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BackgroundStandard treatment for patients with newly diagnosed glioblastoma includes surgery, radiotherapy (RT), and temozolomide (TMZ) chemotherapy (TMZ/RT→TMZ). The proteasome has long been considered a promising therapeutic target because of its role as a central biological hub in tumor cells. Marizomib is a novel pan-proteasome inhibitor that crosses the blood-brain barrier.MethodsEuropean Organisation for Research and Treatment of Cancer 1709/Canadian Cancer Trials Group CE.8 was a multicenter, randomized, controlled, open-label phase 3 superiority trial. Key eligibility criteria included newly diagnosed glioblastoma, age > 18 years and Karnofsky performance status > 70. Patients were randomized in a 1:1 ratio. The primary objective was to compare overall survival (OS) in patients receiving marizomib in addition to TMZ/RT→TMZ with patients receiving the only standard treatment in the whole population and in the subgroup of patients with MGMT promoter-unmethylated tumors.ResultsThe trial was opened at 82 institutions in Europe, Canada, and the U.S. A total of 749 patients (99.9% of the planned 750) were randomized. OS was not different between the standard and the marizomib arm (median 17 vs. 16.5 months; HR = 1.04; P = .64). PFS was not statistically different either (median 6.0 vs. 6.3 months; HR = 0.97; P = .67). In patients with MGMT promoter-unmethylated tumors, OS was also not different between standard therapy and marizomib (median 14.5 vs. 15.1 months, HR = 1.13; P = .27). More CTCAE grade 3/4 treatment-emergent adverse events were observed in the marizomib arm than in the standard arm.ConclusionsAdding marizomib to standard temozolomide-based radiochemotherapy resulted in more toxicity, but did not improve OS or PFS in patients with newly diagnosed glioblastoma.

Phytohormone levels are regulated through specialized enzymes, participating not only in their biosynthesis but also in post-signaling processes for signal inactivation and cue depletion. Arabidopsis thaliana (At) carboxylesterase 15 (CXE15) and carboxylesterase 20 (CXE20) have been shown to deplete strigolactones (SLs) that coordinate various growth and developmental processes and function as signaling molecules in the rhizosphere. Here, we elucidate the X-ray crystal structures of AtCXE15 (both apo and SL intermediate bound) and AtCXE20, revealing insights into the mechanisms of SL binding and catabolism. The N-terminal regions of CXE15 and CXE20 exhibit distinct secondary structures, with CXE15 characterized by an alpha helix and CXE20 by an alpha/beta fold. These structural differences play pivotal roles in regulating variable SL hydrolysis rates. Our findings, both in vitro and in planta, indicate that a transition of the N-terminal helix domain of CXE15 between open and closed forms facilitates robust SL hydrolysis. The results not only illuminate the distinctive process of phytohormone breakdown but also uncover a molecular architecture and mode of plasticity within a specific class of carboxylesterases.

The catalytic performance of a series of mono‐ and bimetallic Ir(I) and Rh(I) complexes bearing the (COC) bis‐triazolylidene ligand, coordinated in a bridging or chelating fashion, was evaluated in the cyclization of 4‐pentynoic acid. The chelated mononuclear cationic complex [Ir(cod)(COC)]PF6 (cod=1,5‐cyclooctadiene; COC=biscarbene ether) displayed the highest reaction rate for 4‐pentynoic acid to form γ‐methyl‐ene‐γ‐butyrolactone (5‐methylenedihydrofuran‐2(3H)‐one). Density Functional Theory calculations were carried out to rationalize the reaction mechanism which proceeds in three steps, namely coordination of the alkyne to the active catalyst followed by intramolecular cyclization and final reductive elimination. Its catalytic performance was further assessed against different substituted 4‐pentynoic acid derivatives. [ABSTRACT FROM AUTHOR]

Herein we describe an efficient methodology for metal‐free hydroborative cleavage of lactones and esters with HBPin (Pin=pinacol) to the corresponding alcohol derivatives using ammonia borane as a pre‐catalyst. The reactions proceed under mild conditions, can be performed in a solvent‐free manner, and do not require an inert atmosphere. Combined experimental and computational mechanistic studies suggest a novel mechanism that involves μ‐aminodiboranes as catalytically active species. [ABSTRACT FROM AUTHOR]

A convenient protocol for the synthesis of A-ring lactones derived from cholesterol was developed. A lactone reduction–lactol separation–reoxidation sequence, applied to the inseparable mixture of diastereomeric lactones, allows the production of multigram amounts of each lactone in pure form. The same sequence applied to A-ring lactones derived from diosgenin produced similar results. A detailed NMR characterization of all the obtained lactones is also provided. X-ray diffraction corroborated the structure of the obtained compounds. [ABSTRACT FROM AUTHOR]

Inherently chiral medium-ring derivatives have important applications in many research fields, such as materials science, molecular recognition, and asymmetric catalysis. However, the enantioselective assembly of these molecules, especially by organocatalytic strategies, remains a formidable challenge, and few methods are available. Here, we report the enantioselective NHC-catalyzed (NHC: N-heterocyclic carbenes) formal high-order (5 + 3) annulation of 1-(2-indolyl)naphthalen-2-ols with ynals. In the presence of an NHC pre-catalyst, base, Lewis acid and oxidant, this protocol enables the catalytic formation of C–C and C-O bonds, providing practical and facile access to an array of inherently chiral saddle-shaped eight-membered lactones featuring an oxocin-2-one scaffold with structural diversity in good efficiency and excellent enantiocontrol. Moreover, the scale-up preparation and representative late-stage transformations of the eight-membered lactones further demonstrate the application potential of this synthetic technology. Inherently chiral medium-ring derivatives have important applications in many research fields, but few enantioselective methods are available. Herein, the authors report the enantioselective N-heterocyclic carbenes-catalyzed formal (5 + 3) annulation of 1-(2-indolyl)naphthalen-2-ols with ynals for the synthesis of eight-membered lactones. [ABSTRACT FROM AUTHOR]

