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Abstract: SIBX is a stabilized (i.e., nonexplosive) formulation of the λ5-iodane 2-iodoxybenzoic acid IBX that can be used as a suspension in various organic solvents to oxidize safely sulfides into sulfoxides. Most yields are comparable to those obtained using IBX or other iodanes such as PhIO and PhIO2. An asymmetric version of this SIBX-mediated sulfoxidation was performed in high chemical yield and moderate enantioselectivity by simple addition of an external chiral source. [Copyright &y& Elsevier]

The reactivity of novel chiral lactamide‐substituted diselenide‐based reagents under oxidative conditions was exploited to develop a metal‐free method for the preparation of enantioenriched allenylamides from simple alkynes in good yields, and with enantiomeric excesses up to 99 %. The key of the success in this method is attributed to the hydrogen‐bonded lactamide appendages that ensure configurational stability of chiral vinyl selenoxide intermediates for an optimal enantiotopic β‐syn‐elimination step. [ABSTRACT FROM AUTHOR]

The reactivity of novel chiral lactamide‐substituted diselenide‐based reagents under oxidative conditions was exploited to develop a metal‐free method for the preparation of enantioenriched allenylamides from simple alkynes in good yields, and with enantiomeric excesses up to 99 %. The key of the success in this method is attributed to the hydrogen‐bonded lactamide appendages that ensure configurational stability of chiral vinyl selenoxide intermediates for an optimal enantiotopic β‐syn‐elimination step. [ABSTRACT FROM AUTHOR]

John Wiley and Sons, Chichester 2016. 470 pp., hardcover, € 112.00.—ISBN 978‐1118627808 [ABSTRACT FROM AUTHOR]

John Wiley and Sons, Chichester 2016. 470 S., geb., 112.00 €.—ISBN 978 ‐ 1118627808 [ABSTRACT FROM AUTHOR]

The article focuses on the use of chemical synthesis to prepare huge quantities of polyphenols which are structurally different compounds obtained from plant-based food products. It states that Snyder and colleagues presented a synthetic strategy which allow them to produce tetramers and resveratrol trimers which are considered as the highest-order prepared resveratrol oligomers. It says that tetramers and resveratrol trimers were synthesized through the bromination agents and substrates.

This study aimed at searching for the enzymes that are responsible for the higher hydroxylation of flavonols serving as UV-honey guides for pollinating insects on the petals of Asteraceae flowers. To achieve this aim, an affinity-based chemical proteomic approach was developed by relying on the use of quercetin-bearing biotinylated probes, which were thus designed and synthesized to selectively and covalently capture relevant flavonoid enzymes. Proteomic and bioinformatic analyses of proteins captured from petal microsomes of two Asteraceae species (Rudbeckia hirta and Tagetes erecta) revealed the presence of two flavonol 6-hydroxylases and several additional not fully characterized proteins as candidates for the identification of novel flavonol 8-hydroxylases, as well as relevant flavonol methyl- and glycosyltransferases. Generally speaking, this substrate-based proteome profiling methodology constitutes a powerful tool for the search for unknown (flavonoid) enzymes in plant protein extracts. [ABSTRACT FROM AUTHOR]

6‐Alkyl‐6‐hydroxycyclohexa‐2,4‐dienone derivatives, commonly referred to as ortho‐quinols, and their simple ester and ether variants constitute a class of organic compounds that aroused much interest amongst chemists over the past 70 years for several reasons related to organic synthesis, natural product chemistry and biochemistry. It was very early on that organic chemists understood the potential of the unique yet versatile chemical reactivity of such compounds to synthesize more complex structures, and it soon emerged that ortho‐quinols could constitute key intermediates in the biosynthesis of certain natural products of various origins. This minireview discusses the chemistry of ortho‐quinols from the point of view of their role in the synthesis and biosynthesis of natural products. Examples of completed syntheses of natural products mostly taken in the literature of the last 20 years or so, together with some chosen pieces from older but pioneering and most remarkable works, are highlighted to illustrate this discussion. [ABSTRACT FROM AUTHOR]

