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1.
J Agric Food Chem ; 2024 Aug 06.
Artículo en Inglés | MEDLINE | ID: mdl-39106342

RESUMEN

Fusarium crown and root rot (FCRR) has emerged as a highly destructive soil-borne disease, posing a significant threat to the safe cultivation of tomatoes in recent years. The pathogen of tomato FCRR is Fusarium oxysporum f. sp. radicis-lycopersici (Forl). To explore potential phytotoxins from Forl, eight undescribed diterpenoids namely fusariumic acids A-H (1-8) were isolated. Their structures were elucidated by using spectroscopic data analyses, quantum chemical calculations, and X-ray crystallography. Fusariumic acids A (1) and C-H (3-8) were typical isocassadiene-type diterpenoids, while fusariumic acid B (2) contained a cage-like structure with an unusual 7,8-seco-isocassadiene skeleton. A biosynthetic pathway of 2 was proposed. Fusariumic acids A (1) and C-H (3-8) were further assessed for their phytotoxic effects on tomato seedlings at 200 µg/mL. Among them, fusariumic acid F (6) exhibited the strongest inhibition against the hypocotyl and root elongation of tomato seedlings, with inhibitory rates of 61.3 and 45.3%, respectively.

2.
Phytochemistry ; 222: 114103, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38636686

RESUMEN

Eight new cytochalasans rosellichalasins A-H (1-8), as well as two new shunt metabolites rosellinins A (9) and B (10) before intramolecular Diels-Alder cycloaddition reaction in cytochalasan biosynthesis, along with nine known cytochalsans (11-19) were isolated from the endophytic fungus Rosellinia sp. Glinf021, which was derived from the medicinal plant Glycyrrhiza inflata. Their structures were characterized by extensive analysis of 1D and 2D NMR as well as HRESIMS spectra and quantum chemical ECD calculations. The cytotoxic activities of these compounds were evaluated against four human cancer cell lines including HCT116, MDA-MB-231, BGC823, and PANC-1 with IC50 values ranging from 0.5 to 58.2 µM.


Asunto(s)
Antineoplásicos , Citocalasinas , Ensayos de Selección de Medicamentos Antitumorales , Xylariales , Humanos , Antineoplásicos/farmacología , Antineoplásicos/química , Antineoplásicos/aislamiento & purificación , Línea Celular Tumoral , Proliferación Celular/efectos de los fármacos , Citocalasinas/química , Citocalasinas/farmacología , Citocalasinas/aislamiento & purificación , Relación Dosis-Respuesta a Droga , Endófitos/química , Estructura Molecular , Relación Estructura-Actividad , Xylariales/química , Xylariales/clasificación
3.
Pest Manag Sci ; 80(6): 2658-2667, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38284314

RESUMEN

BACKGROUND: Phytopathogenic bacteria cause severe losses to crops every year. The management of crop bacterial diseases with chemical agents has been considered as the main strategy. In order to cope with the bactericide resistance made by the pathogens, new antibacterials need to be continuously developed. RESULTS: A chemical investigation from the endophytic fungus Rhexocercosporidium sp. Dzf14 has led to the isolation of 12 diphenyl ethers including two new ones named rhexocerin E (1) and rhexocercosporin G (2), along with two new depsides named rhexocerdepsides A (3) and B (4). The structures and absolute configurations of the new compounds were determined through comprehensive analysis of spectroscopic data and quantum chemical ECD calculations. Diphenyl ethers showed obviously antibacterial activity on Gram-positive bacteria. The structure-activity relationship of diphenyl ethers revealed that prenylation was critical to the antibacterial activity. Among them, rhexocercosporin D (12) possessed the strongest activity against Clavibacter michiganensis and Bacillus subtilis, and was selected for further mechanistic studies. It was found that rhexocercosporin D displayed bactericidal activity by affecting homeostasis of cell membranes. In addition to its rapid bactericidal effects on Gram-positive bacteria, rhexocercosporin D could restore the susceptibility against Gram-negative Agrobacterium tumefaciens by synergistic action with colistin. CONCLUSION: Twelve diphenyl ethers and two depsides were isolated from endophytic fungus Rhexocercosporidium sp. Dzf14. Isopentenyl was critical for diphenyl ethers against Gram-positive bacteria. Rhexocercosporin D could affect homeostasis of bacterial cell membrane to exert rapid bactericidal activity. These findings highlight the antibacterial potential of the diphenyl ethers in crop bacterial disease management. © 2024 Society of Chemical Industry.


