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13 pages, 2257 KiB

Open AccessArticle

(±)-3-Deoxyradicinin Induces Stomata Opening and Chloroplast Oxidative Stress in Tomato (Solanum lycopersicum L.)

by Simone Samperna, Clarissa Zanotti, Patrizia Scafato, Angela Boari, Sabina Visconti, Maurizio Vurro, Stefano Superchi, Antonio Evidente and Mauro Marra

Int. J. Mol. Sci. 2023, 24(10), 8467; https://doi.org/10.3390/ijms24108467 - 9 May 2023

Cited by 4 | Viewed by 1828

Abstract

Radicinin is a phytotoxic dihydropyranopyran-4,5-dione isolated from the culture filtrates of Cochliobolus australiensis, a phytopathogenic fungus of the invasive weed buffelgrass (Cenchrus ciliaris). Radicinin proved to have interesting potential as a natural herbicide. Being interested in elucidating the mechanism of action [...] Read more.

Radicinin is a phytotoxic dihydropyranopyran-4,5-dione isolated from the culture filtrates of Cochliobolus australiensis, a phytopathogenic fungus of the invasive weed buffelgrass (Cenchrus ciliaris). Radicinin proved to have interesting potential as a natural herbicide. Being interested in elucidating the mechanism of action and considering radicinin is produced in small quantities by C. australiensis, we opted to use (±)-3-deoxyradicinin, a synthetic analogue of radicinin that is available in larger quantities and shows radicinin-like phytotoxic activities. To obtain information about subcellular targets and mechanism(s) of action of the toxin, the study was carried out by using tomato (Solanum lycopersicum L.), which, apart from its economic relevance, has become a model plant species for physiological and molecular studies. Results of biochemical assays showed that (±)-3-deoxyradicinin administration to leaves induced chlorosis, ion leakage, hydrogen peroxide production, and membrane lipid peroxidation. Remarkably, the compound determined the uncontrolled opening of stomata, which, in turn, resulted in plant wilting. Confocal microscopy analysis of protoplasts treated with (±)-3-deoxyradicinin ascertained that the toxin targeted chloroplasts, eliciting an overproduction of reactive singlet oxygen species. This oxidative stress status was related by qRT-PCR experiments to the activation of transcription of genes of a chloroplast-specific pathway of programmed cell death. Full article

(This article belongs to the Special Issue Bioactive Natural Products: Isolation, Structural Elucidation and Biological Assays)

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9 pages, 1713 KiB

Open AccessShort Note

5,5,7,7-Tetrametyl-6,7-dihydro-5H-dibenzo[c,e]azepine

by Roberto Bisaccia, Patrizia Scafato, Daniele Casarini and Stefano Superchi

Molbank 2023, 2023(1), M1554; https://doi.org/10.3390/M1554 - 16 Jan 2023

Cited by 1 | Viewed by 1645

Abstract

5,5,7,7-Tetrametyl-6,7-dihydro-5H-dibenzo[c,e]azepine has been synthesized as a possible pro-chiral (or tropos) unit for the construction of a chiral catalyst and as a molecular chirality sensor for the absolute configuration assignment by chiroptical spectroscopy. A straightforward synthetic strategy [...] Read more.

5,5,7,7-Tetrametyl-6,7-dihydro-5H-dibenzo[c,e]azepine has been synthesized as a possible pro-chiral (or tropos) unit for the construction of a chiral catalyst and as a molecular chirality sensor for the absolute configuration assignment by chiroptical spectroscopy. A straightforward synthetic strategy for the preparation of the title compound in high overall yield through sequential addition of the four methyl groups on benzylic positions has been described. A VT-NMR study was used to determine the rotational barrier of the aryl–aryl bond in this biphenylazepine, revealing its torsional flexibility at room temperature, which makes the biphenylazepine suitable as both a chirality probe and a tropos moiety in chiral ligands. Full article

(This article belongs to the Section Organic Synthesis and Biosynthesis)

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15 pages, 3111 KiB

Open AccessArticle

Mitochondrial Role in Intrinsic Apoptosis Induced by a New Synthesized Chalcone in Hepatocellular Carcinoma Cells

by Anna Santarsiero, Ilaria Pappalardo, Gabriella Margherita Rosa, Isabella Pisano, Stefano Superchi, Paolo Convertini, Simona Todisco, Patrizia Scafato and Vittoria Infantino

Biomedicines 2022, 10(12), 3120; https://doi.org/10.3390/biomedicines10123120 - 2 Dec 2022

Cited by 8 | Viewed by 2045

Abstract

Hepatocellular carcinoma (HCC) is the most common type of liver cancer and the fourth cause of cancer-related deaths worldwide. Presently, a few drugs are available for HCC treatment and prevention, including both natural and synthetic compounds. In this study, a new chalcone, ( [...] Read more.

