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This study evaluated the composition and the antinociceptive and anti-inflammatory activity of the crude extracts and two isolated compounds, anamarine (ANA) and 10-epi-olguine (eOL), obtained from the leaves of Cantinoa stricta (Lamiaceae). Crude ethanolic extract (EEt) and dichloromethane extract (DCM), selected based on NMR data, were submitted to pharmacological tests in male Swiss mice. The oral administration of EEt and DCM significantly reduced the second phase of formalin-induced nociception (60%), lipopolysaccharide (LPS)-induced mechanical hyperalgesia (90%), and carrageenan (Cg)-induced edema (25%). ANA and eOL, the major compounds in EEt and DCM extracts, administered orally or locally (in the paw), also reduced the LPS-induced mechanical hyperalgesia (Oral ID50 1.9 and 3.9 mg/kg; Local ID50 93.4 and 677.3 ng, respectively) without changing the thermal acute nociception or the motor performance of the animals. Local administration of ANA and eOL also reduced Cg-induced edema (40 and 23%, respectively). These isolated compounds did not change the mechanical hyperalgesia induced by tumor necrosis factor-α, interleukin-1β, prostaglandin E2, dibutyryl cyclic AMP, or forskolin but reversed the hyperalgesia induced by dopamine, epinephrine, and phorbol 12-myristate 13-acetate. The hyperalgesia induced by epinephrine was reversed in male but not in female mice, in which this response is not dependent on protein kinase C (PKC). These results suggest that C. stricta extracts possess antinociceptive and anti-inflammatory activity which is related to the presence of ANA and eOL. Differently from the known analgesics, these substances seem to exert their action mainly interfering with the sympathetic component of pain, possibly with PKC. [ABSTRACT FROM AUTHOR]

Six lactone derivatives, including four α‐pyrones derivatives (1–4), two α‐furanone derivatives (5 and 6), were isolated from the Dendrobium pendulum. Structural elucidation of these undescribed lactone derivatives were accomplished on the basis of detailed nuclear magnetic resonance analysis, and the absolute configurations of compounds 1–4 were confirmed by electronic circular dichroism (ECD) techniques. The cytotoxic effects of isolated compounds on human breast cancer cell MDA‐MB‐231 were evaluated by the MTT assay. [ABSTRACT FROM AUTHOR]

Two new α -pyrone derivatives, curvulapyrones B (1) and C (2), and a new naturally occurring resorcylic acid lactone (11), along with fourteen known compounds (3 − 10, 12 − 17), were isolated from the rice fermentation of sponge-derived fungus Curvularia sp. ZYX-Z-4. The structures of the new compounds were elucidated from comprehensive analysis of HRESIMS and NMR spectroscopic data as well as NMR and ECD spectra calculations. Among them, compounds 5 and 16 inhibited the release of NO from RAW264.7 cells induced by LPS with the IC 50 values of 43.16 and 64.14 µM, respectively, and without cytotoxicity observed. Compounds 11 and 12 exhibited inhibitory activities against the phytopathogenic fungus Colletotrichum capsici with the same MIC values of 32.0 µg/mL. [Display omitted] • Chemical investigation on the fungus Curvularia sp. ZYX-Z-4 was performed. • Two new α -pyrone derivatives (1 and 2) were isolated and identified. • Compounds 5 and 16 inhibited NO release from RAW264.7 cells induced by LPS. • Compounds 11 and 12 inhibited phytopathogenic fungus Colletotrichum capsici. [ABSTRACT FROM AUTHOR]

Hispidin is a polyketide found in plants and fungi. In bioluminescent fungi, hispidin serves as a precursor of luciferin and is produced by hispidin synthases. Previous studies revealed that hispidin synthases differ in orthologous polyketide synthases from non-bioluminescent fungi by the absence of two domains with predicted ketoreductase and dehydratase activities. Here, we investigated the hypothesis that the loss of these domains in evolution led to the production of hispidin and the emergence of bioluminescence. We cloned three orthologous polyketide synthases from non-bioluminescent fungi, as well as their truncated variants, and assessed their ability to produce hispidin in a bioluminescence assay in yeast. Interestingly, expression of the full-length enzyme hsPKS resulted in dim luminescence, indicating that small amounts of hispidin are likely being produced as side products of the main reaction. Deletion of the ketoreductase and dehydratase domains resulted in no luminescence. Thus, domain truncation by itself does not appear to be a sufficient step for the emergence of efficient hispidin synthases from orthologous polyketide synthases. At the same time, the production of small amounts of hispidin or related compounds by full-length enzymes suggests that ancestral fungal species were well-positioned for the evolution of bioluminescence. [ABSTRACT FROM AUTHOR]

