Synthesis and in vitro cytotoxicity of benzoxazole-based PPARα/γ antagonists in colorectal cancer cell lines.

A series of benzoxazole-based amides and sulfonamides were synthesized and evaluated for their human peroxisome proliferator-activated receptor (PPAR)α and PPARγ activity. All tested compounds showed a dual antagonist profile on both PPAR subtypes; based on transactivation results, seven compounds were selected to test their in vitro antiproliferative activity in a panel of eight cancer cell lines with different expression rates of PPARα and PPARγ. 3f was identified as the most cytotoxic compound, with higher potency in the colorectal cancer cell lines HT-29 and HCT116. Compound 3f induced a concentration-dependent activation of caspases and cell-cycle arrest in both colorectal cancer models. Docking experiments were also performed to shed light on the putative binding mode of this novel class of dual PPARα/γ antagonists.

Food Industry Byproducts as Starting Material for Innovative, Green Feed Formulation: A Sustainable Alternative for Poultry Feeding.

Rising global populations and enhanced standards of living in so-called developing countries have led to an increased demand of food, in particular meat, worldwide. While increasing the production of broiler meat could be a potential solution to this problem, broiler meat is plagued by health concerns, such as the development of antimicrobial resistance and lower meat quality. For this reason, the supplementation of poultry feed with vitamins and antioxidant compounds, such as polyphenols, has become an attractive prospect for research in this sector. Such supplements could be obtained by extraction of agricultural byproducts (in particular, grape pomaces and artichoke leaves and bracts), thus contributing to reductions in the total amount of waste biomass produced by the agricultural industry. In this review, the effects of poultry feed supplementation with bioactive extracts from grape pomace (skins and/or seeds), as well as extracts from artichoke leaves and bracts, were explored. Moreover, the various methods that have been employed to obtain extracts from these and other agricultural byproducts were listed and described, with a particular focus on novel, eco-friendly extraction methods (using, for example, innovative and biocompatible solvents like Deep Eutectic Solvents (DESs)) that could reduce the costs and energy consumption of these procedures, with similar or higher yields compared to standard methods.

A New Series of Aryloxyacetic Acids Endowed with Multi-Target Activity towards Peroxisome Proliferator-Activated Receptors (PPARs), Fatty Acid Amide Hydrolase (FAAH), and Acetylcholinesterase (AChE).

A new series of aryloxyacetic acids was prepared and tested as peroxisome proliferator-activated receptors (PPARs) agonists and fatty acid amide hydrolase (FAAH) inhibitors. Some compounds exhibited an interesting dual activity that has been recently proposed as a new potential therapeutic strategy for the treatment of Alzheimer's disease (AD). AD is a multifactorial pathology, hence multi-target agents are currently one of the main lines of research for the therapy and prevention of this disease. Given that cholinesterases represent one of the most common targets of recent research, we decided to also evaluate the effects of our compounds on the inhibition of these specific enzymes. Interestingly, two of these compounds, (S)-5 and 6, showed moderate activity against acetylcholinesterase (AChE) and even some activity, although at high concentration, against Aß peptide aggregation, thus demonstrating, in agreement with the preliminary dockings carried out on the different targets, the feasibility of a simultaneous multi-target activity towards PPARs, FAAH, and AChE. As far as we know, these are the first examples of molecules endowed with this pharmacological profile that might represent a promising line of research for the identification of novel candidates for the treatment of AD.

Pharmacophore hybridization approach to discover novel pyrazoline-based hydantoin analogs with anti-tumor efficacy.