Hepatocellular carcinoma (HCC) is the most common type of liver cancer and the fourth cause of cancer-related deaths worldwide. Presently, a few drugs are available for HCC treatment and prevention, including both natural and synthetic compounds. In this study, a new chalcone, (E)-1-(2,4,6-triethoxyphenyl)-3-(3,4,5-trimethoxyphenyl)prop-2-en-1-one (ETTC), was synthesized and its effects and mechanisms of action over human hepatoma cells were investigated. Cytotoxic activity was revealed in HCC cells, while no effects were observed in normal hepatocytes. In HCC cells, ETTC caused subG1 cell cycle arrest and apoptosis, characterized by nuclear fragmentation. The activation of caspases 3/7 and 9, the increase in pro-apoptotic BAX, and the decrease in anti-apoptotic BCL-2 suggest the activation of the intrinsic pathway of apoptosis. ETTC mitochondrial targeting is confirmed by the reduction in mitochondrial membrane potential and Complex I activity together with levels of superoxide anion increasing. Our outcomes prove the potential mitochondria-mediated antitumor effect of newly synthesized chalcone ETTC in HCC. Full article

(This article belongs to the Special Issue Mitochondrial Metabolism in Health and Disease)

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14 pages, 2077 KiB

Open AccessArticle

Synthesis and Stereochemical Characterization of a Novel Chiral α-Tetrazole Binaphthylazepine Organocatalyst

by Assunta Summa, Patrizia Scafato, Sandra Belviso, Guglielmo Monaco, Riccardo Zanasi, Giovanna Longhi, Sergio Abbate and Stefano Superchi

Molecules 2022, 27(16), 5113; https://doi.org/10.3390/molecules27165113 - 11 Aug 2022

Cited by 3 | Viewed by 2100

Abstract

A novel α-tetrazole-substituted 1,1′-binaphthylazepine chiral catalyst has been synthesized and its absolute configuration has been determined by DFT computational analysis of the vibrational circular dichroism (VCD) spectrum of its precursor. The VCD analysis, carried out through the model averaging method, allowed to assign [...] Read more.

A novel α-tetrazole-substituted 1,1′-binaphthylazepine chiral catalyst has been synthesized and its absolute configuration has been determined by DFT computational analysis of the vibrational circular dichroism (VCD) spectrum of its precursor. The VCD analysis, carried out through the model averaging method, allowed to assign the absolute configuration of a benzylic stereocenter in the presence of a chiral binaphthyl moiety. The 1,1′-binaphthylazepine tetrazole and the nitrile its immediate synthetic precursor, have been preliminarily tested as chiral organocatalysts in the asymmetric intramolecular oxa-Michael cyclization of 2-hydroxy chalcones for the synthesis of chiral flavanones obtaining low enantioselectivity. Full article

(This article belongs to the Special Issue Organic Chemistry, Synthesis, and Catalysis: Special Issue in Memory of Professor Victor Snieckus for His Outstanding Contributions to Organic Chemistry)

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10 pages, 1079 KiB

Open AccessArticle

In Vitro Effects of Fungal Phytotoxins on Cancer Cell Viability: First Insight into Structure Activity Relationship of a Potent Metabolite of Cochliobolus australiensis Radicinin

by Veronique Mathieu, Stefano Superchi, Marco Masi, Patrizia Scafato, Alexander Kornienko and Antonio Evidente

Toxins 2022, 14(8), 517; https://doi.org/10.3390/toxins14080517 - 29 Jul 2022

Cited by 8 | Viewed by 2678

Abstract

Natural compounds have always represented an important source for new drugs. Although fungi represent one such viable source, to date, no fungal metabolite has been marketed as an anticancer drug. Based on our work with phytotoxins as potential chemical scaffolds and our recent [...] Read more.

Natural compounds have always represented an important source for new drugs. Although fungi represent one such viable source, to date, no fungal metabolite has been marketed as an anticancer drug. Based on our work with phytotoxins as potential chemical scaffolds and our recent findings involving three phytopathogenic fungi, i.e., Cochliobolus australiensis, Kalmusia variispora and Hymenoscyphus fraxineus, herein, we evaluate the in vitro anti-cancer activity of the metabolites of these fungi by MTT assays on three cancer cell models harboring various resistance levels to chemotherapeutic drugs. Radicinin, a phytotoxic dihydropyranopyran-4,5-dione produced by Cochliobolus australiensis, with great potential for the biocontrol of the invasive weed buffelgrass (Cenchrus ciliaris), showed significant anticancer activity in the micromolar range. Furthermore, a SAR study was carried out using radicinin, some natural analogues and hemisynthetic derivatives prepared by synthetic methods developed as part of work aimed at the potential application of these molecules as bioherbicides. This investigation opens new avenues for the design and synthesis of novel radicinin analogues as potential anticancer agents. Full article