There has been a tremendous increase in the rate of new terpenoids from marine-derived fungi being discovered, while new monoterpenes were rarely isolated from marine-derived fungi in the past two decades. Three new monoterpenes, diaporterpenes A–C (1–3), and one new α-pyrones, diaporpyrone A (6), along with nine known polyketides 4, 5, and 7–13 were isolated from the ascidian-derived fungus Diaporthe sp. SYSU-MS4722. Their planar structures were elucidated based on extensive spectroscopic analyses (1D and 2D NMR and HR-ESIMS). The absolute configurations of 1 and 3 were identified by an X-ray crystallographic diffraction experiment using Cu-Ka radiation, and those of compound 2 were assigned by calculating NMR chemical shifts and ECD spectra. It afforded an example of natural epimers with different physical properties, especially crystallization, due to the difference in intermolecular hydrogen bonding. Compounds 9, 10, and 13 showed moderate total antioxidant capacity (0.82 of 9; 0.70 of 10; 0.48 of 13) with Trolox (total antioxidant capacity: 1.0) as a positive control, and compounds 5 and 7 showed anti-inflammatory activity with IC50 values of 35.4 and 40.8 µM, respectively (positive control indomethacin: IC50 = 35.8 µM). [ABSTRACT FROM AUTHOR]

Naturally occurring α‐pyrones with biological activities are mostly synthesised by polyketide synthases (PKSs) via iterative decarboxylative Claisen condensation steps. Remarkably, we found that some enzymes related to the fatty acid β‐oxidation pathway in Escherichia coli, namely the CoA ligase FadD and the thiolases FadA and FadI, can synthesise styrylpyrones with phenylpropionic acids in vivo. The two thiolases directly utilise acetyl‐CoA as an extender unit for carbon‐chain elongation through a non‐decarboxylative Claisen condensation, thus making the overall reaction more efficient in terms of carbon and energy consumption. Moreover, using a cell‐free approach, different styrylpyrones were synthesised in vitro. Finally, targeted feeding experiments led to the detection of styrylpyrones in other species, demonstrating that the intrinsic ability of the β‐oxidation pathway allows for the synthesis of such molecules in bacteria, revealing an important biological feature hitherto neglected. [ABSTRACT FROM AUTHOR]

Intensive study of the organic extract of the marine-derived bacterium Saccharomonospora sp. CNQ-490 has yielded three new α-pyrones, saccharomonopyrones A-C (1-3). The chemical structures of these compounds were assigned from the interpretation of 1D, 2D NMR and mass spectrometry data. Saccharomonopyrone A (1) is the first α-pyrone microbial natural product bearing the ethyl-butyl ether chain in the molecule, while saccharomonopyrones B and C possess unusual 3-methyl and a 6-alkyl side-chain within a 3,4,5,6-tetrasubstituted α-pyrone moiety. Saccharomonopyrone A exhibited weak antioxidant activity using a cation radical scavenging activity assay with an IC50 value of 140 μM.

Seen initially as wonder drugs, the widespread and often inappropriate use of antibiotics led to the development of microbial resistances. As a result, a true emergency has arisen, and a significant need has emerged to discover and develop new safe and valuable antibiotics. The captivating chemical structure of the fungal metabolite diplopyrone C has caught our attention as an excellent candidate for a circumstantial study aimed at revealing its antimicrobial and antibiofilm activities. In this work, we describe the full analytical strategy from the isolation/identification to the evaluation of the metabolomics effect on target microorganisms of this fungal metabolite. Our results show interesting antimicrobial and antibiofilm activities of diplopyrone C against two frequently isolated nosocomial pathogens (i.e., the fungus Candida albicans and the gram-negative bacterium Klebsiella pneumoniae). Moreover, a GC-MS based metabolomics footprinting approach gave an insight into the uptake and excretion of metabolites from and into the culture medium as a response to the presence of this active substance. The workflow employed in this study is suitable to exploit natural resources for the search of lead compounds for drug development. [Display omitted] • Diplopyrone C was isolated and identified from D. corticola cultures. • Diplopyrone C shows antimicrobial and antibiofilm activities against two microorganisms. • A metabolomics strategy gives an insight on the antibiofilm effects of diplopyrone C. • The accumulation of several metabolites was observed in presence of diplopyrone C. • Diplopyrone C reduces the growth rate of C. albicans and K. pneumoniae biofilms. [ABSTRACT FROM AUTHOR]

Six new secondary metabolites, including two new nor-triterpenes (1 and 2), one new sesquiterpene (4), two new α-pyrone derivatives (6 and 7), and one new natural product (5) along with two known compounds (3 and 8) were isolated from an endophytic fungus Colletotrichum gloeosporioides obtained from a toxic medicinal plant Tylophora ovata. Their structures were elucidated by spectroscopic data analyses, while their absolute configurations were determined by CD and X-ray diffraction analyses. The in vitro anti-inflammatory activities of these compounds were evaluated. [ABSTRACT FROM AUTHOR]