Asunto(s)
Antibacterianos , Membrana Celular , Homeostasis , Éteres Fenílicos , Antibacterianos/farmacología , Antibacterianos/química , Membrana Celular/efectos de los fármacos , Éteres Fenílicos/farmacología , Éteres Fenílicos/química , Endófitos/química , Relación Estructura-Actividad , Bacterias Grampositivas/efectos de los fármacos , Estructura Molecular
4.
Nat Prod Res ; : 1-5, 2023 Nov 24.
Artículo en Inglés | MEDLINE | ID: mdl-37999995

RESUMEN

Two new chlorinated phenyloxazole glycosides, named rosellosides A (1) and B (2), were isolated from the endophytic fungus Rosellinia sp. Glinf021, which was derived from the medicinal plant Glycyrrhiza inflata (Leguminosae). Both compounds were rare chlorinated polyketide glycosides bearing an oxazole moiety. Their structures were elucidated by analysis of the NMR and HRESIMS data, and their absolute configurations were determined by quantum chemical ECD calculations and X-ray crystallography.

5.
Int J Mol Sci ; 24(20)2023 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-37894876

RESUMEN

Rice false smut (RFS) caused by Villosiclava virens (anamorph: Ustilaginoidea virens) has become one of the most destructive fungal diseases to decrease the yield and quality of rice grains. An albino strain LN02 was isolated from the white RFS balls collected in the Liaoning Province of China in 2019. The strain LN02 was considered as a natural albino mutant of V. virens by analyzing its phenotypes, internal transcribed spacer (ITS) conserved sequence, and biosynthesis gene clusters (BGCs) for secondary metabolites. The total assembled genome of strain LN02 was 38.81 Mb, which was comprised of seven nuclear chromosomes and one mitochondrial genome with an N50 value of 6,326,845 bp and 9339 protein-encoding genes. In addition, the genome of strain LN02 encoded 19 gene clusters for biosynthesis of secondary metabolites mainly including polyketides, terpenoids and non-ribosomal peptides (NRPs). Four sorbicillinoid metabolites were isolated from the cultures of strain LN02. It was found that the polyketide synthase (PKS)-encoding gene uspks1 for ustilaginoidin biosynthesis in strain LN02 was inactivated due to the deletion of four bases in the promoter sequence of uvpks1. The normal uvpks1 complementary mutant of strain LN02 could restore the ability to synthesize ustilaginoidins. It demonstrated that deficiency of ustilaginoidin biosynthesis is the cause of albinism for RFS albino strain LN02, and V. virens should be a non-melanin-producing fungus. This study further confirmed strain LN02 as a white phenotype mutant of V. virens. The albino strain LN02 will have a great potential in the development and application of secondary metabolites. The physiological and ecological functions of ustilaginoidins in RFS fungus are needed for further investigation.


Asunto(s)
Hypocreales , Oryza , Oryza/genética , Hypocreales/genética , Hypocreales/metabolismo , Familia de Multigenes , Variación Genética , Enfermedades de las Plantas/microbiología
6.
J Nat Prod ; 86(8): 1931-1938, 2023 08 25.
Artículo en Inglés | MEDLINE | ID: mdl-37486731

RESUMEN

Ten new diphenyl ether polyketides, including rhexocerins A-D (1-4) and rhexocercosporins A-F (5-10), together with three known congeners (11-13), were isolated from the endophytic fungus Rhexocercosporidium sp. Dzf14 obtained from Dioscorea zingiberensis. Their structures were elucidated by analysis of NMR and HRESIMS data, and their absolute configurations were determined by quantum chemical ECD calculations and X-ray crystallography. Compounds 1-4 featured an unprecedented tetracyclic carbon skeleton (6/7/5/6). Among them, compounds 1 and 5-9 showed antibacterial activities against methicillin-resistant S. aureus T144 and vancomycin-resistant E. faecalis 10.


