Maria João Matos

Chromone: a valid scaffold in Medicinal Chemistry

This work was supported by the Foundation for Science and Technology (FCT), Portugal (projects PTDC/QUI-QUI/113687/2009 and PEst-C/QUI/UI0081/2013). A.G. (SFRH/BD/43531/2008) and M.J.M. (SFRH/BD/61262/2009) thank FCT for grants.

Synthesis and study of a series of 3-arylcoumarins as potent and selective monoamine oxidase B inhibitors.

New series of 6-substituted-3-arylcoumarins displaying several alkyl, hydroxyl, halogen, and alkoxy groups in the two benzene rings have been designed, synthesized, and evaluated in vitro as human monoamine oxidase A and B (hMAO-A and hMAO-B) inhibitors. Most of the studied compounds showed a high affinity and selectivity to the hMAO-B isoenzyme, with IC(50) values on nanomolar and picomolar range. Ten of the 22 described compounds displayed higher MAO-B inhibitory activity and selectivity than selegiline. Coumarin 7 is the most active compound of this series, being 64 times more active than selegiline and also showing the highest hMAO-B specificity. In addition, docking experiments were carried out on hMAO-A and h-MAO-B structures. This study provided new information about the enzyme-inhibitor interaction and the potential therapeutic application of this 3-arylcoumarin scaffold.

A new series of 3-phenylcoumarins as potent and selective MAO-B inhibitors

6-Methyl-3-phenylcoumarins 3-6 were designed, synthesized and evaluated as monoamine oxidase A and B (MAO-A and MAO-B) inhibitors. The synthesis of these new compounds (resveratrol-coumarin hybrids) was carried out with good yield by a Perkin reaction, from the 5-methylsalicylaldehyde and the corresponding phenylacetic acid. They show high selectivity to the MAO-B isoenzyme, with IC(50) values in the nanomolar range. Compound 5 is the most active compound and is several times more potent and selective than the reference compound, R-(-)-deprenyl.

Synthesis and evaluation of 6-methyl-3-phenylcoumarins as potent and selective MAO-B inhibitors.

A series of 6-methyl-3-phenylcoumarins 3-6 were synthesized and evaluated as monoamine oxidase A and B (MAO-A and MAO-B) inhibitors. A comparative study between the three possible mono methoxy 3-phenyl derivatives and the p-hydroxy analogue is reported. The synthesis of these new resveratrol-coumarin hybrids was carried out by a Perkin reaction between the 5-methylsalicylaldehyde and the corresponding phenylacetic acids. The p-methoxy substituted compound 3 was hydrolyzed to 6 by a traditional reaction with hydriodic acid. The prepared compounds show high selectivity to the MAO-B isoenzyme, some of them with IC(50) values in the low nanomolar range. Compound 4, with the methoxy group in meta position, is the most active of this series, with an IC(50) against MAO-B of 0.80 nM, and is several times more potent and MAO-B selective than the R-(-)-deprenyl (reference compound).

New halogenated 3-phenylcoumarins as potent and selective MAO-B inhibitors.

With the aim to find out the structural features for the MAO inhibitory activity and selectivity, in the present communication we report the synthesis and pharmacological evaluation of a new series of bromo-6-methyl-3-phenylcoumarin derivatives (with bromo atom in both different benzene rings of the skeleton) with and without different number of methoxy substituent at the 3-phenyl ring. The methoxy substituents were introduced, in this new scaffold, in the meta and/or para positions of the 3-phenyl ring. The synthesized compounds 3-7 were evaluated as MAO-A and B inhibitors using R-(-)-deprenyl (selegiline) and iproniazide as reference inhibitors, showing, most of them, MAO-B inhibitory activities in the low nanomolar range. Compounds 4 (IC(50)=11.05 nM), 5 (IC(50)=3.23 nM) and 6 (IC(50)=7.12 nM) show higher activity than selegiline (IC(50)=19.60 nM) and higher MAO-B selectivity, with more than 9050-fold, 30,960-fold and 14,045-fold inhibition levels, with respect to the MAO-A isoform.

Synthesis and Electrochemical and Biological Studies of Novel Coumarin–Chalcone Hybrid Compounds

A series of novel hydroxy-coumarin-chalcone hybrid compounds 2a-i has been synthesized by employing a simple and efficient methodology. An electrochemical characterization using cyclic voltammetry and ESR spectroscopy were carried out to characterize the oxidation mechanism for the target compounds. The antioxidant capacity and reactivity were determined by ORAC and ESR assays, respectively. Biological assays were assessed to evaluate the cytotoxicity and cytoprotection capacity against ROS/RNS on BAEC. The results revealed that all tested compounds present ORAC values that are much higher than other well-known antioxidant compounds such as quercetin and catechin. Compound 2e showed the highest ORAC value (14.1) and also presented a low oxidation potential, good scavenging capacity against hydroxyl radicals, low cytotoxicity, and high cytoprotective activity.

3-Substituted coumarins as dual inhibitors of AChE and MAO for the treatment of Alzheimer's disease

The complex etiology of Alzheimers disease (AD) has encouraged active research in the development of multi-target drugs with two or more complementary biological activities, since they may represent an important advance in the treatment of this disease. A series of 3-substituted coumarins were synthesized and evaluated as monoamino oxidases (MAO) and acetylcholinesterase (AChE) inhibitors. Most of the 3-benzamide coumarin derivatives inhibited both MAO-B and AChE with values in the micromolar range. It might be a promising direction for developing novel drugs as potential agents for the treatment of AD patients.

Antioxidant and Pro-Oxidant Effects of Polyphenolic Compounds and Structure-Activity Relationship Evidence

The research and characterization of new bioactive substances, for the new design of functional foods, nutraceuticals, or drugs, has been intensified. Several studies showing controversial results of exogenous antioxidants, debating that the type, dosage and matrix of these antioxidants may be determining factors impacting the balance between beneficial and deleterious effects of these natural compounds (Bouayed & Bohn, 2010). There are also some proofs that they act as pro-oxidants, under certain conditions, such as high doses or the presence of metal ions (Decker, 1997; Raza & John, 2005; Watjen et al., 2005). The antioxidant or pro-oxidant activity intimately depends on their concentration (Bouayed & Bohn, 2010). The consequences of pro-oxidant activity could be the possible damage to the biomolecules such as DNA, proteins and lipids, and the consequent cellular death (Aruoma, 2003).

8‐Substituted 3‐Arylcoumarins as Potent and Selective MAO‐B Inhibitors: Synthesis, Pharmacological Evaluation, and Docking Studies

Neurodegenerative disorders are becoming more prevalent given the increase in the aging population. This has inspired active research in the development of new drugs that could mark an important advance in the treatment of complex diseases such as Alzheimer′s and Parkinson′s. With the aim of finding new MAO‐B‐selective inhibitors, we report the synthesis, in vitro evaluation, and docking simulation of a new series of 3‐arylcoumarins variously substituted at the 8‐position. Most of the studied compounds show high affinity and selectivity for the hMAO‐B isoform, with IC50 values in the low micro‐ to nanomolar range. Some of them have greater hMAO‐B inhibitory activity and selectivity than the reference compound, selegiline. Compounds 7 and 8 are the most active of this series, with compound 8 being fivefold more potent against MAO‐B and severalfold more selective than selegiline. Docking experiments were carried out with hMAO‐B crystal structures, providing new information about the enzyme–inhibitor interaction and the potential therapeutic application of the new 8‐substituted 3‐arylcoumarins.

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.