In search for new and safer anti-cancer agents, a structurally guided pharmacophore hybridization strategy of two privileged scaffolds, namely diaryl pyrazolines and imidazolidine-2,4-dione (hydantoin), was adopted resulting in a newfangled series of compounds (H1-H22). Herein, a bio-isosteric replacement of "pyrrolidine-2,5-dione" moiety of our recently reported antitumor hybrid incorporating diaryl pyrazoline and pyrrolidine-2,5-dione scaffolds with "imidazoline-2,4-dione" moiety has been incorporated. Complete biological studies revealed the most potent analog among all i.e. compound H13, which was at-least 10-fold more potent compared to the corresponding pyrrolidine-2,5-dione, in colon and breast cancer cells. In-vitro studies showed activation of caspases, arrest of G0/G1 phase of cell cycle, decrease in the expression of anti-apoptotic protein (Bcl-2) and increased DNA damage. In-vivo assay on HT-29 (human colorectal adenocarcinoma) animal xenograft model unveiled the significant anti-tumor efficacy along with oral bioavailability with maximum TGI 36% (i.p.) and 44% (per os) at 50 mg/kg dose. These findings confirm the suitability of hybridized pyrazoline and imidazolidine-2,4-dione analog H13 for its anti-cancer potential and starting-point for the development of more efficacious analogs.

Virtual screening identification and chemical optimization of substituted 2-arylbenzimidazoles as new non-zinc-binding MMP-2 inhibitors.

Matrix metalloproteinases (MMPs) are a large family of zinc-dependent endoproteases known to exert multiple regulatory roles in tumor progression and invasiveness. This encouraged over the years the approach of MMP, and particularly MMP-2, targeting for anticancer treatment. Early generations of MMP inhibitors, based on aspecific zinc binding groups (ZBGs) assembled on (pseudo)peptide scaffolds, have been discontinued due to the clinical emergence of toxicity and further drawbacks, giving the way to inhibitors with alternative zinc-chelator moieties or not binding the catalytic zinc ion. In the present paper, we continue the search for new non-zinc binding MMP-2 inhibitors: exploiting previously identified compounds, a virtual screening (VS) campaign was carried out and led to the identification of a new class of ligands. The structure-activity relationship (SAR) of the benzimidazole scaffold was explored by synthesis of several analogues whose inhibition activity was tested with enzyme inhibition assays. By performing the molecular simplification approach, we disclosed different sets of single-digit micromolar inhibitors of MMP-2, with up to a ten-fold increase in inhibitory activity and ameliorated selectivity towards off-target MMP-8, compared to selected lead compound. Molecular dynamics calculations conducted on complexes of MMP-2 with docked privileged structures confirmed that analyzed inhibitors avoid targeting the zinc ion and dip inside the S1' pocket. Present results provide a further enrichment of our insights for the design of novel MMP-2 selective inhibitors.

Beyond the Canonical Endocannabinoid System. A Screening of PPAR Ligands as FAAH Inhibitors.

In recent years, Peroxisome Proliferator-Activated Receptors (PPARs) have been connected to the endocannabinoid system. These nuclear receptors indeed mediate the effects of anandamide and similar substances such as oleoyl-ethanolamide and palmitoyl-ethanolamide. An increasing body of literature describing the interactions between the endocannabinoid system and PPARs has slowly but surely been accumulating over the past decade, and a multitarget approach involving these receptors and endocannabinoid degrading enzyme FAAH has been proposed for the treatment of inflammatory states, cancer, and Alzheimer's disease. The lack of knowledge about compounds endowed with such an activity profile therefore led us to investigate a library of readily available, well-characterized PPAR agonists that we had synthesized over the years in order to find a plausible lead compound for further development. Moreover, we propose a rationalization of our results via a docking study, which sheds some light on the binding mode of these PPAR agonists to FAAH and opens the way for further research in this field.

Synthesis of novel benzothiazole amides: Evaluation of PPAR activity and anti-proliferative effects in paraganglioma, pancreatic and colorectal cancer cell lines.

The reduced activation of PPARs has a positive impact on cancer cell growth and viability in multiple preclinical tumor models, suggesting a new therapeutic potential for PPAR antagonists. In the present study, the benzothiazole amides 2a-g were synthesized and their activities on PPARs were investigated. Transactivation assay showed a moderate activity of the novel compounds as PPARα antagonists. Notably, in cellular assays they exhibited cytotoxicity in pancreatic, colorectal and paraganglioma cancer cells overexpressing PPARα. In particular, compound 2b showed the most remarkable inhibition of viability (greater than 90%) in two paraganglioma cell lines, with IC50 values in the low micromolar range. In addition, 2b markedly impaired colony formation capacity in the same cells. Taken together, these results show a relevant anti-proliferative potential of compound 2b, which appears particularly effective in paraganglioma, a rare tumor poorly responsive to chemotherapy.

