Design, synthesis and biological activity of selective hCAs inhibitors based on 2-(benzylsulfinyl)benzoic acid scaffold.

A large library of derivatives based on the scaffold of 2-(benzylsulfinyl)benzoic acid were synthesised and tested as atypical inhibitors against four different isoforms of human carbonic anhydrase (hCA I, II, IX and XII, EC 4.2.1.1). The exploration of the chemical space around the main functional groups led to the discovery of selective hCA IX inhibitors in the micromolar/nanomolar range, thus establishing robust structure-activity relationships within this versatile scaffold. HPLC separation of some selected chiral compounds and biological evaluation of the corresponding enantiomers was performed along with molecular modelling studies on the most active derivatives.

Synthesis and biological evaluation of anti-Toxoplasma gondii activity of a novel scaffold of thiazolidinone derivatives.

We designed and synthesised novel N-substituted 1,3-thiazolidin-4-one derivatives for the evaluation of their anti-Toxoplasma gondii efficacy. This scaffold was functionalised both at the N1-hydrazine portion with three structurally different moieties and at the lactam nitrogen with substituted benzyl groups selected on the basis of our previous structure-activity relationships studies. Using three different assay methods, the compounds were assessed in vitro to determine both the levels of efficacy against the tachyzoites of T. gondii (IC50 = 5-148 µM), as well as any evidence of cytotoxicity towards human host cells (TD50 = 68 to ≥320 µM). Results revealed that ferrocene-based thiazolidinones can possess potent anti-tachyzoite activity (TI =2-64).

A novel library of saccharin and acesulfame derivatives as potent and selective inhibitors of carbonic anhydrase IX and XII isoforms.

Small libraries of N-substituted saccharin and N-/O-substituted acesulfame derivatives were synthesized and tested as atypical and selective inhibitors of four different isoforms of human carbonic anhydrase (hCA I, II, IX and XII, EC 4.2.1.1). Most of them inhibited hCA XII in the low nanomolar range, hCA IX with KIs ranging between 19 and 2482nM, whereas they were poorly active against hCA II (KIs >10µM) and hCA I (KIs ranging between 318nM and 50µM). Since hCA I and II are ubiquitous off-target isoforms, whereas the cancer-related isoforms hCA IX and XII were recently validated as drug targets, these results represent an encouraging achievement in the development of new anticancer candidates. Moreover, the lack of a classical zinc binding group in the structure of these inhibitors opens innovative, yet unexplored scenarios for different mechanisms of inhibition that could explain the high inhibitory selectivity. A computational approach has been carried out to further rationalize the biological data and to characterize the binding mode of some of these inhibitors.

New amide derivatives of Probenecid as selective inhibitors of carbonic anhydrase IX and XII: biological evaluation and molecular modelling studies.

Novel amide derivatives of Probenecid were synthesized and discovered to act as potent and selective inhibitors of the human carbonic anhydrase (hCA, EC 4.2.1.1) transmembrane isoforms hCA IX and XII. The proposed chemical transformation of the carboxylic acid into an amide group led to a complete loss of hCA I and II inhibition (Kis >10,000nM) and enhanced the inhibitory activity against hCA IX and XII, with respect to the parent compound (incorporating a COOH function). These promising biological results have been corroborated by molecular modelling studies within the active sites of the four studied human carbonic anhydrases, which enabled us to rationalize both the isoform selectivity and high activity against the tumor-associated isoforms hCA IX/XII.

Computational investigation of the selectivity of salen and tetrahydrosalen compounds towards the tumor-associated hCA XII isozyme.

In previous work, 14 salen and tetrahydrosalen compounds have been synthesized and tested in enzyme inhibition assays against cytosolic human carbonic anhydrase isozymes I and II (hCA I and II) and tumor-associated isozymes IX and XII (hCA IX and XII). These compounds show selectivity against hCA XII over hCA I, II and IX. In this study, molecular modeling and docking studies were applied to understand this preference of the compounds for hCA XII. Most likely, the compounds can displace the zinc-bound water molecule of hCA XII to form a direct interaction with the Zn(2+) ion. In the other isozymes, the compounds might not be able to displace the water molecule nor are they expected to interact with the Zn(2+) ion.

Bioactive compounds of Crocus sativus L. and their semi-synthetic derivatives as promising anti-Helicobacter pylori, anti-malarial and anti-leishmanial agents.

Crocus sativus L. is known in herbal medicine for the various pharmacological effects of its components, but no data are found in literature about its biological properties toward Helicobacter pylori, Plasmodium spp. and Leishmania spp. In this work, the potential anti-bacterial and anti-parasitic effects of crocin and safranal, two important bioactive components in C. sativus, were explored, and also some semi-synthetic derivatives of safranal were tested in order to establish which modifications in the chemical structure could improve the biological activity. According to our promising results, we virtually screened our compounds by means of molecular modeling studies against the main H. pylori enzymes in order to unravel their putative mechanism of action.

