Biological and medicinal significance of benzofuran

A formal [4 + 1] annulation incorporating styrylogous aldol condensation to access functionalized 2-styryl-benzofurans

Despite the well-established aldol reaction and its vinylogous variants, the styrylogous version has been scarcely reported. Herein, we have introduced a styrylogous aldol condensation reaction. A novel base-mediated formal [4 + 1] annulation, integrating O-allylation and styrylogous aldol condensation, has been disclosed. This transformation involves ortho-hydroxyaryl aldehydes/ketones in conjunction with distally-activated cinnamyl (pseudo)halides. The presented transition metal-free process forms C-O and CC bonds, enabling the synthesis of functionalized 2-styryl-benzofuran derivatives in moderate to good yields. The application potential of the developed method has been demonstrated in the efficient syntheses of 2-aminostyryl-benzofuran derivatives, which have proven to act as potent inhibitors for Aβ fibril formation related to Alzheimer's disease (AD).

Direct Access to Benzofurans and Indoles from Ethylene with 2-Methylphenols/Anilines through Iridium-Catalyzed Dehydrogenative Annulation

The direct conversion of o-cresol and 2-methylphenols to 2-methylbenzofurans was achieved by an Ir/DTBE-DPPE-catalyzed reaction under an atmosphere of ethylene (1 atm). The reaction involves the initial selective formation of a C-C bond at the benzylic C(sp3)-H bond of 2-methylphenols with ethylene without the accommodation of the C(sp2)-H bonds at the 6-positions, which is followed by subsequent C-O bond-forming annulation along with associated dehydrogenation and double bond migration steps. The reaction conditions also allowed for the direct conversion of o-toluidine and 2-methylanilines into 2-methylindoles.

Does Lagenaria siceraria seed oil-enriched extender regulate sperm quality, oxidant/antioxidant markers, and sperm mitochondrial enzymes in chilled diluted rabbit semen?

This study investigated the cryoprotective effects of Lagenaria siceraria seed oil (BG) on rabbit sperm quality during a 72-hour period of chilled storage at 4 °C. While a prevalent method for preserving rabbit semen, cryopreservation can elicit cold shock and other stressors, resulting in a decline in sperm quality. Thereafter, the researchers hypothesized that BG, potentially due to its antioxidant properties, could mitigate these detrimental effects. For the experiment, semen samples were diluted in extender and assigned to treatment groups receiving BG at concentrations of 0 (BG0), 100 (BG100), 200 (BG200), or 400 (BG400) µL/mL, followed by storage at 4 °C. Sperm quality parameters (motility, viability, membrane integrity, and morphology) were assessed at 24-, 48-, and 72-hour time points of storage. Results indicated a quadratic improvement in sperm motility, viability, and membrane integrity with the addition of 100 or 200 µL/mL of BG across all time points (P < 0.01). A quadratic relationship was observed between BG supplementation levels and the concentrations of GPx and SOD, indicating a dose-dependent increase. BG treatment at all concentrations led to elevated total antioxidant capacity (TAC) compared to the control, with peak TAC values at 200 and 400 µL/mL BG. Conversely, nitric oxide (NO) levels significantly decreased (P < 0.001) with increasing BG dosage. BG treatment significantly decreased malondialdehyde, H₂O₂, and protein carbonyl levels compared to the control (P < 0.01). Additionally, succinate dehydrogenase (SDH) and malate dehydrogenase (MDH) activities were significantly and quadratically improved at BG concentrations of 200 and 400 µL/mL relative to the 100 µL/mL concentration. In conclusion, supplementing rabbit semen extenders with BG significantly enhanced sperm quality during 72-hour chilled storage by attenuating oxidative stress, bolstering antioxidant capacity, and promoting mitochondrial enzyme activity. These findings suggest that BG is a promising additive for improving the preservation of chilled rabbit semen, potentially benefiting artificial insemination and rabbit breeding programs.

Solvent-Controlled Enantioselective Allylic C-H Alkylation of 2,5-Dihydrofuran via Synergistic Palladium/Nickel Catalysis

Enantioenriched, substituted tetrahydrofuran skeletons extensively occur in natural products, bioactive targets, and organic frameworks. The rapid and diverse synthesis of these tetrahydrofuran molecules is highly desired yet challenging. Herein, we present a practical synthetic strategy for asymmetric allylic C-H bond functionalization of oxyheterocyclic alkenes by making use of the synergistic catalysis of achiral Pd complex and chiral N,N'-dioxide-Ni(II) catalyst. Notably, the chemodivergent synthesis of allylic C-H alkylated products and hydroalkylated products was readily achieved in good outcomes via the regulation of solvents. Furthermore, the post-transformation of these functionalized 2,5-dihydrofurans provides an innovative synthetic route to access tetrahydrofuran skeleton compounds containing multiple stereocenters.

Gold(I)-Catalyzed Synthesis of Benzofurans from Tetrahydropyranyl (THP) Ethers of o-Alkynylphenols

The activation of π-systems in alkenes and alkynes by homogeneous gold catalysts is a powerful tool for the synthesis of benzo-fused heterocycles. Decades of development in the area of gold catalysis have brought an array of new catalysts and with them the discovery of new modes of carbophilic activation of π-systems in alkenes and alkynes, and investigations of previously unknown mechanistic pathways. In alignment with these efforts, we report a cyclization of tetrahydropyranyl ethers of 2-alkynylphenols to form benzofurans catalyzed by a gold(I)-NHC complex. The reaction proceeds efficiently at very low catalyst loadings, and the products form in good yields.

Regiodivergent and Enantioselective Allylic C-H Alkylation of Allyl Ethers: Optimization, Scope, Mechanism and Application

Vinyl ethers and allyl ethers are important motifs in natural products and pharmaceuticals. Among various methods toward their synthesis, direct allylic C-H functionalization of allyl ethers is one of the most efficient approaches. In this study, one of two regioisomers, a vinyl ether or an allyl ether, could be obtained, depending on whether a Lewis acid co-catalyst was present. Furthermore, branched allyl ethers were smoothly prepared in excellent regio- and enantioselectivity (up to 20 : 1 b/l, 99 % ee) by synergistic catalysis with an achiral Pd(0) complex and a chiral Lewis acid catalyst.

Ligand-Modulated Nickel/Photoredox-Catalyzed exo-Arylalkylation of Alkynes

A ligand-modulated synergetic nickel/photoredox-catalyzed exo-arylalkylation of unactivated alkynes was developed that was strikingly different from the known endo-arylalkylation of activated arylacetylenes. The unique arylalkylation pathway was due to the formation of a π-allyl-Ni complex from alkyne where the nickel species was engaged in a distinctive dual-catalytic cycle. The nickel/photoredox-catalyzed exo-alkenylation was applied to the divergent synthesis of tryptamines and benzofurylethylamines.