Natural Scaffolds with Multi-Target Activity for the Potential Treatment of Alzheimer's Disease.

A few symptomatic drugs are currently available for Alzheimer's Disease (AD) therapy, but these molecules are only able to temporary improve the cognitive capacity of the patients if administered in the first stages of the pathology. Recently, important advances have been achieved about the knowledge of this complex condition, which is now considered a multi-factorial disease. Researchers are, thus, more oriented toward the preparation of molecules being able to contemporaneously act on different pathological features. To date, the inhibition of acetylcholinesterase (AChE) and of ß-amyloid (Aß) aggregation as well as the antioxidant activity and the removal and/or redistribution of metal ions at the level of the nervous system are the most common investigated targets for the treatment of AD. Since many natural compounds show multiple biological properties, a series of secondary metabolites of plants or fungi with suitable structural characteristics have been selected and assayed in order to evaluate their potential role in the preparation of multi-target agents. Out of six compounds evaluated, 1 showed the best activity as an antioxidant (EC50 = 2.6 ± 0.2 µmol/µmol of DPPH) while compound 2 proved to be effective in the inhibition of AChE (IC50 = 6.86 ± 0.67 µM) and Aß1⁻40 aggregation (IC50 = 74 ± 1 µM). Furthermore, compound 6 inhibited BChE (IC50 = 1.75 ± 0.59 µM) with a good selectivity toward AChE (IC50 = 86.0 ± 15.0 µM). Moreover, preliminary tests on metal chelation suggested a possible interaction between compounds 1, 3 and 4 and copper (II). Molecules with the best multi-target profiles will be used as starting hit compounds to appropriately address future studies of Structure-Activity Relationships (SARs).

Dual targeting of cancer-related human matrix metalloproteinases and carbonic anhydrases by chiral N-(biarylsulfonyl)-phosphonic acids.

A series of nanomolar phosphonate matrix metalloproteinase (MPP) inhibitors was tested for inhibitory activity against a panel of selected human carbonic anhydrase (CA, EC 4.2.1.1) isozymes, covering the cancer-associated CA IX and XII. None of the reported sulfonyl and sulfonylamino-derivatives sensitively affected the catalytic activity of the cytosolic isoforms CA I and II, which are considered off-target isoforms in view of their physiological role. The most active inhibitors were in the series of chiral N-(sulfonyl)phosphovaline derivatives, which showed good to excellent inhibitory activity over target CAs, with compound 15 presenting the best isoform-selectivity toward CA IX. We suggest here that the phosphonates have the potential as dual inhibitors of MMPs and CAs, both involved in tumor formation, invasion and metastasis.

Statin-induced myotoxicity is exacerbated by aging: A biophysical and molecular biology study in rats treated with atorvastatin.

Statin-induced skeletal muscle damage in rats is associated to the reduction of the resting sarcolemmal chloride conductance (gCl) and ClC-1 chloride channel expression. These drugs also affect the ClC-1 regulation by increasing protein kinase C (PKC) activity, which phosphorylate and close the channel. Also the intracellular resting calcium (restCa) level is increased. Similar alterations are observed in skeletal muscles of aged rats, suggesting a higher risk of statin myotoxicity. To verify this hypothesis, we performed a 4-5-weeks atorvastatin treatment of 24-months-old rats to evaluate the ClC-1 channel function by the two-intracellular microelectrodes technique as well as transcript and protein expression of different genes sensitive to statins by quantitative real-time-PCR and western blot analysis. The restCa was measured using FURA-2 imaging, and histological analysis of muscle sections was performed. The results show a marked reduction of resting gCl, in agreement with the reduced ClC-1 mRNA and protein expression in atorvastatin-treated aged rats, with respect to treated adult animals. The observed changes in myocyte-enhancer factor-2 (MEF2) expression may be involved in ClC-1 expression changes. The activity of PKC was also increased and further modulate the gCl in treated aged rats. In parallel, a marked reduction of the expression of glycolytic and mitochondrial enzymes demonstrates an impairment of muscle metabolism. No worsening of restCa or histological features was found in statin-treated aged animals. These findings suggest that a strong reduction of gCl and alteration of muscle metabolism coupled to muscle atrophy may contribute to the increased risk of statin-induced myopathy in the elderly.