A catalytic asymmetric α-hydroxylation of pyridinone-fused lactones, containing the core structure of camptothecin, is described. Development of a novel spiropyrrolidine amide (SPA) derived triazolium bromide organo-cation catalyst is crucial for a highly enantioselective oxidation, which also accommodates a wide array of lactones with various substituents. The resulting tricyclic tertiary alcohol with an oxa-quaternary carbon center can be further applied in the synthesis of SN-38 and irinotecan, two anti-cancer drugs derived from camptothecin. [ABSTRACT FROM AUTHOR]

We have been able to induce a series of lactonisation reactions of unsaturated acids using a carbocationic intermediate formed in situ. The transformation generates five and six membered lactone rings AND forms a new exocyclic C–C bond at the same time, thus removing the need for further derivatisation of typical lactonisation products (such as from iodo lactonisation). The reaction is operationally straightforward, does not employ any metals and utilises readily accessible alcohol and unsaturated acid substrates. [ABSTRACT FROM AUTHOR]

A series of zinc aryloxides, [Zn4(sal‐Me)8]⋅2.5(C7H8) (1), [Zn4(sal‐Me)8]⋅CH2Cl2 (2), [Zn4(μ3‐OR)2(sal‐R)6] (3) (for R=Me (0.51), Et (0.49)), [Zn4(μ3‐OMe)4(sal‐Me)4(HOMe)4] (4), [Zn(sal‐Me)2(py)2]⋅THF (5), {[Zn(sal‐Me)2(tmbpy)] ⋅ 2(C6H5CH3)}n (6), [Zn2(sal‐Me)2(THF)2Cl2] ⋅ 0.5(C6H5CH3) (7), and [Zn4(μ3‐OMe)2(sal‐Me)4Cl2] (8) (Hsal‐Me=methyl salicylate, py=pyridine, tmbpy=4,4′‐trimethylenedipyridine) were obtained that have different nuclearities and central core topologies and contain ligands of different basicity and coordination abilities. [ABSTRACT FROM AUTHOR]

Herein, we unveil a novel electrochemical oxidative strategy that facilitates the synthesis of lactones from 2‐arylbenzaldehydes and 2‐arylbenzoic acids. Crucially, our method allows for the convergent synthesis of lactones from the combinations of the respective 2‐arylbenzaldehyde and 2‐arylbenzoic acid as starting material, owing to the oxidative process's compatibility within our electrochemical setup. This approach offers a robust and versatile pathway to construct various dibenzopyranones type lactone compounds through an environmentally considerate and economically advantageous process. [ABSTRACT FROM AUTHOR]

We report the utilisation of an iodine(III) reagent to access α,β-unsaturated carbonyls from the corresponding silyl enol ethers of ketones and aldehydes, and from enol phosphates of lactones and lactams. The transformation is rapid, scalable, and can be carried out in one pot, directly dehydrogenating saturated carbonyls. [ABSTRACT FROM AUTHOR]

We have already proven that thiazolylketol acetates, synthetised by addition of 2-lithiothiazole to sugar lactones followed by acetylation, are efficient glycosyl donors in the presence of O-, N-, and P-nucleophiles. We describe here their first use in the C-glycosidation using trimetylsilyl cyanide as the acceptor in order to prepare, after thiazole-to-formyl unmasking and reduction, the corresponding C-ketosides. [ABSTRACT FROM AUTHOR]

The Jurassic relict Royal fern, Osmunda regalis L., is widely distributed across temperate zones in the Northern and Southern hemispheres. Even though this species has been utilised for centuries as a medicinal plant, its phytochemical composition mainly remains unknown. As part of our ongoing research to identify potential lead compounds for future anticancer drugs, 17 natural products were characterised from the aerial parts of Osmunda regalis L. Fifteen of these compounds were identified in this species for the first time, including the six previously undescribed compounds kaempferol 3-O-(2"-O-(2"'-α-rhamnopyranosyl)-β-glucopyranosyl)-β-glucopyranoside, quercetin 3-O-(2"-O-(2"'-α-rhamnopyranosyl)-β-glucopyranosyl)-β-glucopyranoside, kaempferol 3-O-(2"-O-(2"'-α-rhamnopyranosyl-6"'-O-(E)-caffeoyl-)-β-glucopyranosyl)-β-glucopyranoside, 3-methoxy-5-hydroxy-4-olide, 4-hydroxy-3-(3'-hydroxy-4'-(hydroxyethyl)-oxotetrafuranone-5-methyl tetrahydropyranone, and 4-O-(5-hydroxy-4-oxohexanoyl) osmundalactone. The molecular structures were determined by combining several 1D and 2D NMR experiments, circular dichroism spectroscopy, and HRMS. Determination of cytotoxicity against AML MOLM-13, H9c2, and NRK cell lines showed that two isolated lactones exhibited significant cytotoxic activity. [ABSTRACT FROM AUTHOR]