A series of 78 synthetic 7-chloro-(4-thioalkylquinoline) derivatives were investigated for cytotoxic activity against eight human cancer as well as 4 non-tumor cell lines. The results showed, with some exceptions, that sulfanyl 5–40 and sulfinyl 41–62 derivatives exhibited lower cytotoxicity for cancer cell lines than those of well-described sulfonyl N-oxide derivatives 63–82. As for compound 81, the most pronounced selectivity (compared against BJ and MRC-5 cells) was observed for human cancer cells from HCT116 (human colorectal cancer with wild-type p53) and HCT116p53−/− (human colorectal cancer with deleted p53), as well as leukemia cell lines (CCRF-CEM, CEM-DNR, K562, and K562-TAX), lung (A549), and osteosarcoma cells (U2OS). A good selectivity was also detected for compounds 73 and 74 for leukemic and colorectal (with and without p53 deletion) cancer cells (compared to MRC-5). At higher concentrations (5 × IC50) against the CCRF-CEM cancer cell line, we observe the accumulation of the cells in the G0/G1 cell phase, inhibition of DNA and RNA synthesis, and induction of apoptosis. In addition, X-ray data for compound 15 is being reported. These results provide useful scientific data for the development of 4-thioalkylquinoline derivatives as a new class of anticancer candidates. [ABSTRACT FROM AUTHOR]

[Display omitted] • Obovatol's role as α-glucosidase (α-Glu) and α-amylase (α-Amy) inhibitor was assessed. • Synthesis of ten obovatol analogous for α-Glu and α-Amy inhibition. • Compounds 1 , 11 , 22 , 26 and 27 were effective inhibitors and were tested for cytotoxicity. • Interaction with the enzyme was studied by CD analysis, SPR imaging and molecular docking studies. • Obovatol-based neolignans are promising structures for developing novel hypoglycemic drugs. Diabetes mellitus is a metabolic disease characterized by hyperglycemia, which can be counteracted by the inhibition of α-glucosidase (α-Glu) and α-amylase (α-Amy), enzymes responsible for the hydrolysis of carbohydrates. In recent decades, many natural compounds and their bioinspired analogues have been studied as α-Glu and α-Amy inhibitors. However, no studies have been devoted to the evaluation of α-Glu and α-Amy inhibition by the neolignan obovatol (1). In this work, we report the synthesis of 1 and a library of new analogues. The synthesis of these compounds was achieved by implementing methodologies based on: phenol allylation, Claisen/Cope rearrangements, methylation, Ullmann coupling, demethylation, phenol oxidation and Michael-type addition. Obovatol (1) and ten analogues were evaluated for their in vitro inhibitory activity towards α-Glu and α-Amy. Our investigation highlighted that the naturally occurring 1 and four neolignan analogues (11 , 22 , 26 and 27) were more effective inhibitors than the hypoglycemic drug acarbose (α-Amy: 34.6 µM; α-Glu: 248.3 µM) with IC 5O value of 6.2–23.6 µM toward α-Amy and 39.8–124.6 µM toward α-Glu. Docking investigations validated the inhibition outcomes, highlighting optimal compatibility between synthesized neolignans and both the enzymes. Concurrently circular dichroism spectroscopy detected the conformational changes in α-Glu induced by its interaction with the studied neolignans. Detailed studies through fluorescence measurements and kinetics of α-Glu and α-Amy inhibition also indicated that 1 , 11 , 22 , 26 and 27 have the greatest affinity for α-Glu and 1 , 11 and 27 for α-Amy. Surface plasmon resonance imaging (SPRI) measurements confirmed that among the compounds studied, the neolignan 27 has the greater affinity for both enzymes, thus corroborating the results obtained by kinetics and fluorescence quenching. Finally, in vitro cytotoxicity of the investigated compounds was tested on human colon cancer cell line (HCT-116). All these results demonstrate that these obovatol-based neolignan analogues constitute promising candidates in the pursuit of developing novel hypoglycemic drugs. [ABSTRACT FROM AUTHOR]

[Display omitted] • Original approach to search for taste-active compounds in spirits. • Identification of a new taste-active compound: brandy tannin A. • Brandy tannin A is an oxidation product of vescalagin. • Brandy tannin A is mostly present in cognacs. Enjoying a glass of spirits can be one of the delights of life. While it is well known that their taste improves during barrel aging, the molecular explanations of this phenomenon remain largely unknown. The present work aimed at searching for taste-active compounds formed in spirits during aging. An untargeted metabolomic approach using HRMS was applied on "eau-de-vie" of cognac. A fractionation protocol was then performed on brandies to isolate a targeted compound. By using HRMS and NMR, its structure was elucidated for the first time. This new ellagitannin, called brandy tannin A, considerably increased the sweetness of spirits at 2 mg/L. After development of an LC-HRMS quantitation method, it was assayed in various spirits and was detected mainly in cognacs up to 7 mg/L. These findings demonstrate the sensory contribution of this compound and more generally the relevance of combining metabolomics and separative techniques to purify new taste-active compounds. [ABSTRACT FROM AUTHOR]