Asunto(s)
Ascomicetos , Staphylococcus aureus Resistente a Meticilina , Policétidos , Estructura Molecular , Antibacterianos/química , Bacterias Grampositivas , Policétidos/química
7.
J Environ Manage ; 326(Pt A): 116693, 2023 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-36347215

RESUMEN

The antibiotic tetracycline (TC) and its degradation products (TDPs) in degradation solution present serious environmental problems, such as human health damage and ecological risk; thus further treatment is required before being released into the aquatic environment. Furthermore, their environmental impact on microalgae remains unclear. In this study, TC was degraded by photocatalysis using birnessite and UV irradiation, followed by biological purification using the microalga Scenedesmus obliquus. In addition, the photosynthetic activity and transcription of the microalgae were examined to evaluate the toxicity of TC and TDPs. The results show that photocatalytic degradation efficiency reached 92.7% after 30 min, and 11 intermediate products were detected. The microalgae achieved a high TC removal efficiency (99.7%) after 8 days. Exposure to the degraded TC solution (D) resulted in significantly lower (p < 0.05) biomass than the pure TC (T), and S. obliquus in the T treatment showed better resilience than the D treatment. Transcriptomic assays for different treatments revealed differential gene expression mainly involving the photosynthesis, ribosome, translation and peptide metabolic progresses. The up-regulation of photosynthesis-related genes and differential expression of chloroplast genes may be important for S. obliquus to acquire high photosynthetic efficiency and growth recovery when exposed to TC and TDPs. Our study provides a reference for TC removal using a combination of catalytic degradation and microalgal purification, and it is also helpful for understanding the environmental risk of TDPs in natural aquatic environments.


Asunto(s)
Microalgas , Scenedesmus , Humanos , Microalgas/metabolismo , Agua/metabolismo , Fotólisis , Tetraciclina/metabolismo , Biomasa , Fotosíntesis , Antibacterianos/metabolismo
8.
J Fungi (Basel) ; 10(1)2023 Dec 31.
Artículo en Inglés | MEDLINE | ID: mdl-38248941

RESUMEN

Villosiclava virens (anamorph: Ustilaginoidea virens) is the pathogen of rice false smut (RFS), which is a destructive rice fungal disease. The albino strain LN02 is a natural white-phenotype mutant of V. virens due to its incapability to produce toxic ustilaginoidins. In this study, three strains including the normal strain P1, albino strain LN02, and complemented strain uvpks1C-1 of the LN02 strain were employed to investigate the activation of the ustilaginoidin biosynthesis gene uvpks1 in the albino strain LN02 to influence sporulation, conidia germination, pigment production, stress responses, and the inhibition of rice seed germination. The activation of the ustilaginoidin biosynthesis gene uvpks1 increased fungal tolerances to NaCl-induced osmotic stress, Congo-red-induced cell wall stress, SDS-induced cell membrane stress, and H2O2-induced oxidative stress. The activation of uvpks1 also increased sporulation, conidia germination, pigment production, and the inhibition of rice seed germination. In addition, the activation of uvpks1 was able to increase the mycelial growth of the V. virens albino strain LN02 at 23 °C and a pH from 5.5 to 7.5. The findings help in understanding the effects of the activation of uvpks1 in albino strain LN02 on development, pigment production, stress responses, and the inhibition of rice seed germination by controlling ustilaginoidin biosynthesis.