Five new α-pyrones, xylariaopyrones E–I (1–5), along with three known analogues (6–8) were isolated from the cultivation broth of the endophytic fungus Xylariales sp. (HM-1). The structures of the new compounds including their absolute configurations were elucidated by comprehensive spectroscopic methods and quantum ECD calculations. Xylariaopyrone E (1) is the first example of α-pyrone derivative with a novel [3, 2, 0] bridge ring system via a ketal function group in the side chain. In bioactivity assays, xylariaopyrones E–G (1–3) showed moderate inhibiting activities against Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa with MIC values from 25.4 to 64.5 μg/mL, whereras xylariaopyrone G (3) exhibited significant inhibition of monoamine oxidase B with an IC50 value of 15.6 μmol/L. Xylariaopyrone H (4) and the known compound 7 showed moderate toxicity against brine shrimp larvae with inhibition rates of 42.8% and 44.5%, respectively. [ABSTRACT FROM AUTHOR]

Five new α-pyrone derivatives, cryptoyunnanes A − E (1 − 5), together with four known analogues, were isolated from the leaves and twigs of Cryptocarya yunnanensis. Their structures including absolute configurations were elucidated by extensive spectroscopic data and electronic circular dichroism (ECD) analyses. Compounds 4 and 6 showed significant cytotoxicity against A549, HCT-116, MDA-MB-231, PC-3 and HeLa with IC50 values from 2.25 to 8.97 µM. Compounds 1, 2 and 7 also displayed good cytotoxicity against HCT-116, MDA-MB-231 and PC-3 with IC50 values from 1.26 to 8.32 µM. This is the first time to report the isolation and bioactivity evaluation of chemical constituents from C. yunnanensis. [ABSTRACT FROM AUTHOR]

The first direct transition metal‐free access to 3,6‐disubstituted α‐pyrones from α‐chloro aldehydes and β‐tosyl enones is reported. The reactions proceed via the Michael addition/lactonization/elimination cascade. The regioselective addition of NHC‐bound enolates/homoenolates to the enones bearing a bulkier functionality such as tosyl group at the β‐position has remained challenging. The 3,6‐disubstituted α‐pyrones could be converted to valuable products such as 1,2,3,4‐tetrasubstituted benzenes, 1,4‐disubstituted naphthalenes as well as anthracenes and 6,13‐disubstituted dihydro‐ethenopentacenes in a simple operation. [ABSTRACT FROM AUTHOR]

Kavalactones are classes of α-pyrone and 5,6-dihydropyrone derivatives showing various biological activities, and numerous approaches have been reported for the preparation of these molecules. In this review, we discuss the different synthetic approaches towards these naturally occurring lactones, in both racemic and enantiomerically pure forms, that have been reported in the literature to date. It is hoped that this review will assist researchers in the development of additional and efficient synthetic routes towards kavalactones. 1 Introduction 2 Synthetic Approaches for the Preparation of Kavalactones 3 Conclusion [ABSTRACT FROM AUTHOR]

Chemical investigation of the culture extract of an endophyte Xylaria curta YSJ-5 from Alpinia zerumbet (Pers.) Burtt. et Smith resulted in the isolation of eight previously undescribed compounds including five eremophilane sesquiterpenes xylarcurenes A-E, one norsesquiterpene xylarcurene F, and two α -pyrone derivatives xylarpyrones A-B together with eight known related derivatives. Their chemical structures were extensively established based on the 1D- and 2D-NMR spectroscopic analysis, modified Mosher's method, electronic circular dichroism calculations, single-crystal X-ray diffraction experiments, and the comparison with previous literature data. All these compounds were tested for in vitro cytotoxic, anti-inflammatory, α -glucosidase inhibitory, and antibacterial activities. As a result, 6-pentyl-4-methoxy-pyran-2-one was disclosed to display significant antibacterial activity against Staphylococcus aureus and methicillin-resistant S. aureus with minimal inhibitory concentration value of 6.3 μg/mL. Six previously undescribed sesquiterpenes xylarcurenes A-F (1 – 6) and two previously undescribed α -pyrones xylarpyrones A-B (12 – 13) were isolated from Xylaria curta YSJ-5. [Display omitted] • Six previously undescribed sesquiterpenes were isolated from Xylaria curta YSJ-5. • Two previously undescribed α -pyrones were characterized from Xylaria curta YSJ-5. • Compounds 1 , 2 , 3 and 5 were determined by X-ray diffraction techniques. • Compound 15 showed significant antibacterial activity against S. aureus and MRSA. [ABSTRACT FROM AUTHOR]

Starting from substituted alkynones, α-pyrones and/or 1H-pyridines were generated in a Michael addition–cyclocondensation with ethyl cyanoacetate. The peculiar product formation depends on the reaction conditions as well as on the electronic substitution pattern of the alkynone. While electron-donating groups furnish α-pyrones as main products, electron-withdrawing groups predominantly give the corresponding 1H-pyridines. Both heterocycle classes fluoresce in solution and in the solid state. In particular, dimethylamino-substituted α-pyrones, as donor–acceptor systems, display remarkable photophysical properties, such as strongly red-shifted absorption and emission maxima with daylight fluorescence and fluorescence quantum yields up to 99% in solution and around 11% in the solid state, as well as pronounced emission solvatochromism. Also a donor-substituted α-pyrone shows pronounced aggregation-induced emission enhancement.