Abstract: Hydroxytyrosol [1, 2-(3,4-dihydroxyphenyl)ethanol], an olive-derived potent natural antioxidant was conveniently prepared from the clove-derived and commercially available eugenol (8, 4-allyl-2-methoxyphenol) using inexpensive reagents in a two-pot four-step process, which successively encompasses a reductive ozonolysis into homovanillyl alcohol (4, 4-hydroxy-3-methoxyphenethanol) and a sodium periodate-mediated oxidative demethylation using a reductive workup. [Copyright &y& Elsevier]

Abstract: The chestnut fruit processing generates large amounts of residues as pericarp (outer shell; 8.9–13.5%) and integument (inner shell; 6.3–10.1%). These materials clearly have the potential as sources of valuable co-products. The analyses of the pericarp and integument of four Portuguese chestnut cultivars (Judia, Longal, Martaínha and Lada) revealed significant contents of total phenolics, low molecular weight phenolics (gallic and ellagic acid), condensed tannins and ellagitannins including castalagin, vescalagin, acutissimin A and acutissimin B. The integument tissues had the highest levels of total phenolics and condensed tannins. The most efficient extraction solvent for the total phenolics, total condensed tannins and low molecular weight phenolics (in Longal) was 70:30 acetone:water at 20°C. The pericarp and integument tissues of the cultivar Longal were richest in gallic acid and castalagin. It is clear that these materials could be used for the extraction of valuable phenolics. [Copyright &y& Elsevier]

Examines the functionalized indole and quinoline derivatives from nitrogen-tethered orthoquinol acetates. Construction of oxygenated indole; Properties of Amaryllidaceae alkasloids; Determination of intramolecular nucleophilic addition reaction.

Many natural products of plant or microbial origins are derived from enzymatic dearomative oxygenation of 2‐alkylphenolic precursors into 6‐alkyl‐6‐hydroxycyclohexa‐2,4‐dienones. These so‐called ortho‐quinols cyclodimerize via a remarkably selective bispericyclic Diels–Alder reaction. Whether or not the intervention of catalytic or dirigent proteins is involved during this final step of the biosynthesis of these natural products, this cyclodimerization of ortho‐quinols can be chemically reproduced in the laboratory with the same strict level of site‐specific regioselectivity and stereoselectivity. This unique yet unified process, which finds its rationale in the inherent chemical reactivity of those ortho‐quinols, is illustrated herein by an efficient and bioinspired first chemical synthesis of one of the most structurally complex and synthetically challenging examples of such natural cyclodimers, the bisditerpenoid (+)‐maytenone. [ABSTRACT FROM AUTHOR]

Many natural products of plant or microbial origins are derived from enzymatic dearomative oxygenation of 2‐alkylphenolic precursors into 6‐alkyl‐6‐hydroxycyclohexa‐2,4‐dienones. These so‐called ortho‐quinols cyclodimerize via a remarkably selective bispericyclic Diels–Alder reaction. Whether or not the intervention of catalytic or dirigent proteins is involved during this final step of the biosynthesis of these natural products, this cyclodimerization of ortho‐quinols can be chemically reproduced in the laboratory with the same strict level of site‐specific regioselectivity and stereoselectivity. This unique yet unified process, which finds its rationale in the inherent chemical reactivity of those ortho‐quinols, is illustrated herein by an efficient and bioinspired first chemical synthesis of one of the most structurally complex and synthetically challenging examples of such natural cyclodimers, the bisditerpenoid (+)‐maytenone. [ABSTRACT FROM AUTHOR]

A selection of bioactive polyphenols of different structural classes, such as the ellagitannins vescalagin and vescalin, the flavanoids catechin, epicatechin, epigallocatechin gallate (EGCG), and procyanidin B2, and the stilbenoids resveratrol and piceatannol, were chemically modified to bear a biotin unit for enabling their immobilization on streptavidin‐coated sensor chips. These sensor chips were used to evaluate in real time by surface plasmon resonance (SPR) the interactions of three different surface‐bound polyphenolic ligands per sensor chip with various protein analytes, including human DNA topoisomerase IIα, flavonoid leucoanthocyanidin dioxygenase, B‐cell lymphoma 2 apoptosis regulator protein, and bovine serum albumin. The types and levels of SPR responses unveiled major differences in the association, or lack thereof, and dissociation between a given protein analyte and different polyphenolic ligands. Thus, this multi‐analysis SPR technique is a valuable methodology to rapidly screen and qualitatively compare various polyphenol–protein interactions. [ABSTRACT FROM AUTHOR]