Benzofuran-Chalcone Derivatives as VEGFR-2 Inhibitors: Synthesis and Anticancer Evaluation

The discovery and development of efficient VEGFR-2 inhibitors has become a research hotspot in cancer treatment. In this work, a series of new benzofuran-based chalcone derivatives have been prepared, and in vitro anticancer activities have been evaluated. The results revealed that derivatives showed selective cytotoxic activity against HCC1806, Hela, and A549 cell lines, especially 5c exhibited excellent inhibitory effect on VEFGR-2 (IC50 = 1.07 nM). The molecular docking study indicated that 5c had an obvious binding site with the target VEGFR-2 (PDB ID: 3V6B). Therefore, the benzofuran-based chalcone derivatives could be considered as potent VEGFR-2 inhibitors for further study.

Ylide-Induced Ring Contraction of Coumarins to Benzofurans: Applications to the Synthesis of Bis-Heterocycles

We report an unusual ring contraction of 4-chlorocoumarin to benzofuranoyl sulfoxonium ylides using a Corey-ylide. These stabilized ylides were subsequently utilized for the synthesis of various valuable bis-heterocycles under both metal and metal-free conditions. The synthetic utility of this method is illustrated through the synthesis of known bioactive compounds. Detailed mechanistic investigations and quantum chemical calculations have provided valuable insights into the mechanism of the ring contraction reaction.

Design, synthesis, and evaluation of novel benzofuran and pyrazole-based derivatives as dual AChE/BuChE inhibitors with antioxidant properties for Alzheimer's disease management

As a complicated neurodegenerative disorder with several clinical hallmarks, Alzheimer's disease (AD) requires multi-target treatment medicines to address multiple elements of disease progression. In this study, we reported two novel series of compounds: benzofuran-based donepezil analogs (9a-i) and their pyrazole-based counterparts (11a-i) as potential dual inhibitors of AChE and BuChE with additional antioxidant properties, aiming to address multiple pathological aspects of AD simultaneously. The design strategy employed bioisosteric replacement, substituting donepezil's indanone motif with a benzofuran ring in series (9a-i) to maintain crucial hydrogen bonding interactions with the Phe295 residue in the enzyme's active site. Subsequently, the benzofuran ring underwent cleavage, yielding pyrazole-tethered hydroxyphenyl derivatives (11a-i). The biological evaluation revealed that benzofuran-based derivative 9g exhibited exceptional efficacy against both AChE and BuChE, with IC50 values of 0.39 and 0.51 μg/ml, respectively, although it lacked antioxidant activity. Compound 11f demonstrated dual inhibition of AChE (IC50 = 1.24 μg/ml) and BuChE (IC50 = 1.85 μg/ml) while also displaying strong DPPH free radical scavenging activity (IC50 = 3.15 μg/ml). In vivo toxicity studies on compound 11f revealed a favorable safety profile, with no signs of toxicity or adverse events in acute oral toxicity tests in male Wistar rats. Chronic administration of 11f resulted in negligible differences in blood profiles, hepatic enzymes, urea, creatinine, and albumin levels compared to the control group. Histopathological examination of hepatic and kidney tissues from treated rats showed normal histology without damage. In silico molecular docking analysis was performed to rationalize the design approaches and support the experimental findings. This study provides valuable insights into the development of multi-target compounds for potential Alzheimer's disease treatment.

Recent Developments on the Synthesis of Oxygen- and Sulfur-containing Heterocycles and their Derivatives under Visible Light Induced Reactions

Visible-light-mediated reactions have recently emerged as a powerful strategy for the synthesis of diverse organic molecules under mild reaction conditions. Usually, the reactions are performed at room temperature and thus sensitive functional groups remain unaffected. Thus, this protocol has received intense interest from academia as well as industries. The heterocycles, in general, are of much interest because of their biological activities and application in therapeutics. The Oxygen- and Sulfur-containing heterocyclic compounds have recently attracted attention as these compounds showed promising activities as anti-cancer drugs, antibiotics, antifungal and anti-inflammatory agents among other applications. The synthesis of this class of compounds by efficient and greener routes has become an important target. This review highlights the various procedures for the synthesis of these compounds and their derivatives under visible light-induced reactions. The green aspects and mechanism of each procedure have been discussed.

Repurposing Benzbromarone as an Antibacterial Agent against Gram-Positive Bacteria

The rise of antibiotic-resistant Gram-positive pathogens, particularly methicillin-resistant Staphylococcus aureus (MRSA), presents a significant challenge in clinical settings. There is a critical need for new antibacterial agents to combat these resistant strains. Our study reveals that the uricosuric drug Benzbromarone (Benz) exhibits potent antibacterial activity against Gram-positive pathogens, with minimum inhibitory concentrations (MICs) ranging from 8 to 32 μg/mL and minimum bactericidal concentrations (MBCs) ranging from 32 to 128 μg/mL against clinical isolates of S. aureus, S. epidermidis, Enterococcus faecalis, and Streptococcus agalactiae. Furthermore, Benz significantly inhibits biofilm formation at subinhibitory concentrations and eradicates mature biofilms at higher concentrations. Benz also suppresses the hemolytic activity of S. aureus, indicating its potential to reduce virulence. Proteomic and in vitro induced resistance analyses indicate that Benz inhibits protein synthesis and turnover. Additionally, Benz induces membrane depolarization and increases membrane permeability, likely by targeting the membrane phospholipid phosphatidylethanolamine (PE). In the mouse wound infection model, Benz promotes wound healing and significantly reduces bacterial load. These findings suggest that Benz is a promising candidate for developing new antibacterial therapies against Gram-positive bacterial infections.

New Benzofuran-Pyrazole-Based Compounds as Promising Antimicrobial Agents: Design, Synthesis, DNA Gyrase B Inhibition, and In Silico Studies

BACKGROUND/OBJECTIVES

The alarming rise in antibiotic resistance necessitates the discovery of novel antimicrobial agents. This study aims to design, synthesize, and evaluate new benzofuran-pyrazole-based compounds for their antimicrobial, antioxidant, and anti-inflammatory properties.

METHODS

New benzofuran-pyrazole hybrid molecules were synthesized using the Vilsmeier-Haach reaction and other chemical processes. The structures of the synthesized compounds were confirmed through micro-analytical and spectral analyses. Their antimicrobial activities were assessed against various bacterial and fungal strains, while antioxidant and anti-inflammatory properties were evaluated using DPPH-free radical scavenging and HRBC membrane stabilization assays, respectively. The most promising compounds were further tested for DNA gyrase B inhibition.

