Search

Multicomponent reactions (MCRs) represent very interesting tools to reach eco-friendly and sustainable transformations in organic chemistry. In particular, the Biginelli reaction furnishes a very easy approach to the synthesis of a library of biological active compounds in an academic course. Here we describe the realization of several experiments involving the synthesis of potential inhibitors of [beta]-secretase by the Biginelli reaction. All of the obtained compounds were tested with a FRET fluorimetric assay. The experiments were proposed to students either at entry level or during advanced laboratory courses of organic and bioorganic chemistry. The learning objectives at the advanced level were to introduce the students to the practice of combinatorial synthesis and to the evaluation of biological activity of combinatorial libraries by enzyme inhibition assays. The meeting of the learning objectives was probed first by analyzing their daily performance in the laboratory and their increasing proactive attitude, and the contents of their final presentations. The resulting marks obtained by the students were compared with the average evaluation of their career. Second, the students were asked to evaluate the course and their own experience, and the outcome of their evaluation was compared with that of the teachers.

Herein the reaction of methy cinnamates with N‐Iodosuccinimide (NIS) is reported and the possible formation of dihydrobenzofuryl dimeric derivatives (DHBF), known for their biological activities, is explored. Having an oxidizing capacity, we studied the behavior of NIS with methyl ferulate and under optimized reaction conditions we obtained its DHBF dimer in 35% yield. It is worth to note that we did not obtain the DHBF in his natural form, but rather as the demethylated compound, likely due to dismutation reactions activated by the presence of water in the solvent. Methyl caffeate reacted with NIS to furnish the DHBF dimer in 15% yield, while methyl coumarate and methyl isoferulate did not give any form of DHBF dimers, showing the importance of a hydroxyl group in para position on an activated system and an electron‐rich aromatic ring. An electrochemical investigation by cyclic voltammetry was carried out on the three cinnamates and confirmed the correlation between dimerization and oxidation potential: methyl ferulate and methyl caffeate dimerize, while methyl coumarate, due to its higher oxidizing potential, does not. [ABSTRACT FROM AUTHOR]

Permethylated anigopreissin A (PAA), a fully protected form of the natural anigopreissin A, was found in our previous study to be active against several cancer cells, up to IC50 0.24 μM for HepG2 cells. Herein, a total of thirteen PAA analogues with variations in the number, position of substituents and unsaturation were synthesised starting from a common precursor, and their ability to induce cell growth inhibition was tested. By comparing the antiproliferative effect of the analogues with PAA and with the help of computational studies, we have gained valuable insights into both the biological activity and structure of this natural class of compounds. Indeed, we discovered the importance of the C-3 ring in modulating the biological activity of PAA, as well as the crucial role of the trans configuration of the styryl double bond and the significance of substitutions on the other parts of the molecule. [ABSTRACT FROM AUTHOR]

The continuous emergence of SARS-CoV-2 variants caused the persistence of the COVID-19 epidemic and challenged the effectiveness of the existing vaccines. The viral proteases are the most attractive targets for developing antiviral drugs. In this scenario, our study explores the use of HIV-1 protease inhibitors against SARS-CoV-2. An in silico screening of a library of HIV-1 proteases identified four anti-HIV compounds able to interact with the 3CLpro of SARS-CoV-2. Thus, in vitro studies were designed to evaluate their potential antiviral effectiveness against SARS-CoV-2. We employed pseudovirus technology to simulate, in a highly safe manner, the adsorption of the alpha (α-SARS-CoV-2) and omicron (ο-SARS-CoV-2) variants of SARS-CoV-2 and study the inhibitory mechanism of the selected compounds for cell–virus interaction. The results reported a mild activity against the viral proteases 3CLpro and PLpro, but efficient inhibitory effects on the internalization of both variants mediated by cathepsin B/L. Our findings provide insights into the feasibility of using drugs exhibiting antiviral effects for other viruses against the viral and host SARS-CoV-2 proteases required for entry. [ABSTRACT FROM AUTHOR]