Objective: Inflammation is the initial physiological reaction of the immune system to infection or irritation, leading significant risk factors for several forms of cancer. The genus Asteriscus has been observed to possess a notable abundance of sesquiterpenes with anti-inflammatory properties. This study was designed to assess the anti-inflammatory activity of the sesquiterpenoids isolated from Asteriscus graveolens. Methods: The organic extract of the Asteraceae plant A. graveolens was subjected to different chromatographic and spectroscopic techniques for isolation, purification, and identification of sesquiterpenoid contents. The isolated compounds were screened for antiinflammatory activities in two animal models: rat paw edema and rat ear edema. Histopathological examinations as well as biochemical markers of inflammation were assessed. This was followed by in silico screening for anti-inflammatory activity. Results: Four known sesquiterpenoids were isolated from A. graveolens, including two humulene derivatives, namely, 9-oxohumula-4-en-6,15-olide (1), and 9-oxohumula-1(10)(Z),4,7(E)-trien-6,15-olide (2) and two bisabolene derivatives, identified as bisabola-2,10-dien-1-one (3) and 6-hydroxybisabola-2,10-dien-1-one (4) described. In the rat paw edema model, compound 2 showed highest activity in preventing formation carrageenan-induced paw edema. This was confirmed by histopathological examinations that indicated partial preservation of the epidermal and dermal layers. Further, the compound significantly inhibited cyclooxygenase-2 (COX-2) and tumor necrosis factor-a (TNF-a) release. In the croton oil indued rat ear edema, compounds 2 and 4 significantly inhibited ear edema and protected against histopathological alterations. This was associated with prevention of myeloperoxidase (MPO) concentration in ear tissues. Molecular docking and molecular dynamic simulation indicated the affinity and docking stability of compounds 1-4 to the selected inflammatory protein. Conclusion: Phytochemical investigation of A. graveolens resulted in the isolation and characterization of four sesquiterpenes. In particular, compound 2 showed potent anti-inflammatory activity in carrageenan rat paw edema and croton oil ear edema. [ABSTRACT FROM AUTHOR]

Enantioselective halolactonizations of sterically less hindered alkenoic acid substrates without substituents on the carbon–carbon double bond have remained a formidable challenge. To address this limitation, we report herein the asymmetric bromolactonization of 5-hexenoic acid derivatives catalyzed by a BINOL-derived chiral bifunctional sulfide.

Two new lactones, γ-butyrolactone and δ-valerolactone were isolated from the methanolic extract of Solanum nigrum. Structure elucidation was carried out by exhaustive 2D NMR analysis. The structures of the lactones depict the outcome of their isolation as a situation that involve the formation of artifacts. [ABSTRACT FROM AUTHOR]

The list of standard abbreviations for JDS is available at adsa.org/jds-abbreviations-24. Nonstandard abbreviations are available in the Notes. The objective of this study was to examine the sensory interactions between lactones and ketones in a Cheddar simulation matrix through perceptual interaction analysis. The olfactory thresholds of 6 key lactones had values ranging from 8.32 to 58.88 μg/kg, whereas those of the 4 key ketones ranged from 6.61 to 660.69 μg/kg. Both Feller's additive model and σ-τ plots demonstrated complex interactions in 24 binary mixtures composed of the 6 lactones and 4 ketones, including synergy, addition, and masking effects. Specifically, we found that 6 binary mixtures exhibited aroma synergistic effects using both methods. Moreover, the σ-τ plot showed a synergistic effect of aroma in 3 ternary mixtures. The U -model further confirmed the synergistic effects of the 6 groups of binary systems and 3 groups of ternary systems on aroma at actual cheese concentrations. In an aroma addition experiment, the combination of δ-octalactone and diacetyl in binary mixtures had the most pronounced effect on enhancing milk flavor. In ternary mixtures, 2 combinations, namely δ-octalactone/δ-dodecalactone/diacetyl and γ-dodecalactone/δ-dodecalactone/acetoin, significantly enhanced the milky and sweet aroma properties of cheese, while also enhancing the overall acceptability of the cheese aroma. [Display omitted] [ABSTRACT FROM AUTHOR]

The EFSA Panel on Food Additives and Flavourings was requested to evaluate 14 flavouring substances assigned to the Flavouring Group Evaluation 80 (FGE.80), using the Procedure as outlined in the Commission Regulation (EC) No 1565/2000. Thirteen substances have already been considered in FGE.80 and its revision and in FGE.96 [FL‐no: 10.005, 10.024, 10.025, 10.050, 10.061, 10.069, 10.070, 10.072, 10.169, 13.009, 13.012, 13.161 and 16.055]. The remaining flavouring substance 3a,4,5,7a‐tetrahydro‐3,6‐dimethylbenzofuran‐2(3H)‐one [FL‐no: 10.057] has been cleared with respect to genotoxicity in FGE.217Rev3 and it is considered in this revision 2 of FGE.80. The substance [FL‐no: 10.057] was evaluated through a stepwise approach that integrates information on the structure–activity relationships, intake from current uses, threshold of toxicological concern (TTC) and available data on metabolism and toxicity. The Panel concluded that [FL‐no: 10.057] does not give rise to safety concerns at its levels of dietary intake, when estimated on the basis of the 'Maximised Survey‐derived Daily Intake' (MSDI) approach. Besides the safety assessment of the flavouring substance, the specifications for the material of commerce have also been considered and the information provided was complete for [FL‐no: 10.057]. However, for the flavouring substance [FL‐no: 10.057] in the present revision and for eight substances evaluated in previous revisions, the 'modified Theoretical Added Maximum Daily Intakes' (mTAMDIs) values are above the TTC for their structural class (III). For four substances previously evaluated in FGE.80Rev1 and in FGE.96, use levels are still needed to calculate the mTAMDI estimates. Therefore, in total for 13 flavouring substances, data on uses and use levels should be provided to finalise their safety evaluations. For [FL‐no: 10.050, 10.069 and 13.161], information on the composition of stereoisomeric mixtures is needed. [ABSTRACT FROM AUTHOR]

Lactones represent a class of fundamental structural motifs ubiquitous in nature, holding significance across diverse scientific domains such as pharmaceuticals, natural products, drug discovery, and industry. Despite their simplicity, the synthesis of lactones has garnered considerable interest due to their pivotal roles. Gold, traditionally regarded as a noble metal, has emerged as an efficient catalyst, challenging conventional perceptions. The utilization of gold in lactone synthesis has captivated researchers, leading to the development of numerous effective methodologies. Motivated by this, we present a comprehensive compilation of reports on the gold‐catalyzed synthesis of lactones, encompassing literature till date. [ABSTRACT FROM AUTHOR]

