Search Results (483)

Polycyclic aromatic compounds can often be made by a sequence featuring an initial Diels–Alder [4 + 2] cycloaddition reaction, followed by cheletropic extrusion of carbon monoxide. These reactions normally require heating the diene and dieneophile in petrochemical-derived aromatic hydrocarbon solvents, such as xylenes or diphenyl ether. This article summarizes the results of attempts to use renewable solvents in place of those currently in use to prepare pentaphenylbenzene and 1,2,4-triphenyltriphenylene. Dihydrolevoglucosenone, p-cymene, ethyl lactate, diethyl carbonate, and cyclopentyl methyl ether have all been successfully evaluated as renewable solvent alternatives in Diels–Alder/cheletropic reaction sequences. An analysis of the products from the reactions investigated did not show evidence of oxidative degradation of the diene reactants. Furthermore, norbornadien-7-one intermediates were not isolated from any of the reactions tested. Full article

The discovery of bioactive natural compounds from microbes holds promise for regenerative medicine. In this study, we identified and characterized a steroid-like compound, 3,12-dioxochola-4,6-dien-24-oic acid (DOCDA), from a crude extract of Rhodococcus sp. DOCDA significantly promoted wound healing by enhancing HaCaT cell invasion and migration. It upregulated key growth factors (EGF, VEGF-A, IGF, TGF-β, and HGF), indicating the activation of regenerative signaling. Additionally, DOCDA increased the expression of genes related to focal adhesion and cytoskeletal regulation (ITGB1, ITGA4, FAK, SRC, RHOA, CDC42, RAC1, and paxillin), supporting enhanced cellular motility and remodeling. Notably, DOCDA promoted stem-like properties in HaCaT cells, as shown by increased spheroid formation and elevated levels of the stemness markers ALDH1 and CD44. Target prediction and molecular docking identified the glucocorticoid receptor (GR) as the primary target of DOCDA, with a docking score of −7.7 kcal/mol. Network and pathway enrichment analysis revealed that GR-linked pathways were significantly associated with wound healing, including steroid hormone signaling, inflammation, immune responses, and cell migration. In vivo, the topical application of DOCDA led to over 70% wound closure in mice by day 5. These findings suggest that DOCDA is a steroid-like compound that accelerates wound healing and may serve as a potential agent in regenerative therapy. Full article

The base-enabled reaction of buta-2,3-dien-1-yl methanesulfonate with the readily available and cheap dye indigo resulted in the convenient one-pot synthesis of benzoindolonaphthyridinedione and benzoazepinopyridoindolediones, with the latter representing two novel heterocyclic scaffolds. Despite the low yields, the allenylic alkylation of indigo significantly contributes to the new chemistry of this compound, providing new mechanistic insights and reactivity boundaries. Full article

The inhibition of steroid 5-alpha reductase (S5AR), a key mechanism for managing dihydrotestosterone-dependent conditions, has been demonstrated in teak (Tectona grandis L.f.) leaf extracts. Our recent clinical study confirmed the effectiveness of a hair growth formulation containing teak leaf extract in males with androgenic alopecia. However, significant variability in S5AR inhibitory activity among teak leaf samples from different regions underscores the need for quality control of raw materials. This study applied a metabolomics approach to investigate the influence of leaf age, harvesting period, and geographic origin on chemical composition and S5AR inhibitory activity, as well as to identify active S5AR inhibitors. Geographic origin emerged as the primary determinant of variations in chemical profiles and S5AR inhibitory activity. Using orthogonal partial least squares analysis, six diterpenoid S5AR inhibitors were identified, including four compounds reported for the first time as S5AR inhibitors: rhinocerotinoic acid, 7-oxo-8-labden-15-oic acid, 8-hydroxy-labd-13-en-15-oic acid, and a novel diterpene, 7-hydroxy-labd-8,13-dien-15-oic acid. These findings highlight the potential of metabolomics as a powerful tool for discovering bioactive compounds and optimizing raw material selection. By prioritizing proven geographic sources, consistent bioactivity can be achieved, supporting the therapeutic potential of teak leaves in managing S5AR-related conditions. Full article