9.
Toxins (Basel) ; 14(10)2022 Sep 23.
Artículo en Inglés | MEDLINE | ID: mdl-36287930

RESUMEN

Ustilaginoidins are a class of bis-naphtho-γ-pyrone mycotoxins produced by the pathogen Villosiclava virens of rice false smut, which has recently become one of the most devastating diseases in rice-growing regions worldwide. In this research, the nanobody phage display library was established after an alpaca was immunized with the hemiustilaginoidin F-hapten coupled with bovine serum albumin (BSA). Heterologous antigen selection and combing trypsin with competition alternant elution methods were performed for nanobody screening. Two nanobodies, namely, Nb-B15 and Nb-C21, were selected for the establishment of indirect competitive enzyme-linked immunosorbent assays (ic-ELISAs). For Nb-B15 and Nb-C21, their IC50 values were 11.86 µg/mL and 11.22 µg/mL, and the detection ranges were at 3.41-19.98 µg/mL and 1.17-32.13 µg/mL, respectively. Two nanobodies had a broad spectrum to quantify the contents of total ustilaginoidins in rice samples according to cross-reactivity. The recognition mechanisms of Nb-B15 and Nb-C21 against ustilaginoidin A were elucidated by molecular modeling and docking. The key amino acid sites for the binding of Nb-B15 or Nb-C21 to ustilaginoidin A were mainly located in the FR1 and CDR1 regions. As Nb-B15 was superior to Nb-C21 in the aspects of protein expression, ELISA titer, and tolerance to organic solvents, it was selected for application in the detection of actual contaminated rice samples. The total ustilaginoidin contents of rice samples were analyzed by Nb-B15-based ic-ELISA and HPLC-DAD, between which the results were found to be consistent. The developed immunoassay based on the nanobody from the alpaca can be employed as a rapid and effective method for detection of total utilaginoidins in contaminated rice samples.


Asunto(s)
Camélidos del Nuevo Mundo , Micotoxinas , Oryza , Anticuerpos de Dominio Único , Animales , Oryza/química , Pironas , Albúmina Sérica Bovina , Tripsina , Micotoxinas/análisis , Inmunoensayo , Ensayo de Inmunoadsorción Enzimática/métodos , Solventes , Haptenos , Aminoácidos , Antígenos Heterófilos
10.
Int J Mol Sci ; 23(18)2022 Sep 11.
Artículo en Inglés | MEDLINE | ID: mdl-36142466

RESUMEN

Tetracycline (TC) antibiotics can be detected worldwide in the aquatic environment due to their extensive use and low utilization efficiency, and they may affect the physiological processes of non-target organisms. In this study, the acute and sub-acute toxicities of TC on the freshwater microalga Scenedesmus obliquus were investigated with an emphasis on algal photosynthesis and transcription alterations during an 8 d TC exposure. The results showed that the IC10, IC30 and IC50 values were 1.8, 4.1 and 6.9 mg/L, respectively. During sub-acute exposure, the microalgae of the IC10 treatment was able to recover comparable growth to that of the control by day 7, while significantly lower cell densities were observed in the IC30 and IC50 treatments at the end of the exposure. The photosynthetic efficiency Fv/FM of S. obliquus first decreased as the TC concentration increased and then returned to a level close to that of the control on day 8, accompanied by an increase in photosynthetic activities, including light harvesting, electron transport and energy dissipation. Transcriptomic analysis of the IC10 treatment (1.8 mg/L TC) revealed that 2157 differentially expressed genes were up-regulated and 1629 were down-regulated compared with the control. KEGG and GO enrichments demonstrated that 28 photosynthesis-related genes involving light-harvesting chlorophyll protein complex, photosystem I, photosystem II, photosynthetic electron transport and enzymes were up-regulated, which may be the factor responsible for the enhanced photosynthesis and recovery of the microalgae. Our work may be helpful not only for gaining a better understanding of the environmental risk of TC at concentrations close to the real levels in natural waters, but also for explaining photosynthesis and related gene transcription induced by antibiotics.


Asunto(s)
Chlorophyceae , Microalgas , Scenedesmus , Antibacterianos/farmacología , Chlorophyceae/metabolismo , Clorofila/metabolismo , Complejos de Proteína Captadores de Luz/metabolismo , Microalgas/metabolismo , Fotosíntesis , Complejo de Proteína del Fotosistema I/metabolismo , Complejo de Proteína del Fotosistema II/metabolismo , Tetraciclina/farmacología
11.
World J Microbiol Biotechnol ; 38(9): 160, 2022 Jul 14.
Artículo en Inglés | MEDLINE | ID: mdl-35834059

