Chemoproteomics Reveals USP5 (Ubiquitin Carboxyl-Terminal Hydrolase 5) as Promising Target of the Marine Polyketide Gracilioether A

Mass spectrometry-based chemical proteomic approaches using limited proteolysis have become a powerful tool for the identification and analysis of the interactions between a small molecule (SM) and its protein target(s). Gracilioether A (GeA) is a polyketide isolated from a marine sponge, for which we aimed to trace the interactome using this strategy. DARTS (Drug Affinity Responsive Target Stability) and t-LiP-MS (targeted-Limited Proteolysis-Mass Spectrometry) represented the main techniques used in this study. DARTS was applied on HeLa cell lysate for the identification of the GeA target proteins, and t-LiP-MS was employed to investigate the protein's regions involved in the binding with GeA. The results were complemented through the use of binding studies using Surface Plasmon Resonance (SPR) and in silico molecular docking experiments. Ubiquitin carboxyl-terminal hydrolase 5 (USP5) was identified as a promising target of GeA, and the interaction profile of the USP5-GeA complex was explained. USP5 is an enzyme involved in the pathway of protein metabolism through the disassembly of the polyubiquitin chains on degraded proteins into ubiquitin monomers. This activity is connected to different cellular functions concerning the maintenance of chromatin structure and receptors and the degradation of abnormal proteins and cancerogenic progression. On this basis, this structural information opens the way to following studies focused on the definition of the biological potential of Gracilioether A and the rational development of novel USP5 inhibitors based on a new structural skeleton.

Theonella: A Treasure Trove of Structurally Unique and Biologically Active Sterols

The marine environment is considered a vast source in the discovery of structurally unique bioactive secondary metabolites. Among marine invertebrates, the sponge Theonella spp. represents an arsenal of novel compounds ranging from peptides, alkaloids, terpenes, macrolides, and sterols. In this review, we summarize the recent reports on sterols isolated from this amazing sponge, describing their structural features and peculiar biological activities. We also discuss the total syntheses of solomonsterols A and B and the medicinal chemistry modifications on theonellasterol and conicasterol, focusing on the effect of chemical transformations on the biological activity of this class of metabolites. The promising compounds identified from Theonella spp. possess pronounced biological activity on nuclear receptors or cytotoxicity and result in promising candidates for extended preclinical evaluations. The identification of naturally occurring and semisynthetic marine bioactive sterols reaffirms the utility of examining natural product libraries for the discovery of new therapeutical approach to human diseases.

Expanding the Library of 1,2,4-Oxadiazole Derivatives: Discovery of New Farnesoid X Receptor (FXR) Antagonists/Pregnane X Receptor (PXR) Agonists

Compounds featuring a 1,2,4-oxadiazole core have been recently identified as a new chemotype of farnesoid X receptor (FXR) antagonists. With the aim to expand this class of compounds and to understand the building blocks necessary to maintain the antagonistic activity, we describe herein the synthesis, the pharmacological evaluation, and the in vitro pharmacokinetic properties of a novel series of 1,2,4-oxadiazole derivatives decorated on the nitrogen of the piperidine ring with different N-alkyl and N-aryl side chains. In vitro pharmacological evaluation showed compounds 5 and 11 as the first examples of nonsteroidal dual FXR/Pregnane X receptor (PXR) modulators. In HepG2 cells, these compounds modulated PXR- and FXR-regulated genes, resulting in interesting leads in the treatment of inflammatory disorders. Moreover, molecular docking studies supported the experimental results, disclosing the ligand binding mode and allowing rationalization of the activities of compounds 5 and 11.

Discovering New G-Quadruplex DNA Catalysts in Enantioselective Sulfoxidation Reaction

The natural human telomeric G-quadruplex (G4) sequence d(GGGTTAGGGTTAGGGTTAGGG) HT21 was extensively utilized as a G4 DNA-based catalytic system for enantioselective reactions. Nine oligonucleotides (ODNs) based on this sequence and containing 8-bromo-2′-deoxyadenosine (A^Br), 8-oxo-2′-deoxyadenosine (A^oxo) or β-L-2′-deoxyadenosine (A^L) at different single loop positions were investigated to evaluate their performances as DNA catalysts in an enantioselective sulfoxidation reaction of thioanisole. The substitution of an adenosine in the loops of HT21 with these modified residues had a negligible impact on the G4 DNA structural features, thermal stability, and catalytic activity, since almost all investigated ODNs were able to form G-quadruplexes strictly resembling that of HT21 and catalyze a full conversion of the thioanisole substrate. More marked effects were obtained in chiral selectivity of G4 DNA metalloenzymes, considering that in most cases the DNA-modified catalysts induced lower enantioselectivities compared to the natural one. However, the HT21 derivative containing an A^L residue in the first loop sequence significantly proved to be capable of producing about 84% enantiomeric excess, the highest enantioselectivity for DNA-based oxidation reaction to date.