A new 14-membered resorcylic acid lactone (RAL14), chaetolactone A (1), along with three known ones (2−4), was obtained from the fermentation of the soil-derived fungus Chaetosphaeronema sp. SSJZ001. Their structures were established based on extensive spectroscopic data analyses (UV, IR, HRESIMS, 1D, and 2D NMR),13C NMR chemical shifts calculations coupled with the DP4+ probability method, theoretical calculations of ECD spectra, as well as X-ray diffraction analysis. All compounds were evaluated for their cytotoxic effects against A549, HO-8910, and MCF-7 cell lines. [ABSTRACT FROM AUTHOR]

Synthesis of γ and δ‐lactones and lactams are reported in high yield by the cyclization of −COY (Y=OH, NHPh) to the photo redox functionalized benzylic C(sp3)−H bond. [ABSTRACT FROM AUTHOR]

Macrocyclic lactones (MLs) are the only drug class currently licensed for heartworm disease prophylaxis. Macrocyclic lactones kill third- and fourthstage larvae of Dirofilaria immitis, thus preventing the development of adult worms in dogs, which are responsible for heartworm disease, a potentially lifethreatening condition. Despite considerable overlap in terms of endectocide spectrum, several important differences distinguish moxidectin from other MLs. Moxidectin has beneficial pharmacokinetic characteristics, such as a longer half-life and greater tissue distribution compared to ivermectin. Additionally, moxidectin has a greater margin of safety compared to ivermectin in dogs with ABCB1 (previously MDR1) gene-defect, which is commonly recognized in collies and other breeds. Multiple laboratory studies have shown that moxidectin is more effective than other commonly used heartworm preventives against resistant strains of D. immitis. This improved efficacy benefits individual dogs and helps reduce the risk of spreading resistant strains within the community. Despite the presence of proven resistant strains in the United States, noncompliance with preventive measures remains a major factor contributing to the diagnosis of heartworm disease in dogs. In retrospective analyses, the oral moxidectin combination product Simparica Trio® (sarolaner, moxidectin, and pyrantel) was associated with increased compliance, resulting in more time of protection compared to dogs receiving flea/tick and heartworm preventive products separately. Compliance with the extended-release moxidectin injectables ProHeart® 6 and ProHeart® 12 was higher than with monthly heartworm preventives, as they provide 6 months or a full year of protection with one single injection, respectively, and revenues remain in the veterinary clinics as injectable moxidectin cannot be sourced through online retailers. [ABSTRACT FROM AUTHOR]

Synthesis of the A/D/E-ring core compounds of maoecrystal V was achieved. The key Diels-Alder reactions between tricyclic α-methylene lactones and Kitahara-Danishefsky dienes afforded the spirocyclic core compounds in a regioselective and stereoselective manner. [ABSTRACT FROM AUTHOR]

Repurposing enzymes to catalyze non‐natural asymmetric transformations that are difficult to achieve using traditional chemical methods is of significant importance. Although radical C−O bond formation has emerged as a powerful approach for constructing oxygen‐containing compounds, controlling the stereochemistry poses a great challenge. Here we present the development of a dual bio‐/photo‐catalytic system comprising an ene‐reductase and an organic dye for achieving stereoselective lactonizations. By integrating directed evolution and photoinduced single electron oxidation, we repurposed engineered ene‐reductases to steer non‐natural radical C−O formations (one C−O bond for hydrolactonizations and lactonization‐alkylations while two C−O bonds for lactonization‐oxygenations). This dual catalysis gave a new approach to a diverse array of enantioenhanced 5‐ and 6‐membered lactones with vicinal stereocenters, part of which bears a quaternary stereocenter (up to 99 % enantiomeric excess, up to 12.9 : 1 diastereomeric ratio). Detailed mechanistic studies, including computational simulations, uncovered the synergistic effect of the enzyme and the externally added organophotoredox catalyst Rh6G. [ABSTRACT FROM AUTHOR]

Dasania marina (isolate SD1D, with 98.5% sequence similarity to Dasania marina DMS 21967 KOPRI 20902) is a marine bacterium that was isolated from ballast tank fluids as part of a biofilm study in 2014. Our previous work indicated that although this strain produced no detectable biofilm, it was the only isolate to produce N-acyl homoserine lactones (AHLs) in assays using the broad-range reporter strain, Agrobacterium tumefaciens KYC55. The goal of the current study was to determine the types of AHL molecules produced by the D. marina isolate using gas chromatography–mass spectroscopy (GCMS) and C4- to C14-AHL as standards. A time course assay indicated that the D. marina strain produced the highest level of AHLs at 20 h of growth. When extracts were subjected to GCMS, detectable levels of C8- and C10-AHL and higher levels of C12-AHL were observed. Interestingly, several biofilm-forming isolates obtained from the same source also produced detectable amounts of several AHLs. Of the isolates tested, a strain designated SD5, with 99.83% sequence similarity to Alteromonas tagae BCRC 17571, produced unstable biofilms, yet detectable levels of C6-, C8-, C10- and C12-AHL, and isolate SD8, an Alteromonas oceani S35 strain (98.85% sequence similarity), produced robust and stable biofilms accompanied by detectable levels of C8- and C12-AHL. All isolates tested produced C12-AHL at higher levels than the other AHLs. Results from this study suggest that quorum sensing and biofilm formation are uncoupled in D. marina. Whether the suite of AHLs produced by this isolate could modulate biofilm formation in other strains requires further study. [ABSTRACT FROM AUTHOR]