An Effective Virtual Screening Protocol To Identify Promising p53-MDM2 Inhibitors.

The p53-MDM2 interaction is a well-known protein-protein contact, and its disruption is a key event for p53 activation and induction of its oncosuppressor response. The design of small molecules that can block the p53-MDM2 interaction and reactivate the p53 function is a promising strategy for cancer therapy. To date, several compounds have been identified as p53-MDM2 inhibitors, and X-ray structures of MDM2 complexed with several ligands are available in the Brookhaven Protein Data Bank. These data have been exploited to compile a hierarchical virtual screening protocol. The first steps were aimed at selecting a focused library, which was submitted in parallel to docking and pharmacophore model alignment. Selected compounds were subjected to inhibition assays of both cellular vitality (MTT) and p53-MDM2 interaction (ELISA and co-immunoprecipitation), disclosing four nanomolar inhibitors.

Catechol-based matrix metalloproteinase inhibitors with additional antioxidative activity.

New catechol-containing chemical entities have been investigated as matrix metalloproteinase inhibitors as well as antioxidant molecules. The combination of the two properties could represent a useful feature due to the potential application in all the pathological processes characterized by increased proteolytic activity and radical oxygen species (ROS) production, such as inflammation and photoaging. A series of catechol-based molecules were synthesized and tested for both proteolytic and oxidative inhibitory activity, and the detailed binding mode was assessed by crystal structure determination of the complex between a catechol derivative and the matrix metalloproteinase-8. Surprisingly, X-ray structure reveals that the catechol oxygens do not coordinates the zinc atom.

LT175 is a novel PPARα/γ ligand with potent insulin-sensitizing effects and reduced adipogenic properties.

Peroxisome proliferator-activated receptors (PPARs) are ligand-dependent transcription factors regulating lipid and glucose metabolism. Ongoing drug discovery programs aim to develop dual PPARα/γ agonists devoid of the side effects of the marketed antidiabetic agents thiazolidinediones and the dual agonists glitazars. Recently, we described a new dual PPARα/γ ligand, LT175, with a partial agonist profile against PPARγ and interacting with a newly identified region of the PPARγ-ligand binding domain (1). Here we show that LT175 differentially activated PPARγ target genes involved in fatty acid esterification and storage in 3T3-L1-derived adipocytes. This resulted in a less severe lipid accumulation compared with that triggered by rosiglitazone, suggesting that LT175 may have a lower adipogenic activity. Consistent with this hypothesis, in vivo administration of LT175 to mice fed a high-fat diet decreased body weight, adipocyte size, and white adipose tissue mass, as assessed by magnetic resonance imaging. Furthermore, LT175 significantly reduced plasma glucose, insulin, non-esterified fatty acids, triglycerides, and cholesterol and increased circulating adiponectin and fibroblast growth factor 21 levels. Oral glucose and insulin tolerance tests showed that the compound improves glucose homeostasis and insulin sensitivity. Moreover, we demonstrate that the peculiar interaction of LT175 with PPARγ affected the recruitment of the coregulators cyclic-AMP response element-binding protein-binding protein and nuclear corepressor 1 (NCoR1), fundamentals for the PPARγ-mediated adipogenic program. In conclusion, our results describe a new PPAR ligand, modulating lipid and glucose metabolism with reduced adipogenic activity, that may be used as a model for a series of novel molecules with an improved pharmacological profile for the treatment of dyslipidemia and type 2 diabetes.