A facile and highly chemoselective synthesis of doubly activated cyclopropanes is reported where mixtures of alkenes and β‐dicarbonyl‐derived iodonium ylides are irradiated with light from blue LEDs. This metal‐free synthesis gives cyclopropanes in yields up to 96 %, is operative with cyclic and acyclic ylides, and proceeds with a variety of electronically‐diverse alkenes. Computational analysis explains the high selectivity observed, which derives from exclusive HOMO to LUMO excitation, instead of free carbene generation. The procedure is operationally simple, uses no photocatalyst, and provides access in one step to important building blocks for complex molecule synthesis. [ABSTRACT FROM AUTHOR]

A facile and highly chemoselective synthesis of doubly activated cyclopropanes is reported where mixtures of alkenes and β‐dicarbonyl‐derived iodonium ylides are irradiated with light from blue LEDs. This metal‐free synthesis gives cyclopropanes in yields up to 96 %, is operative with cyclic and acyclic ylides, and proceeds with a variety of electronically‐diverse alkenes. Computational analysis explains the high selectivity observed, which derives from exclusive HOMO to LUMO excitation, instead of free carbene generation. The procedure is operationally simple, uses no photocatalyst, and provides access in one step to important building blocks for complex molecule synthesis. [ABSTRACT FROM AUTHOR]

The so‐called Securinega alkaloids constitute a class of tetracyclic biologically active specialised metabolites isolated principally from subtropical plants belonging to the Phyllanthaceae family. Following a strategy based on alternative hypotheses for their biosynthesis, an easy and time‐efficient divergent synthesis enabled access to twelve of those alkaloids featuring (neo)(nor)securinane skeletons. Moreover, this work permitted to reassign the absolute configurations of (+)‐virosine B and (−)‐episecurinol A. [ABSTRACT FROM AUTHOR]

The facile and convenient preparation of both enantiomers of a [7]helicene scaffold from inexpensive (l)‐(+)‐tartaric acid and 4‐methylstyrene is described. These helical structures were transformed into bis‐iodinated ether derivatives in order to explore their potential as precursors of novel chiral organoiodane reagents or as iodoarene pre‐catalysts. Promising results were obtained in hydroxylative phenol dearomatization/[4+2] cycloaddition cascade and dearomative spirolactonization reactions with encouraging enantiomeric excesses. Both enantiomers of [7]carbohelicenes were conveniently prepared from inexpensive starting materials. Bis‐iodinated ether derivatives of such helical systems were examined, for the first time, as precursors of novel chiral iodane reagents and catalysts. Promising results were obtained in asymmetric oxygenative dearomatization reactions. [ABSTRACT FROM AUTHOR]

Abstract The reasons for the loss of characteristic odoriferous thiols during the aging of wine in oak-made barrels and subsequent storage in bottles have been in part attributed to covalent capture of these thiols by polyphenolic wine components that are dehydrogenated into electrophilic ortho -quinones upon wine oxygenation. Herein, FeCl 3 was used as oxidant in oxygen-deprived aqueous solutions to dehydrogenate grape (epi)catechins and oak ellagitannins in the presence of two typical odoriferous thiols, 2-furanmethanethiol (2FMT) and 3-sulfanylhexan-1-ol (3SH). The preparative-scale conditions used enabled the isolation of six novel 2FMT-bearing (epi)catechin derivatives, three known 3SH-bearing catechin derivatives (the structures of two of those were revised to be strictly derived from 1,6-conjugate addition), three novel 2FMT-bearing castalagin derivatives, and one novel 3SH-bearing castalagin derivative. The structures of these castalagin-based thio-adducts revealed that the capture of thiols by the different dehydrogenated pyrogallol rings of castalagin starts at ring IV, then ring III, and finally ring V. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Abstract Actin subunits assemble into actin filaments whose dynamics and three-dimensional architectures are further regulated by a variety of cellular factors to establish the functional actin cytoskeleton. The C -glucosidic ellagitannin vescalagin and its simpler analogue vescalin, affect both the dynamics and the ultrastructure of the actin cytoskeleton by directly binding to F-actin. Herein, we show that in vitro , the two compounds induce the formation of distinct F-actin networks characterized by different superstructures and dynamics. In living mature osteoclasts, highly specialized bone-degrading cells that constantly remodel their cytoskeleton, vescalagin and vescalin alter actin dynamics at podosomes and compromise the integrity of the podosome belt that forms the bone-degrading apparatus. Both compounds target the bone-resorbing activity at concentrations that preserve osteoclastic maturation and survival and with no detectable impact on the behaviour of bone-forming osteoblastic cells. This anti-osteoclastic activity of vescalagin and vescalin reveals the potential of targeting actin dynamics as a new therapeutic opportunity and, in this case, as a plausible approach for the local treatment of osteoporosis. [ABSTRACT FROM AUTHOR]