In this study, mono‐ or poly‐methoxylated phenyl boronic acids, were subjected to Rieche formylation. Unexpectedly the corresponding ipso‐substituted aryl aldehydes were obtained in excellent yields and, for some of these substrates, the formylated arylboronic acids were also synthesized in moderate yields. These findings provide new insights into the general reactivity and versatility of arylboronic acids. [ABSTRACT FROM AUTHOR]

Liver cancer is one of the most common causes of cancer death worldwide. In recent years, substantial progress has been made in the development of systemic therapies, but there is still the need for new drugs and technologies that can increase the survival and quality of life of patients. The present investigation reports the development of a liposomal formulation of a carbamate molecule, reported as ANP0903, previously tested as an inhibitor of HIV-1 protease and now evaluated for its ability to induce cytotoxicity in hepatocellular carcinoma cell lines. PEGylated liposomes were prepared and characterized. Small, oligolamellar vesicles were produced, as demonstrated by light scattering results and TEM images. The physical stability of the vesicles in biological fluids was demonstrated in vitro, alongside the stability during storage. An enhanced cellular uptake was verified in HepG2 cells treated with liposomal ANP0903, resulting in a greater cytotoxicity. Several biological assays were performed to elucidate the molecular mechanisms explaining the proapoptotic effect of ANP0903. Our results allow us to hypothesize that the cytotoxic action in tumor cells is probably due to the inhibition of the proteasome, resulting in an increase in the amount of ubiquitinated proteins within the cells, which in turn triggers activation of autophagy and apoptosis processes, resulting in cell death. The proposed liposomal formulation represents a promising approach to deliver a novel antitumor agent to cancer cells and enhance its activity. [ABSTRACT FROM AUTHOR]

In this work, we describe the synthesis of (±)‐permethylated‐ϵ‐viniferin from resveratrol by successive iodination, methylation and dehalogenation reactions. Iodination reaction by N‐iodosuccinimide (NIS) was studied to optimize and confirm a proposed radical mechanism. Switching to acetyl protecting group, a new straightforward regio‐ and diastereo‐selective biomimetic synthesis of (±)‐ϵ‐viniferin was obtained. Permethylated and free ϵ‐viniferin were isolated up to 20 %yield. [ABSTRACT FROM AUTHOR]

Various polysubstituted benzofurans were reduced by using triethylsilane in trifluoracetic acid. 2,3-Dihydrobenzofurans or bibenzyl compounds were obtained in high yields, depending on the nature of the substituents at C2 and on the benzene ring of the core structure. A p -anisole substituent at C2 of benzofurans always led to the corresponding bibenzyls. [ABSTRACT FROM AUTHOR]

This review gives an overview on recent developments in methods for the construction of compounds with the 2,3-dihydrobenzo-furan core in the period 2012 to 2019. Interest in 2,3-dihydrobenzofurans is constantly increasing. The methods are divided into intermolecular and intramolecular approaches. Intermolecular approaches are subdivided according to the parent intermediate for the key reaction, while intermolecular approaches are subdivided according by which bond is formed in the key reaction. The transformation of benzofurans to dihydrobenzofurans and other miscellaneous methods are also discussed. Approaches useful for the synthesis of natural products are emphasized. 1 Introduction 2 Intermolecular Approaches 2.1 o -Quinone Methides and o -Quinones 2.2 p -Quinone Methides and p -Quinones 2.3 Nitrogen-Containing Phenols and Quinones 2.4 o -Hydroxyphenylcarbonyl Derivatives and Phenols 2.5 Miscellaneous 3 Intramolecular Approaches 3.1 O–C2 Bond Forming 3.2 C2–C3 Bond Forming 3.3 C3–Aryl Bond Forming 3.4 O–Aryl Bond Forming 4 From BF to DHB 5 Rearrangements and Aromatizations [ABSTRACT FROM AUTHOR]