(Thiazol-2-yl)hydrazone derivatives from acetylpyridines as dual inhibitors of MAO and AChE: synthesis, biological evaluation and molecular modeling studies.

Several (thiazol-2-yl)hydrazone derivatives from 2-, 3- and 4-acetylpyridine were synthesized and tested against human monoamine oxidase (hMAO) A and B enzymes. Most of them had an inhibitory effect in the low micromolar/high nanomolar range, being derivatives of 4-acetylpyridine selective hMAO-B inhibitors also at low nanomolar concentrations. The structure-activity relationship, as confirmed by molecular modeling studies, proved that the pyridine ring linked to the hydrazonic nitrogen and the substituted aryl moiety at C4 of the thiazole conferred the inhibitory effects on hMAO enzymes. Successively, the strongest hMAO-B inhibitors were tested toward acetylcholinesterase (AChE) and the most interesting compound showed activity in the low micromolar range. Our results suggest that this scaffold could be further investigated for its potential multi-targeted role in the discovery of new drugs against the neurodegenerative diseases.

Nitric oxide donors and selective carbonic anhydrase inhibitors: a dual pharmacological approach for the treatment of glaucoma, cancer and osteoporosis.

Due to the recognized biological role of nitric oxide (NO) donating derivatives and of selective inhibitors of specific human carbonic anhydrase isoforms (CA, EC 4.2.1.1), promising compounds having an aromatic/heterocyclic primary sulfonamide and functionalized with NO-releasing moieties have been designed. These bifunctional agents have been tested in vitro and in vivo to assess their dual pharmacological activity. According to the encouraging results they could be proposed for the treatment of angle-open glaucoma, cancer regression and osteoporosis, in which both NO and CA activities are involved.

Design, synthesis and evaluation of N-substituted saccharin derivatives as selective inhibitors of tumor-associated carbonic anhydrase XII.

A series of N-alkylated saccharin derivatives were synthesized and tested for the inhibition of four different isoforms of human carbonic anhydrase (CA, EC 4. 2.1.1): the transmembrane tumor-associated CA IX and XII, and the cytosolic CA I and II. Most of the reported derivatives inhibited CA XII in the nanomolar/low micromolar range, hCA IX with KIs ranging between 11 and 390 nM, whereas they were inactive against both CA I (KIs >50 µM) and II (K(I)s ranging between 39.1 nM and 50 µM). Since CA I and II are off-targets of antitumor carbonic anhydrase inhibitors (CAIs), the obtained results represent an encouraging achievement for the development of new anticancer candidates without the common side effects of non-selective CAIs. Moreover, the lack of an explicit zinc binding function on these inhibitors opens the way towards the exploration of novel mechanisms of inhibition that could explain the high selectivity of these compounds for the inhibition of the transmembrane, tumor-associated isoforms over the cytosolic ones.

Identification of the stereochemical requirements in the 4-aryl-2-cycloalkylidenhydrazinylthiazole scaffold for the design of selective human monoamine oxidase B inhibitors.

Exploring the effect that substituents on the cycloaliphatic ring had on the inhibitory activity against human monoamine oxidase B of a series of 4-aryl-2-cycloalkylidenhydrazinylthiazoles led to the synthesis of a new series of 2-methylcyclopentyl and 3-methylcyclopentyl derivatives which were tested in vitro as mixtures of diastereoisomers. In fact, due to the presence of a chiral center on the cycloaliphatic ring and a trisubstituted CN bond, they exist as four diastereoisomers ((E)-(R), (E)-(S), (Z)-(R), (Z)-(S)). 4-(2,4-Difluorophenyl)-2-(2-(3-methylcyclopentylidene)hydrazinyl)thiazole was chosen as a model to investigate the influence of stereochemical requirements on the inhibitory activity against hMAO-B of these derivatives after a stereoconservative synthesis and semi-preparative HPLC diastereoseparation. (R)-(Z) isomer of this compound was endowed with a potent and selective hMAO-B inhibition higher than that of reference drugs as also corroborated by molecular modeling studies.

Modern extraction techniques and their impact on the pharmacological profile of Serenoa repens extracts for the treatment of lower urinary tract symptoms.