Asymmetric sequential hydrogenations of α‐methylene γ‐ or δ‐keto carboxylic acids are established in one‐pot using a bimetallic Ru/Ru catalyst system, achieving the stereodivergent synthesis of all four stereoisomers of both chiral γ‐ and δ‐lactones with two non‐vicinal carbon stereocenters in high yields (up to 99%) and with excellent stereoselectivities (up to >99% ee and >20:1 dr). The compatibility of the two chiral Ru catalyst systems is investigated in detail, and it is found that the basicity of the reaction system plays a key role in the sequential hydrogenation processes. The protocol can be performed on a gram‐scale with a low catalyst loading (up to 11000 S/C) and the resulting products allow for many transformations, particularly for the synthesis of several key intermediates useful for the preparation of chiral drugs and natural products. [ABSTRACT FROM AUTHOR]

N-Acyl-homoserine lactones (AHL) play a major role in the communication of Gram-negative bacteria. They influence processes such as biofilm formation, swarming motility, and bioluminescence in the aquatic environment. A comprehensive analytical method was developed to elucidate the "chemical communication" in pure bacterial cultures as well as in the aquatic environment and engineered environments with biofilms. Due to the high diversity of AHLs and their low concentrations in water, a sensitive and selective LC-ESI-MS/MS method combined with solid-phase extraction was developed for 34 AHLs, optimized and validated to quantify AHLs in bacterial conditioned medium, river water, and treated wastewater. Furthermore, the developed method was optimized in terms of enrichment volume, internal standards, limits of detection, and limits of quantification in several matrices. An unanticipated variety of AHLs was detected in the culture media of Pseudomonas aeruginosa (in total 8 AHLs), Phaeobacter gallaeciensis (in total 6 AHLs), and Methylobacterium mesophilicum (in total 15 AHLs), which to our knowledge have not been described for these bacterial cultures so far. Furthermore, AHLs were detected in river water (in total 5 AHLs) and treated wastewater (in total 3 AHLs). Several detected AHLs were quantified (in total 24) using a standard addition method up to 7.3±1.0 µg/L 3-Oxo-C12-AHL (culture media of P. aeruginosa). [ABSTRACT FROM AUTHOR]

This article explores the olefination of carbonyl compounds, which is an important process in synthetic research for the preparation of alkenes. The article discusses various reagents and mechanisms involved in olefination reactions, including the use of organophosphorus compounds, silanes, boranes, and titanium organometallics. The authors also investigate the potential involvement of ß-lactones, specifically activated carboxylic esters, in carbon-based olefination reactions. The study presents experimental results using esters of fluorinated alcohols and carbonyl compounds, demonstrating the formation of ¿-methylcinnamates through the formation and spontaneous cleavage of ß-lactones. This research suggests that carbon-based reagents can react similarly to heteroatom-based reagents in olefination reactions. [Extracted from the article]

Aigialomycin D, a 14-membered benzannulated macrolactone, was synthesized in a simple, efficient and stereoselective approach using inexpensive and commonly accessible starting materials. The main steps in this convergent synthesis are Corey-Fuchs reaction, Yamaguchi esterification and ring closing metathesis (RCM). [ABSTRACT FROM AUTHOR]

The development of visible light‐regulated polymerizations for precision synthesis of polymers has drawn considerable attention in the past years. In this study, an ancient dye, indigo, is successfully identified as a new and efficient photoacid catalyst, which can readily promote the ring‐opening polymerization of lactones under visible light irradiation in a well‐controlled manner, affording the desired polyester products with predictable molecular weights and narrow dispersity. The enhanced acidity of indigos by excitation is crucial to the H‐bonding activation of the lactone monomers. Chain extension and block copolymer synthesis are also demonstrated with this method. [ABSTRACT FROM AUTHOR]

Eukaryotic organisms coevolved with microbes from the environment forming holobiotic meta-genomic units. Members of host-associated microbiomes have commensalic, beneficial/symbiotic, or pathogenic phenotypes. More than 100 years ago, Lorenz Hiltner, pioneer of soil microbiology, introduced the term 'Rhizosphere' to characterize the observation that a high density of saprophytic, beneficial, and pathogenic microbes are attracted by root exudates. The balance between these types of microbes decide about the health of the host. Nowadays we know, that for the interaction of microbes with all eukaryotic hosts similar principles and processes of cooperative and competitive functions are in action. Small diffusible molecules like (phyto)hormones, volatiles and quorum sensing signals are examples for mediators of interspecies and cross-kingdom interactions. Quorum sensing of bacteria is mediated by different autoinducible metabolites in a density-dependent manner. In this perspective publication, the role of QS-related activities for the health of hosts will be discussed focussing mostly on N -acyl-homoserine lactones (AHL). It is also considered that in some cases very close phylogenetic relations exist between plant beneficial and opportunistic human pathogenic bacteria. Based on a genome and system-targeted new understanding, sociomicrobiological solutions are possible for the biocontrol of diseases and the health improvement of eukaryotic hosts. [ABSTRACT FROM AUTHOR]

The current paper deals with new metabolites of different groups produced by Azotobacter chroococcum XU1. The strain's metabolic diversity is strongly altered by different factors, and some secondary metabolites are being reported for the first time for this species. As an abiotic/biotic stress response, the strain produced a broad spectrum of indole ring-containing compounds, n-alkanes (eicosane, heneicosane, docosane, tetracosane, and hexacosane), alkanes (7-hexyl eicosane and 2-methyloctacosane), saturated fatty acids (hexanoic and octanoic acids), esters (hexadecanoic acid methyl and pentadecanoic acid-14-methyl-methyl esters), and amides (9-Octadecenamide, (Z)- and 13-Docosenamide, (Z)-). Furthermore, to mitigate the abiotic stress the strain actively produced exopolysaccharide (EPS) to biosorb the Na+ ions. Apart from these metabolites, A. chroococcum XU1 synthesized lactones, namely 1,5-d-gluconolactone and d, l-mevalonic acid lactone in response to carbon source modification. [ABSTRACT FROM AUTHOR]