A convergent approach for the synthesis of (±)-myricanol, a strained diarylheptanoid isolated from Myricacae , was undertaken using a Suzuki–Miyaura coupling followed by a ring-closing metathesis (RCM). Herein, we report the unintentional formation of a 26-membered macrocycle as RCM product resulting from a head-to-tail dimerization of the seco -precursor, even in relay ring-closing metathesis (RRCM) conditions. [ABSTRACT FROM AUTHOR]

The preparation and characterization of conformationally well-defined ketal compounds which exhibit medium-high optical rotation (OR) values and are independent of the solvent, and electronic circular dichroism (ECD) spectra is reported. The compounds were obtained through reaction between flexible and optically transparent molecules such as 1,2-, syn- and anti-1,3-diols, 1,3-sulfanylalcohols with fluorenone dimethyl acetal.

The first example of an efficient enantioselective preparation of a chiral calix[4]arene bis-epoxide via a direct asymmetric reaction on the parent 1,3-diformylcalix[4]arene is reported. The results from the [super 1]H and [super 13]C NMR analyses reveal the presence of two biaryl epoxides in obtained compounds.

The convergent synthesis of the lower part of C12-C24 of macrolactin A is explained. The disconnections at the lactone bond and the C11-C12 bond to produce upper and lower moieties are proposed.

ortho‐Oxo substituted trans 2,3‐diaryloxiranes were regio‐ and stereoselectively arylated by arylzinc reagents, obtained from the corresponding boronic acids by B–Zn exchange. The reaction was quite general, irrespective to the aryl nucleophile and proceeded via a ring opening at the α‐carbon with respect to the substituted aryl ring. The stereoselectivity was from high to complete toward the alcohol resulted from retention of configuration at the electrophilic carbon. The method allowed a direct and high yielding access to trans 2,3‐diphenyl‐2,3‐dihydrobenzofuran, which is a key structural motif in resveratrol dimers as viniferins. The use of enantioenriched starting diaryloxiranes resulted in no loss of stereochemical integrity in the final trans 2,3‐dihydrobenzofuran, which was characterized for the first time in enantioenriched form. [ABSTRACT FROM AUTHOR]

A method for C-Br/C-H bis-phenylation of methyl 4-bromocrotonate via nickel-catalyzed cross-coupling reaction has been developed. This protocol involves commercially available catalyst components and furnishes a suitable doubly phenylated building block. [ABSTRACT FROM PUBLISHER]

Abstract: Acetylation/Sonogashira cross-coupling reaction/cyclization has been carried out in one-pot using a Na2PdCl4/2-(di-tert-butylphosphino)-N-phenylindole/CuI system in TMEDA to give 5-nitro-2-substituted benzo[b]furans in excellent yields. We also describe the extension of this method to 4-EWG-2-bromo-phenols obtaining 2,5-disubstituted-benzo[b]furans in good yields. [Copyright &y& Elsevier]

Background: Several pre-clinical and clinical reports suggest that HIV-1 protease inhibitors, in addition to the antiretroviral properties, possess pleiotropic pharmacological effects including anticancer action. Therefore, we investigated the pro-apoptotic activity in tumor cells of two molecules, RDD-19 and RDD-142, which are hydroxyethylamine derivatives' precursors of darunavir and several HIV-1 protease inhibitors. Methods: Three hepatoma cell lines and one non-pathological cell line were treated with RDD-19 and RDD-142, and cell viability was assessed. The expression levels of several markers for ER stress, autophagy, cellular ubiquitination, and Akt activation were quantified in HepG2 cells treated with RDD-19 and RDD-142 to evaluate apoptotic and non-apoptotic cell death. Results: RDD-19 and RDD-142 showed a greater dose-dependent cytotoxicity towards the hepatic tumor cell line HepG2 compared to the non-pathological hepatic cell line IHH. Both molecules caused two types of cell death, a caspase-dependent apoptosis, which was ascertained by a series of biochemical and morphological assays, and a caspase-independent death that was characterized by the induction of ER stress and autophagy. The strong increase of ubiquitinated proteins inside the cells suggested that the target of these molecules could be the proteasome and in silico molecular docking analysis that was used to support the plausibility of this hypothesis. Furthermore, cells treated with the two compounds displayed decreased levels of p-AKT, which interferes with cell survival and proliferation. Conclusions: These findings demonstrate that two compounds, RDD-19 and RDD-142, have pleiotropic effects and that they may represent promising anticancer candidates. [ABSTRACT FROM AUTHOR]