Structural basis of the transactivation deficiency of the human PPARγ F360L mutant associated with familial partial lipodystrophy.

The peroxisome proliferator-activated receptors (PPARs) are transcription factors that regulate glucose and lipid metabolism. The role of PPARs in several chronic diseases such as type 2 diabetes, obesity and atherosclerosis is well known and, for this reason, they are the targets of antidiabetic and hypolipidaemic drugs. In the last decade, some rare mutations in human PPARγ that might be associated with partial lipodystrophy, dyslipidaemia, insulin resistance and colon cancer have emerged. In particular, the F360L mutant of PPARγ (PPARγ2 residue 388), which is associated with familial partial lipodystrophy, significantly decreases basal transcriptional activity and impairs stimulation by synthetic ligands. To date, the structural reason for this defective behaviour is unclear. Therefore, the crystal structure of PPARγ F360L together with the partial agonist LT175 has been solved and the mutant has been characterized by circular-dichroism spectroscopy (CD) in order to compare its thermal stability with that of the wild-type receptor. The X-ray analysis showed that the mutation induces dramatic conformational changes in the C-terminal part of the receptor ligand-binding domain (LBD) owing to the loss of van der Waals interactions made by the Phe360 residue in the wild type and an important salt bridge made by Arg357, with consequent rearrangement of loop 11/12 and the activation function helix 12 (H12). The increased mobility of H12 makes the binding of co-activators in the hydrophobic cleft less efficient, thereby markedly lowering the transactivation activity. The spectroscopic analysis in solution and molecular-dynamics (MD) simulations provided results which were in agreement and consistent with the mutant conformational changes observed by X-ray analysis. Moreover, to evaluate the importance of the salt bridge made by Arg357, the crystal structure of the PPARγ R357A mutant in complex with the agonist rosiglitazone has been solved.

Arylamino bisphosphonates: potent and selective inhibitors of the tumor-associated carbonic anhydrase XII.

A set of matrix metalloproteinases (MMPs) inhibitors, containing a bisphosphonate moiety (BP), has been evaluated for the inhibitory activity of carbonic anhydrases (CAs, EC 4.2.1.1). Human (h) isoforms hCA I, II, IX, XII and XIV were included in the study due to their involvement in crucial physiologic and pathologic processes. Some of these molecules selectively inhibited CA XII in the nanomolar range, showing an attractive dual mechanism (anti-MMP and anti-CA) of action as potential antitumor agents. The BP inhibitors investigated in this study are also excellent leads for obtaining even more effective compounds able to selectively target membrane-bound CA XII and having the potential to be used as tools for understanding physiologic processes regulated by this isoform.

Dual carbonic anhydrase/matrix metalloproteinase inhibitors incorporating bisphosphonic acid moieties targeting bone tumors.

A set of bisphosphonate matrix metalloproteinase (MMP) inhibitors was investigated for inhibitory activity against several carbonic anhydrase (CA, EC 4.2.1.1) isozymes, some of which are overexpressed in hypoxic tumors. Some of the bisphosphonate revealed to be very potent inhibitors (in the low nanomolar range) of the cytosolic isoform CA II and the membrane-bound CA IX, XII and XIV isozymes, a feature useful for considering them as interesting compounds for bone resorption inhibition applications. We suggest here that it is possible to develop dual enzyme inhibitors bearing bisphosphonate moieties that may target both MMPs and CAs, two families of enzymes involved in tumor formation, growth, and metastasis.

A chemical modification of a peroxisome proliferator-activated receptor pan agonist produced a shift to a new dual alpha/gamma partial agonist endowed with mitochondrial pyruvate carrier inhibition and antidiabetic properties.