Among grapevine trunk diseases, Eutypa dieback, caused by the fungus Eutypa lata, is one of the most critical ones, due to its widespread infection in vineyards and the lack of effective treatments. This fungus is a vascular pathogen that enters grapevines through pruning wounds. The infection process is associated with phytotoxic metabolites produced by the fungus, and as such, the identification of new metabolites from different culture conditions and broths could provide valuable insights into the fungus’s enzymatic system and help its control. For the purposes of this study, the OSMAC (one strain, many compounds) approach was applied to investigate the secondary metabolism of E. lata strain 311 isolated from Vitis vinifera plants in Spain. A total of twenty metabolites were isolated, including five reported for the first time from E. lata and four that are newly identified compounds in the literature: eulatagalactoside A, (R)-2-(4′-hydroxy-3′-methylbut-1′-yn-1′-yl)-4-(hydroxymethyl)phenol, (S)-7-hydroxymethyl-3-methyl-2,3-dihydro-1-benzoxepin-3-ol, and (3aR,4S,5R,7aS)-4,5-dihydroxy-6-((R)-3′-methylbuta-1′,3′-dien-1′-ylidene)hexahydrobenzo[d][1,3]dioxol-2-one. These compounds were extracted from fermentation broths using silica gel column chromatography and high-performance liquid chromatography (HPLC). Their structures were elucidated through extensive 1D and 2D NMR spectroscopy, along with high-resolution electrospray ionization mass spectrometry (HRESIMS). Compounds were evaluated for phytotoxicity against Phaseolus vulgaris, with only eulatagalactoside A producing white spots after 48 h. Additionally, the antibacterial activity against Escherichia coli, Staphylococcus aureus, and Klebsiella pneumoniae of selected compounds was tested. The compounds (R)-2-(4′-hydroxy-3′-methylbut-1′-yn-1′-yl)-4-(hydroxymethyl)phenol and (S)-7-(hydroxymethyl)-3-methyl-2,3-dihydrobenzo[b]oxepin-3-ol showed the most significant antimicrobial activity against Gram-positive bacteria, inhibiting S. aureus by over 75%, with IC₅₀ values of 511.4 µg/mL and 617.9 µg/mL, respectively. Full article

The exploitation of underutilised resources is critical for achieving a sustainable society, and non-edible seaweeds are promising candidates. This study focused on the red alga Portieria hornemannii from Okinawa, Japan, a seaweed with a distinctive aroma, and determined its volatile organic compounds (VOCs) and halogenated secondary metabolites using headspace solid-phase microextraction gas chromatography–mass spectrometry (HS-SPME-GC-MS) at various extraction temperatures. HS-SPME-GC-MS analysis revealed 52 VOCs in Okinawan P. hornemannii, including predominant compounds α-pinenyl bromide (IUPAC name: 2-bromomethyl-6,6-dimethylbicyclo [3.1.1]hept-2-ene; halogenated monoterpene), myrcene disulfide (3-(6-methyl-2-methylidenehept-5-enylidene)dithiirane), and 5,6-dimethyl-1H-benzimidazole, the content of which in the extract increased with increasing extraction temperature from 30 to 60 °C. On the other hand, the β-myrcene (7-methyl-3-methyleneocta-1,6-diene) content, which likely contributes majorly to the distinct fresh odour of the algae, declined as the temperature increased. Furthermore, the proportion of β-myrcene obtained using SPME was significantly higher than that extracted using solvent liquid extraction (SLE) (7.20% in SPME at 30 °C vs. 0.09%, respectively). However, SLE-GC-MS provided a different P. hornemannii volatile profile, allowing for the acquisition of more furan-, alcohol-, ester-, and carboxylic acid-containing compounds. These data provide valuable information, such as a systematic analytical framework for volatiles profiling in the marine macroalgae P. hornemannii, with potential applicability in the development of food and fragrance products. Full article