A stereoselective synthesis of new (6Z,10Z)-16-hydroxyhexadeca-6,10-dienoic and (7Z,11Z)-18-hydroxyoctadeca-7,11-dienoic acid that involved the Ti-catalyzed homocyclomagnesiation of the functionally substituted 1,2-dienes was developed. Subsequent intramolecular cyclization of the synthesized ω-hydroxyalkadienoic acids in the presence of catalytic amounts (2.5–10 mol.%) of hafnium(iv) triflate gave unsaturated macrocyclic lactones and diolides with pharmacophoric 1Z,5Z-diene moieties. [ABSTRACT FROM AUTHOR]

Sodium hypochlorite pentahydrate (NaClO·5H2O, 1) has recently been employed in organic synthesis as an oxidant for alcohols, sulfides, glycols, etc. In most of these reactions, however, reagent 1 functions just as a simple oxidant, and the variations of the reactions have not been well explored. In this study, we report another useful and fascinating reaction, in which reagent 1 functions as a green chlorinating reagent toward β,γ-unsaturated carboxylic acid (2). When substrate 2 was stirred at room temperature with 1 (2 eq) in acetonitrile for 1 h, α,β-unsaturated lactone (3) was obtained in moderate yields (up to 62%). The same reaction proceeded in various organic and aqueous solvents as well. When excess reagent 1 was employed, lactone 3 was further oxidized to the corresponding epoxide (4) for some cases. The conversion is initiated by electrophilic attack of HOCl to the C=C bond of 2 to generate a chloronium ion intermediate, which is cyclized to β-chlorolactone (5) and then 3 through the elimination of HCl. The usefulness of 1 as a chlorinating reagent was further demonstrated in the electrophilic substitution of activated aromatic compounds. [ABSTRACT FROM AUTHOR]

BackgroundNudibranchs comprise a group of > 6000 marine soft-bodied mollusk species known to use secondary metabolites (natural products) for chemical defense. The full diversity of these metabolites and whether symbiotic microbes are responsible for their synthesis remains unexplored. Another issue in searching for undiscovered natural products is that computational analysis of genomes of uncultured microbes can result in detection of novel biosynthetic gene clusters; however, their in vivo functionality is not guaranteed which limits further exploration of their pharmaceutical or industrial potential. To overcome these challenges, we used a fluorescent pantetheine probe, which produces a fluorescent CoA-analog employed in biosynthesis of secondary metabolites, to label and capture bacterial symbionts actively producing these compounds in the mantle of the nudibranch Doriopsilla fulva.ResultsWe recovered the genome of Candidatus Doriopsillibacter californiensis from the Ca. Tethybacterales order, an uncultured lineage of sponge symbionts not found in nudibranchs previously. It forms part of the core skin microbiome of D. fulva and is nearly absent in its internal organs. We showed that crude extracts of D. fulva contained secondary metabolites that were consistent with the presence of a beta-lactone encoded in Ca. D. californiensis genome. Beta-lactones represent an underexplored group of secondary metabolites with pharmaceutical potential that have not been reported in nudibranchs previously.ConclusionsAltogether, this study shows how probe-based, targeted sorting approaches can capture bacterial symbionts producing secondary metabolites in vivo. Video Abstract.

TERT promoter mutations are a hallmark of glioblastoma (GBM). Accordingly, TERT and GABPB1, a subunit of the upstream mutant TERT promoter transcription factor GABP, are being considered as promising therapeutic targets in GBM. We recently reported that the expression of TERT or GABP1 modulates flux via the pentose phosphate pathway (PPP). Here, we investigated whether 13C magnetic resonance spectroscopy (MRS) of hyperpolarized (HP) δ- [1-13C]gluconolactone can serve to image the reduction in PPP flux following TERT or GABPB1 silencing. We investigated two different human GBM cell lines stably expressing shRNAs targeting TERT or GABPB1, as well as doxycycline-inducible shTERT or shGABPB1cells. MRS studies were performed on live cells and in vivo tumors, and dynamic sets of 13C MR spectra were acquired following injection of HP δ-[1-13C]gluconolactone. HP 6-phosphogluconolactone (6PG), the product of δ-[1-13C]gluconolactone via the PPP, was significantly reduced in TERT or GABPB1-silenced cells or tumors compared to controls in all our models. Furthermore, a positive correlation between TERT expression and 6PG levels was observed. Our data indicate that HP δ-[1-13C]gluconolactone, an imaging tool with translational potential, could serve to monitor TERT expression and its silencing with therapies that target either TERT or GABPB1 in mutant TERT promoter GBM patients.

We report a general, intramolecular cycloisomerization of unactivated olefins with pendant nucleophiles. The reaction proceeds under mild conditions and tolerates ethers, esters, protected amines, acetals, pyrazoles, carbamates, and arenes. It is amenable to N‐, O‐, as well as C‐nucleophiles, yielding a number of different heterocycles including, but not limited to, pyrrolidines, piperidines, oxazolidinones, and lactones. Use of both a benzothiazinoquinoxaline as organophotocatalyst and a Co‐salen catalyst obviates the need for stoichiometric oxidant or reductant. We showcase the utility of the protocol in late‐stage drug diversification and synthesis of several small natural products. [ABSTRACT FROM AUTHOR]

A sequential rhodium(III)-catalyzed spiroannulation and lactonization strategy has been developed for the synthesis of a highly rigid spirobenzosultam lactones in good yields with high regioselectivity by means of aromatic ortho-C–H bond activation/functionalization of 3-aryl N-sulfonyl ketimines with 4-hydroxy-2-alkynoates. The reaction proceeds through a cascade of C–H activation followed by spiroannulation and lactonization. In this approach, two C–C and C–O bonds are formed in a single step. This is the first report on the spiroannulation of cyclic N-sulfonyl ketimines with hydroxyalkynoates. [ABSTRACT FROM AUTHOR]