There has been a tremendous increase in the rate of new terpenoids from marine-derived fungi being discovered, while new monoterpenes were rarely isolated from marine-derived fungi in the past two decades. Three new monoterpenes, diaporterpenes A–C (1–3), and one new α-pyrones, diaporpyrone A (6), along with nine known polyketides 4, 5, and 7–13 were isolated from the ascidian-derived fungus Diaporthe sp. SYSU-MS4722. Their planar structures were elucidated based on extensive spectroscopic analyses (1D and 2D NMR and HR-ESIMS). The absolute configurations of 1 and 3 were identified by an X-ray crystallographic diffraction experiment using Cu-Ka radiation, and those of compound 2 were assigned by calculating NMR chemical shifts and ECD spectra. It afforded an example of natural epimers with different physical properties, especially crystallization, due to the difference in intermolecular hydrogen bonding. Compounds 9, 10, and 13 showed moderate total antioxidant capacity (0.82 of 9; 0.70 of 10; 0.48 of 13) with Trolox (total antioxidant capacity: 1.0) as a positive control, and compounds 5 and 7 showed anti-inflammatory activity with IC50 values of 35.4 and 40.8 µM, respectively (positive control indomethacin: IC50 = 35.8 µM).

• Two tetrasubstituted α -pyrones were identified from the endophytic fungus Neurospora udagawae • Udagawanone B constitutes a rare example of a C-4 O -demethylated α -pyrone. • Their antimicrobial and cytotoxic activities are reported. Two new α -pyrone derivatives, udagawanones A (1) and B (2), along with the known compounds (Z)-4-hydroxy-3-(3-hydroxy-3-methylbut-1-en-1-yl)benzoic acid (3), isosclerone (4), cyclo -(L -Leu- L -Pro) (5), and cyclo -(L -Pro- L -Tyr) (6), were isolated from cultures of the endophyte Neurospora udagawae. Their structures were elucidated by extensive spectroscopic methods and single crystal X-ray diffraction. Both compounds feature oxidized functionalities at the C-2 position not previously observed in other tetrasubstituted α -pyrones from fungi. Compound 1 exhibited moderate antibacterial (vs. Staphylococcus aureus) and antifungal (vs. Rhodoturula glutinis) activities and cytotoxicity against KB3.1 cells. [ABSTRACT FROM AUTHOR]

Two new α-pyrones, fupyrones A and B (1 and 2) and a biosynthetically related known α-pyrone, 4-methyl-5,6-dihydro-2H-pyran-2-one (3), were isolated from an endophytic fungus, Fusarium sp. F20, harbored in the stems of the Chinese medicinal plant Mahonia fortunei. Their structures were determined on the basis of spectroscopic data including MS and NMR. The antibacterial efficacies of compounds 1–3 were evaluated against four selected Gram-positive and Gram-negative bacteria, and their quorum sensing inhibitory activity was also investigated against the test organism, Chromobacterium violaceum. [ABSTRACT FROM AUTHOR]

The fungal strain was isolated from a soil sample collected in Giza province, Egypt, and was identified as Aspergillus ochraceopetaliformis based on phenotypic and genotypic data. The ethyl acetate extract of the fungal strain exhibited promising activity levels against several pathogenic test organisms and through a series of 1H NMR guided chromatographic separations, a new α-pyrone-C-lyxofuranoside (1) along with four known compounds (2–5) were isolated. The planar structure of the new metabolite was elucidated by detailed analysis of its 1D/2D NMR and HRMS/IR/UV spectroscopic data, while the relative configuration of the sugar moiety was determined by a combined study of NOESY and coupling constants data, with the aid of theoretical calculations. The structures of the known compounds—isolated for the first time from A. ochraceopetaliformis—were established by comparison of their spectroscopic data with those in the literature. All isolated fungal metabolites were evaluated for their antibacterial and antifungal activities against six Gram-positive and Gram-negative bacteria as well as against three human pathogenic fungi.

The zoanthid-derived fungus Cochliobolus lunatus (TA26-46) has been proven to be a source of bioactive 14-membered resorcylic acid lactones (RALs). In the present study, chemical epigenetic manipulation was applied to this fungal strain with a DNA methyltransferase inhibitor resulting in the significant changes of the secondary metabolites. Cultivation of C. lunatus (TA26-46) with 10 μM 5-azacytidine in Czapek-Dox liquid medium led to the isolation of new types of metabolites, including two α-pyrones, cochliobopyrones A (1) and B (2), along with three isocoumarins (3–5) and one chromone (6). The planar structures of the new compounds (1–2) were elucidated by comprehensive analyses of NMR and HRESIMS data. Their challenging relative configurations were established by a combination of acetonide reaction, coupling constants and NOESY correlations analysis, and DP4+ probability calculation. Their absolute configurations were determined by comparing with the ECD calculation data of the fragment molecules, 6-(1,2-dihydroxypropyl)-4-methoxy-2H-pyran-2-ones. It is the first time to obtain α-pyrone compounds with the epoxy ring or bromine atom on the seven-numbered side chain. It could be concluded that chemical epigenetic agents could induce C. lunatus to produce new types of secondary metabolites differing from its original products (RALs).