Synergism of a Novel 1,2,4-oxadiazole-containing Derivative with Oxacillin against Methicillin-Resistant Staphylococcus aureus

Staphylococcusaureus is an important opportunistic pathogen that causes many infections in humans and animals. The inappropriate use of antibiotics has favored the diffusion of methicillin-resistant S. aureus (MRSA), nullifying the efforts undertaken in the discovery of antimicrobial agents. Oxadiazole heterocycles represent privileged scaffolds for the development of new drugs because of their unique bioisosteric properties, easy synthesis, and therapeutic potential. A vast number of oxadiazole-containing derivatives have been discovered as potent antibacterial agents against multidrug-resistant MRSA strains. Here, we investigate the ability of a new library of oxadiazoles to contrast the growth of Gram-positive and Gram-negative strains. The strongest antimicrobial activity was obtained with compounds 3 (4 µM) and 12 (2 µM). Compound 12, selected for further evaluation, was found to be noncytotoxic on the HaCaT cell line up to 25 µM, bactericidal, and was able to improve the activity of oxacillin against the MRSA. The highest synergistic interaction was obtained with the combination values of 0.78 μM for compound 12, and 0.06 μg/mL for oxacillin. The FIC index value of 0.396 confirms the synergistic effect of compound 12 and oxacillin. MRSA treatment with compound 12 reduced the expression of genes included in the mec operon. In conclusion, 12 inhibited the growth of the MRSA and restored the activity of oxacillin, thus resulting in a promising compound in the treatment of MRSA infection.

Biological Profile of Two Gentiana lutea L. Metabolites Using Computational Approaches and In Vitro Tests

Natural products have been the main source of bioactive molecules for centuries. We tested the biological profile of two metabolites extracted from Gentiana lutea L. by means of computational techniques and in vitro assays. The two molecules (loganic acid and gentiopicroside) were tested in silico using an innovative technique, named Inverse Virtual Screening (IVS), to highlight putative partners among a panel of proteins involved in inflammation and cancer events. A positive binding with cyclooxygenase-2 (COX-2), alpha-1-antichymotrypsin, and alpha-1-acid glycoprotein emerged from the computational experiments and the outcomes from the promising interaction with COX-2 were confirmed by Western blot, highlighting the reliability of IVS in the field of the natural products.

Genomics-Metabolomics Profiling Disclosed Marine Vibrio spartinae 3.6 as a Producer of a New Branched Side Chain Prodigiosin

A wide range of prescreening tests for antimicrobial activity of 59 bacterial isolates from sediments of Ria Formosa Lagoon (Algarve, Portugal) disclosed Vibrio spartinae 3.6 as the most active antibacterial producing strain. This bacterial strain, which has not previously been submitted for chemical profiling, was subjected to de novo whole genome sequencing, which aided in the discovery and elucidation of a prodigiosin biosynthetic gene cluster that was predicted by the bioinformatic tool KEGG BlastKoala. Comparative genomics led to the identification of a new membrane di-iron oxygenase-like enzyme, annotated as Vspart_02107, which is likely to be involved in the biosynthesis of cycloprodigiosin and analogues. The combined genomics-metabolomics profiling of the strain led to the isolation and identification of one new branched-chain prodigiosin (5) and to the detection of two new cyclic forms. Furthermore, the evaluation of the minimum inhibitory concentrations disclosed the major prodigiosin as very effective against multi-drug-resistant pathogens including Stenotrophomonas maltophilia, a clinical isolate of Listeria monocytogenes, as well as some human pathogens reported by the World Health Organization as prioritized targets.

GPBAR1 Activation by C6-Substituted Hyodeoxycholane Analogues Protect against Colitis

GPBAR1 agonists have been identified as potential leads for the treatment of diseases related to colon inflammation such as Crohn's and ulcerative colitis. In this paper, we report the discovery of a small library of hyodeoxycholane analogues, decorated at C-6 with different substituents, as potent and selective GPBAR1 agonists. In vitro pharmacological assays showed that compound 6 selectively activates GPBAR1 (EC₅₀ = 0.3 μM) and reduces the production of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) in THP1 cells. The binding mode of compound 6 in GPBAR1 was elucidated by docking calculations. Moreover, compound 6 protects against TNBS-induced colitis in Gpbar1^+/+ rodent model, representing an intriguing lead for the treatment of these inflammatory disorders.

Crellastatin A, a PARP-1 Inhibitor Discovered by Complementary Proteomic Approaches

Crellastatin A, a cytotoxic sulfated bis-steroid isolated from the Vanuatu Island marine sponge Crella sp., was selected as an interesting probe for a comprehensive proteomic analysis directed at the characterization of its protein interactors. Given its peculiar structural features, A was submitted to a mass spectrometry-based drug affinity responsive target stability (DARTS) assay combined with (targeted-limited proteolysis-multiple reaction monitoring (t-LiP MRM), rather than a classical affinity purification strategy. Poly-ADP-ribose-polymerase-1 (PARP-1) emerged as the main crellastatin A cellular partner. This result was confirmed by both biochemical and in silico analyses. Further in vitro biological assays highlighted an interesting crellastatin A inhibitory activity on PARP-1.

Wound healing activity and phytochemical screening of purified fractions of Sempervivum tectorum L. leaves on HCT 116

INTRODUCTION

Sempervivum tectorum L. (Crassulaceae), is a succulent perennial plant widespread in Mediterranean countries and commonly used in traditional medicine for ear inflammation, ulcers and skin rashes as a refrigerant and astringent.

OBJECTIVE

To demonstrate the therapeutic effects of the plant, various fractions were purified and characterised. The potential wound healing activity, proliferation rate and intracellular signalling cascades were investigated by using human epithelial colorectal carcinoma (HCT 116) cells.

