Nuria Cabedo

Terretonins E and F, inhibitors of the mitochondrial respiratory chain from the marine-derived fungus Aspergillus insuetus (#).

Two new meroterpenoids, terretonins E and F (1, 2), together with three known compounds, aurantiamine (3), linoleic acid, and uridine, were isolated as fermentation products of the marine-derived fungus Aspergillus insuetus, which was associated with the sponge Petrosia ficiformis. Structures of all isolates were elucidated employing spectroscopic methods, mainly by two-dimensional NMR techniques. Compounds 1-3 showed activity as inhibitors of the mammalian mitochondrial respiratory chain.

Tetrahydroisoquinolines as dopaminergic ligands: 1-Butyl-7-chloro-6-hydroxy-tetrahydroisoquinoline, a new compound with antidepressant-like activity in mice.

Three series of 1-substituted-7-chloro-6-hydroxy-tetrahydroisoquinolines (1-butyl-, 1-phenyl- and 1-benzyl derivatives) were prepared to explore the influence of each of these groups at the 1-position on the affinity for dopamine receptors. All the compounds displayed affinity for D(1)-like and/or D(2)-like dopamine receptors in striatal membranes, and were unable to inhibit [(3)H]-dopamine uptake in striatal synaptosomes. Different structure requirements have been observed for adequate D(1) or D(2) affinities. This paper details the synthesis, structural elucidation, dopaminergic binding assays, structure-activity relationships (SAR) of these three series of isoquinolines. Moreover, 1-butyl-7-chloro-6-hydroxy-tetrahydroisoquinoline (1e) with the highest affinity towards D(2)-like receptors (K(i) value of 66nM) and the highest selectivity (49-fold D(2) vs D(1)) by in vitro binding experiments was then evaluated in behavioral assays (spontaneous activity and forced swimming test) in mice. Compound 1e increased locomotor activity in a large dose range (0.04-25mg/kg). Furthermore, this lead compound produced reduction in immobility time in the forced swimming test at a dose (0.01mg/kg) that did not modify locomotor activity. The haloperidol (0.03mg/kg), a D(2) receptor preferred antagonist, blocked the antidepressant-like effect of compound 1e.

3-Hydroxypropionic Acid as an Antibacterial Agent from Endophytic Fungi Diaporthe phaseolorum

Endophytic fungi are considered a rich source of active compounds resulting from their secondary metabolism. Fungi from marine environment grow in a habitat with unique conditions that can contribute to the activation of metabolic pathways of synthesis of different unknown molecules. The production of these compounds may support the adaptation and survival of the fungi in the marine ecosystem. Mangroves are ecosystems situated between land and sea. They are frequently found in tropical and subtropical areas and enclose approximately 18.1 million hectares of the planet. The great biodiversity found in these ecosystems shows the importance of researching them, including studies regarding new compounds derived from the endophytic fungi that inhabit these ecosystems. 3-hydroxypropionic acid (3-HPA) has been isolated from the mangrove endophytic fungus Diaporthe phaseolorum, which was obtained from branches of Laguncularia racemosa. The structure of this compound was elucidated by spectroscopic methods, mainly 1D and 2D NMR. In bioassays, 3-HPA showed antimicrobial activities against both Staphylococcus aureus and Salmonella typhi. The structure of this antibiotic was modified by the chemical reaction of Fischer-Speier esterification to evaluate the biologic activity of its chemical analog. The esterified product, 3-hydroxypropanoic ethyl ester, did not exhibit antibiotic activity, suggesting that the free carboxylic acid group is important to the pharmacological activity. The antibiotic-producing strain was identified with internal transcribed spacer sequence data. To the best of our knowledge, this is the first report of antibacterial activity by 3-HPA against the growth of medically important pathogens.

An Overview on Benzylisoquinoline Derivatives with Dopaminergic and Serotonergic Activities

Dopamine and serotonin are important neurotransmitters in the mammalian central nervous system (CNS) involved in numerous physiological and behavioural disorders such as schizophrenia, major depression, anxiety, Parkinsons and Huntingtons diseases, and attention deficit hyperactivity disorder. Several natural and synthetic benzylisoquinoline derivatives have displayed affinity for dopamine and serotonin receptors in nanomolar or micromolar ranges. This review covers the last three decades of dopaminergic and serotonergic activities, and especially focuses on structure-activity relationships of natural and synthetic benzylisoquinoline derivatives. We have included aporphines, 1-benzyltetrahydroisoquinolines, bis-benzylisoquinolines, protoberberines, cularines and other structural analogues. Further molecular modelling calculations have been considered as important tools to not only obtain structural information of both neurotransmitter receptors, but to also identify their pharmacophore features. The development of selective potential ligands like benzylisoquinoline derivatives may help in the therapy of diseases related to CNS dysfunction.