In this paper, we described the discovery of two Nocardiopsis strains HDN154-146 and HDN154-168 from Takla Makan desert soil samples using seawater based medium. Chemical investigation of these two strains led to the discovery of eight new α-pyrone derivatives named nocahypyrones A-H (1–8), together with one known analogue germicidin G (9). The structures of these compounds, including absolute configurations, were elucidated by extensive NMR, MS, and CD analyses. Compounds 1–9 were tested for their cyto-protective activities and for the first time we found α-pyrones 5 and 8 exhibited capabilities to induce expression of phase II detoxifying enzymes. [ABSTRACT FROM AUTHOR]

Abstract Due to the widespread occurrence and spread of anthelmintic resistance, there is a need to develop new drugs against resistant parasitic nematodes of livestock animals. The Nobel Prize-winning discovery and development of the anti-parasitic drugs avermectin and artemisinin has renewed the interest in exploring natural products as anthelmintics. In the present study, we screened 7500 plant extracts for in vitro-activity against the barber's pole worm, Haemonchus contortus , a highly significant pathogen of ruminants. The anthelmintic extracts from two plants, Cryptocarya novoguineensis and Piper methysticum , were fractionated by high-performance liquid chromatography (HPLC). Subsequently, compounds were purified from fractions with significant biological activity. Four α-pyrones, namely goniothalamin (GNT), dihydrokavain (DHK), desmethoxyyangonin (DMY) and yangonin (YGN), were purified from fractions from the two plants, GNT from C. novoguineensis , and DHK, DMY and YGN (= kavalactones) from P. methysticum. The three kavalactones induced a lethal, eviscerated (Evi) phenotype in treated exsheathed third-stage larvae (xL3s), and DMY and YGN had moderate potencies (IC 50 values of 31.7 ± 0.23 μM and 23.7 ± 2.05 μM, respectively) at inhibiting the development of xL3s to fourth-stage larvae (L4s). Although GNT had limited potency (IC 50 of 200–300 μM) at inhibiting L4 development, it was the only compound that reduced L4 motility (IC 50 of 6.25–12.50 μM). The compounds purified from each plant affected H. contortus in an irreversible manner. These findings suggest that structure-activity relationship studies of α-pyrones should be pursued to assess their potential as anthelmintics. Graphical abstract Image 1 Highlights • 7500 plant extracts were screened against Haemonchus for anthelmintic activity. • Three of these extracts were potent inhibitors of larval motility and/or development. • Pure α-pyrones isolated from active fractions exhibited significant nematocidal activity. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • 11 metabolites were obtained from the EtOAc extract of fungus Cephalotrichum microsporum. • Most of the isolated compounds were α -pyrones, including 9 compounds unreported. • Compound 1 displayed significant inhibitory effects on MR S. aureus , S. aureus , and B. cereus. • α -Pyrones 2 , 3 , 5 – 7 displayed moderate inhibitory effects on MR S. aureus , S. aureus , and B. subtilis. • Compounds 1 , 4 , 5 displayed significant cytotoxicity on five cancer cell lines, with the IC 50 < 20 μ M. Abstract Cephalotrichum microsporum (SYP-F 7763) was a fungus isolated from the rhizosphere soil of traditional Chinese medicine Panax notoginseng. The EtOAc extract of Cephalotrichum microsporum cultivated on sterilized moistened-rice medium was separated by various chromatographic techniques, which yielded 11 metabolites (1–11) of this fungus. On the basis of the widely spectroscopic data, the chemical structures of isolated metabolites were determined, most of which were α -pyrones, including 5 compounds (4–7 , and 10) unreported. In the anti-bacterial bioassay, compound 1 displayed significant inhibitory effects on three pathogenic bacteria, MR S. aureus , S. aureus , and B. cereus. α -Pyrones 2 , 3 , and 5–7 also displayed moderate inhibitory effects on MR S. aureus , S. aureus , and B. subtilis , which could be the major anti-bacterial constituents of Cephalotrichum microsporum. Additionally, compounds 1 , 4 , and 5 displayed significant cytotoxicity on five human cancer cell lines, with the IC 50 values < 20 μ M, which are more effective than positive control 5-fluorouracil. Therefore, α -pyrones were important secondary metabolites of Cephalotrichum microsporum , which displayed anti-bacterial and anti-tumor activities. [ABSTRACT FROM AUTHOR]

The α-pyrone moiety is a structural feature found in a huge variety of biologically active metabolites. In recent times new insights into additional biosynthetic mechanisms, yielding in such six-membered unsaturated ester ring residues have been obtained. The purpose of this mini-review is to give a brief overview of α-pyrones and the mechanisms forming the basis of their natural synthesis. Especially the chain interconnecting enzymes, showing homology to ketosynthases which catalyze Claisen-like condensation reactions, will be presented.