METHODOLOGY

An extraction method without organic solvents was applied for the first time. The purification was carried out by droplet counter current chromatography (DCCC) coupled with high-performance liquid chromatography (HPLC) and electrospray ionisation mass spectrometry (ESI-MS) data. By nuclear magnetic resonance (NMR) [¹ H, ¹³ C and two-dimensional (2D) experiments] pure components were identified. Wound healing and cell proliferation assays were utilised to determine the role of the isolated S. tectorum (SVT) fraction on cellular migration and proliferation. The signalling pathways elicited from the SVT fractions, were analysed by Western blot analysis.

RESULTS

In this study two rare natural components were identified, namely monosaccharide sedoheptulose and polyalcohol 2-C-methyl-D-erythritol, along with known organic acids and flavonoids. The fractions with high level of sedoheptulose enhance the proliferation and the cellular migration of epithelial HCT 116 cells. The intracellular signalling cascades elicited from the purified fractions induce the c-Src-mediated transactivation of EGFR and the activation of the STAT3 pathway which, in turn, are crucially involved in the cellular proliferation and migration.

CONCLUSIONS

Our study demonstrates the efficacy of purified fractions of S. tectorum L. in enhancing cellular proliferation and migration, suggesting their potential role as topical therapeutic treatments for wound healing.

Phytochemical and Biological Studies of Nepeta asterotricha Rech. f. (Lamiaceae): Isolation of Nepetamoside

The n-butanolic extract, from an Iranian specimen of Nepeta asterotricha Rech. f. (NABE), displayed anti-inflammatory effects on lipopolysaccharide (LPS)-stimulated J774A.1 macrophages, which reduced nitrites and cytokines production. Bioassay guided fractionation of the extract led to the isolation of four iridoid glycosides, including a new one known as nepetamoside (1), one hexenyl-diglycoside, and some polyphenol and flavonoid components. None of the isolated iridoid components displayed significant effects on nitrites formation in an in vitro LPS-induced model of inflammation, thus suggesting that the plant anti-inflammatory effect is probably due to a synergistic action among its constituents.

Investigation around the Oxadiazole Core in the Discovery of a New Chemotype of Potent and Selective FXR Antagonists

Recent findings have shown that Farnesoid X Receptor (FXR) antagonists might be useful in the treatment of cholestasis and related metabolic disorders. In this paper, we report the discovery of a new chemotype of FXR antagonists featured by a 3,5-disubstituted oxadiazole core. In total, 35 new derivatives were designed and synthesized, and notably, compounds 3f and 13, containing a piperidine ring, displayed the best antagonistic activity against FXR with promising cellular potency (IC₅₀ = 0.58 ± 0.27 and 0.127 ± 0.02 μM, respectively). The excellent pharmacokinetic properties make compound 3f the most promising lead identified in this study.

Chemistry and Pharmacology of GPBAR1 and FXR Selective Agonists, Dual Agonists, and Antagonists

In the recent years, bile acid receptors FXR and GPBAR1 have attracted the interest of scientific community and companies, as they proved promising targets for the treatment of several diseases, ranging from liver cholestatic disorders to metabolic syndrome, inflammatory states, nonalcoholic steatohepatitis (NASH), and diabetes.Consequently, the development of dual FXR/GPBAR1 agonists, as well as selective targeting of one of these receptors, is considered a hopeful possibility in the treatment of these disorders. Because endogenous bile acids and steroidal ligands, which cover the same chemical space of bile acids, often target both receptor families, speculation on nonsteroidal ligands represents a promising and innovative strategy to selectively target GPBAR1 or FXR.In this review, we summarize the most recent acquisition on natural, semisynthetic, and synthetic steroidal and nonsteroidal ligands, able to interact with FXR and GPBAR1.

Glucokinase deficit and birthweight: does maternal hyperglycemia always meet fetal needs?

AIMS

Many authors do not recommend hypoglycemic treatment during pregnancy in women affected by monogenic diabetes due to heterozygous glucokinase (GCK) mutations (MODY 2) in case of affected fetus, because maternal hyperglycemia would be necessary to achieve a normal birthweight. We aimed to evaluate differences in birthweight between MODY 2 affected children according to the parent who carried the mutation.

METHODS

We retrospectively studied 48 MODY 2 affected children, whose mothers did not receive hypoglycemic treatment during pregnancy, divided into two groups according to the presence of the mutation in the mother (group A) or in the father (group B). Data were extracted from the database of the Regional Centre of Pediatric Diabetology of the University of Campania, Naples, collected from 1996 to 2016. We analyzed birthweight and centile birthweight.

RESULTS

Percentage of small for gestational age was significantly higher in group B than in group A. We found three large for gestational age in the group that inherited the deficit from the mother, all with the same novel GCK mutation (p.Lys458-Cys461del).

CONCLUSIONS

We hypothesize that not all MODY 2 affected fetuses need the same levels of hyperglycemia to have an appropriate growth, maybe because different kinds of GCK mutations may result in different phenotypes. Consequently, a "tailored therapy" of maternal hyperglycemia, based on fetal growth frequently monitored through ultrasounds, is essential in MODY 2 pregnancies.

Hypertensive disorders during pregnancy and 3 years after delivery in women with gestational hyperglycemia

AIMS

Women with gestational hyperglycemia commonly experience hypertensive disorders during pregnancy. More information is needed about how hypertension develops in these patients over time. We investigated the prevalence of hypertension during and 3 years after pregnancy in Caucasian women with gestational hyperglycemia. We also investigated metabolic syndrome presence, glucose tolerance status, insulin sensitivity and insulin secretion levels in the follow-up period.

