Recent advances on synthesis and biological activities of aurones

Halogen substituted aurones as potential apoptotic agents: synthesis, anticancer evaluation, molecular docking, ADMET and DFT study

A series of halogen-substituted aurone derivatives (2a-k) were synthesized and evaluated for an anti-proliferative study against NCI 60 cancer cell line panel and showed that most of the compounds predominantly exhibited promising activity against MCF-7. Compound 2e exhibited promising anticancer activity against the MCF-7 cancer cell line with 84.98% percentage growth inhibition in a single dose assay of 10 μM with an IC50 value of 8.157 ± 0.713 μM. In apoptotic assay, the effect of compound 2e on the cell cycle progression indicated that exposure of MCF-7 cells to compound 2e induced a significant disruption in the cell cycle profile including a time-dependent decrease in the cell population at G0/G1 and G2/M phase and arrests the cell cycle at the S phase. In silico, molecular docking ADME and toxicity studies of all compounds were also carried out. The docking study revealed that all the aurone derivatives displayed good docking scores ranging from -7.066 to -8.573. The results of Molecular Electrostatic Potential Mapping (MESP) and Density Functional Theory (DFT) studies of the most active compound 2e and least active compound 2k also favoured the experimental results.

Synthesis and biological evaluation of O4'-benzyl-hispidol derivatives and analogs as dual monoamine oxidase-B inhibitors and anti-neuroinflammatory agents

Design, synthesis, and biological evaluation of two series of O4'-benzyl-hispidol derivatives and the analogous corresponding O3'-benzyl derivatives aiming to develop selective monoamine oxidase-B inhibitors endowed with anti-neuroinflammatory activity is reported herein. The first O4'-benzyl-hispidol derivatives series afforded several more potentially active and MAO-B inhibitors than the O3'-benzyl derivatives series. The most potential compound 2e of O4'-benzyl derivatives elicited sub-micromolar MAO-B IC50 of 0.38 µM with a selectivity index >264 whereas most potential compound 3b of O3'-benzyl derivatives showed only 0.95 MAO-B IC50 and a selectivity index >105. Advancement of the most active compounds showing sub-micromolar activities to further cellular evaluations of viability and induced production of pro-neuroinflammatory mediators confirmed compound 2e as a potential lead compound inhibiting the production of the neuroinflammatory mediator nitric oxide significantly by microglial BV2 cells at 3 µM concentration without significant cytotoxicity up to 30 µM. In silico molecular docking study predicted plausible binding modes with MAO enzymes and provided insights at the molecular level. Overall, this report presents compound 2e as a potential lead compound to develop potential multifunctional compounds.

Scaffold-Hopping Strategies in Aurone Optimization: A Comprehensive Review of Synthetic Procedures and Biological Activities of Nitrogen and Sulfur Analogues

Aurones, particular polyphenolic compounds belonging to the class of minor flavonoids and overlooked for a long time, have gained significative attention in medicinal chemistry in recent years. Indeed, considering their unique and outstanding biological properties, they stand out as an intriguing reservoir of new potential lead compounds in the drug discovery context. Nevertheless, several physicochemical, pharmacokinetic, and pharmacodynamic (P3) issues hinder their progression in more advanced phases of the drug discovery pipeline, making lead optimization campaigns necessary. In this context, scaffold hopping has proven to be a valuable approach in the optimization of natural products. This review provides a comprehensive and updated picture of the scaffold-hopping approaches directed at the optimization of natural and synthetic aurones. In the literature analysis, a particular focus is given to nitrogen and sulfur analogues. For each class presented, general synthetic procedures are summarized, highlighting the key advantages and potential issues. Furthermore, the biological activities of the most representative scaffold-hopped compounds are presented, emphasizing the improvements achieved and the potential for further optimization compared to the aurone class.

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.

Aurones: Unexplored Visible-Light Photoswitches for Aqueous Medium

The development of synthetically accessible photoswitches showing an efficient performance in aqueous medium has recently become an urgent task due to the rapid progress of photopharmacology and novel biomedical applications. In response to this challenge, in this work, aurone derivatives are introduced as a novel class of efficient visible-light photoswitches for aqueous medium. In general, aurones exhibit superior performance in water, including significantly higher quantum yields, compared with other indigoid photoswitches (hemithioindigo and hemiindigo). Especially remarkable are the half-lives of the photoinduced E-isomers of aurones in water, reaching up to 7 years. Further modification of the aurone scaffold with substituents that increase water solubility does not affect most of the photoswitching characteristics and even improves some them. The highly advantageous property profile of the aurone photoswitches make them a perfect novel platform for the design of light-controllable systems in the areas requiring photoswitching in aqueous medium.