(This article belongs to the Special Issue Characterization and Action Mechanism of Phytotoxins)

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11 pages, 1882 KiB

Open AccessArticle

Computational Approaches and Use of Chiroptical Probes in the Absolute Configuration Assignment to Natural Products by ECD Spectroscopy: A 1,2,3-Trihydroxy-p-menthane as a Case Study

by Giulia Marsico, Umberto Calice, Patrizia Scafato, Sandra Belviso, Antonio Evidente and Stefano Superchi

Biomolecules 2022, 12(3), 421; https://doi.org/10.3390/biom12030421 - 9 Mar 2022

Cited by 1 | Viewed by 2776

Abstract

In this study, the computational analysis of electronic circular dichroism (ECD) spectra and the employment of biphenyl chiroptical probes were compared in the absolute configuration assignment of (-)-1α,2α,3β-trihydroxy-p-menthane (1), taken as a representative example of a UV-transparent chiral natural [...] Read more.

In this study, the computational analysis of electronic circular dichroism (ECD) spectra and the employment of biphenyl chiroptical probes were compared in the absolute configuration assignment of (-)-1α,2α,3β-trihydroxy-p-menthane (1), taken as a representative example of a UV-transparent chiral natural product. The usefulness of chiroptical probes in the configurational assignments of natural products and their complementarity to the computational protocols is herein highlighted. The biphenyl probe approach proves to be straightforward, reliable, and suitable for conformationally mobile and ECD silent compounds, not treatable by computational analysis of chiroptical data. Full article

(This article belongs to the Special Issue State-of-the-Art Isolation, Chemical and Biological Characterization, Synthesis and Formulation of Natural Products in Italy 2020–2021)

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12 pages, 2274 KiB

Open AccessCommunication

Chirality Transfer in a Calixarene-Based Directional Pseudorotaxane Complex

by Gerardo Concilio, Carmine Gaeta, Paolo Della Sala, Veronica Iuliano, Carmen Talotta, Guglielmo Monaco, Stefano Superchi, Sandra Belviso and Placido Neri

Chemistry 2021, 3(3), 1089-1100; https://doi.org/10.3390/chemistry3030079 - 18 Sep 2021

Cited by 2 | Viewed by 2782

Abstract

Hexamethoxycalix[6]arene 3 forms a directional pseudorotaxane complex with the chiral axle (S)-(α-methyl-benzyl)benzylammonium 2⁺. Between the two (endo-chiral)-2⁺@3 and (exo-chiral)-2⁺@3 pseudorotaxane stereoisomers, the former is preferentially formed. This result confirms [...] Read more.

Hexamethoxycalix[6]arene 3 forms a directional pseudorotaxane complex with the chiral axle (S)-(α-methyl-benzyl)benzylammonium 2⁺. Between the two (endo-chiral)-2⁺@3 and (exo-chiral)-2⁺@3 pseudorotaxane stereoisomers, the former is preferentially formed. This result confirms the validity of the “endo-α-methyl-benzyl rule”, previously reported by us. DFT calculations suggest that C-H … π interactions between the methyl group of 2⁺ and the calixarene aromatic rings, determine the stereoselectivity of the threading process toward the “endo-α-methyl-benzyl preference”. An amplification of optical rotation is observed upon formation of the pseudorotaxane complex (endo-chiral)-2⁺@3 with respect to free axle 2⁺. Thus, the specifical rotation of the 1:1 mixture of chiral 2⁺·B(ArF)₄⁻ salt and achiral 3 was augmented upon formation of the pseudorotaxane and DFT calculations were used to rationalize this result. Full article

(This article belongs to the Special Issue Current Density and Spectroscopy—A Themed Issue in Honor of Professor Riccardo Zanasi on the Occasion of His 70th Birthday)

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13 pages, 4329 KiB

Open AccessArticle

Absolute Configuration Sensing of Chiral Aryl- and Aryloxy-Propionic Acids by Biphenyl Chiroptical Probes

by Stefania Vergura, Stefano Orlando, Patrizia Scafato, Sandra Belviso and Stefano Superchi

Chemosensors 2021, 9(7), 154; https://doi.org/10.3390/chemosensors9070154 - 24 Jun 2021

Cited by 6 | Viewed by 3093

Abstract

The absolute configuration of chiral 2-aryl and 2-aryloxy propionic acids, which are among the most common chiral environmental pollutants, has been readily and reliably established by either electronic circular dichroism spectroscopy or optical rotation measurements employing suitably designed 4,4′-disubstituted biphenyl probes. In fact, [...] Read more.

