The use of privileged structures in drug discovery has proven to be an effective strategy, allowing the generation of innovative hits/leads and successful optimization processes. Chromone is recognized as a privileged structure and a useful template for the design of novel compounds with potential pharmacological interest, particularly in the field of neurodegenerative, inflammatory, and infectious diseases as well as diabetes and cancer. This perspective provides the reader with an update of an earlier article entitled "Chromone: A Valid Scaffold in Medicinal Chemistry" ( Chem. Rev. 2014 , 114 , 4960 - 4992 ) and is mainly focused on chromones of biological interest, including those isolated from natural sources. Moreover, as drug repurposing is becoming an attractive drug discovery approach, recent repurposing studies of chromone-based drugs are also reported.

The discovery of new chemical entities endowed with potent, selective, and reversible monoamine oxidase B inhibitory activity is a clinically relevant subject. Therefore, a small library of chromone derivatives was synthesized and screened toward human monoamine oxidase isoforms (hMAO-A and hMAO-B). The structure-activity relationships studies strengthen the importance of the amide spacer and the direct linkage of carbonyl group to the γ-pyrone ring, along with the presence of meta and para substituents in the exocyclic ring. The most potent MAO-B inhibitors were N-(3'-chlorophenyl)-4-oxo-4H-chromene-3-carboxamide (20) (IC50 = 403 pM) and N-(3',4'-dimethylphenyl)-4-oxo-4H-chromene-3-carboxamide (27) (IC50 = 669 pM), acting as competitive and noncompetitive reversible inhibitors, respectively. Computational docking studies provided insights into enzyme-inhibitor interactions and a rationale for the observed selectivity and potency. Compound 27 stands out due to its favorable toxicological profile and physicochemical properties, which pointed toward blood-brain barrier permeability, thus being a valid candidate for subsequent animal studies.

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The discovery of potent and selective monoamine oxidase-B inhibitors for the management of neurodegenerative diseases such as Alzheimer's and Parkinson's diseases is still a challenging endeavor. Herein, we report the discovery of two new classes of potent and selective MAO-B inhibitors based on chromane-2,4-dione and chromone-3-carboxamide scaffolds.

Several authors have studied the factors that influence a firm's export performance, but few have addressed the relationship between industry characteristics and export intensity. The objective of the present study was to analyze the impact of industry characteristics on a firm's export intensity, the latter a measure commonly used to assess export performance, seeking to add empirical evidence to this relatively neglected research area. Based on a sample of 19,504 Portuguese manufacturing firms, 7,930 of which were exporting, during the period 2010-2013, and using panel data estimation, the empirical results show that some industry characteristics (labor productivity, export orientation, concentration), as well as characteristics of the firm (labor productivity, size and age of the firm) are important determinants of a firm's export intensity. It is concluded in particular that a firm's export intensity is positively affected by the export orientation of the industry, as well as by the firm's labor productivity, confirming the belief that firms and governments need to direct their policies towards increased productivity in order to improve competitiveness in foreign markets. It is argued that, in order to enhance the positive effects of these policies, the policies should be directed towards industries with the highest export focus.

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