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.

A concise update on the synthetic transformation of aurones via asymmetric cycloaddition, annulation, and Michael/Mannich reactions

This review provides a comprehensive overview of the significance of aurone cores in organic chemistry, highlighting their crucial role as synthetic intermediates. With their innate electrophilic reactivity and convenient accessibility, aurone cores play a vital role in catalysing the development of novel methodologies and facilitating the creation of intricate compounds. The objective of this review is to present a current and insightful compilation that summarizes the progress in aurone synthetic transformations, focusing on diverse cycloaddition ([3 + 2], [4 + 2], [4 + 3], [10 + 2]) and annulation reactions.

Design, synthesis, biological evaluation and molecular docking of alkoxyaurones as potent pancreatic lipase inhibitors

Aurones are a minor subgroup of flavonoids. Unlike other subgroups such as chalcones, flavones, and isoflavones, aurones have not been extensively explored as pancreatic lipase inhibitors. In this work, we studied the pancreatic lipase inhibitory potency of synthetic aurone derivatives. Thirty-six compounds belonging to four series (4,6-dihydroxyaurone, 6-hydroxyaurone, 4,6-dialkoxyaurone, and 6-alkoxyaurone) were designed and synthesized. Their in vitro inhibitory activities were determined by spectrophotometric assay in comparison with quercetin and orlistat. Alkoxyaurone derivatives with long-chain (6-10 carbons) alkoxy substituents showed greater potency. Of them, 4,6-dialkoxyaurone 8 displayed the highest activity against pancreatic lipase (IC50 of 1.945 ± 0.520 µM) relative to quercetin (IC50 of 86.98 ± 3.859 µM) and orlistat (IC50 of 0.0334 ± 0.0015 µM). Fluorescence quenching measurement confirmed the affinity of alkoxyaurone derivatives to pancreatic lipase. Kinetic study showed that 8 inhibited lipase through a competitive mechanism (Ki of 1.288 ± 0.282 µM). Molecular docking results clarified the role of long-chain substituents on ring A in interacting with the hydrophobic pockets and pushing the inhibitor molecule closer to the catalytic triad. The findings in this study may contribute to the development of better pancreatic lipase inhibitors with aurone structure.

Aurones and derivatives as promising New Delhi metallo-β-lactamase (NDM-1) inhibitors

Bacterial resistance is undoubtedly one of the main public health concerns especially with the emergence of metallo-β-lactamases (MBLs) able to hydrolytically inactivate β-lactam antibiotics. Currently, there are no inhibitors of MBLs in clinical use to rescue antibiotic action and the New Delhi metallo-β-lactamase-1 (NDM-1) is still considered as one of the most relevant targets for inhibitor development. Following a fragment-based strategy to find new NDM-1 inhibitors, we identified aurone as a promising scaffold. A series of 60 derivatives were then evaluated and two of them were identified as promising inhibitors with Ki values as low as 1.7 and 2.5 µM. Moreover, these two most active compounds were able to potentiate meropenem in in vitro antimicrobial susceptibility assays. The molecular modelling provided insights about their likely interactions with the active site of NDM-1, thus enabling further improvement in the structure of this new inhibitor family.

Synthesis and Biological Evaluation of 2-Azolylmethylene-3-(2H)-benzofuranone Derivatives as Potent Monoamine Oxidases Inhibitors

A series of 2-azolylmethylene-3-(2H)-benzofuranone derivatives, 2-indolylmethylene-3-(2H)-benzofuranone and 2-pyrrolylmethylene-3-(2H)-benzofuranone derivatives, were synthesized, and their monoamine oxidase (MAO) A and B inhibitory activities were evaluated. Compounds 1b, 3b, 6b, 7b, and 10b showed strong inhibitory activity against MAO-A, and compound 3b showed the highest potency and selectivity, with an IC50 value of 21 nM and a MAO-A selectivity index of 48. Compounds 3c, 4c, 9a, 9c, 10c, 11a, and 11c showed strong inhibitory activity against MAO-B, and compound 4c showed the highest potency and selectivity, with an IC50 value of 16 nM and a MAO-B selectivity index of >1100. Further analysis of these compounds indicated that compound 3b for MAO-A and compound 4c for MAO-B were competitive inhibitors, with Ki values of 10 and 6.1 nM, respectively. Furthermore, computational analyses, such as quantitative structure-activity relationship (QSAR) analysis of the 2-azolylmethylene-3-(2H)-benzofuranone derivatives conducting their pIC50 values with the Molecular Operating Environment (MOE) and Mordred, and molecular docking analysis using MOE-Dock supported that the 2-azolylmethylene-3-(2H)-benzofuranone derivatives are a privileged scaffold for the design and development of novel MAO inhibitors.