Two new α-pyrone derivatives, violapyrones H (1) and I (2), along with known violapyrones B (3) and C (4) were isolated from the fermentation broth of a marine actinomycete Streptomyces sp. The strain was derived from a crown-of-thorns starfish, Acanthaster planci, collected from Chuuk, Federated States of Micronesia. The structures of violapyrones were elucidated by the analysis of 1D and 2D NMR and HR-ESIMS data. Violapyrones (1–4) exhibited cytotoxicity against 10 human cancer cell lines with GI50 values of 1.10–26.12 μg/mL when tested using sulforhodamine B (SRB) assay. This is the first report on the cytotoxicity of violapyrones against cancer cell lines and the absolute configuration of violapyrone C.

Five new α-pyrones namely nocapyrones O-S (2–6) and nocapyrone F (1) were isolated from a deep-sea sediment strainNocardiopsissp. YIM M13066. Their structures were elucidated by their NMR spectroscopic data, HR-ESI-MS and crystal X-ray diffraction. Their cytotoxic activities against H1299, HeLa, HL7702, MCF-7, PC3 and U251 cell lines were evaluated. [ABSTRACT FROM PUBLISHER]

Intensive study of the organic extract of the marine-derived bacterium Saccharomonospora sp. CNQ-490 has yielded three new α-pyrones, saccharomonopyrones A-C (1-3). The chemical structures of these compounds were assigned from the interpretation of 1D, 2D NMR and mass spectrometry data. Saccharomonopyrone A (1) is the first α-pyrone microbial natural product bearing the ethyl-butyl ether chain in the molecule, while saccharomonopyrones B and C possess unusual 3-methyl and a 6-alkyl side-chain within a 3,4,5,6-tetrasubstituted α-pyrone moiety. Saccharomonopyrone A exhibited weak antioxidant activity using a cation radical scavenging activity assay with an IC50 value of 140 μM. [ABSTRACT FROM AUTHOR]

Hypocrealean fungi have proved to be prolific bioactive metabolite producers; they have caught the attention of mycologists throughout the world. However, only a few studies on the insect and spider parasitic genus Akanthomyces have so far been carried out. In this study, we report the isolation, structural elucidation and biological activities of four unprecedented glycosylated α-pyrone derivatives, akanthopyrones A-D (1-4), from a culture of Akanthomyces novoguineensis collected in Thailand. The chemical structures of the akanthopyrones were determined by extensive 1D- and 2D-NMR, and HRMS spectroscopic analysis. Their absolute configurations were determined. Akanthopyrone A (1) exhibited weak antimicrobial activity against Bacillus subtilis DSM10 and cytotoxicity against the HeLa cell line KB-3-1, while akanthopyrone D (4) showed weak activity against Candida tenuis MUCL 29892. [ABSTRACT FROM AUTHOR]

Eighteen ( 1 – 18 ) and seven ( 1 , 4 , 6 – 8 , 17 and 18 ) compounds were isolated from organic extracts of axenic cultures of two freshwater fungi Clohesyomyces sp. and Clohesyomyces aquaticus (Dothideomycetes, Ascomycota), respectively. Compounds 1 – 12 belong to the α-pyrone class of natural products, compounds 13 and 14 were tetrahydroxanthones, compounds 15 and 16 were hexahydroxanthones, while compounds 17 and 18 were cyclodepsipeptides. The structures were elucidated using a set of spectroscopic and spectrometric techniques. The absolute configurations of compounds 2 , 3 , 6 , and 7 were assigned via a modified Mosher’s ester method using 1 H NMR data. The relative configurations of compounds 14 – 16 were determined through NOE data. Compounds 1 , 2 , 6 , 8 , 13 , 14 , and 15 were found to inhibit the essential enzyme bacterial peptidyl-tRNA hydrolase (Pth1), with ( 13 ; secalonic acid A) being the most potent. Compounds 1 and 4 – 18 were also evaluated for antimicrobial activity against an array of bacteria and fungi but were found to be inactive. [ABSTRACT FROM AUTHOR]

It has been established that an electron-deficient CpE rhodium(III) complex catalyzes the oxidative [4+2] annulation of substituted arenecarboxylic and acrylic acids with alkynes under ambient conditions (at RT-40 °C, under air) without using excess amounts of substrates to produce the corresponding substituted isocoumarins and α-pyrones in high yields. Minor modification of reaction conditions depending on the coordination ability of alkynes realized the high efficiency. [ABSTRACT FROM AUTHOR]

Hypocrealean fungi have proved to be prolific bioactive metabolite producers; they have caught the attention of mycologists throughout the world. However, only a few studies on the insect and spider parasitic genus Akanthomyces have so far been carried out. In this study, we report the isolation, structural elucidation and biological activities of four unprecedented glycosylated α-pyrone derivatives, akanthopyrones A–D (1–4), from a culture of Akanthomyces novoguineensis collected in Thailand. The chemical structures of the akanthopyrones were determined by extensive 1D- and 2D-NMR, and HRMS spectroscopic analysis. Their absolute configurations were determined. Akanthopyrone A (1) exhibited weak antimicrobial activity against Bacillus subtilis DSM10 and cytotoxicity against the HeLa cell line KB-3-1, while akanthopyrone D (4) showed weak activity against Candida tenuis MUCL 29892.

