Benedetta Era

New halogenated phenylcoumarins as tyrosinase inhibitors

With the aim to find out structural features for the tyrosinase inhibitory activity, in the present communication we report the synthesis and pharmacological evaluation of a new series of phenylcoumarin derivatives with different number of hydroxyl or ether groups and bromo substituent in the scaffold. The synthesized compounds 5-12 were evaluated as mushroom tyrosinase inhibitors showing, two of them, lower IC(50) than the umbelliferone. Compound 12 (IC(50)=215 μM) is the best tyrosinase inhibitor of this series.

Tyrosinase inhibitor activity of coumarin-resveratrol hybrids.

In the present work we report on the contribution of the coumarin moiety to tyrosinase inhibition. Coumarin-resveratrol hybrids 1-8 have been resynthesized to investigate the structure-activity relationships and the IC50 values of these compounds were measured. The results showed that these compounds exhibited tyrosinase inhibitory activity. Compound 3-(3’,4’,5’-trihydroxyphenyl)-6,8-dihydroxycoumarin (8) is the most potent compound (0.27 mM), more so than umbelliferone (0.42 mM), used as reference compound. The kinetic studies revealed that compound 8 caused non-competitive tyrosinase inhibition.

2-Phenylbenzofuran derivatives as butyrylcholinesterase inhibitors: Synthesis, biological activity and molecular modeling.

A series of 2-phenylbenzofurans compounds was designed, synthesized and evaluated as cholinesterase inhibitors. The biological assay experiments showed that most of the compounds displayed a clearly selective inhibition for butyrylcholinesterase (BChE), while a weak or no effect towards acetylcholinesterase (AChE) was detected. Among these benzofuran derivatives, compound 16 exhibited the highest BChE inhibition with an IC50 value of 30.3 μM. This compound was found to be a mixed-type inhibitor as determined by kinetic analysis. Moreover, molecular dynamics simulations revealed that compound 16 binds to both the catalytic anionic site (CAS) and peripheral anionic site (PAS) of BChE and it displayed the best interaction energy value, in agreement with our experimental data.

Design and discovery of tyrosinase inhibitors based on a coumarin scaffold

In this manuscript we report the synthesis, pharmacological evaluation and docking studies of a selected series of 3-aryl and 3-heteroarylcoumarins with the aim of finding structural features for the tyrosinase inhibitory activity. The synthesized compounds were evaluated as mushroom tyrosinase inhibitors. Compound 12b showed the lowest IC50 (0.19 μM) of the series, being approximately 100 times more active than kojic acid, used as a reference compound. The kinetic studies of tyrosinase inhibition revealed that 12b acts as a competitive inhibitor of mushroom tyrosinase with L-DOPA as the substrate. Furthermore, the absence of cytotoxicity in B16F10 melanoma cells was determined for this compound. The antioxidant profile of all the derivatives was evaluated by measuring radical scavenging capacity (ABTS and DPPH assays). Docking experiments were carried out on mushroom tyrosinase structures to better understand the structure–activity relationships.

Synthesis and biological evaluation of a novel series of bis-salicylaldehydes as mushroom tyrosinase inhibitors.

A series of novel bis-salicylaldehydes were synthesised and evaluated as tyrosinase inhibitors using a tyrosinase-dependent L-DOPA oxidation assay. The bis-salicylaldehydes exhibited greater inhibitory activity than salicylaldehyde. Our data suggests that these novel compounds may serve as a structural template for the design and development of novel tyrosinase inhibitors.

Metabolomics analysis and modeling suggest a lysophosphocholines-PAF receptor interaction in fibromyalgia.

Fibromyalgia Syndrome (FMS) is a chronic disease characterized by widespread pain, and difficult to diagnose and treat. We analyzed the plasma metabolic profile of patients with FMS by using a metabolomics approach combining Liquid Chromatography-Quadrupole-Time Of Flight/Mass Spectrometry (LC-Q-TOF/MS) with multivariate statistical analysis, aiming to discriminate patients and controls. LC-Q-TOF/MS analysis of plasma (FMS patients: n = 22 and controls: n = 21) identified many lipid compounds, mainly lysophosphocholines (lysoPCs), phosphocholines and ceramides. Multivariate statistical analysis was performed to identify the discriminating metabolites. A protein docking and molecular dynamic (MD) study was then performed, using the most discriminating lysoPCs, to validate the binding to Platelet Activating Factor (1-alkyl-2-acetyl-sn-glycero-3-phosphocholine, PAF) Receptor (PAFr). Discriminating metabolites between FMS patients and controls were identified as 1-tetradecanoyl-sn-glycero-3-phosphocholine [PC(14∶0/0∶0)] and 1-hexadecanoyl-sn-glycero-3-phosphocholine [PC(16∶0/0∶0)]. MD and docking indicate that the ligands investigated have similar potentialities to activate the PAFr receptor. The application of a metabolomic approach discriminated FMS patients from controls, with an over-representation of PC(14∶0/0∶0) and PC(16∶0/0∶0) compounds in the metabolic profiles. These results and the modeling of metabolite-PAFr interaction, allowed us to hypothesize that lipids oxidative fragmentation might generate lysoPCs in abundance, that in turn will act as PAF-like bioactivators. Overall results suggest disease biomarkers and potential therapeutical targets for FMS.

Tyrosine-like condensed derivatives as tyrosinase inhibitors

Objectives  We report the pharmacological evaluation of a new series of 3‐aminocoumarins differently substituted with hydroxyl groups, which have been synthesized because they include in their structures the tyrosine fragment (tyrosine‐like compounds), with the aim of discovering structural features necessary for tyrosinase inhibitory activity.