BACKGROUND: Bioactive compounds from plants (i.e., Serenoa repens) are often used in medicine in the treatment of several pathologies, among which benign prostatic hyperplasia (BPH) associated to lower urinary tract symptoms (LUTS). DISCUSSION: There are different techniques of extraction, also used in combination, with the aim of enhancing the amount of the target molecules, gaining time and reducing waste of solvents. However, the qualitative and quantitative composition of the bioactives depends on the extractive process, and so the brands of the recovered products from the same plant are different in terms of clinical efficacy (no product interchangeability among different commercial brands). SUMMARY: In this review, we report on several and recent extraction techniques and their impact on the composition/biological activity of S. repens-based available products.

Salen and tetrahydrosalen derivatives act as effective inhibitors of the tumor-associated carbonic anhydrase XII--a new scaffold for designing isoform-selective inhibitors.

Salen and tetrahydrosalen derivatives possess metal-chelating properties and have been used as ligands in organic synthesis and as scaffolds for developing therapeutic agents. Fourteen such compounds were synthesized in order to explore their ability to inhibit the zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1). Human (h) isoforms hCA I, hCA II, hCA IX and hCA XII were included in the investigation. Several aliphatic and aromatic spacers were introduced between the two chelating groups from salen/tetrahydrosalen in order to explore a diverse chemical space for designing CA inhibitors, which incorporate both phenol and polyamine fragments in their molecule. Some of these compounds showed CA inhibitory activity in the low micromolar-nanomolar range and a pronounced selectivity for inhibiting an isoform over-expressed in hypoxic tumors, hCA XII, over hCA I, II and IX.

Synthesis and selective human monoamine oxidase B inhibition of heterocyclic hybrids based on hydrazine and thiazole scaffolds.

A new scaffold of hydrazothiazoles has been designed as monoamine oxidase (MAO) inhibitors combining the hydrazine moiety of iproniazid and the thiazole nucleus of glitazones, a class of peroxisome proliferator-activated receptor (PPAR)γ agonists recently co-crystallized with human MAO-B. The resulting derivatives were synthesized and assayed to evaluate their in vitro activity against both the A and B isoforms of hMAO. All compounds were shown to be selective hMAO-B inhibitors with IC(50) values in the low micromolar/high nanomolar range. Such results suggest that the hydrazothiazole scaffold could be considered as an interesting pharmacophore for the future design of new lead compounds as coadjuvants for the treatment of neurodegenerative diseases.

Synthesis and selective inhibitory activity against human COX-1 of novel 1-(4-substituted-thiazol-2-yl)-3,5-di(hetero)aryl-pyrazoline derivatives.

Novel 1-(4-ethyl carboxylate-thiazol-2-yl)-3,5-di(hetero)aryl-2-pyrazoline derivatives were obtained by reacting 3,5-di(hetero)aryl-1-thiocarbamoyl-2-pyrazolines with the ethyl ester of α-bromo-pyruvic acid. The synthesized compounds were confirmed by spectroscopic data and assayed to evaluate their in vitro ability to inhibit both isoforms of human cyclooxygenase (hCOX). Some derivatives (compounds 5, 6, 13, 16, and 17) displayed promising selectivity against hCOX-1 in the micromolar range and were shown to have a selectivity index similar or better than the reference drugs (indometacin, diclofenac). The introduction of a phenyl or a 4-F-phenyl ring on the C5 associated with a 4-substituted phenyl or a heteroaryl group on the C3 of (4-substituted-thiazol-2-yl)pyrazoline derivatives improved the activity against hCOX-1. Thanks to these preliminary results it could be possible to extend our knowledge of the pharmacophoric requirements for the discovery of new pyrazoline-based hCOX-1 inhibitors.

Design, synthesis and biochemical evaluation of novel multi-target inhibitors as potential anti-Parkinson agents.

New 4-(3-nitrophenyl)thiazol-2-ylhydrazone derivatives are proposed as dual-target-directed monoamine oxidase B (MAO-B) and acetylcholinesterase (AChE) inhibitors, as well as antioxidant agents, for the treatment of neurodegenerative disorders such as Parkinson's disease. Rational molecular design, target recognition and predicted pharmacokinetic properties have been evaluated by means of molecular modelling. Based on these properties, compounds were synthesized and evaluated in vitro as MAO-B and AChE inhibitors, and compared to the activities at their corresponding isozymes, monoamine oxidase A (MAO-A) and butyrylcholinesterase (BuChE), respectively. Anti-oxidant properties, potentially useful in the treatment of neurodegenerative disorders, have been also investigated in vitro. Among the evaluated compounds, three inhibitors may be considered as promising dual inhibitors of MAO-B and AChE, in vitro. MAO-B inhibition was also shown to be competitive and reversible for compound 19.

Synthesis, biological evaluation and quantitative structure-active relationships of 1,3-thiazolidin-4-one derivatives. A promising chemical scaffold endowed with high antifungal potency and low cytotoxicity.