RESULTS

Compounds 9, 10, and 11b-d exhibited significant broad-spectrum antimicrobial activity with MIC values ranging from 2.50 to 20 µg/mL. Compounds 4, 6, 9, 11b, and 11d demonstrated high antioxidant activity, with DPPH scavenging percentages between 84.16% and 90.52%. Most compounds showed substantial anti-inflammatory effects, with HRBC membrane stabilization percentages ranging from 86.70% to 99.25%. Compound 9 notably inhibited E. coli DNA gyrase B with an IC50 of 9.80 µM, comparable to ciprofloxacin.

CONCLUSIONS

The benzofuran-pyrazole-based compounds, particularly compound 9, show great potential as new antimicrobial agents due to their broad-spectrum activity and potent DNA gyrase B inhibition. These findings support further development and optimization of these compounds for clinical applications.

Synthesis of Indole- and Benzofuran-Based Benzylic Sulfones by Palladium-Catalyzed Sulfonylation of ortho-Iodoaryl Allenes

A highly efficient palladium-catalyzed domino coupling reaction of ortho-iodoaryl allene with sodium sulfonates under mild conditions is described. This novel method provides a practical protocol to access diverse indole- and benzofuran-containing sulfones by simultaneous construction of C(sp2)-C(sp2) bond and a C(sp3)-S bonds in one pot. The salient features of this transformation include simple operations, broad substrate scope, and good functional group tolerance.

Base-Mediated Annulation of ortho-Iminophenols and ortho-Vinylphenols with MBH Carbonates of Isatins: Straightforward Access to Dihydrobenzofuran and Benzofuran Derivatives

We have developed a convenient synthetic protocol for efficient construction of significant dihydrobenzofuran and benzofuran scaffolds by Lewis base-mediated annulation reaction ortho-iminophenols and ortho-vinylphenols with MBH carbonates of isatins under mild and metal-free conditions. The selective generation of different kinds of dihydrobenzofuran and benzofuran derivatives was successfully achieved by employing different substituted isatin-derived MBH carbonates with ortho-N-tosyliminophenols and ortho-vinylphenols. The features included broad substrate scopes, excellent functional group compatibility, high molecular diversity, and atomic economy.

Synthesis and anti-tumor activity of new benzofuran-based chalcone derivatives as potent VEGFR-2 inhibitors

Cancer is one of the most significant public health problems worldwide, and the discovery and development of efficient VEGFR-2 inhibitors has been a research hotspot in cancer treatment. In the present work, a series of novel benzofuran-based chalcone derivatives have been prepared, and in vitro anti-tumor activities of them have been evaluated. The results indicated that the compounds displayed potent anticancer activity against HCC1806, HeLa and A549 cell lines. The preliminary mechanism study showed that 4g could effectively induce the apoptosis of HCC1806 cells, and showed inhibitory effect on VEFGR-2. The molecular docking study indicated that 4g had an obvious binding site with the target VEGFR-2 (PDB ID: 4BSK). Therefore, the benzofuran-based chalcone derivatives could be considered as potent VEGFR-2 inhibitors.

Photocatalytic Sulfonylation: Innovations and Applications

Photosynthesis, converting sustainable solar energy into chemical energy, has emerged as a promising craft to achieve diverse organic transformations due to its mild reaction conditions, sustainability, and high efficiency. The synthesis of sulfonated compounds has drawn significant attention in the pharmaceuticals, agrochemicals, and materials industries due to the unique structure and electronic properties of the sulfonyl groups. Over the past decades, many photocatalytic sulfonylation reactions have been developed. In this review, the recent advances in photocatalyzed sulfonylation have been reviewed since 2020, with a primary focus on discussing reaction design and mechanism.

A one-pot five component reaction for the synthesis of tetrazol-benzofuran hybrids and their inhibitory activity against Mucor lusitanicus

A synthetic strategy for obtaining a new series of 1,5-disubstituted tetrazole-benzofuran hybrid systems via a one-pot five-component reaction is described. This process involves a Ugi-azide multicomponent reaction coupled to an intramolecular cyclization catalyzed by Pd/Cu, resulting in low to moderate yields from 21 to 67%. This protocol allowed the synthesis of highly substituted benzofurans at the 2-position through an operationally simple process under mild reaction conditions and with high bond forming efficiency due to the formation of six new bonds (two C-C, two C-N, one N-N, and one C-O). Besides, to evaluate the antifungal activity of 1,5-disubstituted tetrazole-benzofurans 9a-n, in vitro studies against Mucor lusitanicus were performed, finding that compound 9b exhibits bioactivity comparable to the commercial antifungal drug Amphotericin B. These results suggest potential for use in controlling mucormycosis infections in animal models, highlighting the importance of these findings given the limited antifungal drug options and high mortality rates associated with this infection.

Discovery of 7-alkoxybenzofurans as PDE4 inhibitors with hepatoprotective activity in D-GalN/LPS-induced hepatic sepsis

Sepsis can quickly result in fatality for critically ill individuals, while liver damage can expedite the progression of sepsis, necessitating the exploration of new strategies for treating hepatic sepsis. PDE4 has been identified as a potential target for the treatment of liver damage. The scaffold hopping of lead compounds FCPR16 and Z19153 led to the discovery of a novel 7-methoxybenzofuran PDE4 inhibitor 4e, demonstrating better PDE4B (IC50 = 10.0 nM) and PDE4D (IC50 = 15.2 nM) inhibitor activity as a potential anti-hepatic sepsis drug in this study. Compared with FCPR16 and Z19153, 4e displayed improved oral bioavailability (F = 66 %) and longer half-life (t1/2 = 2.0 h) in SD rats, which means it can be more easily administered and has a longer-lasting effect. In the D-GalN/LPS-induced liver injury model, 4e exhibited excellent hepatoprotective activity against hepatic sepsis by decreasing ALT and AST levels and inflammatory infiltrating areas.