METHODS

In a prospective longitudinal study with a 3-year follow-up, we assessed hypertension status and clinical-related characteristics of 103 consecutive women with gestational hyperglycemia sub-grouped according to their hypertensive status during and after pregnancy.

RESULTS

Overall, 29 (28.1%) women had hypertension during pregnancy (24 gestational hypertension; 4 chronic hypertension; 1 preeclampsia). At follow-up 16 (15.5%) women were diagnosed as having hypertension (11 with hypertension in pregnancy; 5 with a normotensive pregnancy). Women with hypertension after pregnancy had higher BMI, metabolic syndrome rate and worse insulin resistance indexes than normotensive women. Weight increase at follow-up (OR 1.17, 95% CI 1.00-1.35) and hypertension in pregnancy (OR 6.72, 95% CI 1.17-38.64) were associated with hypertension after pregnancy.

CONCLUSIONS

Women with gestational hyperglycemia should undergo regular monitoring during and after pregnancy to detect metabolic and clinical impairments and to prevent cardiovascular harm.

Identification of a Sorbicillinoid-Producing Aspergillus Strain with Antimicrobial Activity Against Staphylococcus aureus: a New Polyextremophilic Marine Fungus from Barents Sea

The exploration of poorly studied areas of Earth can highly increase the possibility to discover novel bioactive compounds. In this study, the cultivable fraction of fungi and bacteria from Barents Sea sediments has been studied to mine new bioactive molecules with antibacterial activity against a panel of human pathogens. We isolated diverse strains of psychrophilic and halophilic bacteria and fungi from a collection of nine samples from sea sediment. Following a full bioassay-guided approach, we isolated a new promising polyextremophilic marine fungus strain 8Na, identified as Aspergillus protuberus MUT 3638, possessing the potential to produce antimicrobial agents. This fungus, isolated from cold seawater, was able to grow in a wide range of salinity, pH and temperatures. The growth conditions were optimised and scaled to fermentation, and its produced extract was subjected to chemical analysis. The active component was identified as bisvertinolone, a member of sorbicillonoid family that was found to display significant activity against Staphylococcus aureus with a minimum inhibitory concentration (MIC) of 30 μg/mL.

Discovering the Biological Target of 5-epi-Sinuleptolide Using a Combination of Proteomic Approaches

Sinuleptolide and its congeners are diterpenes with a norcembranoid skeleton isolated from the soft coral genus Sinularia. These marine metabolites are endowed with relevant biological activities, mainly associated with cancer development. 5-epi-sinuleptolide has been selected as a candidate for target discovery studies through the application of complementary proteomic approaches. Specifically, a combination of conventional chemical proteomics based on affinity chromatography, coupled with high-resolution mass spectrometry and bioinformatics, as well as drug affinity responsive target stability (DARTS), led to a clear identification of actins as main targets for 5-epi-sinuleptolide. Subsequent in-cell assays, performed with cytochalasin D as reference compound, gave information on the ability of 5-epi-sinuleptolide to disrupt the actin cytoskeleton by loss of actin fibers and formation of F-actin amorphous aggregates. These results suggest the potential application of 5-epi-sinuleptolide as a useful tool in the study of the molecular processes impaired in several disorders in which actin is thought to play an essential role.

Determination of Gymnemic Acid I as a Protein Biosynthesis Inhibitor Using Chemical Proteomics

The plant Gymnema sylvestre has been used widely in traditional medicine as a remedy for several diseases, and its leaf extract is known to contain a group of bioactive triterpene saponins belonging to the gymnemic acid class. Gymnemic acid I (1) is one of the main components among this group of secondary metabolites and is endowed with an interesting bioactivity profile. Since there is a lack of information about its specific biological targets, the full interactome of 1 was investigated through a quantitative chemical proteomic approach, based on stable-isotope dimethyl labeling. The ribosome complex was found to be the main partner of compound 1, and a full validation of the proteomics results was achieved by orthogonal approaches. Further biochemical and biological investigations revealed an inhibitory effect of 1 on the ribosome machinery.

Targeting Bile Acid Receptors: Discovery of a Potent and Selective Farnesoid X Receptor Agonist as a New Lead in the Pharmacological Approach to Liver Diseases

Bile acid (BA) receptors represent well-defined targets for the development of novel therapeutic approaches to metabolic and inflammatory diseases. In the present study, we report the generation of novel C-3 modified 6-ethylcholane derivatives. The pharmacological characterization and molecular docking studies for the structure-activity rationalization, allowed the identification of 3β-azido-6α-ethyl-7α-hydroxy-5β-cholan-24-oic acid (compound 2), a potent and selective FXR agonist with a nanomolar potency in transactivation assay and high efficacy in the recruitment of SRC-1 co-activator peptide in Alfa Screen assay. In vitro, compound 2 was completely inactive towards common off-targets such as the nuclear receptors PPARα, PPARγ, LXRα, and LXRβ and the membrane G-coupled BA receptor, GPBAR1. This compound when administered in vivo exerts a robust FXR agonistic activity increasing the liver expression of FXR-target genes including SHP, BSEP, OSTα, and FGF21, while represses the expression of CYP7A1 gene that is negatively regulated by FXR. Collectively these effects result in a significant reshaping of BA pool in mouse. In summary, compound 2 represents a promising candidate for drug development in liver and metabolic disorders.