New synthetic derivatives of isoindoline-dione: synthesis, neuroprotection assay and impact on the expression level of oxidative stress-related genes in neuronal-like cell line

PURPOSE

Oxidative stress can damage cells and cause age-related illnesses such as Alzheimer's, Parkinson's, and Huntington's. This study looked at newly synthesized isoindole derivatives and their effects on SH-SY5Y as a neuroblastoma cell under oxidative stress through the NRF2 signaling pathway. NRF2 transcription factor plays a vital role in the oxidative stress response and cellular homeostasis.

METHOD

Three isoindoline-dione derivatives were synthesized by reacting phthalic anhydrides with 4-(2-aminoethyl)-1-benzyl piperidine. Their structures were confirmed through FT-IR, NMR, and Mass spectroscopy. The derivatives were then tested on human SH-SY5Y cells under an oxidative stress model induced by hydrogen peroxide (H2O2). The cell viability, ROS levels, protein carbonyl content, and gene expression of NRF2 and phase II antioxidative enzymes were measured after 24 h.

RESULTS

Three isoindoline derivatives (3a-3c) were observed to increase the viability of SH-SY5Y cells by protective against oxidative stress, reducing intracellular reactive oxygen species and carbonylated proteins, and increasing gene expression levels of NRF2 and associated genes such as NQO-1, and GSTK1.

CONCLUSION

Isoindoline derivatives demonstrated a neuroprotective effect on SH-SY5Y cells through various neuroprotective mechanisms, although more studies are needed.

Recent Trends in the Antidiabetic Prominence of Natural and Synthetic Analogues of Aurones

Natural products are a boundless source for the development of pharmaceutical agents against a wide range of human diseases. Accordingly, naturally occurring aurones possess various biological benefits, such as anticancer, antioxidant, antimicrobial, antidiabetic, anti-inflammatory, antiviral and neuroprotective effects. In addition, various studies have revealed that aurones are potential templates for the regulation of diabetes mellitus and its associated complications. Likewise, certain aurones and their analogues have been found to be remarkable kinase inhibitors of DARK2, PPAR-γ, PTPM1, AGE, α-amylase and α-glucosidase, which represents a promising approach for the treatment of chronic metabolic disorders such as diabetes. Therefore, in our present study, we provide a detailed account of the advances in aurones as antidiabetic agents over the past decade.

Synthesis and biological evaluation of substituted aurone derivatives as potential tyrosinase inhibitors: in vitro, kinetic, QSAR, docking and drug-likeness studies

Tyrosinase enzyme plays an essential role in melanin biosynthesis and enzymatic browning of fruits and vegetables. To discover potent tyrosinase inhibitors, the present studies were undertaken. In this context, synthetic aurone derivatives 26-50 were designed, synthesized, and structurally elucidated by various spectroscopic techniques including IR, UV, 1H- & 13C-NMR and mass spectrometry. The target compounds 26-50 were screened for their anti-tyrosinase inhibitory potential, and thus kinetic mechanism was analyzed by Lineweaver-Burk plots. All target compounds exhibited good to excellent IC50 values in the range of 7.12 ± 0.32 μM to 66.82 ± 2.44 μM. These synthesized aurone derivatives were found as potent tyrosinase inhibitors relative to the standard kojic acid (IC50 = 16.69 ± 2.81 μM) and the compound 39 inhibited tyrosinase non-competitively (Ki = 11.8 μM) by forming an enzyme-inhibitor complex. The binding modes of these molecules were ascribed through molecular docking studies against tyrosinase protein (PDB ID: 2Y9X). The quantitative structure-activity relationship studies displayed a good correlation between 26-50 structures and their anti-tyrosinase activity (IC50) with a correlation coefficient (R2) of 0.9926. The computational studies were coherent with experimental results and these ligands exhibited good binding values against tyrosinase and interacted with core residues of target protein. Moreover, the drug-likeness analysis also showed that some compounds have a linear correlation with Lipinski's rule of five, indicating good drug-likeness and bioactivity scores for pharmacological targets.Communicated by Ramaswamy H. Sarma.