BM7, a derivative of benzofuran, effectively fights cancer by promoting cancer cell apoptosis and impacting IL-6 levels

The BM7 compound, a bromo derivative of methyl 6-acetyl-5-hydroxy-2-methyl-1-benzofuran-3-carboxylate, was previously identified as cytotoxic to human leukaemia cells (K562 and HL60) and human cervical cancer (HeLa), while showing no toxicity to non-cancerous primary endothelial cells (HUVEC). In this study, we present the first demonstration of BM7's anticancer efficacy in vivo using a mouse chronic myeloid leukaemia xenograft model. Administered intraperitoneally in a mixture of 10% Solutol HS 15/10% ethanol, BM7 exhibited no visible toxicity and significantly reduced tumor weight, comparable to standard drugs imatinib and hydroxyurea. Further supporting its anticancer potential, a multi-model in vitro study involving seven human cancer cell lines revealed the most promising responses in colon cancer (SW480, SW620, HCT116), liver cancer (HEPG2), and breast adenocarcinoma (MDA-MB-231) cells. BM7 demonstrated multifaceted anticancer mechanisms, inducing apoptosis while elevating reactive oxygen species (ROS) levels and suppressing interleukin-6 (IL-6) release in these cell lines. These findings position BM7 as a candidate of significant interest for cancer therapy. Its ability to not only induce apoptosis but also modulate cellular processes such as ROS levels and immune responses, specifically IL-6 suppression, makes BM7 a versatile and promising agent for further exploration in the realm of cancer treatment.

Identification of new benzofuran derivatives as STING agonists with broad-spectrum antiviral activity

The Stimulator of Interferon Genes (STING) is involved in cytosolic DNA sensing and type I Interferons (IFN-I) induction. Aiming to identify new STING agonists with antiviral activity and given the known biological activity of benzothiazole and benzimidazole derivatives, a series of benzofuran derivatives were tested for their ability to act as STING agonists, induce IFN-I and inhibit viral replication. Compounds were firstly evaluated in a gene reporter assay measuring luciferase activity driven by the human IFN-β promoter in cells expressing exogenous STING (HEK293T). Seven of them were able to induce IFN-β transcription while no induction of the IFN promoter was observed in the presence of a mutated and inactive STING, showing specific protein-ligand interaction. Docking studies were performed to predict their putative binding mode. The best hit compounds were then tested on human coronavirus 229E replication in BEAS-2B and MRC-5 cells and three derivatives showed EC50 values in the μM range. Such compounds were also tested on SARS-CoV-2 replication in BEAS-2B cells and in Calu-3 showing they can inhibit SARS-CoV-2 replication at nanomolar concentrations. To further confirm their IFN-dependent antiviral activity, compounds were tested to verify their effect on phospho-IRF3 nuclear localization, that was found to be induced by benzofuran derivatives, and SARS-CoV-2 replication in Vero E6 cells, lacking IFN production, founding them to be inactive. In conclusion, we identified benzofurans as STING-dependent immunostimulatory compounds and host-targeting inhibitors of coronaviruses representing a novel chemical scaffold for the development of broad-spectrum antivirals.

Synthesis of 2,3-Dialkyl-5-hydroxybenzofurans via a One-pot, Three-step Reaction Sequence of 2-Monosubstituted 1,3-Diketones and 1,4-Benzoquinones

An economical one-pot, three-step reaction sequence of readily available 2-monosubstituted 1,3-diketones and 1,4-benzoquinones has been explored for the facile access of 2,3-dialkyl-5-hydroxybenzofurans. By using cheap K2CO3 and conc. HCl as the reaction promoters, the reaction occurs smoothly via sequential Michael addition, aromatization, retro-Claisen, deacylation, hemiketalization, and dehydration processes under mild conditions in a practical manner. Additionally, an interesting phenomenon was observed during the derivatization studies, where the dihydroquinoline was converted into tetrahydroquinoline and quinoline products, respectively, via a disproportionation process.

Palladium-Catalyzed Three-Component Cascade Carbonylation Reaction to Construct Benzofuran Derivatives

A novel three-component cyclization carbonylation reaction of iodoarene-tethered propargyl ethers with amine and CO is reported. This palladium-catalyzed cascade reaction undergoes a sequence of oxidative addition, unsaturated bond migration, carbonyl insertion, and nucleophilic attack to deliver the benzofuran skeleton. Both aromatic amines and aliphatic amines could proceed smoothly in this transformation under one atm of CO.

A Comprehensive Review on Benzofuran Synthesis Featuring Innovative and Catalytic Strategies

Benzofurans have intrigued both pharmaceutical researchers and chemists owing to the medicinal usage of their derivatives against copious disease-causing agents (i.e., bacteria, viruses, and tumors). These heterocyclic scaffolds are pervasively encountered in a number of natural products and drugs. The ever-increasing utilization of benzofuran derivatives as pharmaceutical agents persuaded the chemists to devise novel and facile methodological approaches to assemble the biologically potent benzofuran nucleus. This review summarizes the current developments regarding the innovative synthetic routes and catalytic strategies to procure the synthesis of benzofuran heterocycles with their corresponding mechanistic details, reported by several research groups during 2021-2023.

Difluorocarbene Enables Access to 2,2-Difluorohydrobenzofurans and 2-Fluorobenzofurans from ortho-Vinylphenols

2-Fluorobenzofurans are the backbone structures of many drug molecules and have many potential therapeutic bioactivities. Despite the potential applications in medicinal chemistry, practical and efficient synthetic methods for the construction of 2-fluorobenzofuran are very limited. Herein, we report an efficient and general method for the construction of 2-fluorobenzofurans. Contrary to the previous functionalizations of the existing backbone of benzofuran, our strategy directly constructs benzofuran scaffolds alongside the incorporation of fluorine atom on C2 position in a formal [4 + 1] cyclization from readily accessible ortho-vinylphenols and difluorocarbene. In our strategy, ClCF2H decomposes into difluorocarbene in the presence of base, which is further captured by the oxygen anion from the hydroxy group in ortho-hydroxychalcones; subsequent intramolecular Michael addition to the α, β-unsaturated system leads to 2,2-difluorohydrobenzofurans, and further fluorine elimination renders 2-fluorobenzofurans by forming one C-O bond and one C-C double bond. Of note, various complex 2,2-difluorohydrobenzofurans and 2-fluorobenzofurans could be readily accessed through our protocol via the late-stage elaborations.

Design, Synthesis, Antibacterial Activity, and Mechanisms of Novel Benzofuran Derivatives Containing Disulfide Moieties

The unsatisfactory effects of conventional bactericides and antimicrobial resistance have increased the challenges in managing plant diseases caused by bacterial pests. Here, we report the successful design and synthesis of benzofuran derivatives using benzofuran as the core skeleton and splicing the disulfide moieties commonly seen in natural substances with antibacterial properties. Most of our developed benzofurans displayed remarkable antibacterial activities to frequently encountered pathogens, including Xanthomonas oryzae pv oryzae (Xoo), Xanthomonas oryzae pv oryzicola (Xoc), and Xanthomonas axonopodis pv citri (Xac). With the assistance of the three-dimensional quantitative constitutive relationship (3D-QSAR) model, the optimal compound V40 was obtained, which has better in vitro antibacterial activity with EC50 values of 0.28, 0.56, and 10.43 μg/mL against Xoo, Xoc, and Xac, respectively, than those of positive control, TC (66.41, 78.49, and 120.36 μg/mL) and allicin (8.40, 28.22, and 88.04 μg/mL). Combining the results of proteomic analysis and enzyme activity assay allows the antibacterial mechanism of V40 to be preliminarily revealed, suggesting its potential as a versatile bactericide in combating bacterial pests in the future.