A concise synthesis of two scyphostatin analogues is achieved from readily available ortho-substituted phenols. Key features include an asymmetric and biomimetic hydroxylative phenol dearomatization (HPD) reaction promoted by a chiral salen-type bis-(λ5-iodane) reagent, followed by an in situ regio- and diastereocontrolled epoxidation. [ABSTRACT FROM AUTHOR]

The first total synthesis of the 2,3,5- O-( S, R)-nonahydroxytriphenoylated (NHTP) C-glucosidic ellagitannin (−)-vescalin was accomplished through a series of transformations mimicking the sequence of events leading to its biogenesis. The key steps of this synthesis encompass a Wittig-mediated ring opening of a glucopyranosic hemiacetal, a C-glucosidation event through a phenolic aldol-type reaction, and a Wynberg-Feringa-Yamada-type oxidative phenolic coupling, which forged the NHTP unit of (−)-vescalin. [ABSTRACT FROM AUTHOR]

The first total synthesis of the 2,3,5- O-( S, R)-nonahydroxytriphenoylated (NHTP) C-glucosidic ellagitannin (−)-vescalin was accomplished through a series of transformations mimicking the sequence of events leading to its biogenesis. The key steps of this synthesis encompass a Wittig-mediated ring opening of a glucopyranosic hemiacetal, a C-glucosidation event through a phenolic aldol-type reaction, and a Wynberg-Feringa-Yamada-type oxidative phenolic coupling, which forged the NHTP unit of (−)-vescalin. [ABSTRACT FROM AUTHOR]

The preparation of new chiral biphenylic λ 3-iodane reagents bearing transferable alkynyl ligands is described. These reagents transfer their carbon-based ligands onto β-ketoesters with an enantiomeric excess ( ee) up to 68 %, and most remarkably, enable the dearomative alkynylation of naphthols in good to high yields up to 84 % ee. [ABSTRACT FROM AUTHOR]

Five previously undescribed triterpene saponins, billiosides A-E, and a known analogue, were isolated from the seeds of Billia rosea (Planch. & Linden) C. Ulloa & P. Jørg. Their structures were elucidated on the basis of extensive 1D and 2D NMR experiments ( 1 H, 13 C, DEPT, COSY, TOCSY, NOESY, ROESY, HSQC, and HMBC) and mass spectrometry as (3β,21β,22α)-3-[(2- O -β-D-glucopyranosyl- O -[α-L-arabinopyranosyl-(1 → 4)]-β-D-glucopyranosyl)oxy]-21-[((2 E ,6 S )-2,6-dimethyl-6-hydroxyocta-2,7-dienoyl)oxy]-22-(acetyloxy)-24-hydroxyolean-12-en-28-oic acid, (3β,21β,22α)-3-[(2- O -β-D-galactopyranosyl-β-D-glucopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O -α-L-arabinopyranosyl-(1 → 4)-β-D-glucopyranoside, (3β,21β,22α)-3-[(2- O -β-D-galactopyranosyl- O -[α-L-arabinopyranosyl-(1 → 4)]-β-D-xylopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O -β-D-glucopyranoside, (3β,21β,22α)-3-[(2- O -β-D-galactopyranosyl- O -[α-L-arabinopyranosyl-(1 → 4)]-β-D-glucopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O -β-D-glucopyranoside, (3β,21β,22α)-3 - [(2- O -β-D-galactopyranosyl- O -[α-L-arabinopyranosyl-(1 → 4)]-β-D-glucopyranosyl)oxy]-21,22-dihydroxyolean-12-en-28-yl O -β-D-glucopyranosyl-(1 → 6)-β-D-glucopyranoside, and dipteroside A. Billiosides B and C exhibited moderate effects when tested as hepatic glucose-6-phosphatase inhibitors and as glucose intestinal absorption inhibitors, using in situ rat intestinal segments. [ABSTRACT FROM AUTHOR]