Phenylbutanoids, commonly found in various medicinal plants, have attracted significant attention due to their remarkable biological activities, including antioxidant, anti-inflammatory, and neuroprotective effects, as well as for their versatility as starting materials in organic synthesis. Among phenylbutanoids, phenyl-1,3-butadienes represent a unique class of conjugated dienes, characterized by a phenyl (C₆H₅) group attached to a 1,3-butadiene (-CH=CH-CH=CH₂) backbone. In this study, we synthesized the hydroxylated biphenyl 5,5′-di((E)-buta-1,3-dien-1-yl)-2,2′,3,3′-tetramethoxy-1,1′-biphenyl 1, closely related to its corresponding monomer 2, which is known for its broad range of pharmacological activities. The synthesis was carried out using microwave-assisted technologies. The structure of the synthesized compound was confirmed through elemental analysis, ¹³C-NMR, ¹H-NMR, and ESI-MS spectrometry. Furthermore, we computed this novel compound’s conformational energy profile (CEP), evaluating how its energy varies with changes in the dihedral bond angle. Full article

Erica spiculifolia Salisb. (formerly Bruckenthalia spiculifolia Benth.) (Balkan heath) is renowned for its traditional usage as a diuretic, anti-inflammatory and antioxidant agent. For the first time, acylquinic acids, flavonoids and numerous proanthocyanidin oligomers were annotated/dereplicated by liquid chromatography–high-resolution mass spectrometry in methanol–aqueous extracts from E. spiculifolia aerial parts harvested at the early and full flowering stage. Chlorogenic acid and proanthocyanidin tetra- and trimer A, B-type together with quercitrin and (+) catechin were the predominant compounds in the semi-quantitative analysis. Neutral triterpenoids, triterpenoid acids and phytosterols were determined in apolar extracts by gas chromatography–mass spectrometry. Triterpenoid acids accounted for 80% of the total triterpenoid content, dominated by ursolic and oleanolic acid, reaching up to 32.2 and 6.1 mg/g dw, respectively. Ursa/olean-2,12-dien-28-oic acids and 3-keto-derivatives together with α-amyrin acetate as a chemotaxonomic marker, α-amyrenone, α- and β-amyrin were evaluated. Total phenolic and flavonoid contents were 83.85 ± 0.89 mg gallic acid equivalents/g and 78.91 ± 0.41 mg rutin equivalents/g, respectively. The extract actively scavenged DPPH and ABTS radicals (540.01 and 639.11 mg Trolox equivalents (TE)/g), possessed high potential to reduce copper and iron ions (660.32 and 869.22 mg TE/g, respectively), and demonstrated high metal chelating capacity (15.57 Ethylenediaminetetraacetic acid equivalents/g). It exhibited prominent anti-lipase (18.32 mg orlistat equivalents/g) and anti-tyrosinase (71.90 mg kojic acid equivalents/g) activity. The extract inhibited α-glucoside (1.35 mmol acarbose equivalents/g) and acetylcholinesterase (2.56 mg galanthamin equivalents/g), and had moderate effects on α-amylase, elastase, collagenase and hyaluronidase. Balkan heath could be recommended for raw material production with antioxidant and enzyme inhibitory properties. Full article

We synthesized 16 representatives of a new class of tetraene macrodiolides with two pharmacophore cis,cis-1,5-diene fragments of the molecule in their structure in rather high yields (from 67 to 84%), which, in turn, were synthesized by a catalytic intermolecular cyclocondensation reaction of α,ω-alka-nZ,(n+4)Z-diendiols with α,ω-alka-nZ,(n+4)Z-diendioic acids using Hf(OTf)₄. The synthesis of starting substrates with 1Z,5Z-diene moieties with a high degree of stereoselectivity was carried out using the authors’ original reaction of catalytic homo-cyclomagnesiation of O-containing allenes. The cytotoxic potential of the examined compounds was assessed using the following cell lines: Jurkat, K562, U937, HL60, HEK293, and Wi-38 (fibroblasts). Biological tests of the synthesized compounds showed a direct effect on mitochondrial biogenesis by the dissociation of oxidation and phosphorylation and the release of cytochrome P450 into the cell cytosol, as well as the induction of mitochondrial apoptosis. The selectivity index demonstrates significant variability, ranging from approximately 2.5 to 5.3 for Jurkat cells and from 3.0 to 5.8 for the other cell lines. Full article