"On-Water" accelerated dearomative cycloaddition via aquaphotocatalysis

Sulfur(VI) fluoride exchange (SuFEx) has emerged as an innovative click chemistry to harness the pivotal connectivity of sulfonyl fluorides. Synthesizing such alkylated S(VI) molecules through a straightforward process is of paramount importance, and their water-compatibility opens the door to a plethora of applications in biorelevant and materials chemistry. Prior aquatic endeavors have primarily focused on delivering catalysts involving ionic mechanisms, studies regarding visible-light photocatalytic transformation are unprecedented. Herein we report an on-water accelerated dearomative aquaphotocatalysis for heterocyclic alkyl SuFEx hubs. Notably, water exerts a pronounced accelerating effect on the [2 + 2] cycloaddition between (hetero)arylated ethenesulfonyl fluorides and inert heteroaromatics. This phenomenon is likely due to the high-pressure-like reactivity amplification at the water-oil interface. Conventional solvents proved totally ineffective, leading to the isomerization of the starting material.

Development of novel transition metal-catalyzed synthetic approaches for the synthesis of a dihydrobenzofuran nucleus: a review

The synthesis of dihydrobenzofuran scaffolds bears pivotal significance in the field of medicinal chemistry and organic synthesis. These heterocyclic scaffolds hold immense prospects owing to their significant pharmaceutical applications as they are extensively employed as essential precursors for constructing complex organic frameworks. Their versatility and importance make them an interesting subject of study for researchers in the scientific community. While exploring their synthesis, researchers have unveiled various novel and efficient pathways for assembling the dihydrobenzofuran core. In the wake of extensive data being continuously reported each year, we have outlined the recent updates (post 2020) on novel methodological accomplishments employing the efficient catalytic role of several transition metals to forge dihydrobenzofuran functionalities.

Diastereoselective Synthesis of Dihydrobenzofuran Spirooxindoles and Their Transformation into Benzofuroquinolinones by Ring Expansion of Oxindole Core

A mild and efficient approach for the diastereoselective synthesis of dihydrobenzofuran spirooxindoles using 3-chlorooxindoles and imines is presented. This process involves a formal [4 + 1] annulation, yielding the product with excellent diastereoselectivity. Furthermore, a novel method for constructing benzofuroquinolinone scaffolds through the ring expansion of oxindoles has been established. This method involves a lactam ring expansion to the quinolinone skeleton. Besides, a one-pot procedure for creating benzofuroquinolinone scaffolds from 3-chlorooxindoles and imines is also provided.

Synthesis of Benzofuran-Fused Oxepines through Cs2CO3-Promoted [4 + 3] Annulation of Aurones with Crotonate-Derived Sulfonium Salts

Benzofuran-fused derivatives display important and reliable therapeutic properties. Herein, we describe the synthesis of benzofuran-fused oxepines using aurones and crotonate-derived sulfonium salts via a [4 + 3] annulation reaction in the presence of Cs2CO3. This reaction proceeds under mild and operationally simple conditions. The synthetic utility of this approach was highlighted by several transformations, including the efficient synthesis of a novel tetracyclic fused benzofuran derivative.

Anticancer Evaluation of Novel Benzofuran-Indole Hybrids as Epidermal Growth Factor Receptor Inhibitors against Non-Small-Cell Lung Cancer Cells

The epidermal growth factor receptor (EGFR), also known as ErbB1 and HER1, belongs to the receptor tyrosine kinase family. EGFR serves as the primary driver in non-small-cell lung cancer (NSCLC) and is a promising therapeutic target for NSCLC. In this study, we synthesized a novel chemical library based on a benzofuran-indole hybrid scaffold and identified 8aa as a potent and selective EGFR inhibitor. Interestingly, 8aa not only showed selective anticancer effects against NSCLC cell lines, PC9, and A549, but it also showed significant inhibitory effects against the double mutant L858R/T790M EGFR, which frequently occurs in NSCLC. In addition, in PC9 and A549 cells, 8aa potently blocked the EGFR signaling pathway, cell viability, and cell migration. These findings suggest that 8aa, a benzofuran-indole hybrid derivative, is a novel EGFR inhibitor that may be a potential candidate for the treatment of NSCLC patients with EGFR mutations.

Microtubule destabilising activity of selected 7-methoxy-2-phenylbenzo[b]furan derivative against primary and metastatic melanoma cells

Herein, we report the results of anticancer screening of two 2-phenylbenzo[b]furan derivatives functionalised at the 3-position with 4-hydroxy-3,5-dimethoxybenzoyl (BF2) or 3,4,5-trimethoxybenzoyl (BF3) against 60 different cancer cell lines. The results confirmed the anticancer potential of the tested compounds against different cancer cell types, especially colon cancer, brain cancer and melanoma. BF3 was defined as the most potent (also as a tubulin polymerisation inhibitor). Its anticancer activity against melanoma cell lines that originated from different stages, i.e., primary skin-derived A375 and metastatic WM9/MDA-MB-435S, was evaluated (as the clinical success of melanoma therapy strictly depends on the disease stage). Moreover, to determine the BF3 mode of action and its effect on cell proliferation, intracellular microtubule networks, cell cycle phase distribution and apoptosis were evaluated. Our study revealed that BF3 inhibited cell proliferation in a dose-dependent manner, with IC50 yielding 0.09 ± 0.01 μM, 0.11 ± 0.01 μM and 0.18 ± 0.05 μM for A375, MDA-MB435S and WM9, respectively. The strong antiproliferative activity of compound BF3 correlated well with its inhibitory effect on tubulin polymerisation. Molecular docking proved that BF3 belongs to the colchicine binding site inhibitors (CBSIs), and experimental studies revealed that it disturbs cell cycle progression leading to G2/M arrest and apoptosis.

Direct α-Arylation of Benzo[b]furans Catalyzed by a Pd3 Cluster

As an interim paradigm for the catalysts between those based on more conventional mononuclear molecular Pd complexes and Pdn nanoparticles widely used in organic synthesis, polynuclear palladium clusters have attracted great attention for their unique reactivity and electronic properties. However, the development of Pd cluster catalysts for organic transformations and mechanistic investigations is still largely unexploited. Herein, we disclose the use of trinuclear palladium (Pd3Cl) species as an active catalyst for the direct C-H α-arylation of benzo[b]furans with aryl iodides to afford 2-arylbenzofurans in good yields under mild conditions. With this method, broad substrate adaptability was observed, and several drug intermediates were synthesized in high yields. Mechanistic studies indicated that the Pd3 core most likely remained intact throughout the reaction course.