With reference to recent studies reporting on the various biological properties of the thiazolidinone scaffold, we synthesized more than a hundred compounds characterized by a 1,3-thiazolidin-4-one nucleus derivatised at the C2 with a hydrazine bridge linked to (cyclo)aliphatic or hetero(aryl) moieties, and their N-benzylated derivatives. These molecules were assayed as potential anti-Candida agents and they were shown to possess comparable, and in some cases higher biological activity than well-established topical and systemic antimycotic drugs (i.e. clotrimazole, fluconazole, ketoconazole, miconazole, tioconazole, amphotericin B). Compounds endowed with the lowest MICs underwent further testing in order to assess their cytotoxic effect (CC50) on Hep2 cells, which demonstrated their relative safety. Finally, QSAR and 3-D QSAR models were used to predict putative chemical modifications of the 1,3-thiazolidin-4-one scaffold in order to design new and potential more active compounds against Candida spp.

Geographical characterization by MAE-HPLC and NIR methodologies and carbonic anhydrase inhibition of Saffron components.

A microwave-assisted extraction method was optimised for the recovery of bioactive compounds from Crocus sativus L. stigmas with the use of water/ethanol mixture. HPLC-DAD was employed to evaluate the extraction parameters, in particular, solvent type and volume, and the duration of the procedure. Microwave-assisted extraction enhanced the recovery of the active principles, limiting extraction time and solvent waste. Moreover, NIR experiments were performed in order to compare spectra in pseudo-absorbance of Saffron samples with different geographical origins through the application of the chemometric techniques. Moreover, the biological evaluation of crocin 1, safranal and its semisynthetic derivatives as selective inhibitors of five isoforms of human carbonic anhydrase was also explored.

Opening New Scenarios for Human MAO Inhibitors.

Despite the considerable interest in the search of new and potent human MAO inhibitors, an increasing number of research works deal with new therapeutic and analytical approaches regarding these molecules. Our interest was focused on the detailed analysis of (i) new pharmacological options for selective hMAO inhibitors; (ii) innovative analytical procedures to discover/screen hMAO inhibitors, and (iii) the recent possibility of using labeled hMAO inhibitors to unravel neurodegenerative diseases and drug distribution. All these three aspects could open new scenarios stimulating the interest of researchers in this field.

Anti-Candida activity and cytotoxicity of a large library of new N-substituted-1,3-thiazolidin-4-one derivatives.

On the basis of the recent findings about the biological properties of thiazolidinones and taking into account the encouraging results about the antifungal activity of some (thiazol-2-yl)hydrazines, new N-substituted heterocyclic derivatives were designed combining the thiazolidinone nucleus with the hydrazonic portion. In details, 1,3-thiazolidin-4-ones bearing (cyclo)aliphatic or (hetero)aromatic moieties linked to the N1-hydrazine at C2 were synthesized and classified into three series according to the aromatic or bicyclic rings connected to the lactam nitrogen of the thiazolidinone. These molecules were assayed for their anti-Candida effects in reference to the biological activity of the conventional topic (clotrimazole, miconazole, tioconazole) and systemic drugs (fluconazole, ketoconazole, amphotericin B). Finally, we investigated the selectivity against fungal cells by testing the compounds endowed with the best MICs on Hep2 cells in order to assess their cell toxicity (CC50) and we noticed that two derivatives were less cytotoxic than the reference drug clotrimazole. Moreover, a preliminary molecular modelling approach has been performed against lanosterol 14-α demethylase (CYP51A1) to rationalize the activity of the tested compounds and to specify the target protein or enzyme.

Novel 1,3-thiazolidin-4-one derivatives as promising anti-Candida agents endowed with anti-oxidant and chelating properties.

Pursuing our recent outcomes regarding the antifungal activity of N-substituted 1,3-thiazolidin-4-ones, we synthesized thirty-six new derivatives introducing aliphatic, cycloaliphatic and heteroaromatic moieties at N1-hydrazine connected with C2 position of the thiazolidinone nucleus and functionalizing the lactam nitrogen with differently substituted (NO2, NH2, Cl and F) benzyl groups. These compounds were tested to evaluate their minimum inhibitory concentration (MIC) against several clinical Candida spp. with respect to topical and systemic reference drugs (clotrimazole, fluconazole, ketoconazole, miconazole, tioconazole, amphotericin B). Moreover, anti-oxidant properties were also evaluated by using different protocols including free radical scavenging (DPPH and ABTS), reducing power (CUPRAC and FRAP), metal chelating and phosphomolybdenum assays. Moreover, for the most active derivatives we assessed the toxicity (CC50) against Hep2 human cells in order to characterize them as multi-target agents for fungal infections.