New insights into highly potent tyrosinase inhibitors based on 3-heteroarylcoumarins: Anti-melanogenesis and antioxidant activities, and computational molecular modeling studies

Melanogenesis is a physiological pathway for the formation of melanin. Tyrosinase catalyzes the first step of this process and down-regulation of its activity is responsible for the inhibition of melanogenesis. The search for molecules capable of controlling hyperpigmentation is a trend topic in health and cosmetics. A series of heteroarylcoumarins have been synthesized and evaluated. Compounds 4 and 8 exhibited higher tyrosinase inhibitory activities (IC50=0.15 and 0.38μM, respectively), than the reference compound, kojic acid (IC50=17.9μM). Compound 4 acts as competitive, while compound 8 as uncompetitive inhibitor of mushroom tyrosinase. Furthermore, compounds 2 and 8 inhibited tyrosinase activity and melanin production in B16F10 cells. In addition, compounds 2-4 and 8 proved to have an interesting antioxidant profile in both ABTS and DPPH radicals scavenging assays. Docking experiments were carried out in order to study the interactions between these heteroarylcoumarins and mushroom tyrosinase.

Chemical composition of Lycium europaeum fruit oil obtained by supercritical CO2 extraction and evaluation of its antioxidant activity, cytotoxicity and cell absorption

We studied the total phenols and flavonoids, liposoluble antioxidants, fatty acid and triacylglycerol profiles, and oxidative status of oil obtained from Lycium europaeum fruits following supercritical CO2 extraction (at 30MPa and 40°C). Linoleic (52%), palmitic (18%), oleic (13%), and α-linolenic (6%) were the main oil fatty acids, while trilinolein and palmitodilinolein/oleodilinolein represented the main triacylglycerols. The oil was characterized by high levels of all-trans-zeaxanthin and all-trans-β-carotene (755 and 332μg/g of oil, respectively), α-tocopherol (308μg/g of oil), total phenols (13.6mg gallic acid equivalents/g of oil), and total flavonoids (6.8mg quercetin equivalents/g of oil). The oil showed radical scavenging activities (ABTS and DPPH assays) and inhibited Caco-2 cell growth. Moreover, the incubation of differentiated Caco-2 cells with a non-toxic oil concentration (100μg/mL) induced a significant intracellular accumulation of essential fatty acids. The results qualify L. europaeum oil as a potential source for food/pharmaceutical applications.

A preliminary study on serum proteomics in fibromyalgia syndrome

Fibromyalgia syndrome (FMS) is a complex illness to diagnose and treat, which presents symptoms that may be part of, or overlap with other diseases or syndromes. The most widely used diagnostic criteria are those of the American College of Rheumatology [1]; no laboratory test has been validated for FMS diagnosis which remains primarily clinically based. Oxidative stress has been proposed as a relevant event in the pathogenesis of FMS with an increase of lipid peroxidation (LPO) [2] and a decrease in vitamin A and E concentrations [3]. Although the etiology of FMS remains unclear, genetic predisposition is likely to be an important factor and transmission is thought to be polygenic [4, 5]. If FMS is a multi-genetic disease then it could be hypothesized that differences exist in the type of proteins or protein expression levels in sera of FMS patients compared with healthy controls. Proteomic analysis is a powerful tool for the global evaluation of protein expression and plays a central role in clinical diagnosis and monitoring. Some studies [6] reported interesting proteomic analysis data with an overexpression of transaldolase and phosphoglicerate mutase I in salivary fluid of FMS patients and focused on the role of oxidative stress in the pathogenesis of the disease. The aim of this preliminary study was to evaluate, using two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MS), changes in protein profiles of FMS patients with respect to control subjects to identify potential serum biomarkers useful for disease diagnosis and management. Sixteen females (52 ± 12 years) affected by FMS and 12 healthy females (48 ± 13 years) were enrolled; all patients fulfilled new ACR diagnostic criteria [1] (Table 1). The presence of a major clinical condition other than fibromyalgia was excluded by physical examination and routine blood and urine screening. No patients suffered of thyroid dysfunction. Psychiatric examination data of patients were reported in a previous study [7]. Study was approved from our Local Ethical Committee and informed consent was obtained from all subjects. Serum protein concentrations were quantified using the PlusOne 2D Quant Kit (GE Healthcare); first dimension isoelectric focusing (IEF) was carried out with 18 cm immobilized pH gradient strips of pH 3–10. The IPG strips were applied onto 10% acrylamide sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) slab gels (25.5 cm × 20.5 cm × 1.0 mm) and overlaid with a solution of 0.5% agarose with a trace of bromophenol blue. Gels were fixed, stained with Coomassie Brilliant Blue G-250 colloidal for 24 h and stored at room temperature. At least three sample replicates were performed. 2D data were processed with Progenesis SameSpots software, which computed multiplication fold, false discovery rate (FDR) q-value, p-values of all spots using one-way ANOVA analysis. A p-value < 0.05 was considered statistically significant; no difference has been found in protein expression according to patient therapy. After normalization, volume calculation and statistical analysis, same data differences were observed between *Corresponding author: Dr. Antonella Fais, Dipartimento di Scienze della Vita e dell’Ambiente, Università di Cagliari, 09042 Monserrato, Cagliari, Italy, Phone: +39 0706754506, Fax: +39 0706754523, E-mail: fais@unica.it Valeria Ruggiero and Enrico Cacace: Dipartimento di Scienze Mediche “Mario Aresu”, Università di Cagliari, Monserrato, Cagliari, Italy Benedetta Era, Marcella Corda and Stefania Utzeri: Dipartimento di Scienze della Vita e dell’Ambiente, Università di Cagliari, Monserrato, Cagliari, Italy Laura Molin: CNR-ISTM, Corso Stati Uniti 4, Padova, Italy