Mask and Release Strategy-Enabled Diversity-Oriented Synthesis for DNA-Encoded Library

An ideal DNA-encoded library (DEL) selection requires the library to consist of diverse core skeletons and cover chemical space as much as possible. However, the lack of efficient on-DNA synthetic approaches toward core skeletons has greatly restricted the diversity of DEL. To mitigate this issue, this work disclosed a "Mask & Release" strategy to streamline the challenging on-DNA core skeleton synthesis. N-phenoxyacetamide is used as a masked phenol and versatile directing group to mediate diversified DNA-compatible C-H functionalization, introducing the 1st-dimensional diversity at a defined site, and simultaneously releasing the phenol functionality, which can facilitate the introduction of the 2nd diversity. This work not only provides a set of efficient syntheses toward DNA-conjugated drug-like core skeletons such as ortho-alkenyl/sulfiliminyl/cyclopropyl phenol, benzofuran, dihydrobenzofuran but also provides a paradigm for on-DNA core skeleton synthetic method development.

Scalable Diastereoselective Electrosynthesis of Spiro[benzofuran-2,2'-furan]-3-ones

Spirobenzofuran scaffolds, because of their three-dimensional structure, are incorporated into several valuable natural products and drug candidate molecules. Herein, with the assistance of electrosynthesis, we introduce a novel electrochemical approach for achieving spirobenzofurans in a user-friendly and operationally simple undivided cell setup under constant current. This metal-catalyst-free electrochemical procedure afforded spiro[benzofuran-2,2'-furan]-3-ones with high diastereoselectivity. Compatibility with gram-scale synthesis along with the convenient accessibility of reaction instruments and starting materials collectively raised the importance of this protocol compared to previous challenging methods. Furthermore, mechanistic cognizance of this reaction is obtained by the investigation of the cyclic voltammetry spectra of reactants.

Synthesis and Cytotoxic Activity of Quinazoline-benzofuran Conjugates

AIMS

In order to study on structure-activity relationships of benzofurans.

BACKGROUND

Benzofuran is a kind of natural compound widely existing in nature with pharmacological effects. The development of new anticancer benzofuran derivatives has attracted more and more attention.

METHODS

We have introduced an active quinazoline unit into piperazine-substituted benzofuran, prepared a series of quinazoline-benzofuran compounds, and evaluated cytotoxic activity against a panel of human tumor cell lines by MTT assay.

RESULTS

48 novel quinazoline-substituted benzofuran derivatives have been prepared, and in vitro, cytotoxic activity against five human tumor cell lines was evaluated. The results indicated that some quinazoline-benzofuran conjugates showed selective inhibitory activity against tumor cell lines.

CONCLUSION

We have found that compound 14x displayed excellent cytotoxic activity, which could be considered a potential anticancer agent.

Nickel-Catalyzed Regioselectivity-Switchable Hydroheteroarylation of Vinylarenes with Electron-Rich Heteroarenes

We report the first example of a regioselectivity switch in the hydroheteroarylation of vinylarenes with electron-rich heteroarenes, including benzofurans, benzothiophenes, and indoles, using an expedient ligand-controlled strategy. In the presence of NaOtBu, Ni(IMesMe)[P(OEt)3]Br2 yields C2-alkylated heteroarenes with high branched selectivity, whereas the use of Ni(IPr*OMe)[P(OEt)3]Br2 favors the formation of the corresponding linear products. This robust method also provides easy access to a range of C2-alkylated electron-rich heteroarenes without employing directing groups.

Copper ion-based chemical elicitation induces production of new benzofurans in Anthostomella brabeji, an endophytic fungus of Paepalanthus planifolius

The present work reports the effects of chemical elicitors and epigenetic modifiers on the production and diversification of secondary metabolites produced by Anthostomella brabeji - an endophytic fungus isolated from Paepalanthus planifolius (Eriocaulaceae). The fungus was cultivated under four different small-scale culture conditions in potato dextrose broth (PDB): PDB (control), PDB + Mg+2, PDB + Cu+2 and PDB + 5-AZA (5-azacytidine). The incorporation of Cu+2 into PDB medium yielded the most promising results as the most significant differences in the metabolic profile of A. brabeji were observed under this condition. The chemical analysis of the PDB + Cu+2 extract resulted in the isolation of seven metabolites, including three new benzofuran derivatives (2, 4 and 6) and four known compounds (1, 3, 5 and 7). The metabolites were tested using the Gram-positive bacterium Staphylococcus aureus, Gram-negative bacteria Salmonella sp. and Escherichia coli, and six yeasts of Candida albicans and non-albicans. The EtOAc extract (PDB + Cu+2), and compounds 1, 2 and 7 exhibited relevant antifungal activity against Candida spp., with minimum inhibitory concentration ranging from 62.5 to 500.0 μg/mL.

Facile access to benzofuran derivatives through radical reactions with heteroatom-centered super-electron-donors

The development of suitable electron donors is critical to single-electron-transfer (SET) processes. The use of heteroatom-centered anions as super-electron-donors (SEDs) for direct SET reactions has rarely been studied. Here we show that heteroatom anions can be applied as SEDs to initiate radical reactions for facile synthesis of 3-substituted benzofurans. Phosphines, thiols and anilines bearing different substitution patterns work well in this inter-molecular radical coupling reaction and the 3-functionalized benzofuran products bearing heteroatomic functionalities are given in moderate to excellent yields. The reaction mechanism is elucidated via control experiments and computational methods. The afforded products show promising applications in both organic synthesis and pesticide development.