The phytochemical study of two cultivars of Pittosporum tenuifolium Banks & Sol. ex Gaertn, “variegatum” and “gold star”, led to the isolation of eight oleanane-type glycosides: seven previously undescribed and a known one. Their aglycons are oxygenated oleanane derivatives as barringtogenol C, camelliagenin A, hederagenin, and 22α-hydroxyoleanolic acid. Their structures were established by 2D NMR spectroscopic techniques and mass spectrometry as 3- O -β-D-galactopyranosyl-(1 → 2)-[α-L-arabinopyranosyl-(1 → 3)]-β-D-glucuronopyranosyl-21- O -angeloyl-22- O- acetylbarringtogenol C, 3- O -β-D-galactopyranosyl-(1 → 2)-[α-L-arabinopyranosyl-(1 → 3)]-β-D-glucuronopyranosyl-21,22-di- O- angeloylbarringtogenol C, 3- O -β-D-galactopyranosyl-(1 → 2)-[α-L-arabinopyranosyl-(1 → 3)]-β-D-glucuronopyranosyl-22- O -angeloylcamelliagenin A, 3- O -β-D-glucopyranosyl-(1 → 2)-[β-D-glucopyranosyl-(1 → 6)]-β-D-glucopyranosyl-22- O -[(6- O -acetyl)-β-D-glucopyranosyl]camelliagenin A, 3- O -β-D-galactopyranosyl-(1 → 2)-[α-L-arabinofuranosyl-(1 → 4)]-β-D-glucuronopyranosylhederagenin 28- O -β-D-glucopyranosyl ester, 3- O -α-L-arabinofuranosyl-(1 → 4)-β-D-glucuronopyranosylhederagenin 28- O -β-D-glucopyranosyl ester, 3- O -β-D-galactopyranosyl-(1 → 2)-[α-L-arabinofuranosyl-(1 → 4)]-β-D-glucuronopyranosyl-22α-hydroxyoleanolic acid 28- O -β-D-glucopyranosyl ester, and the known ilexoside XLIX. These results represent a significative contribution to the chemotaxonomy of the genus Pittosporum , highlighting hederagenin-type saponins as chemotaxonomic markers of P. tenuifolium cultivars. [ABSTRACT FROM AUTHOR]

The asymmetric phase-transfer catalytic effect of chiral Cinchona alkaloid-derived quaternary ammonium salts was investigated in the context of the λ 3 -iodane-mediated dearomative spirolactonization of naphthols. The scope and limitations of this methodology were evaluated using various substrates, which were converted into spirolactones in good yields and with enantiomeric excesses up to 58%. [ABSTRACT FROM AUTHOR]

Two model ortho-quinol acetates were easily prepared by iodane-mediated acetoxylative phenol dearomatization and evaluated for their reactivity toward various aryl-based nucleophiles, i.e., aryl metallic reagents and phenolic derivatives. Novel modes of reactivity, allowing the formation of biaryl linkages, were revealed and here exploited for the synthesis of two natural phenolics. [ABSTRACT FROM AUTHOR]

• New C -glucosidic ellagitannin-derived spirit compounds quantification in Cognac eaux-de-vie. • Identification and quantification of a new compound, called brandy tannin B. • Oxidation compounds derived from ellagitannins are identified and quantified for the first time. • Brandy tannin B influences the gustative perception of Cognac eau-de-vie. Ellagitannins are the main extractible phenolic compounds in oak wood. They can be extracted by eaux-de-vie aging in barrels but rapidly undergo chemical transformations, such as hydrolysis, reduction, oxidation, or even substitution reactions. Given gaps in knowledge about their composition in spirits, the goal of this work was to explore ellagitannin behavior during Cognac eaux-de-vie aging and search for new C-glucosidic ellagitannin-derived compounds. A purification protocol was followed to isolate the new formed compounds. UPLC-UV-Q-ToF and NMR spectroscopy were used to characterize a new C-glucosidic ellagitannin, named brandy tannin B. Two new forms of whiskey tannins were also isolated. The new compound, Brandy tannin B along with β -1- O -ethylvescalagin and β -1- O -ethylvescalin, and whiskey tannins were identified and quantified for the first time in Cognac eaux-de-vie. In addition, the organoleptic impact of brandy tannin B was evaluated. This work brings new insights into ellagitannin composition and their contribution to spirit quality. [ABSTRACT FROM AUTHOR]