A stereoselective and scalable strategy for the synthesis of phosphorus-containing bicyclic and tricyclic compounds from 1-phenylphosphin-2-en-4-one 1-oxide is presented. This activated dienophile, available in both racemic and enantiopure forms, undergoes smooth [4+2] cycloadditions with acyclic and cyclic dienes, affording products with excellent yields and controlled stereochemistry. Notably, the cis/trans-fusion of the cycloadducts (phosphadecalones and phosphahexahydrochrysene) can be selectively controlled by fine-tuning the conditions of microwave-assisted cycloaddition reaction. The influence of temperature, time, and steric effects on cis/trans and endo/exo selectivity was examined in detail. The molecular structure, including the absolute configuration, of eight products has been determined by X-ray crystallography. These analyses further established the endo-selective nature of the cycloaddition, favoring the P=O face of the dienophile. Post-cycloaddition transformations of selected P-stereogenic phosphadecalone, such as isomerization, reduction and deoxygenation, demonstrate the synthetic versatility of the resulting products. Full article

The aim of this work was to prepare a large set of variously substituted 3-aminophthalates starting from substituted 3-acylamino-2H-pyran-2-ones acting as dienes in Diels–Alder reactions with dialkyl acetylenedicarboxylates having the role of dienophiles. These thermally allowed [4+2] cycloadditions were taking place with normal electron demand due to rather electron-deficient dienophiles and relatively electron-rich dienes; however, they still required quite harsh reaction conditions: heating in closed vessels at 190 °C for up to 17 h was sufficient in most cases (albeit for a few reactions the time needed was up to 58 h) to achieve conversions above 95%. Such conditions, unfortunately, necessitated the use of a larger excess of dienophiles (as undesired polymerization takes place concomitantly); nevertheless, the straightforward isolation procedures enabled access to the target compounds in moderate to high yields (average yield 56%). All products were characterized by standard analytical and spectroscopic methods. With the goal of changing the reaction conditions to be more environmentally friendly, we investigated the effect of various solvents (water, n-butanol, butyl acetate, xylene, para-cymene, n-nonane, etc.) and the temperature applied (130–190 °C) on the conversion. We found that higher temperatures are necessary in most cases (except for the most reactive 2H-pyran-2-ones) regardless of the solvent used. Relative reactivity was determined for both sets of reactants and the experimentally obtained data show good agreement with the computational results. Full article

The use of vacuum impregnation with onion and beetroot juice can help with the challenge of modifying plant tissue and fits in with current trends in the development of plant-based snacks. This study aimed to determine the effect of vacuum impregnation (VI) as a pretreatment before drying on the volatile compounds, texture profile, color, dry matter, water activity, and density of cauliflower. The pretreatment was carried out at a pressure of 0.06 MPa, and the total process time was 21 min. Two types of impregnation solutions were used: onion juice and beetroot juice. The samples were dried by freeze-drying and vacuum. Numerous volatile compounds were identified: twenty-two for raw cauliflower, twenty-nine for cauliflower after VI with beetroot juice, and twenty-four for cauliflower after vacuum impregnation with onion juice. The following volatile compounds were present in the highest amounts: 1-heptene, 2-methyl-(>60%), 2-ethylcyclobutanol (>4%), nona-3,5-dien-2-one (>1.8%), and two unidentified compounds, unknown 1 (probably an isomer of nona-3,5-dien-2-one (>1.8%)) and unknown 2 (probably a fatty acid) (>9.8%). The pretreatment had a significant effect on water activity, density, texture profile and color. The freeze-drying method proved to be effective in obtaining lower values of water activity and density. In addition, dried products obtained by this method were characterized by a higher degree of color recovery after rehydration and textural properties similar to fresh raw material. The use of different impregnation solutions had a significant impact on the properties studied. The greatest color change occurred in cauliflower treated with beetroot juice. Full article

