A mild and efficient method for large scale synthesis of 3-aminocoumarins and its further application for the preparation of 4-bromo-3-aminocoumarins

Myeloperoxidase Inhibitory and Antioxidant Activities of (E)-2-Hydroxy-α-aminocinnamic Acids Obtained through Microwave-Assisted Synthesis

Myeloperoxidase (MPO) is an enzyme present in human neutrophils, whose main role is to provide defenses against invading pathogens. However, highly reactive oxygen species (ROS), such as HOCl, are generated from MPO activity, leading to chronic diseases. Herein, we report the microwave-assisted synthesis of a new series of stable (E)-(2-hydroxy)-α-aminocinnamic acids, in good yields, which are structurally analogous to the natural products (Z)-2-hydroxycinnamic acids. The radical scavenging activity (RSA), MPO inhibitory activity and cytotoxicity of the reported compounds were evaluated. The hydroxy derivatives showed the most potent RSA, reducing the presence of DPPH and ABTS radicals by 77% at 0.32 mM and 100% at 0.04 mM, respectively. Their mechanism of action was modeled with BDE_OH, IP and ΔE_H-L theoretical calculations at the B3LYP/6 − 31 + G(d,p) level. Compounds showed in vitro inhibitory activity of MPO with IC₅₀ values comparable to indomethacin and 5-ASA, but cytotoxicities below 15% at 100–200 µM. Docking calculations revealed that they reach the amino acid residues present in the distal cavity of the MPO active site, where both the amino and carboxylic acid groups of the α-aminopropenoic acid arm are structural requirements for anchoring. (E)-2-hydroxy-α-aminocinnamic acids have been synthesized for the first time with a reliable method and their antioxidant properties demonstrated.

Rational design, synthesis and biological evaluation of novel multitargeting anti-AD iron chelators with potent MAO-B inhibitory and antioxidant activity

A series of (3-hydroxypyridin-4-one)-coumarin hybrids were developed and investigated as potential multitargeting candidates for the treatment of Alzheimer's disease (AD) through the incorporation of iron-chelating and monoamine oxidase B (MAO-B) inhibition. This combination endowed the hybrids with good capacity to inhibit MAO-B as well as excellent iron-chelating effects. The pFe³⁺ values of the compounds were ranging from 16.91 to 20.16, comparable to more potent than the reference drug deferiprone (DFP). Among them, compound 18d exhibited the most promising activity against MAO-B, with an IC₅₀ value of 87.9 nM. Moreover, compound 18d exerted favorable antioxidant activity, significantly reversed the amyloid-β_1-42 (Aβ_1-42) induced PC12 cell damage. More importantly, 18d remarkably ameliorated the cognitive dysfunction in a scopolamine-induced mice AD model. In brief, a series of hybrids with potential anti-AD effect were successfully obtained, indicating that the design of iron chelators with MAO-B inhibitory and antioxidant activities is an attractive strategy against AD progression.

Recent Advances in the Synthesis of Coumarin Derivatives from Different Starting Materials

The study of coumarin dates back to 1820 when coumarin was first extracted from tonka bean by Vogel. Compounds containing coumarin backbone are a very important group of compounds due to their usage in pharmacy and medicine. Properties and biological activities of coumarin derivatives have a significant role in the development of new drugs. Therefore, many different methods and techniques are developed in order to synthesize coumarin derivatives. Coumarin derivatives could be obtained from different starting materials with various methods but with big differences in yield. This review summarized various methods, techniques and reaction conditions for synthesis of coumarins from different compounds such as aldehydes, phenols, ketones and carboxylic acids.

Use of Bromine and Bromo-Organic Compounds in Organic Synthesis

Bromination is one of the most important transformations in organic synthesis and can be carried out using bromine and many other bromo compounds. Use of molecular bromine in organic synthesis is well-known. However, due to the hazardous nature of bromine, enormous growth has been witnessed in the past several decades for the development of solid bromine carriers. This review outlines the use of bromine and different bromo-organic compounds in organic synthesis. The applications of bromine, a total of 107 bromo-organic compounds, 11 other brominating agents, and a few natural bromine sources were incorporated. The scope of these reagents for various organic transformations such as bromination, cohalogenation, oxidation, cyclization, ring-opening reactions, substitution, rearrangement, hydrolysis, catalysis, etc. has been described briefly to highlight important aspects of the bromo-organic compounds in organic synthesis.