Interactions between plant polyphenols and biomacromolecules such as proteins and pectins have been studied by several methods in solution (e.g. isothermal titration calorimetry, dynamic light scattering, nuclear magnetic resonance and spectrophotometry). Herein, these interactions were investigated in real time by Surface Plasmon Resonance (SPR) analysis after immobilization of flavan-3-ols onto a sensor chip surface. (−)-epicatechin, (+)-catechin and flavan-3-ol oligomers with an average degree of polymerization of 2 and 8 were chemically modified using N -(2-(tritylthio)ethyl)propiolamide in order to introduce a spacer unit onto the catecholic B ring. Modified flavan-3-ols were then immobilized onto a carboxymethylated dextran surface (CM5). Immobilization was validated and further verified by evaluating flavan-3-ol interaction with bovine serum albumin (BSA), poly- l -proline or commercial pectins. BSA was found to have a stronger association with monomeric flavan-3-ols than oligomers. SPR analysis of selected flavan-3-ols immobilized onto CM5 sensor chips showed a stronger association for citrus pectins than apple pectins, regardless of flavan-3-ol degree of polymerization. [ABSTRACT FROM AUTHOR]

Ellagitannins are a subclass of hydrolysable tannins that have been suggested to function as defensive compounds of plants against herbivores. However, it is known that the conditions in the digestive tracts of different herbivores are variable, so it seems reasonable to anticipate that the reactivities and modes of actions of these ingested defensive compounds would also be different. A previous study on a few ellagitannins has shown that these polyphenolic compounds are highly oxidizable at high pH and that their bioactivity can be attributed to certain structural features. Herein, the activities of 13 ellagitannins using the deoxyribose assay were measured. The results provided information about the anti-oxidant, pro-oxidant and metal chelating properties of ellagitannins. Surprisingly, many of the tested ellagitannins exhibited pro-oxidant activities even at neutral pH and only moderate to low radical scavenging activities, although the metal chelating capacities of all tested ellagitannins were relatively high. [ABSTRACT FROM AUTHOR]

The first total and biomimetic synthesis of the natural bis(sesquiterpene) (-)-bacchopetiolone (revised structure) was completed through a highly diastereoselective hydroxylative phenol dearomatization/[4+2]-dimerization cascade conversion of (+)-curcuphenol using a novel C2-symmetrical chiral Salen-type bis(λ5-iodane). [ABSTRACT FROM AUTHOR]

The screening of natural products in the search for new lead compounds against AlzheimerÏs disease has unveiled several plant polyphenols that are capable of inhibiting the formation of toxic β-amyloid fibrils. Gallic acid based gallotannins are among these polyphenols, but their antifibrillogenic activity has thus far been examined using "tannic acid", a commercial mixture of gallotannins and other galloylated glucopyranoses. The first total syntheses of two true gallotannins, a hexagalloylglucopyranose and a decagalloylated compound whose structure is commonly used to depict "tannic acid", are now described. These depsidic gallotannins and simpler galloylated glucose derivatives all inhibit amyloid β-peptide (Aβ) aggregation in vitro, and monogalloylated a-glucogallin and a natural β-hexagalloylglucose are shown to be the strongest inhibitors. [ABSTRACT FROM AUTHOR]

The screening of natural products in the search for new lead compounds against Alzheimer's disease has unveiled several plant polyphenols that are capable of inhibiting the formation of toxic β-amyloid fibrils. Gallic acid based gallotannins are among these polyphenols, but their antifibrillogenic activity has thus far been examined using "tannic acid", a commercial mixture of gallotannins and other galloylated glucopyranoses. The first total syntheses of two true gallotannins, a hexagalloylglucopyranose and a decagalloylated compound whose structure is commonly used to depict "tannic acid", are now described. These depsidic gallotannins and simpler galloylated glucose derivatives all inhibit amyloid β-peptide (Aβ) aggregation in vitro, and monogalloylated αa-glucogallin and a natural β-hexagalloylglucose are shown to be the strongest inhibitors. [ABSTRACT FROM AUTHOR]

The decrease of the level of characteristic odoriferous thiols in wines has been in part imputed to chemical transformations that take place during aging of wines in oak-made barrels and subsequent storage in bottles. Oxygen dissolved in wines certainly plays a role in such chemical transformations, such as the oxidation of catecholic catechins into thiol-trapping ortho -quinones. However, wines aged in barrels or supplemented with oak chips contain pyrogallolic C -glucosidic ellagitannins, which can also trap thiols in mildly acidic and oxygenated wine solutions by both nucleophilic substitution and oxidative addition reactions. The C -glucosidic ellagitannin vescalagin and methyl gallate were chosen as substrates to investigate these reactions in the presence of two well-known wine odoriferous thiols, 3-sulfanylhexan-1-ol (3SH) and 2-furanmethanethiol (2FMT). Three novel thio-vescalagin condensates were thus hemisynthesized under acidic conditions, and the FeCl 3 -mediated oxidation of methyl gallate furnish different thiogallate adducts under conditions applicable to the oxidative hemisynthesis of thio-ellagitannin adducts. [ABSTRACT FROM AUTHOR]