Here, we report the synthesis, enzyme inhibition and structure–activity relationship studies of a new potent class of HIV-1 protease inhibitors, which contain a pseudo-symmetric hydroxyethylamine core and heteroarylcarboxyamide moieties. The simple synthetic pathway furnished nine compounds in a few steps with high yields. The compounds were designed taking into account our previous results on other series of inhibitors with different substituents at P' and P" and different ways of linking them to the inhibitor core. Potent inhibitory activity was obtained with nanomolar IC50 values measured with a standard fluorimetric test in 100 mM MES buffer, pH 5.5, containing 400 mM NaCl, 1 mM EDTA, 1 mM DTT and 1 mg/ml BSA. Compounds 9a–c, containing the indole ring in P1, exhibited an HIV-1 protease inhibitory activity more powerful than darunavir in the same assay. To obtain molecular insight into the binding properties of these compounds, docking analysis was performed, and their binding properties were also compared. [ABSTRACT FROM AUTHOR]

Metabolic reprogramming is a hallmark of cancer cells required to ensure high energy needs and the maintenance of redox balance. A relevant metabolic change of cancer cell bioenergetics is the increase in glutamine metabolism. Hepatocellular carcinoma (HCC), one of the most lethal cancer and which requires the continuous development of new therapeutic strategies, shows an up-regulation of human glutamate dehydrogenase 1 (hGDH1). GDH1 function may be relevant in cancer cells (or HCC) to drive the glutamine catabolism from L-glutamate towards the synthesis of α-ketoglutarate (α-KG), thus supplying key tricarboxylic acid cycle (TCA cycle) metabolites. Here, the effects of hGLUD1 gene silencing (siGLUD1) and GDH1 inhibition were evaluated. Our results demonstrate that siGLUD1 in HepG2 cells induces a significant reduction in cell proliferation (58.8% ± 10.63%), a decrease in BCL2 expression levels, mitochondrial mass (75% ± 5.89%), mitochondrial membrane potential (30% ± 7.06%), and a significant increase in mitochondrial superoxide anion (25% ± 6.55%) compared to control/untreated cells. The inhibition strategy leads us to identify two possible inhibitors of hGDH1: quercetin and Permethylated Anigopreissin A (PAA). These findings suggest that hGDH1 could be a potential candidate target to impair the metabolic reprogramming of HCC cells. [ABSTRACT FROM AUTHOR]