Abstract: Chromatographic analysis of an ethyl acetate extract of Pestalotiopsis virgatula rice cultures yielded four new α-pyrone derivatives, pestalotiopyrones I–L, and the new (6S,1′S,2′S)-hydroxypestalotin, in addition to three known compounds. The planar structures of the new compounds were elucidated on the basis of extensive NMR spectroscopic and mass spectrometric analyses. The absolute configurations of the new compounds were determined on the basis of biosynthetic considerations, coupling constants, and for pestalotiopyrone L by TDDFT ECD calculations of solution conformers. [Copyright &y& Elsevier]

Reflux of isopropenyl acetate with an excess of AlCl in 1,2-dichloroethane affords 3,5-diacetyl-2,6-dimethyl-4 H-pyran-4-one in 17% yield. The mild acidic cleavage of the latter (2% HCl, 20 °C, 16 h) gives 3-acetyl-2,6-dimethyl-4 H-pyran-4-one in 87% yield, whereas this reaction under more drastic conditions (17% HCl, reflux, 3 h) gives 2,6-dimethyl-4 H-pyran-4-one in 61% yield. [ABSTRACT FROM AUTHOR]

Abstract: An efficient synthetic protocol of fully substituted α-pyrones has been developed starting from the Baylis–Hillman adducts. Subsequent Diels–Alder reaction of the α-pyrones and DMAD produced poly-substituted aromatic compounds in high yields. [Copyright &y& Elsevier]

The aqueous ethanolic extract from the fresh cladodes of Opuntia dillenii HAW. was found to show anti-inflammatory activity. Two new α-pyrones, named opuntioside II ( 1) and opuntioside III ( 2), were isolated from the extract together with six known compounds. The structures of the new compounds were determined on the basis of chemical and physicochemical evidence. [ABSTRACT FROM AUTHOR]

Abstract: 3,5,6-Trisubstituted α-pyrones were synthesized starting from the Baylis–Hillman adducts. The synthesis was carried out via the sequential introduction of ketone at the primary position of Baylis–Hillman adduct, lactonization, and the following oxidation with PCC. [Copyright &y& Elsevier]

Dichloromethane extracts of both the roots and the leaves of Raimondia cf. monoica showed in vitro antiplasmodial and leishmanicidal activities against Plasmodium falciparum and Leishmania panamensis , respectively. Three 6-substituted 5,6-dihydro- 2H -pyran-2-ones were isolated. ( 1 ) and ( 2 ) were identified as (6 S )-(5′-oxohepten-1′ E ,3′ E -dienyl)-5,6-dihydro- 2H -pyran-2-one ( 1 ) and (6 R )-(5′-oxohepten-1′ Z ,3′ E -dienyl)-5,6-dihydro- 2H -pyran-2-one ( 2 ), respectively. (-)-Argentilactone ( 3 ) was also isolated. The structure of the new compound ( 1 ) was determined by spectroscopic methods; additional spectroscopic data for ( 2 ) are reported for the first time. [ABSTRACT FROM AUTHOR]

With the increasingly serious antimicrobial resistance, discovering novel antibiotics has grown impendency. The Antarctic abundant microbial resources, especially fungi, can produce unique bioactive compounds for adapting to the hostile environment. In this study, three Antarctic fungi, Chrysosporium sp. HSXSD-11-1, Cladosporium sp. HSXSD-12 and Acrostalagmus luteoalbus CH-6, were found to have the potential to produce antimicrobial compounds. Furthermore, the crude extracts of CH-6 displayed the strongest antimicrobial activities with 72.3-84.8% growth inhibition against C. albicans and Aeromonas salmonicida . The secondary metabolites of CH-6 were researched by bioactivity tracking combined with molecular networking and led to the isolation of two new α -pyrones, acrostalapyrones A ( 1 ) and B ( 2 ), along with one known analog ( 3 ), and three known indole diketopiperazines ( 4 - 6 ). The absolute configurations of 1 and 2 were identified through modified Mosher's method. Compounds 4 and 6 showed strong antimicrobial activities. Remarkably, the antibacterial activity of 6 against A. salmonicida displayed two times higher than that of the positive drug Ciprofloxacin. This is the first report to discover α -pyrones from the genus Acrostalagmus , and the significant antimicrobial activities of 4 and 6 against C. albicans and A. salmonicida . This study further demonstrates the great potential of Antarctic fungi in the development of new compounds and antibiotics.