The absolute configuration of chiral 2-aryl and 2-aryloxy propionic acids, which are among the most common chiral environmental pollutants, has been readily and reliably established by either electronic circular dichroism spectroscopy or optical rotation measurements employing suitably designed 4,4′-disubstituted biphenyl probes. In fact, the 4,4′-biphenyl substitution gives rise to a red shift of the diagnostic electronic circular dichroism signal of the biphenyl A band employed for the configuration assignment, removing its overlap with other interfering dichroic bands and allowing its clear sign identification. The largest A band red shift, and thus the most reliable results, are obtained by employing as a probe the 4,4′-dinitro substituted biphenylazepine 3c. The method was applied to the absolute configuration assignment of 2-arylpropionic acids ibuprofen (1a), naproxen (1b), ketoprofen (1c) and flurbiprofen (1d), as well as to the 2-aryloxypropionic acids 2-phenoxypropionic acid (2a) and 2-naphthoxypropionic acid (2b). This approach, allowing us to reveal the sample’s absolute configuration by simple optical rotation measurements, is potentially applicable to online analyses of both the enantiomeric composition and absolute configuration of these chiral pollutants. Full article

(This article belongs to the Collection Novel Chirogenic Systems and Sensing Materials for Stereoselective Sensors Development)

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10 pages, 1430 KiB

Open AccessFeature PaperArticle

Synthesis and Herbicidal Activity Against Buffelgrass (Cenchrus ciliaris) of (±)-3-deoxyradicinin

by Giulia Marsico, Maria Sabrina Ciccone, Marco Masi, Fabrizio Freda, Massimo Cristofaro, Antonio Evidente, Stefano Superchi and Patrizia Scafato

Molecules 2019, 24(17), 3193; https://doi.org/10.3390/molecules24173193 - 3 Sep 2019

Cited by 14 | Viewed by 4218

Abstract

A novel synthetic strategy for obtainment of (±)-3-deoxyradicinin (2) is reported. This synthetic methodology is more efficient than those previously reported in the literature and also shows higher versatility towards the introduction of different side-chains at both C-7 and C-2. The [...] Read more.

A novel synthetic strategy for obtainment of (±)-3-deoxyradicinin (2) is reported. This synthetic methodology is more efficient than those previously reported in the literature and also shows higher versatility towards the introduction of different side-chains at both C-7 and C-2. The obtained compound (±)-2 shows phytotoxicity against the grass-weed buffelgrass comparable to that of the natural phytotoxin radicinin (1). Therefore, (±)-2 can constitute a more practical synthetic alternative to 1 as bioherbicide for buffelgrass control. Full article

(This article belongs to the Special Issue Natural Compound to Biocontrol Agrarian Pests)

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11 pages, 2146 KiB

Open AccessFeature PaperArticle

Assignment Through Chiroptical Methods of The Absolute Configuration of Fungal Dihydropyranpyran-4-5-Diones Phytotoxins, Potential Herbicides for Buffelgrass (Cenchrus ciliaris) Biocontrol

by Ernesto Santoro, Giuseppe Mazzeo, Giulia Marsico, Marco Masi, Giovanna Longhi, Stefano Superchi, Antonio Evidente and Sergio Abbate

Molecules 2019, 24(17), 3022; https://doi.org/10.3390/molecules24173022 - 21 Aug 2019

Cited by 14 | Viewed by 3252

Abstract

Radicinin and cochliotoxin (1 and 2) two phytotoxic pyranpyran-4,5-diones were isolated together with their close metabolites 3-epi-radicinin, radicinol, and its 3-epimer (3–5), from the culture filtrates of Cochliobolus australiensis, a fungus proposed as mycoherbcide [...] Read more.

Radicinin and cochliotoxin (1 and 2) two phytotoxic pyranpyran-4,5-diones were isolated together with their close metabolites 3-epi-radicinin, radicinol, and its 3-epimer (3–5), from the culture filtrates of Cochliobolus australiensis, a fungus proposed as mycoherbcide for biocontrol of buffelgrass, a very noxious and dangerous weed. The absolute configuration of cochliotoxin was determined by chiroptical Optical Rotatory Dispersion (ORD), Electronic Circular Dichroism (ECD), and Vibrational Circular Dichroism (VCD)) and computational methods. The same methods were used to confirm that of radicinin, radicinol and their 3-epimers, previously determined with chemical, spectroscopic and ECD methods. Full article

(This article belongs to the Special Issue Natural Compound to Biocontrol Agrarian Pests)

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