Biomolecular proteomics discloses ATP synthase as the main target of the natural glycoside deglucoruscin

Extracts of Ruscus aculeatus are a rich source of bioactive steroidal glycosides, such as ruscogenins which are reported to act against chronic venous disorders. Nowadays, several preparations of its roots, commonly used in traditional medicine, are on the market as food supplements for health care and maintenance. Although spirostanol deglucoruscin is one of the main metabolites in these extracts, literature reports about its pharmacological profile are scarce. In this paper, a multi-disciplinary approach, based on chemical proteomics, molecular modelling and bio-organic assays, has been used to disclose the whole interactome of deglucoruscin and the F0-F1 ATP synthase complex has been found as its main target.

Navigation in bile acid chemical space: discovery of novel FXR and GPBAR1 ligands

Bile acids are signaling molecules interacting with nuclear receptors and membrane G-protein-coupled receptors. Among these receptors, the farnesoid X receptor (FXR) and the membrane G-coupled receptor (GPBAR1) have gained increasing consideration as druggable receptors and their exogenous dual regulation represents an attractive strategy in the treatment of enterohepatic and metabolic disorders. However, the therapeutic use of dual modulators could be associated to severe side effects and therefore the discovery of selective GPBAR1 and FXR agonists is an essential step in the medicinal chemistry optimization of bile acid scaffold. In this study, a new series of 6-ethylcholane derivatives modified on the tetracyclic core and on the side chain has been designed and synthesized and their in vitro activities on FXR and GPBAR1 were assayed. This speculation resulted in the identification of compound 7 as a potent and selective GPBAR1 agonist and of several derivatives showing potent dual agonistic activity.

Insights on FXR selective modulation. Speculation on bile acid chemical space in the discovery of potent and selective agonists

Bile acids are the endogenous modulators of the nuclear receptor FXR and the membrane receptor GPBAR1. FXR represents a promising pharmacological target for the treatment of cholestatic liver disorders. Currently available semisynthetic bile acid derivatives cover the same chemical space of bile acids and therefore they are poorly selective toward BA receptors, increasing patient risk for adverse side effects. In this report, we have investigated around the structure of CDCA describing the synthesis and the in vitro and in vivo pharmacological characterization of a novel family of compounds modified on the steroidal tetracyclic core and on the side chain. Pharmacological characterization resulted in the identification of several potent and selective FXR agonists. These novel agents might add utility in the treatment of cholestatic disorders by potentially mitigating side effects linked to unwanted activation of GPBAR1.

Investigation on bile acid receptor regulators. Discovery of cholanoic acid derivatives with dual G-protein coupled bile acid receptor 1 (GPBAR1) antagonistic and farnesoid X receptor (FXR) modulatory activity

Bile acids, the end products of cholesterol metabolism, activate multiple mechanisms through the interaction with membrane G-protein coupled receptors including the bile acid receptor GPBAR1 and nuclear receptors such as the bile acid sensor, farnesoid X receptor (FXR). Even if dual FXR/GPBAR1 agonists are largely considered a novel opportunity in the treatment of several liver and metabolic diseases, selective targeting of one of these receptors represents an attractive therapeutic approach for a wide range of disorders in which dual modulation is associated to severe side effects. In the present study we have investigated around the structure of LCA generating a small library of cholane derivatives, endowed with dual FXR agonism/GPBAR1 antagonism. To the best of our knowledge, this is the first report of bile acid derivatives able to antagonize GPBAR1.

Structure-based drug design targeting the cell membrane receptor GPBAR1: exploiting the bile acid scaffold towards selective agonism

Bile acids can regulate nutrient metabolism through the activation of the cell membrane receptor GPBAR1 and the nuclear receptor FXR. Developing an exogenous control over these receptors represents an attractive strategy for the treatment of enterohepatic and metabolic disorders. A number of dual GPBAR1/FXR agonists are known, however their therapeutic use is limited by multiple unwanted effects due to activation of the diverse downstream signals controlled by the two receptors. On the other hand, designing selective GPBAR1 and FXR agonists is challenging since the two proteins share similar structural requisites for ligand binding. Here, taking advantage of our knowledge of the two targets, we have identified through a rational drug design study a series of amine lithocholic acid derivatives as selective GPBAR1 agonists. The presence of the 3α-NH2 group on the steroidal scaffold is responsible for the selectivity over FXR unveiling unprecedented structural insights into bile acid receptors activity modulation.

Anti-inflammatory and analgesic activities with gastroprotective effect of semi-purified fractions and isolation of pure compounds from Mediterranean gorgonian Eunicella singularis

OBJECTIVE

To explore anti-inflammatory activities of organic extract and its semi-purified fractions (ethanol, acetone, methanol/dichloromethane) from the Mediterranean gorgonian Eunicella singularis.

METHODS

The anti-inflammatory and analgesic activities were evaluated, using the carrageenan-induced rat paw edema model and the acetic acid writhing test in mice. The gastroprotective activity was determined using HCl/EtOH induced gastric ulcers in rats. The purification and structure elucidation of compound(s) from the more effective fraction were determined by chromatographic and spectroscopic methods and in comparison with data reported in the literature.

RESULTS

The fraction F-EtOH showed an important anti-inflammatory activity associated with significant analgesic and gastroprotective properties. The purification and structure elucidation of compound(s) from this fraction lead to the identification of one diterpenoid and four sterols.