Myelomeningocele (MMC) is a congenital defect of the spine characterised by meningeal and spinal cord protrusion through the open vertebral arches. This defect causes progressive prenatal damage of the spinal cord, leading to lifelong handicap. Although mid‐trimester surgical repair may reduce part of the handicap, an earlier and less invasive approach would further improve the prognosis, possibly minimising maternal and foetal risks. Several studies have proposed an alternative approach to surgical repair by covering the defect with a patch and protecting the exposed neural tissue. Our study aims to elaborate on a waterproof and biodegradable bioactive patch for MMC prenatal foetal repair. We developed a double‐layer patch that can provide a waterproof coverage for the spinal cord, with a bioactive side, conducive to cell proliferation, and an antiadhesive side to avoid its attachment to the medulla. [ABSTRACT FROM AUTHOR]

Chemical study of the nematicidal biocontrol fungus Pochonia chlamydosporia PC-170 led to discovery of six resorcylic acid lactones (RALs), including three nematicidal glycosylated RALs, monocillin VI glycoside (1), colletogloeolactone A (2) and monocillin II glycoside (3), and three antibacterial non-glycosylated RALs, monocillin VI (4), monocillin IV (5) and monocillin II (6). The planar structure of the new compound monocillin VI glycoside (1) was elucidated using HRESIMS and NMR data, and its monosaccharide configuration was further determined through sugar hydrolysis experiment and GC--MS analysis method. Furthermore, their two biosynthetic-related PKS genes, pchE and pchI, were identified through the gene knockout experiment. The glycosylated RALs 1--3 exhibited nematicidal activity against Meloidogyne incognita, with LC50 values of 94, 152 and 64 μg/mL, respectively, and thus had great potential in the development of new nematicidal natural products to control M. incognita in the future. [ABSTRACT FROM AUTHOR]

Stringent response and quorum sensing (QS) are two essential mechanisms that control bacterial global metabolism for better survival. Sphingomonads are a clade of bacteria that survive successfully in diverse ecosystems. In silico survey indicated that 36 out of 79 investigated sphingomonads strains contained more than one luxI homolog, the gene responsible for the biosynthesis of QS signal acyl homoserine lactones (AHLs). Investigation of the regulatory effects of the stringent response gene rsh on QS related bioactivities were carried out using rsh mutants of Sphingobium japonicum UT26 and Sphingobium sp. SYK-6, both had three luxI homologs. Results indicated that deletion of rsh upregulated the overall production of AHLs and extracellular polymeric substances (EPS) in both UT26 and SYK-6 in rich medium, but affected expressions of these luxI/luxR homologs in different ways. In the poor medium (1% LB), rsh mutant of SYK-6 significantly lost AHLs production in broth cultivation but not in biofilm cultivation. The regulatory effects of rsh on QS activities were growth phase dependent in UT26 and culture condition dependent in SYK-6. Our results demonstrated the negative regulatory effect of rsh on QS activities in sphingomonads, which were very different from the positive effect found in sphingomonads containing only one luxI/R circuit. This study extends the current knowledge on the intricate networks between stringent response and QS system in sphingomonads, which would help to understand their survival advantage. [ABSTRACT FROM AUTHOR]

Light‐mediated processes have received significant attention, since they have re‐surfaced unconventional reactivity platforms, complementary to conventional polar chemistry. γ‐Lactones and cyclopropanes are prevalent moieties, found in numerous natural products and pharmaceuticals. Among various methods for their synthesis, light‐mediated protocols are coming to the spotlight, although these are contingent upon the use of photoorgano‐ or metal‐based catalysts. Herein, we introduce a novel photochemical activation of iodo‐reagents via the use of cheap sodium ascorbate or ascorbic acid to enable their homolytic scission and addition onto double bonds. The developed protocol was applied successfully to the formal [3+2] cycloaddition for the synthesis of γ‐lactones, traditional atom transfer radical addition (ATRA) reactions and the one‐pot two‐step conversion of alkenes to cyclopropanes. In all cases, the desired products were obtained in good to high yields, while the reaction mechanism was thoroughly investigated. Depending on the nature of the iodo‐reagent, a halogen or a hydrogen‐bonded complex is formed, which initiates the process. [ABSTRACT FROM AUTHOR]

Anti-inflammatory activities of catechin-rich green tea extract (GTE) in obese rodents protect against metabolic endotoxemia by decreasing intestinal permeability and absorption of gut-derived endotoxin. However, translation to human health has not been established. We hypothesized that GTE would reduce endotoxemia by decreasing gut permeability and intestinal and systemic inflammation in persons with metabolic syndrome (MetS) compared with healthy persons. A randomized, double-blind, placebo-controlled, crossover trial in healthy adults (n = 19, 34 ± 2 years) and adults with MetS (n = 21, 40 ± 3 years) examined 4-week administration of a decaffeinated GTE confection (890 mg/d total catechins) on serum endotoxin, intestinal permeability, gut and systemic inflammation, and cardiometabolic parameters. Compared with the placebo, the GTE confection decreased serum endotoxin (P =.023) in both healthy persons and those with MetS, while increasing concentrations of circulating catechins (P <.0001) and γ-valerolactones (P =.0001). Fecal calprotectin (P =.029) and myeloperoxidase (P =.048) concentrations were decreased by GTE regardless of health status. Following the ingestion of gut permeability probes, urinary lactose/mannitol (P =.043) but not sucralose/erythritol (P >.05) was decreased by GTE regardless of health status. No between-treatment differences (P >.05) were observed for plasma aminotransferases, blood pressure, plasma lipids, or body mass nor were plasma tumor necrosis factor-α, interleukin-6, or the ratio of lipopolysaccharide-binding protein/soluble cluster of differentiation-14 affected. However, fasting glucose in both study groups was decreased (P =.029) by the GTE confection compared with within-treatment arm baseline concentrations. These findings demonstrate that catechin-rich GTE is effective to decrease circulating endotoxin and improve glycemic control in healthy adults and those with MetS, likely by reducing gut inflammation and small intestinal permeability but without affecting systemic inflammation. • A novel green tea extract (GTE) confection was provided to healthy adults and adults with metabolic syndrome. • GTE increased circulating catechins and valerolactones regardless of health status. • GTE decreased intestinal inflammation and small intestinal permeability. • GTE decreased circulating endotoxin. • GTE decreased fasting glucose without affecting systemic inflammation. • Gut-level benefits by GTE support research translation for cardioprotection by green tea. Healthy adults and adults with metabolic syndrome were randomized to a placebo or GTE (1 g; 890 mg catechins) confection for 1 month and then crossed-over to the alternative treatment following a 1-month washout. Regardless of health status, the GTE confection decreased fecal biomarkers of intestinal inflammation (calprotectin and myeloperoxidase) and small intestinal permeability based on a differential sugar absorption test while decreasing serum endotoxin. Abbreviations: GTE, green tea extract; MetS, metabolic syndrome [Display omitted] [ABSTRACT FROM AUTHOR]