The fungal strain was isolated from a soil sample collected in Giza province, Egypt, and was identified as Aspergillus ochraceopetaliformis based on phenotypic and genotypic data. The ethyl acetate extract of the fungal strain exhibited promising activity levels against several pathogenic test organisms and through a series of 1H NMR guided chromatographic separations, a new α-pyrone-C-lyxofuranoside (1) along with four known compounds (2–5) were isolated. The planar structure of the new metabolite was elucidated by detailed analysis of its 1D/2D NMR and HRMS/IR/UV spectroscopic data, while the relative configuration of the sugar moiety was determined by a combined study of NOESY and coupling constants data, with the aid of theoretical calculations. The structures of the known compounds—isolated for the first time from A. ochraceopetaliformis—were established by comparison of their spectroscopic data with those in the literature. All isolated fungal metabolites were evaluated for their antibacterial and antifungal activities against six Gram - positive and Gram-negative bacteria as well as against three human pathogenic fungi. [ABSTRACT FROM AUTHOR]

The dramatic increase in bacterial resistance over the past three decades has greatly reduced the effectiveness of nearly all clinical antibiotics, bringing infectious disease to the forefront as a dire threat to global health. To combat these infections, adjuvant therapies have emerged as a way to reactivate known antibiotics against resistant pathogens. Herein, we report the evaluation of simplified α-pyrone adjuvants capable of potentiating penicillin G against Pseudomonas aeruginosa , a Gram-negative pathogen whose multidrug-resistant strains have been labeled by the Centers for Disease Control and Prevention as a serious threat to public health. [ABSTRACT FROM AUTHOR]

• It provides a divergent way to form different products from the same precursor. • The reaction was successfully realized upon regulation of base promoters. • Also a D-A reaction to furnish aromatic amines 7 has been elaborated. • The D-A method features mild reaction condition, high yield and regioselectivity. A series of fully substituted 2-pyridone 2 and functionalized α-pyrones 3 are synthesized starting from cyclobutenones 1 under a base-promoter in toluene at 80 °C. This rearrangement is complimentary to the previously reported ring expansion of cyclobutenones, providing a divergent synthesis of corresponding products from the same precursor 1. In addition, α-pyrones 3 has also been applied to the synthesis of aromatic amines 7 in good yields (64–83%) and in a highly regioselective manner via D-A reaction under mild conditions. [ABSTRACT FROM AUTHOR]

Three new arylalkenyl α , β -unsaturated δ -lactones, cryptobrachytones A – C (1 – 3), together with one known analogue kurzilactone (4), were isolated from the leaves and twigs of Cryptocarya brachythyrsa. Their structures were elucidated based on extensive spectroscopic data and electronic circular dichroism (ECD) analysis. All the isolates were evaluated in vitro for anti-proliferative activity against a panel of five human cancer cell lines and one human normal cell, respectively, and the results showed 1 , 2 and 4 possessing significant selective cytotoxicity toward the human cancer cell lines with IC 50 values from 5.41 to 15.43 μM. This is the first study for C. brachythyrsa. Unlabelled Image [ABSTRACT FROM AUTHOR]

Starting from substituted alkynones, α-pyrones and/or 1 H -pyridines were generated in a Michael addition-cyclocondensation with ethyl cyanoacetate. The peculiar product formation depends on the reaction conditions as well as on the electronic substitution pattern of the alkynone. While electron-donating groups furnish α-pyrones as main products, electron-withdrawing groups predominantly give the corresponding 1 H -pyridines. Both heterocycle classes fluoresce in solution and in the solid state. In particular, dimethylamino-substituted α-pyrones, as donor-acceptor systems, display remarkable photophysical properties, such as strongly red-shifted absorption and emission maxima with daylight fluorescence and fluorescence quantum yields up to 99% in solution and around 11% in the solid state, as well as pronounced emission solvatochromism. Also a donor-substituted α-pyrone shows pronounced aggregation-induced emission enhancement., (Copyright © 2019, Breuer et al.; licensee Beilstein-Institut.)

The zoanthid-derived fungus Cochliobolus lunatus (TA26-46) has been proven to be a source of bioactive 14-membered resorcylic acid lactones (RALs). In the present study, chemical epigenetic manipulation was applied to this fungal strain with a DNA methyltransferase inhibitor resulting in the significant changes of the secondary metabolites. Cultivation of C. lunatus (TA26-46) with 10 μM 5-azacytidine in Czapek-Dox liquid medium led to the isolation of new types of metabolites, including two α-pyrones, cochliobopyrones A ( 1 ) and B ( 2 ), along with three isocoumarins ( 3 - 5 ) and one chromone ( 6 ). The planar structures of the new compounds ( 1 - 2 ) were elucidated by comprehensive analyses of NMR and HRESIMS data. Their challenging relative configurations were established by a combination of acetonide reaction, coupling constants and NOESY correlations analysis, and DP4+ probability calculation. Their absolute configurations were determined by comparing with the ECD calculation data of the fragment molecules, 6-(1,2-dihydroxypropyl)-4-methoxy-2 H -pyran-2-ones. It is the first time to obtain α -pyrone compounds with the epoxy ring or bromine atom on the seven-numbered side chain. It could be concluded that chemical epigenetic agents could induce C. lunatus to produce new types of secondary metabolites differing from its original products (RALs)., (Copyright © 2019 Wu, Shi, Zhang, Yu, Fu, Li, Chen, Guo, Shao and Wang.)