RESUMEN

Photosynthetic and metabolomic performance of Euglena gracilis was examined and compared under autotrophic and mixotrophic conditions. Autotrophic protozoa (AP) obtained greater biomass (about 33% higher) than the mixotrophic protozoa (MP) after 12 days of growth. AP maintained steady photosynthesis, while MP showed a remarkable decrease in photosynthetic efficiency and dropped to an extremely low level at day 12. In MP, low light absorption and photosynthetic electron transport efficiency, and high energy dissipation were reflected by the chlorophyll (chl a) fluorescence (OJIP) of the protozoa. The values of ΨO, ΦEo, and ETO/RC of MP decreased to extremely low levels, to 1/15, 1/46, and 1/9 those of AP, respectively, while DIO/RC increased to approximately 16 times that of AP. A total of 137 metabolites were showed significant differences between AP and MP. AP accumulated more monosaccharide, lipids, and alkaloids, while MP produced more amino acids, peptides, and long-chain fatty acids including poly-unsaturated fatty acids. The top nine most important enriched pathways obtained from KEGG mapping were related to ABC transporters, biosynthesis of amino acids, purine metabolism, and carbohydrate metabolism. There were significant differences between AP and MP in photosynthetic activity, metabolites, and metabolic pathways. This work presented useful information for the production of high value bioproducts in E. gracilis cultured under different nutritional conditions.


Asunto(s)
Euglena gracilis , Aminoácidos/metabolismo , Biomasa , Clorofila/metabolismo , Euglena gracilis/metabolismo , Fotosíntesis
12.
Environ Sci Pollut Res Int ; 29(16): 23461-23473, 2022 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-34806148

RESUMEN

Microplastics (MPs) released into aquatic environment interact with other pollutants that already exist in water, potentially altering their toxicity, which poses a new problem for aquatic ecosystems. In the present study, we first evaluated the effects of polystyrene MPs (mPS) on copper (Cu) toxicity to the protozoan Euglena gracilis using three methods based on 96-h acute toxicity, orthogonal test and 12-d sub-acute toxicity data. Thereafter, the 12-d sub-acute exposure was employed to investigate protozoan growth, photosynthetic parameters and pigments, soluble protein, total antioxidant capacity and trace metal accumulation in E. gracilis after exposure to either 1.5 mg/L of Cu, 75-nm mPS (1 and 5 mg/L) or a combination therein, with the objective to understand the underlined mechanisms. The results show that the concentration and exposure time are key factors influencing the effects of the mPS on Cu toxicity. A mPS concentration of 5 mg/L caused significantly more dissipation energy, which is used for photosynthesis and thus decreased photosynthetic efficiency, but this effect weakened after 12 d of exposure. Exposure to Cu alone resulted in significantly high Cu accumulation in the cells and inhibited uptake of manganese and zinc. The presence of mPS did not influence the effects of Cu on trace metal accumulation. Our result suggests that application of multiple methods and indices could provide more information for a comprehensive understanding of the effects of mPS on toxicity of other pollutants. In addition, long-term exposure seems necessary for evaluating mPS toxicity.


Asunto(s)
Euglena gracilis , Contaminantes Químicos del Agua , Cobre/toxicidad , Ecosistema , Microplásticos , Fotosíntesis , Plásticos/toxicidad , Poliestirenos/toxicidad , Contaminantes Químicos del Agua/toxicidad
13.
Chem Sci ; 12(44): 14883-14892, 2021 Nov 17.
Artículo en Inglés | MEDLINE | ID: mdl-34820104

RESUMEN

Ustilaginoidins are a type of mycotoxin featuring a dimeric naphtho-γ-pyrone skeleton, produced by the rice false smut pathogen Ustilaginoidea virens. Here we used gene disruption, heterologous expression in Aspergillus oryzae, feeding experiments, and in vitro experiments to fully elucidate the biosynthesis of ustilaginoidins. A new route to dimeric 2,3-unsaturated naphtho-γ-pyrones via dimerization of YWA1 (and 3-methyl YWA1) followed by dehydration was discovered. Intriguingly, the reduction of the 2,3-double bond of the pyrenone ring was catalyzed by a phospholipid methyltransferase-like enzyme (UsgR). The reductase was specific for reduction of monomeric, linear naphtho-γ-pyrenones, but not for the dimers. Atroposelective coupling of various monomers by the laccase (UsgL) led to diverse ustilaginoidins. Moreover, 3-epimerism of the 3-methyl-2,3-dihydro-naphtho-γ-pyrones adds additional complexity to the biosynthesis.