HIV-1 nucleocapsid protein (NC) is a nucleic acid chaperone implicated in several steps of the virus replication cycle and an attractive new target for drug development. In reverse transcription, NC destabilizes nucleic acid secondary structures and catalyzes the annealing of HIV-1 TAR RNA to its DNA copy (cTAR) to form the heteroduplex TAR/cTAR. A screening program led to the identification of the plant polyphenols acutissimins A and B as potent inhibitors of NC in different assays. These two flavano-ellagitannins, which are found in wine aged in oak barrels, exhibited different mechanisms of protein inhibition and higher potency relatively to their epimers, epiacutissimins A and B, and to simpler structures notably representing hydrolytic fragments and metabolites therefrom. [ABSTRACT FROM AUTHOR]

The long-standing quest for chiral hypervalent organoiodine compounds (i.e., iodanes) as metal-free reagents for asymmetric synthesis continues. Although remarkable progress has recently been made in organoiodine-catalyzed reactions using a terminal oxidant in stoichiometric amounts, there is still a significant need for 'flaskable' chiral iodane reagents. Herein, we describe the synthesis of new iodobinaphthyls and iodobiphenyls, their successful and selective DMDO-mediated oxidation into either λ3- or λ5-iodanes, and the evaluation of their capacity to promote asymmetric hydroxylative phenol dearomatization (HPD) reactions. Most notably, a C2-symmetrical biphenylic λ5-iodane promoted the HPD-induced conversion of the monoterpene thymol into the corresponding ortho-quinol-based [4+2] cyclodimer (i.e., bis(thymol)) with enantiomeric excesses of up to 94 %. [ABSTRACT FROM AUTHOR]

The long-standing quest for chiral hypervalent organoiodine compounds (i.e., iodanes) as metal-free reagents for asymmetric synthesis continues. Although remarkable progress has recently been made in organoiodine-catalyzed reactions using a terminal oxidant in stoichiometric amounts, there is still a significant need for 'flaskable' chiral iodane reagents. Herein, we describe the synthesis of new iodobinaphthyls and iodobiphenyls, their successful and selective DMDO-mediated oxidation into either λ3- or λ5-iodanes, and the evaluation of their capacity to promote asymmetric hydroxylative phenol dearomatization (HPD) reactions. Most notably, a C2-symmetrical biphenylic λ5-iodane promoted the HPD-induced conversion of the monoterpene thymol into the corresponding ortho-quinol-based [4+2] cyclodimer (i.e., bis(thymol)) with enantiomeric excesses of up to 94 %. [ABSTRACT FROM AUTHOR]

The C-glucosidic ellagitannins vescalagin and vescalin are among the plant polyphenols that have been shown to interact with protein targets in a specific manner. This work describes a protecting-group-free method to immobilize these protein-binding natural products on a solid support, and a functionalizing cleavage method, which is adaptable to the solution-phase synthesis of vescal(ag)in derivatives, and which advantageously permitted the preparation of 1-alkylamino derivatives of vescalagin. [ABSTRACT FROM AUTHOR]

Highlights: [•] Five oleanane-type glycosides were isolated from the barks. [•] Structures were determined by 2D NMR and by mass spectrometry. [•] Two saponins possessed an unusual substitution of the Fuc-4 position by an ester group formed by two symmetrical C5 nilic acid. [•] Chemotaxonomic conclusions were discussed. [•] Cytotoxicity and anti-iflammatory activity of the isolated compounds were evaluated. [Copyright &y& Elsevier]

Under the auspices of Bacchus! Acutissimins, natural flavano‐ellagitannins, occur in oak‐aged wine as a result of a diastereoselective condensation reaction of the flavan‐3‐ol catechin, a component of grapes, with the C‐glucosidic ellagitannin vescalagin, found in oak. The acutissimins are further converted into natural mongolicains and analogues of camelliatannin G in a remarkably chemoselective fashion by simple aerobic oxidation. [ABSTRACT FROM AUTHOR]