2,3,9- and 2,3,11-Trisubstituted tetrahydroprotoberberines as D2 dopaminergic ligands

Dopamine-mediated neurotransmission plays an important role in relevant psychiatric and neurological disorders. Nowadays, there is an enormous interest in the development of new dopamine receptors (DR) acting drugs as potential new targets for the treatment of schizophrenia or Parkinsons disease. Previous studies have revealed that isoquinoline compounds such as tetrahydroisoquinolines (THIQs) and tetrahydroprotoberberines (THPBs) can behave as selective D2 dopaminergic alkaloids since they share structural similarities with dopamine. In the present study we have synthesized eleven 2,3,9- and 2,3,11-trisubstituted THPB compounds (six of them are described for the first time) and evaluated their potential dopaminergic activity. Binding studies on rat striatal membranes were used to evaluate their affinity and selectivity towards D1 and D2 DR and establish the structure-activity relationship (SAR) as dopaminergic agents. In general, all the tested THPBs with protected phenolic hydroxyls showed a lower affinity for D1 and D2 DR than their corresponding homologues with free hydroxyl groups. In previous studies in which dopaminergic affinity of 1-benzyl-THIQs (BTHIQs) was evaluated, the presence of a Cl into the A-ring resulted in increased affinity and selectivity towards D2 DR. This is in contrast with the current study since the existence of a chlorine atom into the A-ring of the THPBs caused increased affinity for D1 DR but dramatically reduced the selectivity for D2 DR. An OH group in position 9 of the THPB (9f) resulted in a higher affinity for DR than its homologue with an OH group in position 11 (9e) (250 fold for D2 DR). None of the compounds showed any cytotoxicity in freshly isolated human neutrophils. A molecular modelling study of three representative THPBs was carried out. The combination of MD simulations with DFT calculations provided a clear picture of the ligand binding interactions from a structural and energetic point of view. Therefore, it is likely that compound 9d (2,3,9-trihydroxy-THPB) behave as D2 DR agonist since serine residues cluster are crucial for agonist binding and receptor activation.

Tetrahydroisoquinolines acting as dopaminergic ligands. A molecular modeling study using MD simulations and QM calculations

A molecular modeling study on 16 1-benzyl tetrahydroisoquinolines (BTHIQs) acting as dopaminergic ligands was carried out. By combining molecular dynamics simulations with ab initio and density functional theory (DFT) calculations, a simple and generally applicable procedure to evaluate the binding energies of BTHIQs interacting with the human dopamine D2 receptor (D2 DR) is reported here, providing a clear picture of the binding interactions of BTHIQs from both structural and energetic viewpoints. Molecular aspects of the binding interactions between BTHIQs and the D2 DR are discussed in detail. A significant correlation between binding energies obtained from DFT calculations and experimental pKi values was obtained, predicting the potential dopaminergic effect of non-synthesized BTHIQs.

Enhanced Efficacy and Broadening of Antibacterial Action of Drugs via the Use of Capped Mesoporous Nanoparticles

Bug busters: A novel nanodevice consisting of mesoporous nanoparticles loaded with vancomycin and capped with ε-poly-L-lysine (ε-PL) was prepared and its interaction with different Gram-negative bacteria studied. A remarkable improvement in the efficacy of the antimicrobial drug ε-PL and a broadening of the antimicrobial spectrum of vancomycin is demonstrated.

Evaluation of nonpolar metabolites in plant extracts by 13C NMR spectroscopy

(13)C nuclear magnetic resonance (NMR) spectroscopy was explored as a simple and efficient technique for the quantitative analysis of nonpolar metabolites in plants. The method was first optimized with a mixture of known metabolites and then applied to the nonpolar leaf extracts of plants harvested in the Valencian community (eastern Spain) belonging to three different genera: Euphorbia (Euphorbiaceae), Araujia (Apocynaceae), and Morus (Moraceae). Furthermore, an exhaustive analysis of Euphorbia characias leaf and stem extracts from different geographic locations allowed that quantitative (13)C NMR spectroscopy is a suitable tool for metabolic profiling purpose.

3-acetylaltholactone and related styryl-lactones, mitochondrial respiratory chain inhibitors.

A novel furano-pyrone, 3-acetylaltholactone, and two other known styryl-lactones, altholactone and 5-acetoxyisogoniothalamin oxide, have been isolated from Goniothalamus arvensis (Annonaceae) stem bark. We report here the isolation and structural elucidation of these compounds with furane-pyrone and styryl-pyrone skeletons, postulating also for the first time their mechanism of cytotoxicity based on inhibition on mammalian mitochondrial respiratory chain.

Synthesis of new antimicrobial pyrrolo[2,1-a]isoquinolin-3-ones

The attractive structure of the pyrroloisoquinoline moiety, together with its potential antimicrobial activity, encouraged us to prepare six 8-substituted and seven 8,9-disubstituted-1,2,3,5,6,10b-hexahydropyrrolo[2,1-a]isoquinolin-3-ones in a few steps with good yields. We applied a convenient methodology via double intramolecular cyclization conducted by a Bischler-Napieralski cyclodehydration-imine reduction sequence, which is widely employed in the synthesis of isoquinoline alkaloids. Therefore, we synthesized three series of these pyrrolo[2,1-a]isoquinolin-3-ones characterized by the substituent at the 8-position or 8,9-positions of the aromatic ring: (a) different side chains are attached to an 8-OH group (series 1); (b) a chlorine atom is attached to the 8-position (series 2); and (c) 8- and 9-carbons are bearing an identical group (series 3). The compounds bearing a benzylic moiety at the 8-position, for example, 8-benzyloxy-pyrrolo[2,1-a]isoquinolin-3-one (1a) and 8-(4-fluorobenzyloxy)-pyrrolo[2,1-a]isoquinolin-3-one (1e), as well as, a 8-chloro-9-methoxy moiety including the 8-chloro-9-methoxy-pyrrolo[2,1-a]isoquinolin-3-one (2a), provided the most fungicide and bactericide agents, respectively.