The leaves of Vitis vinifera L. have been used for a long time in traditional medicine for the treatment of many ailments. Grape polyphenols, indeed, have been demonstrated to be able to defend against oxidative stress, responsible for various disorders such as cancer, diabetes and neurodegenerative diseases. The effects of different extraction techniques, Soxhlet (SOX), Accelerated Solvent (ASE 40, ASE 50) and Ultrasound Assisted Extraction (UAE) were studied in this work to evaluate their impact on the chemical profile and bioactive potential of Vitis vinifera L. (cv. Aglianico) leaf extracts. The phytochemical profile was investigated by HPLC-DAD and 9 phenolic compounds were identified and quantified in the extract. Moreover, the antioxidant, anticholinesterase and antityrosinase activities were evaluated. In detail, the total polyphenol content and antioxidant activity (2,2-diphenyl-1-picrylhydrazyl, Oxygen Radical Absorbance Capacities and β-Carotene Bleaching assays) were evaluated and compared to assess the Relative Antioxidant Capacity Index (RACI). To test the inhibitory activity of extracts towards cholinesterases, acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition assays were performed. SOX and ASE 50 have shown the highest value of RACI, 0.76 and 0.65, respectively. Regarding enzymatic inhibitory activity, ASE 50 (IC50 = 107.16 ± 8.12 μg/mL) and SOX (IC50 = 171.34 ± 12.12 μg/mL) extracts exhibited the highest AChE and BChE inhibitory activity, respectively, while UAE (IC50 = 293.2 ± 25.6 μg/mL, followed by SOX (IC50 = 302.5 ± 38.3 μg/mL) showed the highest tyrosinase inhibition value. Our results demonstrated for the first time that Aglianico leaves are important sources of phenols that could be used to prevent oxidative stress and be potentially helpful in diseases treatable with tyrosinase and cholinesterase inhibitors, like myasthenia gravis or Alzheimer's. [ABSTRACT FROM AUTHOR]

This review describes the progress of the last decade on the synthesis of substituted benzofurans, which are useful scaffolds for the synthesis of numerous natural products and pharmaceuticals. In particular, new intramolecular and intermolecular C–C and/or C–O bond-forming processes, with transition-metal catalysis or metal-free are summarized. (1) Introduction. (2) Ring generation via intramolecular cyclization. (2.1) C7a–O bond formation: (route a). (2.2) O–C2 bond formation: (route b). (2.3) C2–C3 bond formation: (route c). (2.4) C3–C3a bond formation: (route d). (3) Ring generation via intermolecular cyclization. (3.1) C7a-O and C3–C3a bond formation (route a + d). (3.2) O–C2 and C2–C3 bond formation: (route b + c). (3.3) O–C2 and C3–C3a bond formation: (route b + d). (4) Benzannulation. (5) Conclusion. [ABSTRACT FROM AUTHOR]

The genus Minthostachys belonging to the Lamiaceae family, and is an important South American mint genus used commonly in folk medicine as an aroma in cooking. The phytochemical-rich samples of the aerial parts of Minthostachys diffusa Epling. were tested for pharmacological and health-promoting bioactivities using in vitro chemical and enzymatic assays. A range of radical scavenging activities of the samples against biological radicals such as nitric oxide and superoxide anion and against synthetic 2,2-diphenyl-1-picrylhydrazyl and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radicals, the ferric reducing antioxidant power and the lipid peroxidation inhibition were determined and ranked using the 'relative antioxidant capacity index' (RACI). The ethyl acetate fraction showed the highest RACI of +1.12. Analysis of the various fractions' inhibitory ability against enzymes involved in diabetes (α-amylase and α-glucosidase), and against enzymes associated with Parkinson's or Alzheimer's diseases (acetylcholinesterase and butyrylcholinesterase) also suggested that the ethyl acetate fraction was the most active. Liquid chromatography–tandem mass spectrometry analysis of the ethyl acetate fraction showed more than 30 polyphenolic compounds, including triterpenes. The inhibitory cholinesterase effects of the triterpenes identified from M. diffusa were further analysed by in silico docking of these compounds into 3D-structures of acetylcholinesterase and butyrylcholinesterase. This is the first study on pharmacological activities and phytochemical profiling of the aerial parts of M. diffusa, showing that this plant, normally used as food in South America, is also rich in health-promoting phytochemicals. [ABSTRACT FROM AUTHOR]