Antioxidant capacity of simplified oxygen heterocycles and proposed derivatives by theoretical calculations

CONTEXT

Some structural properties can be involved in the antioxidant capacity of several polyphenol derivatives, among them their simplified structures. This study examines the contribution of simplified structure for the antioxidant capacity of some natural and synthetic antioxidants. The resonance structures were related to the π-type electron system of carbon-carbon double bonds between both phenyl rings. Trans-resveratrol, phenyl-benzofuran, phenyl-indenone, and benzylidene-benzofuranone are the best basic antioxidant templates among the simplified derivatives studied here. Additionally, the stilbene moiety was found on the molecules with the best antioxidant capacity. Furthermore, our investigation suggests that these compounds can be used as antioxidant scaffold for designing and developing of new promising derivatives.

METHODS

To investigate the structure-antioxidant capacity for sixteen simplified natural and proposed derivatives we have employed density functional theory and used Gaussian 09. Our DFT calculations were performed using the B3LYP functional and the 6-31+G(d,p) basis set. All electron transfer mechanisms were investigated by using values of HOMO, ionization potential, energy affinity, stabilization energies, and spin density distributions.

Aurones: A Promising Scaffold to Inhibit SARS-CoV-2 Replication

Aurones are a small subgroup of flavonoids in which the basic C6-C3-C6 skeleton is arranged as (Z)-2-benzylidenebenzofuran-3(2H)-one. These compounds are structural isomers of flavones and flavonols, natural products reported as potent inhibitors of SARS-CoV-2 replication. Herein, we report the design, synthesis, and anti-SARS-CoV-2 activity of a series of 25 aurones bearing different oxygenated groups (OH, OCH3, OCH2OCH3, OCH2O, OCF2H, and OCH2C6H4R) at the A- and/or B-rings using cell-based screening assays. We observed that 12 of the 25 compounds exhibit EC50 < 3 μM (8e, 8h, 8j, 8k, 8l, 8m, 8p, 8q, 8r, 8w, 8x, and 8y), of which five presented EC50 < 1 μM (8h, 8m, 8p, 8q, and 8w) without evident cytotoxic effect in Calu-3 cells. The substitution of the A- and/or B-ring with OCH3, OCH2OCH3, and OCF2H groups seems beneficial for the antiviral activity, while the corresponding phenolic derivatives showed a significant decrease in the anti-SARS-CoV-2 activity. The most potent compound of the series, aurone 8q (EC50 = 0.4 μM, SI = 2441.3), is 2 to 3 times more effective than the polyphenolic flavonoids myricetin (2) and baicalein (1), respectively. Investigation of the five more active compounds as inhibitors of SARS-CoV-2 3CLpro based on molecular dynamic calculations suggested that these aurones should detach from the active site of 3CLpro, and, probably, they could bind to another SARS-CoV-2 protein target (either receptor or enzyme).

Palladium-Catalyzed Carbonylation for General Synthesis of Aurones Using CO2

The carbonylation of alkynes using CO₂ to generate aurones is to date unknown. In this study, a palladium-catalyzed carbonylation of terminal aromatic alkynes and the waste hydrosilane, poly(methylhydrosiloxane) (PMHS), is carried out with 2-iodophenol using CO₂ to produce aurones. A variety of terminal alkynes and substituted 2-iodophenols are transformed into aurones in good yields. Preliminary mechanistic studies indicate that silyl formate, generated from CO₂ and PMHS, plays a crucial role in the carbonylation reaction.

