1-[(2,3-Dihydro-1-benzofuran-2-yl) methyl]piperazines as novel anti-inflammatory compounds: Synthesis and evaluation on H3 R/H4 R

Iodine-Catalyzed Claisen-Rearrangements of Allyl Aryl Ethers and Subsequent Iodocyclizations

Iodine can be considered as the simplest halogen-bond donor. Previous investigations have revealed its remarkable catalytic effect in various reactions. The catalytic activity of iodine can often even compete with that of traditional Lewis acids. So far, iodine was typically used to activate carbonyl derivatives like Michael acceptors. We now demonstrate that iodine can also be used to activate allyl aryl ethers in Claisen rearrangements. The formed ortho-allylic phenols rapidly undergo iodocyclizations to afford dihydrobenzofurans, which are important building blocks for medicinal applications. A comparison with different catalysts further highlights the potential of iodine catalysis for this reaction. Computational and mechanistic investigations provide deeper insights into the underlying non-covalent interactions and their role for the catalysis.

Neurotoxicity Assessment of 1-[(2,3-Dihydro-1-Benzofuran-2-yl)Methyl]Piperazine (LINS01 Series) Derivatives and their Protective Effect on Cocaine-Induced Neurotoxicity Model in SH-SY5Y Cell Culture

Excessive levels of dopamine in the synaptic cleft, induced by cocaine for example, activates dopaminergic receptors, mainly D₁R, D₂R, and D₃R subtypes, contributing to neurotoxic effects. New synthetic 1-[(2,3-dihydro-1-benzofuran-2-yl)methyl]piperazine derivatives (the LINS01 compounds), designed as histaminergic receptor (H₃R) ligands, are also dopaminergic receptor ligands, mainly D₂R and D₃R. This study aims to evaluate the neurotoxicity of these new synthetic LINS01 compounds (LINS01003, LINS01004, LINS01011, and LINS01018), as well as to investigate their protective potential on a cocaine model of dopamine-induced neurotoxicity using SH-SY5Y cell line culture. Neurotoxicity was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH), and automated cell counting with fluorescent dyes (acridyl orange and propidium iodide) assays. Concentration-response curves (CRCs) were performed for all LINS compounds and cocaine using MTT assay. The results show that LINS series did not decrease cell viability after 48h of exposure-except for 100 µM LINS01018, which was discontinued from the study. Likewise, MTT, LDH, and fluorescent dyes staining showed no difference is cell viability for LINS compounds at 10 µM. When incubated with 2.5 mM cocaine (lethal concentration 50) for 48h, 10 µM of each LINS compound, metoclopramide (D₂R antagonist) and haloperidol (D₂R/D₃R antagonist), ameliorated cocaine-induced neurotoxicity. However, only metoclopramide, haloperidol, and LINS01011 compound significantly decreased LDH released in the culture medium, suggesting that this new synthetic compound presents a more robust effect. This preliminary in vitro neurotoxicity study suggests that LINS01 compounds are not neurotoxic, and that they play a promising role in preventing cocaine-induced neurotoxicity.

Evaluation of the Histamine H3 Receptor Antagonists from LINS01 Series as Cholinesterases Inhibitors - Enzymatic and Modeling Studies

Histamine is involved in several CNS processes including cognition. In the last years, H₃ receptor (H₃ R) antagonists have been widely explored for their potential on dementias and other cognitive dysfunctions, and the cooperative role between histamine and acetylcholine neurotransmissions on cognitive processes is widely known in literature. This motivated us to assess the potential of 1-[(2,3-dihydrobenzofuran-1-yl)methyl]piperazines (LINS01 compounds) as inhibitors of cholinesterases, and thus this work presents the inhibitory effect of such compounds against acetyl (AChE) and butyrylcholinesterase (BChE). A set of 16 selected compounds were evaluated, being compounds 2d and 2e the most potent inhibitors of both cholinesterases (IC₅₀ 13.2 - 33.9 μM) by competitive mechanism, as indicated by the kinetic assays. Molecular docking simulations suggested that the allylpiperazine and dihydrobenzofuran motifs present in these compounds are important to perform π-interactions with key tryptophan residues from the enzymes, increasing their affinity for both H₃ R and cholinesterases. Metric analysis support that compound 2d (LINS01022) should be highlighted due to its balanced lipophilicity (ClogP 2.35) and efficiency (LE 0.32) as AChE inhibitor. The results add important information to future design of dual H₃ R-cholinesterases ligands.

Exploration of piperazine-derived thioureas as antibacterial and anti-inflammatory agents. In vitro evaluation against clinical isolates of colistin-resistant Acinetobacter baumannii

A. baumannii is one of the most important multidrug-resistant microorganisms in hospital units. It is resistant to many classes of antibiotics and the development of new therapeutic strategies is necessary. The aim of this study was to evaluate the antibacterial activity of a set of piperazine-derived thioureas against 13 clinical strains of colistin-resistant A. baumannii. Six derivatives were identified to inhibit bacterial growth of 46% of the A. baumannii strains at low micromolar concentrations (Minimum Inhibitory Concentration from 1.56 to 6.25 μM). A common structural feature in most active compounds was the presence of a 3,5-bis-trifluoromethyl phenyl ring at the thiourea function. In addition, the ability of the compounds to inhibit production of nitric oxide (NO) was examined in RAW 264.7 murine macrophages, highlighting the potential of piperazine-derived thioureas as promising scaffolds for the design of new combined anti-bacterial/anti-inflammatory agents.