Oxidative stress is involved in different diseases, such as diabetes and neurodegenerative diseases. The genus Azorella includes about 70 species of flowering plant species; most of them are commonly used as food and in particular as a tea infusion in the Andean region of South America in folk medicine to treat various chronic diseases. Azorella glabra Wedd. aerial parts were firstly analyzed for their in vitro antioxidant activity using different complementary assays. In particular, radical scavenging activity was tested against biological neutral radical DPPH; ferric reducing power and lipid peroxidation inhibitory capacity (FRAP and Beta-Carotene Bleaching tests) were also determined. The Relative Antioxidant Capacity Index (RACI) was used to compare data obtained by different assays. Then, the inhibitory ability of samples was investigated against α-amylase and α-glucosidase enzymes involved in diabetes and against acetylcholinesterase and butyrylcholinesterase enzymes considered as strategy for the treatment of Parkinson's or Alzheimer's diseases. Moreover, the phytochemical profile of the sample showing the highest RACI (1.35) and interesting enzymatic activities (IC50 of 163.54 ± 9.72 and 215.29 ± 17.10 μg/mL in α-glucosidase and acetylcholinesterase inhibition, respectively) was subjected to characterization and quantification of its phenolic composition using LC-MS/MS analysis. In fact, the ethyl acetate fraction derived from ethanol extract by liquid/liquid extraction showed 29 compounds, most of them are cinnamic acid derivatives, flavonoid derivatives, and a terpene. To the best of our knowledge, this is the first report about the evaluation of significant biological activities and phytochemical profile of A. glabra, an important source of health-promoting phytochemicals. [ABSTRACT FROM AUTHOR]

Multiple myeloma (MM) is the second most common hematologic malignancy and, although the development of novel agents has improved survival of patients, to date, it remains incurable. Thus, newer and more effective therapeutic strategies against this malignancy are necessary. Plant extracts play an important role in anti-tumor drug discovery. For this reason, in the investigation of novel natural anti-MM agents, we evaluated the phytochemical profiles, in vitro antioxidant activity, and effects on MM cells of Azorella glabra (AG) Wedd. Total polyphenols (TPC), flavonoids (TFC), and terpenoids (TTeC) contents were different among samples and the richest fractions in polyphenols demonstrated a higher antioxidant activity in in vitro assays. Some fractions showed a dose and time dependent anti-proliferative activity on MM cells. The chloroform fraction (CHCl3) showed major effects in terms of reduction of cell viability, induction of apoptosis, and cell cycle arrest on MM cells. The apoptosis induction was also confirmed by the activation of caspase-3. Importantly, the CHCl3 fraction exhibited a negligible effect on the viability of healthy cells. These results encourage further investigations on AG extracts to identify specific bioactive compounds and to define their potential applications in MM. [ABSTRACT FROM AUTHOR]

Antioxidant phytochemicals play a key role in oxidative stress control and in the prevention of related disorders, such as premature aging, degenerative diseases, diabetes, and cancer. The aim of this study was to investigate the potential antioxidant activity and the phytochemical profile of Senecio clivicolus Wedd., a perennial shrub, belonging to the Asteraceae family. Despite the wide interest of this family, this specie has not been investigated yet. S. clivicolus aerial parts were extracted with 96% ethanol. Then, the ethanol extract was fractionated by liquid/liquid extraction using an increasing solvents polarity. Total polyphenol and terpenoid contents were measured. Moreover, the antioxidant activity was evaluated by six different complementary in vitro assays. The Relative Antioxidant Capacity Index (RACI) was used to compare data obtained by different tests. The sample showing the highest RACI was subjected to characterization and quantitation of its phenolic composition using LC-MS/MS analysis. The ethyl acetate fraction, investigated by LC-MS/MS analysis, showed 30 compounds, most of them are chlorogenic acid and flavonoid derivatives. To the best of our knowledge, this is the first report about the evaluation of antioxidant activity and phytochemical profile of S. clivicolus, underlying the importance of this species as a source of health-promoting phytochemicals. [ABSTRACT FROM AUTHOR]

Amberlyst-15 is demonstrated to be an efficient catalyst for the ring opening of ortho-substituted trans-2-aryl-3-phenyl-oxiranes to give the corresponding syn-diols (II) selectively. [ABSTRACT FROM AUTHOR]

An unexpected Ni-catalyzed double phenylation of an allyl bromide system is described. [ABSTRACT FROM AUTHOR]