The aim of this study was to establish an analytical method for the simultaneous detection of chloramphenicol, stilbenes, and resorcylic acid lactones. After enzymatic hydrolysis, pork samples were extracted by ethyl acetate. Two methods were used for purification: a C18 cartridge and immunoaffinity microextraction in a packed syringe. The samples were analyzed by UPLC–MS/MS on an Acquity UPLC® BEH C18 column with gradient elution. The methods were demonstrated to be suitable for the determination of chloramphenicol, stilbenes, and resorcylic acid lactones in pork. The SPE–UPLC–MS/MS had average recoveries of 42.4–97.1%. The intra-day and inter-day RSDs ranged from 6.1 to 16.9% and 3.7 to 18.4%, respectively. The IA–MPES–UPLC–MS/MS had average recoveries of 14.6–33.3%, and the intra-day and the inter-day RSDs ranged from 4.7 to 19.2% and 1.0 to 16.5%, respectively. Overall, the immunoaffinity microextraction in a packed syringe saves the organic reagent when balancing the C18 cartridge; thus, the dose of the organic reagent is less. However, the recovery of extraction by immunoaffinity microextraction in a packed syringe is less ideal. [ABSTRACT FROM AUTHOR]

In this work, we investigated aroma volatiles emanated by dry roots, stems, leaves, flowers, and fruits of Cardaria draba (L.) Desv. growing wild in Tunisia and its aerial part essential oils (EOs) composition. A total of 37 volatile organic compounds (96.7%-98.9%) were identified; 4 esters, 4 alcohols, 7 hydrocarbons, 12 aldehydes, 5 ketones, 1 lactone, 1 organosulfur compound, 2 organonitrogen compounds, and 1 acid. The hydrocarbons form the main group, representing 49.5%-84.6% of the total detected volatiles. The main constituent was 2,2,4,6,6-pentamethylheptane (44.5%-76.2%) reaching the highest relative percentages. Forty-two compounds were determined in the two fractions of EOs, representing 98.8% and 97.2% of the total oil composition, respectively. The principal components were hexadecanoic acid (34.6%), 6-methyl-5-hepten-2-one (18.3%), decanal (15.0%), 6,10,14-trimethyl2-pentadecanone (13.2%), and n-pentacosane (13%). Micromorphological details of the leaf and stem epidermis using light microscopy revealed polygonal cells with sinuous walls in the adaxial and abaxial leaf surfaces and nearly rectangular and long ones with linear and thick walls for the stem epidermis. The stomata complexes were anisocytic in the leaf epidermis and mainly anisocytic and rarely paracytic in the stem epidermis. Non-glandular trichomes were unbranched and long with an acute apex or short with a convex apex. The glandular ones were identified for the first time in this species. They were short-stalked with a large secretory head. The highest stomatal index (17.02%) was recorded in the abaxial leaf surface. The identification of headspace volatiles and essential oil compounds can be used to characterize this species, and the various epidermis micromorphological features are very useful for biosystematics taxonomic studies within Brassicaceae. [ABSTRACT FROM AUTHOR]

Transplanting rice varieties grown in different seasons can lead to different yields due to different dry matter production. Early-season rice varieties transplanted in the late season can obtain high yields with short-growth duration and higher yields driven by higher dry matter production. To make clear the variations in dry matter production across seasons, four early-season rice varieties were chosen for late-season transplantation. The grain yield, dry matter accumulation, leaf photosynthetic, and leaf stomatal properties were studied. It was observed that the average yields of these four varieties in the late season were 33% greater, despite a reduced growth period of 13 days in comparison with the early season. Furthermore, there was a notable increase in both total and postheading dry matter production during the late season. The leaf net photosynthetic rate, stomatal area, stomatal width, and stomatal length were higher in the late season. Despite no significant difference in stomatal density between seasons, strong positive linear relationships were observed between net photosynthetic rate and stomatal conductance, and between stomatal conductance and area. These relationships demonstrate that the increase of the stomatal width and length of the leaves in the late season leads to an increase in the stomatal area, thereby increasing the stomatal conductance and enhancing the photosynthesis of the leaves. Consequently, this leads to greater dry matter production and a higher yield compared to the early season. Therefore, when breeding new high-yielding and short-growing varieties, the large stomatal area can be used as a reference index. [ABSTRACT FROM AUTHOR]

Medium-sized lactones are an important class of natural products with diverse biological activities. Unlike conventional organic compounds, these molecules exhibit elevated levels of conformational flexibility. This inherent structural feature occasionally exacerbates the complexities associated with determining their conformation, thereby posing challenges in deciphering their stereochemistry or, in certain instances, leading to incorrect structures. This review highlights specific scenarios in which synthetic studies and computational chemistry have assumed pivotal roles in unveiling the structures of lactones, which have previously eluded definitive elucidation. [ABSTRACT FROM AUTHOR]