14.
Nat Prod Res ; 35(22): 4616-4620, 2021 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-31782665

RESUMEN

Five chromone derivatives, including 2,6-dimethyl-5-methoxyl-7-hydroxylchromone (1), 6-hydroxymethyleugenin (2), 6-methoxymethyleugenin (3), chaetoquadrin D (4), and isoeugenitol (5), and three isocoumarin congeners, namely diaporthin (6), 8-hydroxy-6-methoxy-3-methylisocoumarin (7), and 6-methoxymellein (8), were isolated from the culture of the endophytic fungus Xylomelasma sp. Samif07 derived from the medicinal plant Salvia miltiorrhiza Bunge. Among them, compound 1 was a new natural product. Their structures were determined by spectroscopic methods and comparison with the literature. The isolated compounds were evaluated for their antibacterial and antioxidant activities. Compound 5 showed notable antitubercular activity against Mycobacterium tuberculosis with MIC value of 10.31 µg/mL, while compounds 1-3, and 5-7 displayed inhibitory activities against the other bacteria with MIC range of 25 ∼ 100 µg/mL. Meanwhile, compound 6 showed potent hydroxyl radical-scavenging activity with EC50 value of 15.1 µg/mL, while compounds 5-7 showed certain ferric reducing ability.


Asunto(s)
Antioxidantes , Ascomicetos , Antibacterianos/farmacología , Antioxidantes/farmacología , Antituberculosos , Cromonas/farmacología , Isocumarinas/farmacología , Pruebas de Sensibilidad Microbiana , Estructura Molecular
15.
Nat Prod Res ; 35(2): 272-281, 2021 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-31180238

RESUMEN

Two new nitrogen-containing metabolites methyl N-acetyl-O-(4-acetylphenyl)-L-homoserinate (1), dimethyl (1H-indole-3-carbonyl)-D-glutamate (2), and two new natural products, 1,2-O-isopropylidene-D-mannitol (3), N-acetyl-ß-methyl-L-phenylalanine (4), along with five known compounds (5-9) were isolated from the rice false smut pathogen Villosiclava virens UV-8b cultured in the solid rice medium. The structures were elucidated by spectroscopic analysis and by comparison of their physical and spectroscopic data with the literature. These metabolites were evaluated for their antibacterial and phytotoxic activities. Compounds 5-7 showed weak inhibition against the tested bacteria, while compounds 4-6 and 9 displayed inhibitory activity against the radicle elongation of rice seeds.


Asunto(s)
Antibacterianos/farmacología , Hypocreales/metabolismo , Oryza/microbiología , Antibacterianos/química , Espectroscopía de Resonancia Magnética , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Nitrógeno/química , Oryza/efectos de los fármacos , Enfermedades de las Plantas/microbiología , Semillas/efectos de los fármacos , Espectrometría de Masa por Ionización de Electrospray , Relación Estructura-Actividad
16.
Front Chem ; 8: 596889, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33195106

RESUMEN

Fourteen new eremophilane-type sesquiterpenoids, named rhizoperemophilanes A~N (1~14), together with eight known congeners, were isolated from the culture of the endophytic fungus Rhizopycnis vagum. The structures of the new compounds were elucidated by extensive spectroscopic analyses, as well as ECD calculations and the modified Mosher's method for the assignment of the absolute configurations. Rhizoperemophilane J (10) contains an uncommon C-4/C-11 epoxy ring, while rhizoperemophilane N (14) features an unprecedented 3-nor-eremophilane lactone-lactam skeleton. These metabolites were evaluated for their antibacterial, cytotoxic, and phytotoxic activities. Among them, compounds 11, 16, and 20 displayed antibacterial activities, while 14 showed selective cytotoxicity against NCI-H1650 and BGC823 tumor cells. Moreover, compounds 5, 6, 12, 13, 16, and 19 exhibited strong phytotoxic activities against the radicle elongation of rice seedlings.