Design, synthesis and evaluation of 5-chloro-6-methylaurone derivatives as potential anti-cancer agents

A series of novel 5-chloro-6-methylaurone derivatives (6a-p) were synthesized and characterized by various spectroscopic techniques. The synthesized compounds were tested for anticancer activity against 60-human cancer cell line panel derived from nine cancer types at NCI, Bethesda, USA. Among the synthesized compounds, six compounds (6e, 6f, 6h, 6i, 6k and 6 m) exhibited growth inhibition and cytotoxic activity against various human cancer cell lines in one-dose data. The most potent compound among the series, 6i was active against 55 out of 60 human cancer cell lines. Compound 6i showed remarkable % growth inhibition and cytotoxicity against various cancer cell lines exhibiting % GI in the range 36.05-199.03. The compound 6i was further evaluated for five dose assay and exhibited GI50 1.90 µM and 2.70 µM against melanoma and breast cancer cell lines respectively. Further evaluation of 6i for five-dose assay exhibited a diverse spectrum of anti-cancer activity towards all the 60 human cancer cell line panel with the selectivity index ratio ranging 0.854-1.42  and 0.66-1.35  for GI50 and TGI respectively. Based on one-dose and five-dose data compound 6i was further evaluated for cell apoptosis against MDA-MB-468 breast cancer cell line and was found to induce early apoptosis in cells explaining its mode of action. The in-silico studies for the synthesized compounds as LSD1 inhibitors (2H94) have shown better docking score and binding energy comparable to vafidemstat. All the compounds followed Lipinski rule of five. These findings concluded that the compound 6i could lead to the development of a promising therapeutic anticancer agent.

Parallel Synthesis of Aurones Using a Homogeneous Scavenger

The ability to synthesize arrays of related compounds quickly and with good purity has become critical for a rapid exploration of their properties for biological or material applications. While a number of methods have been developed to enable this combinatorial synthesis, the existing options were not readily appliable to the synthesis of aurones using the simple Knoevenagel condensation approach. In order to avoid the time, expense, and lowered yields associated with flash column chromatography, we developed a scavenging approach for their synthesis. This method uses an excess of aldehyde to ensure complete conversion to aurones, followed by selective removal of the remaining aldehyde using a simple, inexpensive scavenger – isoniazid – and subsequent extraction with dilute acid, to produce the desired compounds with good purity under operationally simple conditions. This approach is expected to be applicable to many other reactions involving aldehydes as one of the reactants.

Design, Synthesis, and Biological Evaluation of 3-Substituted-Indolin-2-One Derivatives as Potent Anti-Inflammatory Agents

This study aimed to synthesize and evaluate the anti-inflammatory activity of 3-substituted-indolin-2-one derivatives. Cell viability of 3-substituted-indolin-2-one derivatives was measured with the EZ-Cytox reagent; interleukin (IL)-6, tumor necrosis factor (TNF)-α, and inducible NOS mRNA levels were measured using Taqman qRT-PCR; pro-inflammatory cytokine IL-6 and TNF-α levels were determined using ELISA kits; the phosphorylation of Akt, JNK, ERK, p38, p65, and IκB protein levels were measured by immunoblotting. Among the nineteen 3-substituted-indolin-2-one derivatives synthesized, 3-(3-hydroxyphenyl)-indolin-2-one showed the highest anti-inflammatory activity, inhibiting the nitric oxide production related to inflammation, suppressing the production of TNF-α and IL-6 in a concentration-dependent manner and mRNA expression. Moreover, 3-(3-hydroxyphenyl)-indolin-2-one significantly inhibited lipopolysaccharide (LPS)-induced signal pathways such as the Akt, MAPK, and NF-κB signaling pathways. Our findings revealed that a 3-substituted-indolin-2-one derivative, 3-(3-hydroxyphenyl)-indolin-2-one, possesses excellent anti-inflammatory activity and can be considered for future research.

Activation of C-Br Bond of CBr4 and CBrCl3 Using 9-Mesityl-10-methylacridinium Perchlorate Photocatalyst

Herein, we report the activation of the C-Br bond of CBrX₃ (X = Cl, Br) using 9-mesityl-10-methylacridinium perchlorate as a visible-light (12W blue LED, 450-455 nm) photocatalyst for the synthesis of gem-dihaloenones from terminal alkynes. An electron transfer from CBrX₃ to Mes-Acr-MeClO₄ led to the formation of ^•+CBrX₃ which subsequently resulted in the intermediate ⁺CX₃. Next, C-C cross-coupling of ⁺CX₃ with terminal alkynes was the key path to obtain the gem-dihaloenones. Radical trapping experiments with TEMPO, BHT, and Stern-Volmer quenching studies helped to understand that the reaction proceeded via the SET mechanism.

