding of cholesterol enhances its rigidifying effect on this region of the bilayer. Finally, the cholesterol-rich fluid-ordered membrane looses the ability to include Abeta(25-35).

Novel sterically hindered cannabinoid CB1 receptor ligands.

In the present study, 11 novel N-(3,3-diphenyl)propyl-2,2-diphenylacetamide derivatives (4a-d and 9a-g) and six triphenylacetamides (10a-c and 11a-c) were synthesized and tested as ligands of cannabinoid CB(1) and CB(2) receptors. All compounds exhibited affinity for CB(1) and CB(2) receptors. Four compounds (4b, 9a, 9b, and 11a) showed selectivity for CB(1) versus CB(2) receptors, although only the N-(3,3-diphenyl)propyl-2,2-diphenylacetamide (4b) can be considered a potent CB(1) ligand (K(i)=58 nM). It was 140-fold selective over CB(2) receptors (K(i)=7800 nM) and behaved as an inverse agonist by stimulating forskolin-induced cAMP formation in mouse N18TG2 neuroblastoma cells. This compound is the first of a novel class of tetraphenyl CB(1) ligands that, in view of its easy synthesis and high affinity for CB(1) receptors and despite its sterical hindrance, will be useful for the design of new blockers of this therapeutically exploitable receptor type.