CONCLUSIONS

These results suggested that components from the active fraction can be used to treat various anti-inflammatory diseases.

Antioxidant activity and chemical components as potential anticancer agents in the olive leaf (Olea europaea L. cv Leccino.) decoction

Epidemiological studies have shown that a reduced risk of chronic diseases such as cancer and cardiovascular diseases is correlated with a regular consumption of fruits and vegetable, many of which are rich in polyphenols. The additive and synergistic effect of phytochemicals in fruits and vegetables may reduce chronic diseases related to oxidative stress in human body. Olea europaea L. leaf are rich in phenolic components, which have been proposed to play a role in cancer prevention. The purpose of this study was to identify the main components in the Olea europaea L. leaf (cv. Leccino) preserved during the decoction preparation, in order to delineate the antioxidant activities of the crude extracts and its isolated compounds by using different in vitro assays including DPPH radicalscavenging capacity, total antioxidant capacity (TAC), xanthine oxidase (XO) inhibitory effect and the ability to delay the linoleic acid peroxidation process (ALP). The aqueous decoction was partitioned obtaining four extracts and the n-butanol extract showed the highest antioxidant activity and the highest total phenolic content. Phytochemical investigation leads to the isolation of thirteen secondary metabolites including simple phenolics, flavonoids, secoiridoids whose structures were elucidated by spectroscopic data (1D and 2D NMR) and spectrometric techniques. A significant free radical scavenging effect against DPPH has been evidenced in fraxamoside (1) (EC50 62.6 µM) and taxifolin (5) (EC50 50.0 µM), isolated for the first time from the water decoction. The most active compound in the TAC evaluation, was the 3,4 dihydro-phenyl glycol (8) (0.90 caffeic acid equiv.) while taxifolin and fraxamoside resulted as the most efficient inhibitors of XO activity (IC50 2.7 and 5.2 µM, respectively). Secoxyloganin (4), oleuropein (2) and tyrosol (6) showed the highest ALP activity. This study adds to the growing body of data supporting the bioactivities of phytochemicals and their potential impact on human health.

Molecular decodification of gymnemic acids from Gymnema sylvestre. Discovery of a new class of liver X receptor antagonists

The individual chemical components of commercial extract of Gymnema sylvestre, a medicinal plant used in the traditional systems of the Indian medicine for its antidiabetic and hypolipidemic properties, were isolated and evaluated for their capability to act as modulators of nuclear and membrane receptors involved in glucose and lipid homeostasis. The study disclosed for the first time that individual gymnemic acids are potent and selective antagonists for the β isoform of LXR. Indeed the above activity was shared by the most abundant aglycone gymnemagenin (10) whereas gymnestrogenin (11) was endowed with a dual LXRα/β antagonistic profile. Deep pharmacological investigation demonstrated that gymnestrogenin, reducing the expression of SREBP1c and ABCA1 in vitro, is able to decrease lipid accumulation in HepG2 cells. The results of this study substantiate the use of G. sylvestre extract in LXR mediated dislypidemic diseases.

Pharmacological evaluation of the semi-purified fractions from the soft coral Eunicella singularis and isolation of pure compounds

BACKGROUND

Gorgonians of the genus Eunicella are known for possessing a wide range of pharmacological activities such as antiproliferative and antibacterial effect. The aim of this study was to evaluate the anti-inflammatory and gastroprotective effect of the organic extract and its semi-purified fractions from the white gorgonian Eunicella singularis and the isolation and identification of pure compound(s) from the more effective fraction.

METHODS

Anti-inflammatory activity was evaluated, using the carrageenan-induced rat paw edema test and in comparison to the reference drug Acetylsalicylate of Lysine. The gastroprotective activity was determined using HCl/EtOH induced gastric ulcers in rats. The purification of compound(s) from the more effective fraction was done by two chromatographic methods (HPLC and MPLC). The structure elucidation was determined by extensive spectroscopic analysis (1H and 13C NMR, COSY, HMBC, HMQC and NOESY) and by comparison with data reported in the literature.

RESULTS

The evaluation of the anti-inflammatory activity of different fractions from Eunicella singularis showed in a dependent dose manner an important anti-inflammatory activity of the ethanol fraction, the percentage of inhibition of edema, 3 h after carrageenan injection was 66.12%, more effective than the reference drug (56.32%). In addition, this ethanolic fraction showed an interesting gastroprotective effect compared to the reference drugs, ranitidine and omeprazol. The percentage of inhibition of gastric ulcer induced by HCl/ethanol in rats was 70.27%. The percentage of the reference drugs (ranitidine and omeprazol) were 65 and 87.53%, respectively. The purification and structure elucidation of compound(s) from this ethanolic fraction were leading to the isolation of five sterols: cholesterol (5α-cholest-5-en-3β-ol) (1); ergosterol (ergosta-5,22-dien-3β-ol) (2); stigmasterol (24-ethylcholesta-5,22-dien-3b-ol) (3); 5α,8α-epidioxyergosta 6,22-dien-3β-ol (4) and 3β-hydroxy-5α,8α-epidioxyergosta-6-ene (5); and one diterpenoid: palmonine D (6).

CONCLUSION

Based on data presented here, we concluded that diterpenoids and sterols detected in the ethanolic fraction can be responsible for its pharmacological activity.