Discovery of novel benzofuran-based derivatives as acetylcholinesterase inhibitors for the treatment of Alzheimer's disease: Design, synthesis, biological evaluation, molecular docking and 3D-QSAR investigation

A series of novel benzofuran-based compounds 7a-s were designed, synthesized, and investigated in vitro as acetylcholinesterase inhibitors (AChEIs). Compounds 7c and 7e displayed promising inhibitory activity with IC50 values of 0.058 and 0.086 μM in comparison to donepezil with an IC50 value of 0.049 μM. The new molecules' antioxidant evaluation revealed that 7c, 7e, 7j, 7n, and 7q produced the strongest DPPH scavenging activity when compared to vitamin C. As it was the most promising AChEI, compound 7c was selected for further biological evaluation. Acute and chronic toxicity studies exhibited that 7c showed no signs of toxicity or adverse events, no significant differences in the blood profile, and an insignificant difference in hepatic enzymes, glucose, urea, creatinine, and albumin levels in the experimental rat group. Furthermore, 7c did not produce histopathological damage to normal liver, kidney, heart, and brain tissues, ameliorated tissue malonaldehyde (MDA) and glutathione (GSH) levels and reduced the expression levels of the APP and Tau genes in AD rats. Molecular docking results of compounds 7c and 7e showed good binding modes in the active site of the acetylcholinesterase enzyme, which are similar to the native ligand donepezil. 3D-QSAR analysis revealed the importance of the alkyl group in positions 2 and 3 of the phenyl moiety for the activity. Overall, these findings suggested that compound 7c could be deemed a promising candidate for the management of Alzheimer's disease.

Novel Pyrazole-Based Benzofuran Derivatives as Anticancer Agents: Synthesis, Biological Evaluation, and Molecular Docking Investigations

In this work, the design, synthesis, and mechanistic studies of novel pyrazole-based benzofuran derivatives 1-8 as anticancer agents were discussed. Cytotoxic potency of the title compounds was evaluated against the lung carcinoma A-549, human-derived colorectal adenocarcinoma HT-29, breast adenocarcinoma MCF-7 cells as well as mouse fibroblast 3T3-L1 cells using XTT assay. Anticancer mechanistic studies were carried out with flow cytometry. XTT results revealed that all compounds exhibited dose-dependent anti-proliferative activity against the tested cancer cells, and especially compound 2 showed the strongest anti-proliferative activity with an IC50 value of 7.31 μM and the highest selectivity (15.74) on MCF-7 cells. Flow cytometry results confirmed that the cytotoxic power of compound 2 on MCF-7 cells is closely related to mitochondrial membrane damage, caspase activation, and apoptosis orientation. Finally, molecular docking studies were applied to determine the interactions between compound 2 and caspase-3 via in-silico approaches. By molecular docking studies, free binding energy (ΔGBind), docking score, Glide score values as well as amino acid residues in the active binding site were determined. Consequently, these results constitute preliminary data for in vivo anticancer studies and have the potential as a chemotherapeutic agent.

Unfolding the Antibacterial Activity and Acetylcholinesterase Inhibition Potential of Benzofuran-Triazole Hybrids: Synthesis, Antibacterial, Acetylcholinesterase Inhibition, and Molecular Docking Studies

In this study, a series of novel benzofuran-based 1,2,4-triazole derivatives (10a-e) were synthesized and evaluated for their inhibitory potential against acetylcholinesterase (AChE) and bacterial strains (E. coli and B. subtilis). Preliminary results revealed that almost all assayed compounds displayed promising efficacy against AChE, while compound 10d was found to be a highly potent inhibitor of AChE. Similarly, these 5-bromobenzofuran-triazoles 10a-e were screened against B. subtilis QB-928 and E. coli AB-274 to evaluate their antibacterial potential in comparison to the standard antibacterial drug penicillin. Compound 10b was found to be the most active among all screened scaffolds, with an MIC value of 1.25 ± 0.60 µg/mL against B. subtilis, having comparable therapeutic efficacy to the standard drug penicillin (1 ± 1.50 µg/mL). Compound 10a displayed excellent antibacterial therapeutic efficacy against the E. coli strain with comparable MIC of 1.80 ± 0.25 µg/mL to that of the commercial drug penicillin (2.4 ± 1.00 µg/mL). Both the benzofuran-triazole molecules 10a and 10b showed a larger zone of inhibition. Moreover, IFD simulation highlighted compound 10d as a novel lead anticholinesterase scaffold conforming to block entrance, limiting the swinging gate, and disrupting the catalytic triad of AChE, and further supported its significant AChE inhibition with an IC50 value of 0.55 ± 1.00 µM. Therefore, compound 10d might be a promising candidate for further development in Alzheimer's disease treatment, and compounds 10a and 10b may be lead antibacterial agents.

2-(4-Benzyloxy-3-methoxyphenyl)-5-(carbethoxyethylene)-7-methoxy-benzofuran, a Benzofuran Derivative, Suppresses Metastasis Effects in P53-Mutant Hepatocellular Carcinoma Cells

2-(4-Benzyloxy-3-methoxyphenyl)-5-(carbethoxyethylene)-7-methoxy-benzofuran (BMBF), a benzofuran derivative, is an intermediate found in the process of total synthesis of ailanthoidol. Benzofuran derivatives are a class of compounds that possess various biological and pharmacological activities. The present study explored the anti-metastasis effects of BMBF in hepatocellular carcinoma (HCC). Our preliminary findings indicate that BMBF suppresses the proliferation and changes the morphology of Huh7-an HCC cell line with a mutated p53 gene (Y220C). According to a scratching motility assay, non-cytotoxic concentrations of BMBF significantly inhibited the motility and migration in Huh7 cells. BMBF upregulated the expression of E-cadherin and downregulated the expression of vimentin, Slug, and MMP9, which are associated with epithelial-mesenchymal transition (EMT) and metastasis in Huh7 cells. BMBF decreased the expression of integrin α7, deactivated its downstream signal FAK/AKT, and inhibited p53 protein levels. Cell transfection with p53 siRNA resulted in the prevention of cell invasion because of the reduction in integrin α7, Slug, and MMP-9 in Huh7 cells. BMBF had anti-metastatic effects in PLC/PRF/5-an HCC cell line with R249S, a mutated p53 gene. Our findings indicate that BMBF has anti-metastatic effects in downregulating p53 and mediating the suppression of integrin α7, EMT, and MMP-9 in HCC cells with a mutated p53 gene.

Research progress of STAT3-based dual inhibitors for cancer therapy

Signal transducer and activator of transcription 3 (STAT3), a transcription factor, regulates gene levels that are associated with cell survival, cell cycle, and immune reaction. It is correlated with the grade of malignancy and the development of various cancers and targeting STAT3 protein is a potentially promising therapeutic strategy for tumors. Over the past 20 years, various compounds have been found to directly inhibit STAT3 activity via different strategies. However, numerous difficulties exist in the development of STAT3 inhibitors, such as serious toxic effects, poor therapeutic effects, and intrinsic and acquired drug resistance. STAT3 inhibitors synergistically suppress cancer development with additional anti-tumor drugs, such as indoleamine 2,3-dioxygenase 1 inhibitors (IDO1i), histone deacetylase inhibitors (HDACi), DNA inhibitors, pro-tumorigenic cytokine inhibitors (PTCi), NF-κB inhibitors, and tubulin inhibitors. Therefore, individual molecule- based dual-target inhibitors can be the candidate alternative or complementary treatment to overcome the disadvantages of just STAT3 or other targets as a monotherapy. In this review, we discuss the theoretical basis for formulating STAT3-based dual-target inhibitors and also summarize their structure-activity relationships (SARs).