A total of 31 compounds were isolated from the ethyl acetate and n-butanol fractions of Anchusa italica Retz., which contained one ursane triterpenoid, 2α,3β,19α-trihydroxy-23-formyl-urs-12-en-28,21β-olide (1), and five norisoprenoids: (2R,6R,9S)-9-hydroxy-4-megastigmen-3-one-2-O-β-D-glucopyranoside (3); (2R,6S,9S)-9-hydroxy-megastigman-4,7-dien-3-one-2-O-β-D-glucopyranoside (4); (+)-isololiolide β-D-glucopyranoside (5); (2S,8R)-loliolide β-D-glucopyranoside (6a); and (2R,8S)-loliolide β-D-glucopyranoside (6b). It also contained 25 known compounds (2 and 7–30). The chemical structures of the compounds, inclusive of their absolute configurations, were ascertained using spectroscopic methods such as NMR, HR-MS, and quantum chemical calculations (computational NMR and ECD), in combination with relevant literature data. Moreover, the chemotaxonomic significance of the isolated substances was discussed, with compounds 1, 2, and 7–13 potentially broadening the application of triterpenes as taxonomic markers for the classification of the genus Anchusa. Full article

Sustainable ethylene propylene diene monomer (EPDM) elastomers are gaining traction as eco-friendly sealing materials in fuel cell applications. This study evaluates the mechanical degradation behavior of two ECO EPDM formulations—one reinforced with circular carbon black (CCB EPDM), and the other with recycled carbon black (RCB EPDM)—under conditions representative of acidic fuel cell environments. The samples underwent thermal aging at 90 °C for 1000 h, and were immersed in aqueous H₂SO₄ solutions of varying concentrations (1 M, 0.1 M, and 0.001 M) for 1000 h at the same temperature. Gravimetric and volumetric swelling measurements revealed that RCB EPDM experienced significantly higher mass and volume uptake, particularly at intermediate acid concentration, indicating greater susceptibility to fluid ingress. Mechanical testing, including measurement of tensile strength, Shore A hardness, and IRHD microhardness, showed that while RCB EPDM exhibited higher initial strength, it degraded more severely under thermal and acidic exposure. SEM-EDS analysis revealed microstructural damage and compositional changes, with RCB EPDM displaying more pronounced oxidation and surface erosion. In contrast, CCB EPDM demonstrated greater retention of mechanical integrity, greater dimensional stability, and lower variability across aging conditions. These findings highlight the advantages of circular carbon black in enhancing the durability of ECO EPDM compounds in acidic and thermally dynamic fuel cell environments. Full article

Catalyst- and additive-free reactions for synthesizing valuable organic compounds have garnered significant attention in the context of sustainable development. As crucial structural motifs, allylic sulfones find extensive applications in pharmaceutical development and organic synthesis. Despite remarkable advances in allylic sulfone construction, catalyst-free and additive-free methodologies remain an underexplored frontier. Herein, we present an environmentally benign and atom-economical approach for synthesizing allylic sulfones by reacting electron-rich aryl-1,3-dienes with sulfinic acids, achieving yields of 10–94%. This transformation proceeds under ambient air at room temperature, eliminating the need for catalysts or additives. The protocol demonstrates exceptional regio- and chemo-selectivity, streamlined operational simplicity, and excellent scalability potential. This methodology establishes a sustainable and cost-effective paradigm for allylic sulfone synthesis, aligning with green chemistry principles. Full article