Modification on ursodeoxycholic acid (UDCA) scaffold. discovery of bile acid derivatives as selective agonists of cell-surface G-protein coupled bile acid receptor 1 (GP-BAR1)

Bile acids are signaling molecules interacting with the nuclear receptor FXR and the G-protein coupled receptor 1 (GP-BAR1/TGR5). GP-BAR1 is a promising pharmacological target for the treatment of steatohepatitis, type 2 diabetes, and obesity. Endogenous bile acids and currently available semisynthetic bile acids are poorly selective toward GP-BAR1 and FXR. Thus, in the present study we have investigated around the structure of UDCA, a clinically used bile acid devoid of FXR agonist activity, to develop a large family of side chain modified 3α,7β-dihydroxyl cholanoids that selectively activate GP-BAR1. In vivo and in vitro pharmacological evaluation demonstrated that administration of compound 16 selectively increases the expression of pro-glucagon 1, a GP-BAR1 target, in the small intestine, while it had no effect on FXR target genes in the liver. Further, compound 16 results in a significant reshaping of bile acid pool in a rodent model of cholestasis. These data demonstrate that UDCA is a useful scaffold to generate novel and selective steroidal ligands for GP-BAR1.

Scalarane sesterterpenes from Thorectidae sponges as inhibitors of TDP-43 nuclear factor

The chemical analysis of two Thorectidae sponges led to the isolation of five new scalarane derivatives along with fifteen known compounds. Their binding capability to TDP-43 was assessed by bio-physical techniques and resulted in the identifications of potent inhibitors.

Plakilactones G and H from a marine sponge. Stereochemical determination of highly flexible systems by quantitative NMR-derived interproton distances combined with quantum mechanical calculations of (13)C chemical shifts

In this paper the stereostructural investigation of two new oxygenated polyketides, plakilactones G and H, isolated from the marine sponge Plakinastrella mamillaris collected at Fiji Islands, is reported. The stereostructural studies began on plakilactone H by applying an integrated approach of the NOE-based protocol and quantum mechanical calculations of (13)C chemical shifts. In particular, plakilactone H was used as a template to extend the application of NMR-derived interproton distances to a highly flexible molecular system with simultaneous assignment of four non-contiguous stereocenters. Chemical derivatization and quantum mechanical calculations of (13)C on plakilactone G along with a plausible biogenetic interconversion between plakilactone G and plakilactone H allowed us to determine the absolute configuration in this two new oxygenated polyketides.

Oxygenated polyketides from Plakinastrella mamillaris as a new chemotype of PXR agonists

Further purification of the apolar extracts of the sponge Plakinastrella mamillaris, afforded a new oxygenated polyketide named gracilioether K, together with the previously isolated gracilioethers E-G and gracilioethers I and J. The structure of the new compound has been elucidated by extensive NMR (1H and 13C, COSY, HSQC, HMBC, and ROESY) and ESI-MS analysis. With the exception of gracilioether F, all compounds are endowed with potent pregnane-X-receptor (PXR) agonistic activity and therefore represent a new chemotype of potential anti-inflammatory leads. Docking calculations suggested theoretical binding modes of the identified compounds, compatible with an agonistic activity on hPXR, and clarified the molecular basis of their biological activities.

Binding mechanism of the farnesoid X receptor marine antagonist suvanine reveals a strategy to forestall drug modulation on nuclear receptors. Design, synthesis, and biological evaluation of novel ligands

Here, we report suvanine, a marine sponge sesterterpene, as an antagonist of the mammalian bile acid sensor farnesoid-X-receptor (FXR). Using suvanine as a template, we shed light on the molecular bases of FXR antagonism, identifying the essential conformational changes responsible for the transition from the agonist to the antagonist form. Molecular characterization of the nuclear corepressor NCoR and coactivator Src-1 revealed that receptor conformational changes are associated with a specific dynamic of recruitment of these cofactors to the promoter of OSTα, a FXR regulated gene. Using suvanine as a novel hit, a library of semisynthetic derivatives has been designed and prepared, leading to pharmacological profiles ranging from agonism to antagonism toward FXR. Deep pharmacological evaluation demonstrated that derivative 19 represents a new chemotype of FXR modulator, whereas alcohol 6, with a simplified molecular scaffold, exhibits excellent antagonistic activity.

A simultaneous multielement non-dispersive atomic-fluorescence spectrometer using modulated sources and frequency discrimination of fluorescence signals

Commercial radiofrequency-excited electrodeless discharge lamps can be run from a square-wave modulated power supply so as to give a low level of continuous emission when modulated in the frequency range 3-10 kHz. Use of a different modulation frequency and lock-in amplifier for each lamp allows multielement non-dispersive atomic-fluorescence spectrometry to be performed. Very low detection limits have been obtained for arsenic, selenium, tin and mercury. The use of low-cost electronic components in the system largely offsets the high cost of the individual excitation power supplies and tuned a.c. detectors.