Unveiling the inhibitory mechanism of aureusidin targeting xanthine oxidase by multi-spectroscopic methods and molecular simulations

Xanthine oxidase (XO) is a key target for gout treatment. Great efforts have been made towards the discovery and development of new XO inhibitors. Aureusidin (AUR), a natural compound, emerges as the second reported XO inhibitor with an aurone skeleton with an IC₅₀ value of 7.617 ± 0.401 μM in vitro. The inhibitory mechanism of AUR against XO was explored through enzyme kinetic studies, multi-spectroscopic methods, computer simulation techniques, and ADME prediction. The results showed that AUR acts as a rapid reversible and mixed-type XO inhibitor and its binding to XO was driven by hydrogen bonding and hydrophobic interaction. Moreover, AUR presented a strong fluorescence quenching effect through a static quenching process and induced a conformation change of XO. Its binding pattern with XO was revealed through molecular docking, and its affinity toward XO was enhanced through interactions with key amino acid residues in the active pocket of XO. Further, AUR demonstrated good stability and pharmacokinetic behavior properties in molecular dynamics simulation and ADME prediction. In short, the current work clarified in depth the inhibitory mechanism of AUR on XO firstly and then provided fresh insights into its further development as a natural potent XO inhibitor with aurone skeleton.

A New Method of Preparing Aurone by Marine Actinomycetes and Its Potential Application in Agricultural Fungicides

A strain of marine actinomycetes was isolated from an intertidal zone and identified as Streptomyces cinereoruber. Through the fermentation of this strain, a compound with fungicidal activity was extracted and purified. Using mass spectrometry (MS) and nuclear magnetic resonance (NMR) data, the metabolite was determined to be an aurone. The toxicity of the aurone toward four kinds of tumor cells-SH-SY5Y, HepG2, A549, and HeLa cells-was verified by the MTT method, delivering IC₅₀ values of 41.81, 47.19, 63.95, and 51.92 μg/mL, respectively. Greenhouse bioassay showed that the aurone exhibited a high fungicidal activity against powder mildew (Botrytis cinerea), cucurbits powder mildew (Sphaerotheca fuliginea (Schlecht ex Ff.) Poll), and rice blast (Pyricularia oryzae).

Green synthesis of 2-benzylidene-1-benzofuran-3-ones and in vitro neuraminidase study using molecular docking

An improved and green method has been developed for the synthesis of substituted 2-benzylidene-1-benzofuran-3-ones by treating 2-hydroxychalcones with CuBr₂ in DMF-water mixture (7:3; v/v) using grinding methodology. Molecular docking and in vitro studies were also carried out, and it was revealed that compound #4h binds with the active amino Glu-277, Try-406 and Arg-152 of neuraminidase against influenza virus. Compound 4h exerts best inhibition activity (13 ± 1.8%) which was found similar to oseltamivir (12 ± 0.89%).

Comprehensive Phytochemical Profiling, Biological Activities, and Molecular Docking Studies of Pleurospermum candollei: An Insight into Potential for Natural Products Development

The purpose of this study was to find the biological propensities of the vegetable plant Pleurospermum candollei by investigating its phytochemical profile and biological activities. Phytochemical analysis was done by spectroscopic methods to investigate the amount of total polyphenols, and biological evaluation was done by the different antioxidant, enzyme inhibitory (tyrosinase, α-amylase, and α-glucosidase), thrombolytic, and antibacterial activities. The highest amount of total phenolic and flavonoid contents was observed in methanolic extract (240.69 ± 2.94 mg GAE/g and 167.59 ± 3.47 mg QE/g); the fractions showed comparatively less quantity (57.02 ± 1.31 to 144.02 ± 2.11 mg GAE/g, and 48.21 ± 0.75 to 96.58 ± 2.30 mg QE/g). The effect of these bioactive contents was also related to biological activities. GCMS analysis led to the identification of bioactive compounds with different biological effects from methanolic extract (antioxidant; 55.07%, antimicrobial; 56.41%), while the identified compounds from the n-hexane fraction with antioxidant properties constituted 67.86%, and those with antimicrobial effects constituted 82.95%; however, the synergetic effect of polyphenols may also have contributed to the highest value of biological activities of methanolic extract. Molecular docking was also performed to understand the relationship of identified secondary metabolites with enzyme-inhibitory activities. The thrombolytic activity was also significant (40.18 ± 1.80 to 57.15 ± 1.10 % clot lysis) in comparison with streptokinase (78.5 ± 1.53 to 82.34 ± 1.25% clot lysis). Methanolic extract also showed good activity against Gram-positive strains of bacteria, and the highest activity was observed against Bacillus subtilis. The findings of this study will improve our knowledge of phytochemistry, and biological activities of P. candollei, which seems to be a ray of hope to design formulations of natural products for the improvement of health and prevention of chronic diseases; however, further research may address the development of novel drugs for use in pharmaceuticals.