In Silico Development of Novel Benzofuran-1,3,4-Oxadiazoles as Lead Inhibitors of M. tuberculosis Polyketide Synthase 13

Benzofuran and 1,3,4-oxadiazole are privileged and versatile heterocyclic pharmacophores which display a broad spectrum of biological and pharmacological therapeutic potential against a wide variety of diseases. This article reports in silico CADD (computer-aided drug design) and molecular hybridization approaches for the evaluation of the chemotherapeutic efficacy of 16 S-linked N-phenyl acetamide moiety containing benzofuran-1,3,4-oxadiazole scaffolds BF1-BF16. This virtual screening was carried out to discover and assess the chemotherapeutic efficacy of BF1-BF16 structural motifs as Mycobacterium tuberculosis polyketide synthase 13 (Mtb Pks13) enzyme inhibitors. The CADD study results revealed that the benzofuran clubbed oxadiazole derivatives BF3, BF4, and BF8 showed excellent and remarkably significant binding energies against the Mtb Pks13 enzyme comparable with the standard benzofuran-based TAM-16 inhibitor. The best binding affinity scores were displayed by 1,3,4-oxadiazoles-based benzofuran scaffolds BF3 (-14.23 kcal/mol), BF4 (-14.82 kcal/mol), and BF8 (-14.11 kcal/mol), in comparison to the binding affinity score of the standard reference TAM-16 drug (-14.61 kcal/mol). 2,5-Dimethoxy moiety-based bromobenzofuran-oxadiazole derivative BF4 demonstrated the highest binding affinity score amongst the screened compounds, and was higher than the reference Pks13 inhibitor TAM-16 drug. The bindings of these three leads BF3, BF4, and BF8 were further confirmed by the MM-PBSA investigations in which they also exhibited strong bindings with the Pks13 of Mtb. Moreover, the stability analysis of these benzofuran-1,3,4-oxadiazoles in the active sites of the Pks13 enzyme was achieved through molecular dynamic (MD) simulations at 250 ns virtual simulation time, which indicated that these three in silico predicted bio-potent benzofuran tethered oxadiazole molecules BF3, BF4, and BF8 demonstrated stability with the active site of the Pks13 enzyme.

Oxidative transformations of olefins employing persulfate/visible light irradiation in water

We present a green and economical approach for the photooxidation of diverse olefins through the use of ammonium persulfate and blue light irradiation, resulting in the formation of vicinal diols from styrenes and aliphatic alkenes, and vinyl esters and diacids from α,β-unsaturated ketones. The involvement of sulfate radicals in the reaction medium was established as the primary species responsible for the selective generation of the products. A significant advantage of the method lies in its broad substrate scope and economic feasibility, making it a promising alternative to conventional transition metal photocatalysis.

In-silico assay of a dosing vehicle based on chitosan-TiO2 and modified benzofuran-isatin molecules against Pseudomonas aeruginosa

A high priority of the World Health Organization (WHO) is the study of drugs against Pseudomonas aeruginosa, which has developed antibiotic resistance. In this order, recent research is analyzing biomaterials and metal oxide nanoparticles, such as chitosan (QT) and TiO2 (NT), which can transport molecules with biological activity against bacteria, to propose them as drug carrier candidates. In the present work, 10 modified benzofuran-isatin molecules were studied through computational simulation using density functional theory (DFT) and molecular docking assays against Hfq and LpxC (proteins of P. aeruginosa). The results show that the ligand efficiency of commercial drugs C-CP and C-AZI against Hfq is low compared with the best-designed molecule MOL-A. However, we highlight that the influence of NT promotes a better interaction of some molecules, where MOL-E generates a better interaction by 0.219 kcal/mol when NT is introduced in Hfq, forming the system Hfq-NT (Target-NT). Similar behavior is observed in the LpxC target, in which MOL-J is better at 0.072 kcal/mol. Finally, two pharmacophoric models for Hfq and LpxC implicate hydrophobic and aromatic-hydrophobic fragments.

Anticancer therapeutic potential of benzofuran scaffolds

Benzofuran moiety is the main component of many biologically active natural and synthetic heterocycles. These heterocycles have unique therapeutic potentials and are involved in various clinical drugs. The reported results confirmed the extraordinary inhibitory potency of such benzofurans against a panel of human cancer cell lines compared with a wide array of reference anticancer drugs. Several publications about the anticancer potencies of benzofuran-based heterocycles were encountered. The recent developments of anticancer activities of both natural and synthetic benzofuran scaffolds during 2019-2022 are thoroughly covered. Many of the described benzofurans are promising candidates for development as anticancer agents based on their outstanding inhibitory potency against a panel of human cancer cells compared with reference anticancer drugs. These findings encourage medicinal chemists to explore new areas to improve human health and reduce suffering.

Aminobenzofuran-containing analogues of proximicins exhibit higher antiproliferative activity against human UG-87 glioblastoma cells compared to temozolomide

A new series of proximicin analogues containing a benzofuran moiety as the replacement of the di-furan scaffold of the parent compound were synthesised and evaluated for their anti-proliferative activities against human glioblastoma cells U-87 MG. Proximicins A, B, and C are secondary metabolites produced by Verrucosispora Fiedleri MG-37, a Gram-positive actinomycete isolated from deep-sea sediment. Proximicins exhibit significant cytotoxic and apoptotic effects in a number of tumour cell lines, although further investigations on these natural products biological activity are hampered by the challenging synthesis of their constitutive di-furan unit. Therefore, the easily-synthesisable benzofuran ring was elected as a replacement of the di-furan platform, and a library of proximicin analogues was prepared in which different substituents were introduced at both the N-terminus and C-terminus of the benzofuran core unit. The novel compounds were tested against U-87 MG, as it was previously found that proximicins targeted this cancerous cell line, and the human healthy cell line WI-38. Temozolomide, the chemotherapeutic agent of choice for the treatment of glioblastoma, was used as a control. Analysis of growth inhibitory concentration values revealed that a number of furan-benzofuran-containing proximicin analogues, including 23(16) (IC_{50 U-87 MG} = 6.54 μg mL^-1) exhibited higher antiproliferative activity against glioblastoma cells compared to both proximicins A-C and temozolomide (IC_{50 U-87 MG} = 29.19 μg mL^-1) in U-87 MG.