Plakilactones from the marine sponge Plakinastrella mamillaris. Discovery of a new class of marine ligands of peroxisome proliferator-activated receptor γ

In this paper we report the isolation and the molecular characterization of a new class of PPARγ ligands from the marine environment. Biochemical characterization of a library of 13 oxygenated polyketides isolated from the marine sponge Plakinastrella mamillaris allowed the discovery of gracilioether B and plakilactone C as selective PPARγ ligands in transactivation assays. Both agents covalently bind to the PPARγ ligand binding domain through a Michael addition reaction involving a protein cysteine residue and the α,β-unsaturated ketone in their side chains. Additionally, gracilioether C is a noncovalent agonist for PPARγ, and methyl esters 1 and 2 are noncovalent antagonists. Structural requirements for the interaction of these agents within the PPARγ ligand binding domain were obtained by docking analysis. Gracilioether B and plakilactone C regulate the expression of PPARγ-dependent genes in the liver and inhibit the generation of inflammatory mediators by macrophages.

Imbricatolic acid from Juniperus communis L. prevents cell cycle progression in CaLu-6 cells

Imbricatolic acid was isolated from the methanolic extract of the fresh ripe berries of Juniperus communis (Cupressaceae) together with sixteen known compounds and a new dihydrobenzofuran lignan glycoside named juniperoside A. Their structures were determined by spectroscopic methods and by comparison with the spectral data reported in literature. Imbricatolic acid was evaluated for its ability to prevent cell cycle progression in p53-null CaLu-6 cells. This compound induces the upregulation of cyclin-dependent kinase inhibitors and their accumulation in the G1 phase of the cell cycle, as well as the degradation of cyclins A, D1, and E1. Furthermore, no significant imbricatolic acid-induced apoptosis was observed. Therefore, this plant-derived compound may play a role in the control of cell cycle.

Carbon dioxide insufflation versus air insufflation during endoscopic retrograde cholangiopancreatography under general anesthesia

AIM

The aim of this paper was to evaluate the effect of carbon dioxide (CO2) vs. air insufflation on post-endoscopic retrograde cholangiopancreatography (ERCP) abdominal pain and distension. In addition, we investigated the changes in the partial pressure of end-tidal CO2 (PetCO2) and the partial pressure of arterial CO2 (PaCO2).

METHODS

From October 2009 to January 2010, all patients admitted to our centre for ERCP were screened for enrollment; the patients recruited were randomised to CO2 or air insufflation. The patients were asked to rate their abdominal pain intensity and distension using a 100-mm Visual Analogue Scale (VAS) before, in the recovery room and at 1, 3, 6 and 24 hours after the ERCP. All anesthesiological and endoscopic details and complications were evaluated.

RESULTS

We included 76 patients, 39 in the Air group and 37 in the CO2 group. The groups were similar for age, gender, indications and duration of the procedure. Post-procedure mean values of pain (in the recovery room and at 1, 3 and 6 hours) and distension (at recovery room, and at 1 and 3 hours) according to the VAS were significantly reduced in the CO2 group as compared to the Air group. At baseline, the PetCO2 values were similar between the two groups while, during the ERCP, they increased significantly in CO2 group as compared to the Air group; these values were reduced by simply increasing the ventilation.

CONCLUSION

CO2 insufflation during ERCP significantly reduces post-procedural abdominal pain and distension. Increased PetCO2 and PaCO2 values remained within acceptable or readily controllable ranges.

Lauroside B, a megastigmane glycoside from Laurus nobilis (bay laurel) leaves, induces apoptosis in human melanoma cell lines by inhibiting NF-κB activation

Malignant melanoma is a highly aggressive tumor that frequently resists chemotherapy, so the search for new agents for its treatment is of great importance. In the present study, the antiproliferative propensity against human melanoma cell lines of lauroside B (1), a megastigmane glycoside isolated from Laurus nobilis (bay laurel) leaves, was investigated. This compound suppressed the proliferation of three human melanoma cell lines, namely, A375, WM115, and SK-Mel-28. The 1-induced inhibition of human melanoma cell proliferation was due to the induction of apoptosis, as demonstrated by FACS analysis with annexin V/PI staining and confirmed by activation of caspase-3 and by the cleavage of poly(ADP-ribose) polymerase (PARP). Growing evidence implicates NF-κB as an important contributor to metastasis and increased chemoresistance of melanoma. Thus, it was hypothesized that 1-induced apoptosis could be associated with suppression of NF-κB activation. The results showed that exposure of human melanoma cells to 1 inhibited IκB-α degradation and constitutive NF-κB DNA-binding activity as well as the expression, regulated by NF-κB, of two antiapoptotic genes, XIAP and c-FLIP. Induction of apoptosis by 1 in human aggressive melanoma cell lines has a potential high biological value.

Solomonamides A and B, new anti-inflammatory peptides from Theonella swinhoei

Two unprecedented cyclic peptides, solomonamides A and B, were isolated from the marine sponge Theonella swinhoei. The structures were elucidated on the basis of comprehensive 1D and 2D NMR analysis and high-resolution mass spectrometry. A combined approach, involving Marfey's method, QM J based analysis, and DFT J/(13)C calculations, was used for establishing the absolute configuration of the entire molecule. Solomonamide A showed in vivo anti-inflammatory activity.

Solomonsterols A and B from Theonella swinhoei. The first example of C-24 and C-23 sulfated sterols from a marine source endowed with a PXR agonistic activity

The finding of new PXR modulators as potential leads for treatment of human disorders characterized by dysregulation of innate immunity and with inflammation is of wide interest. In this paper, we report the identification of the first example of natural marine PXR agonists, solomonsterols A and B, from a Theonella swinhoei sponge. The structures were determined by interpretation of NMR and ESIMS data, and the putative binding mode to PXR has been obtained through docking calculations.