17.
RSC Adv ; 10(12): 6985-6991, 2020 Feb 13.
Artículo en Inglés | MEDLINE | ID: mdl-35493878

RESUMEN

Four new 3,4-dihydroisocoumarin congeners, named lophiostomin A-D (1-4), together with two known α-pyridones (5 and 6) were isolated from cultures of the endophytic fungus Lophiostoma sp. Sigrf10 obtained from Siraitia grosvenorii. The structures of the new compounds were determined via combined analysis involving 1D and 2D NMR, high-resolution electrospray ionization mass spectrometry (HRESIMS), and electronic circular dichroism (ECD) spectra, as well as quantum chemical ECD computations for assigning the absolute configurations. All the compounds were evaluated for their antibacterial and antifungal activities. Compounds 1 and 2 displayed moderate inhibitory activities against the spore germination of Magnaporthe oryzae, whereas 5 and 6 were active against the following tested pathogenic bacteria: Bacillus subtilis, Agrobacterium tumefaciens, Ralstonia solanacearum, and Xanthomonas vesicatoria.

18.
RSC Adv ; 10(47): 27894-27898, 2020 Jul 27.
Artículo en Inglés | MEDLINE | ID: mdl-35519149

RESUMEN

Rhizovagine A (1), a novel dibenzo-α-pyrone alkaloid with an unprecedented 5/5/6/6/6 fused pentacyclic skeleton, was isolated from the endophytic fungus Rhizopycnis vagum Nitaf22. The structure was elucidated by comprehensive spectroscopic analysis, in combination with quantum chemical 13C NMR and electronic circular dichroism (ECD) calculations for configurational assignment. A plausible biosynthetic pathway for 1 was proposed. Compound 1 displayed acetylcholinesterase inhibitory activity.

19.
Front Chem ; 7: 435, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31249829

RESUMEN

Ustilaginoidea virens, the causal fungus of rice false smut, was found in previous studies to produce two types of metabolites, ustiloxins and ustilaginoidins. However, genome sequencing of U. virens revealed a plethora of secondary-metabolites-biosynthetic core genes that were capable to biosynthesize unreported metabolites. A large-scale fermentation of U. virens was thus performed, and the fungal extract was chemically re-investigated. After removing the known metabolites, we found a fraction containing unknown phytotoxic substances. Fractionation of this part has led to the isolation of six new sorbicillinoids, namely ustisorbicillinols A~F (1~6), and two new sorbicillinoid-related pyrones, named ustilopyrones A (7) and B (8), together with nine known cogeners (9~17). The structures of the new compounds were elucidated by analysis of their NMR, HRMS, and CD spectra, while ECD, 13C NMR and optical rotation calculations were additionally used for configurational assignments. Plausible biosynthetic pathways for the new compounds were proposed. Phytotoxicity assays revealed that the major sorbicillinoids (12~14, and 16) showed strong inhibition against the radicle and germ elongation of rice and lettuce seeds, with compound 12 displaying the strongest inhibition. The isolated compounds were also evaluated for their cytotoxic, antibacterial, and antifungal activities. Compounds 10, and 12~14 showed moderate cytotoxicities against the tested cell lines with IC50s of 8.83~74.7 µM. Compounds 2, and 10~13 were active against the tested bacteria (MICs 4~128 µg/mL), while compounds 11~13 displayed moderate antifungal activities.

20.
Molecules ; 25(1)2019 Dec 27.
Artículo en Inglés | MEDLINE | ID: mdl-31892246

RESUMEN

Two new decalin/tetramic acid hybrid metabolites, hyalodendrins A (1) and B (2) were isolated from plant endophytic fungus Hyalodendriella sp. Ponipodef12. The structures of the new compounds were elucidated by analysis of the spectroscopic data, including NMR, HRMS and ECD, and by chemical conversion. Compounds 1 and 2 were phomasetin analogues, and both showed potent larvicidal activity against the fourth-instar larvae of Aedes aegypti with the median lethal dose (LC50) values of 10.31 and 5.93 µg/mL, respectively.


Asunto(s)
Aedes/crecimiento & desarrollo , Ascomicetos/química , Insecticidas , Piperazinas , Animales , Insecticidas/química , Insecticidas/aislamiento & purificación , Insecticidas/farmacología , Larva/crecimiento & desarrollo , Piperazinas/química , Piperazinas/aislamiento & purificación , Piperazinas/farmacología
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