Promising Antifungal Activity of Encephalartos laurentianus de Wild against Candida albicans Clinical Isolates: In Vitro and In Vivo Effects on Renal Cortex of Adult Albino Rats

Candida albicans can cause various infections, especially in immunocompromised patients. Its ability to develop resistance to the current antifungal drugs as well as its multiple virulence factors have rendered the problem even more complicated. Thus, in the present investigation, we elucidated an in vitro and in vivo antifungal activity of Encephalartos laurentianus methanol extract (ELME) against C. albicans clinical isolates for the first time. A phytochemical identification of 64 compounds was conducted in ELME using LC-MS/MS. Interestingly, ELME exhibited antifungal activity with MIC values that ranged from 32–256 µg/mL. Furthermore, we investigated the antibiofilm activity of ELME against the biofilms formed by C. albicans isolates. ELME displayed antibiofilm activity using a crystal violet assay as it decreased the percentages of cells, moderately and strongly forming biofilms from 62.5% to 25%. Moreover, the antibiofilm impact of ELME was elucidated using SEM and fluorescent microscope. A significant reduction in the biofilm formation by C. albicans isolates was observed. In addition, we observed that ELME resulted in the downregulation of the biofilm-related tested genes (ALS1, BCR1, PLB2, and SAP5) in 37.5% of the isolates using qRT-PCR. Besides, the in vivo antifungal activity of ELME on the kidney tissues of rats infected with C. albicans was investigated using histological and immunohistochemical studies. ELME was found to protect against C. albicans induced renal damage, decrease desmin and inducible nitric oxide synthase, increase alkaline phosphatase, and increase infected rats’ survival rate. Additionally, the cytotoxicity of ELME was elucidated on Human Skin Fibroblast normal cells using MTT assay. ELME had an IC50 of 31.26 µg/mL. Thus, we can conclude that ELME might be a promising future source for antifungal compounds.

L-Proline-Based Natural Deep Eutectic Solvents as Efficient Solvents and Catalysts for the Ultrasound-Assisted Synthesis of Aurones via Knoevenagel Condensation

Aurones are minor flavonoids that possess a wide variety of bioactivity, including antioxidant, anticancer, and enzyme inhibitory activity. L-proline-based natural deep eutectic solvents (NaDES) were synthesized and applied as solvents and catalysts for the Knoevenagel condensation reaction between benzofuranone and substituted benzaldehydes to produce aurones in high yields and purity. The reaction between benzofuranone and vanillin served as the model reaction. After screening three NaDESs, and testing microwave, as well as ultrasound as energy sources, we concluded that the optimum results are obtained using L-proline/glycerol 1:2 as catalyst and solvent and ultrasound irradiation. The scope of the reaction was evaluated using a variety of benzaldehydes, and the corresponding aurones were obtained in moderate to satisfactory yields (57–89%) and high purity. An important additional feature of the described methodology is the recyclability and reusability of the NaDES, which was recycled and effectively reused after 6 cycles.

Aurone-derived 1,2,3-triazoles as potential fluorescence molecules in vitro

Aurones are a class of naturally occurring compounds with fluorescent derivatives. Here we show a newly synthesized derivative of aurones containing a 1,2,3-triazole which is fluorescent in aqueous environments and has potential to be used as a probe in vitro.

Aurones: A Golden Resource for Active Compounds

Deemed as poorly represented in nature, aurones have been often overlooked by researchers compared to other members of the flavonoid superfamily. However, over the past two decades, they have been reassessed by the scientific community, who are increasingly appreciating their ability to modulate several biological pathways. This review summarizes the recent literature on this class of compounds, which has been analyzed from both a chemical and a functional point of view. Original articles, reviews and editorials featured in Pubmed and Scifinder over the last twenty years have been taken into account to provide the readers with a view of the chemical strategies to obtain them, their functional properties, and their potential of technological use. The resulting comprehensive picture aims at raising the awareness of these natural derivatives as effective drug candidates, fostering the development of novel synthetic analogues.