New analogs of the PPAR pan agonist AL29-26 encompassed ligand (S)-7 showing potent activation of PPARα and -γ subtypes as a partial agonist. In vitro experiments and docking studies in the presence of PPAR antagonists were performed to help interpretation of biological data and investigate the main interactions at the binding sites. Further in vitro experiments showed that (S)-7 induced anti-steatotic effects and enhancement of the glucose uptake. This latter effect could be partially ascribed to a significant inhibition of the mitochondrial pyruvate carrier demonstrating that (S)-7 also acted through insulin-independent mechanisms. In vivo experiments showed that this compound reduced blood glucose and lipid levels in a diabetic mice model displaying no toxicity on bone, kidney, and liver. To our knowledge, this is the first example of dual PPARα/γ partial agonist showing these combined effects representing, therefore, the potential lead of new drugs for treatment of dyslipidemic type 2 diabetes.

Arylamino methylene bisphosphonate derivatives as bone seeking matrix metalloproteinase inhibitors.

The complexity of matrix metalloproteinase inhibitors (MMPIs) design derives from the difficulty in carefully addressing their inhibitory activity towards the MMP isoforms involved in many pathological conditions. In particular, specific metalloproteinases, such as MMP-2 and MMP-9, are key regulators of the 'vicious cycle' occurring between tumor metastases growth and bone remodeling. In an attempt to devise new approaches to selective inhibitor derivatives, we describe novel bisphosphonate bone seeking MMP inhibitors (BP-MMPIs), capable to be selectively targeted and to overcome undesired side effects of broad spectrum MMPIs. In vitro activity (IC50 values) for each inhibitor was determined against MMP-2, -8, -9 and -14, because of their relevant role in skeletal development and renewal. The results show that BP-MMPIs reached IC50 values of enzymatic inhibition in the low micromolar range. Computational studies, used to rationalize some trends in the observed inhibitory profiles, suggest a possible differential binding mode in MMP-2 that explains the selective inhibition of this isoform. In addition, survival assay was conducted on J774 cell line, a well known model system used to evaluate the structure-activity relationship of BPs for inhibiting bone resorption. The resulting data, confirming the specific activity of BP-MMPIs, and their additional proved propensity to bind hydroxyapatite powder in vitro, suggest a potential use of BP-MMPIs in skeletal malignancies.

Biological Screening and Crystallographic Studies of Hydroxy γ-Lactone Derivatives to Investigate PPARγ Phosphorylation Inhibition.

PPARγ represents a key target for the treatment of type 2 diabetes and metabolic syndrome. To avoid serious adverse effects related to the PPARγ agonism profile of traditional antidiabetic drugs, a new opportunity is represented by the development of molecules acting as inhibitors of PPARγ phosphorylation by the cyclin-dependent kinase 5 (CDK5). Their mechanism of action is mediated by the stabilization of the PPARγ ß-sheet containing Ser273 (Ser245 in PPARγ isoform 1 nomenclature). In this paper, we report the identification of new γ-hydroxy-lactone-based PPARγ binders from the screening of an in-house library. These compounds exhibit a non-agonist profile towards PPARγ, and one of them prevents Ser245 PPARγ phosphorylation by acting mainly on PPARγ stabilization and exerting a weak CDK5 inhibitory effect.

A New Antidiabetic Agent Showing Short- and Long-Term Effects Due to Peroxisome Proliferator-Activated Receptor Alpha/Gamma Dual Agonism and Mitochondrial Pyruvate Carrier Inhibition.

A new series of analogues or derivatives of the previously reported PPARα/γ dual agonist LT175 allowed the identification of ligand 10, which was able to potently activate both PPARα and -γ subtypes as full and partial agonists, respectively. Docking studies were performed to provide a molecular explanation for this different behavior on the two different targets. In vivo experiments showed that this compound induced a significant reduction in blood glucose and lipid levels in an STZ-induced diabetic mouse model displaying no toxic effects on bone, kidney, and liver. By examining in depth the antihyperglycemic activity of 10, we found out that it produced a slight but significant inhibition of the mitochondrial pyruvate carrier, acting also through insulin-independent mechanisms. This is the first example of a PPARα/γ dual agonist reported to show this inhibitory effect representing, therefore, the potential lead of a new class of drugs for treatment of dyslipidemic type 2 diabetes.