Enigmatic Histamine Receptor H4 for Potential Treatment of Multiple Inflammatory, Autoimmune, and Related Diseases

The histamine H4 receptor, belonging to the family of G-protein coupled receptors, is an increasingly attractive drug target. It plays an indispensable role in many cellular pathways, and numerous H4R ligands are being studied for the treatment of several inflammatory, allergic, and autoimmune disorders, including pulmonary fibrosis. Activation of H4R is involved in cytokine production and mediates mast cell activation and eosinophil chemotaxis. The importance of this receptor has also been shown in inflammatory models: peritonitis, respiratory tract inflammation, colitis, osteoarthritis, and rheumatoid arthritis. Recent studies suggest that H4R acts as a modulator in cancer, neuropathic pain, vestibular disorders, and type-2 diabetes, however, its role is still not fully understood.

Novel potent vasodilating agents: Evaluation of the activity and potency of LINS01005 and derivatives in rat aorta

Cardiovascular diseases (CVDs) present high prevalence rates in the current world. It is estimated that approximately one-third of the global deaths are related to CVDs, and thus there is still a need for novel drugs to treat these disorders. We serendipitously discovered that LINS01005 (5a) is a potent vasodilating agent in rat aorta, and therefore a set of analogues were evaluated for the vasodilating potency in Wistar and SHR rat thoracic aorta precontracted with norepinephrine, with endothelium intact (E+) or denuded (E-) aortic rings. Compounds 5a and 5b were the most potent, showing submicromolar potency for endothelium intact vessels (EC₅₀ 853 and 941 nM, respectively) and micromolar values for E- vessels (EC₅₀ 2.4 and 7.1 µM, respectively). These compounds were indeed significantly more potent vasodilating agents in SHR-derived aortic rings (p < 0.001), showing nanomolar potency for 5a [EC₅₀ 2.4 nM (E+) 9.0 nM (E-)] and 5b [EC₅₀ 20 nM (E+) 2.1 µM (E-)]. SAR analysis though PCA and HCA were performed, suggesting that N-phenylpiperazine is essential to the activity, while increasing volume in the substituted aromatic moiety is detrimental to the potency. This is the first report of the vasodilating properties of such compounds, and studies regarding the mechanism of action are in progress in our group.

An update on benzofuran inhibitors: a patent review

Introduction: Benzofuran is a fundamental unit in numerous bioactive heterocycles. They have attracted chemists and medical researchers due to their broad range of biological activity, where some of them possess unique anticancer, antitubercular, antidiabetic, anti-Alzheimer and anti-inflammatory properties. The benzofuran nucleus is present in a huge number of bioactive natural and synthetic compounds. Benzofuran derivatives have potent applications in pharmaceuticals, agriculture, and polymers. The recent developments considering the biological activities of benzofuran compounds are reported. They have a vital role as pronounced inhibitors against a number of diseases, viruses, fungus, microbes, and enzymes. Areas covered: This review covers the recent developments of biological activities of benzofurans during the period 2014-2019. The covered areas here comprised antimicrobial, anti-inflammatory, antitumor, antitubercular, antidiabetic, anti-Alzheimer, antioxidant, antiviral, vasorelaxant, anti-osteoporotic and enzyme inhibitory activities. Expert opinion: In addition to the already commercialized 34 benzofurans-based drugs in the market, this chapter outlines several potent benzofuran derivatives that may be useful as potential pro-drugs. It is also focused on providing details of SAR and the effect of certain functional groups on the activity of the benzofuran compounds. The presence of -OH, -OMe, sulfonamide, or halogen contributed greatly to increasing the therapeutic activities comparing with reference drugs.

Pharmacological Characterization of 5-Substituted 1-[(2,3-dihydro-1-benzofuran-2-yl)methyl]piperazines: Novel Antagonists for the Histamine H3 and H4 Receptors with Anti-inflammatory Potential

The histamine receptors (HRs) are traditional G protein-coupled receptors of extensive therapeutic interest. Recently, H₃R and H₄R subtypes have been targeted in drug discovery projects for inflammation, asthma, pain, cancer, Parkinson’s, and Alzheimer’s diseases, which includes searches for dual acting H₃R/H₄R ligands. In the present work, nine 1-[(2,3-dihydro-1-benzofuran-2-yl)methyl]piperazine (LINS01 series) molecules were synthesized and evaluated as H₃R and H₄R ligands. Our data show that the N-allyl-substituted compound LINS01004 bears the highest affinity for H₃R (pK_i 6.40), while the chlorinated compound LINS01007 has moderate affinity for H₄R (pK_i 6.06). In addition, BRET assays to assess the functional activity of G_i1 coupling indicate that all compounds have no intrinsic activity and act as antagonists of these receptors. Drug-likeness assessment indicated these molecules are promising leads for further improvements. In vivo evaluation of compounds LINS01005 and LINS01007 in a mouse model of asthma showed a better anti-inflammatory activity of LINS01007 (3 g/kg) than the previously tested compound LINS01005. This is the first report with functional data of these compounds in HRs, and our results also show the potential of their applications as anti-inflammatory.