Diversity-Oriented Synthesis: Amino Acetophenones as Building Blocks for the Synthesis of Natural Product Analogs

Diversity-Oriented Synthesis (DOS) represents a strategy to obtain molecule libraries with diverse structural features starting from one common compound in limited steps of synthesis. During the last two decades, DOS has become an unmissable strategy in organic synthesis and is fully integrated in various drug discovery processes. On the other hand, natural products with multiple relevant pharmacological properties have been extensively investigated as scaffolds for ligand-based drug design. In this article, we report the amino dimethoxyacetophenones that can be easily synthesized and scaled up from the commercially available 3,5-dimethoxyaniline as valuable starting blocks for the DOS of natural product analogs. More focus is placed on the synthesis of analogs of flavones, coumarins, azocanes, chalcones, and aurones, which are frequently studied as lead compounds in drug discovery.

2-Benzylidenebenzofuran-3(2H)-ones as a new class of alkaline phosphatase inhibitors: synthesis, SAR analysis, enzyme inhibitory kinetics and computational studies

The excelling role of organic chemistry in the medicinal field continues to be one of the main leads in the drug development process. Particularly, this industry requires organic chemists to discover small molecular structures with powerful pharmacological potential. Herein, a diverse range of chalcone (1–11) and aurone (12–22) derivatives was designed and synthesized and for the first time, and both motifs were evaluated as potent inhibitors of alkaline phosphatases (APs). Structural identification of the target compounds (1–22) was accomplished using common spectroscopic techniques. The effect of the nature and position of the substituent was interestingly observed and justified based on the detailed structure–activity relationship (SAR) of the target compounds against AP. It was concluded from the obtained results that all the newly synthesized compounds exhibit high inhibitory potential against the AP enzyme. Among them, compounds 12 (IC₅₀ = 2.163 ± 0.048 μM), 15 (IC₅₀ = 2.146 ± 0.056 μM), 16 (IC₅₀ = 2.132 ± 0.034 μM), 18 (IC₅₀ = 1.154 ± 0.043 μM), 20 (IC₅₀ = 1.055 ± 0.029 μM) and 21 (IC₅₀ = 2.326 ± 0.059 μM) exhibited excellent inhibitory activity against AP, and even better/more active than KH₂PO₄ (standard) (IC₅₀ = 2.80 ± 0.065 μM). Remarkably, compound 20 (IC₅₀ = 1.055 ± 0.029 μM) may serve as a lead structure to design more potent inhibitors of alkaline phosphatase. To the best of our knowledge, these synthetic compounds are the most potent AP inhibitors with minimum IC₅₀ values reported to date. Furthermore, a molecular modeling study was performed against the AP enzyme (1EW2) to check the binding interaction of the synthesized compounds 1–22 against the target protein. The Lineweaver–Burk plots demonstrated that most potential derivative 20 inhibited h-IAP via a non-competitive pathway. Finally, molecular dynamic (MD) simulations were performed to evaluate the dynamic behavior, stability of the protein–ligand complex, and binding affinity of the compounds, resulting in the identification of compound 20 as a potential inhibitor of AP. Accordingly, excellent correlation was observed between the experimental and theoretical results. The pharmacological studies revealed that the synthesized analogs 1–22 obey Lipinski's rule. The assessment of the ADMET parameters showed that these compounds possess considerable lead-like characteristics with low toxicity and can serve as templates in drug design.

Aurones are the plant secondary metabolites belonging to the flavonoid’s family. The bioactivities of aurones are very promising, thus these heterocyclic compounds can be considered as an alluring scaffold for drug design and development.

Metabolic Engineering of Microbial Cell Factories for Biosynthesis of Flavonoids: A Review

Flavonoids belong to a class of plant secondary metabolites that have a polyphenol structure. Flavonoids show extensive biological activity, such as antioxidative, anti-inflammatory, anti-mutagenic, anti-cancer, and antibacterial properties, so they are widely used in the food, pharmaceutical, and nutraceutical industries. However, traditional sources of flavonoids are no longer sufficient to meet current demands. In recent years, with the clarification of the biosynthetic pathway of flavonoids and the development of synthetic biology, it has become possible to use synthetic metabolic engineering methods with microorganisms as hosts to produce flavonoids. This article mainly reviews the biosynthetic pathways of flavonoids and the development of microbial expression systems for the production of flavonoids in order to provide a useful reference for further research on synthetic metabolic engineering of flavonoids. Meanwhile, the application of co-culture systems in the biosynthesis of flavonoids is emphasized in this review.