A new anthraquinone from mangrove endophytic fungus Aspergillus sp. 16-5C.

A new anthraquinone, asperquinone A (1), and four known anthraquinone derivatives 2-5 were isolated from the mangrove endophytic fungus Aspergillus sp. 16-5C. These structures were elucidated by spectroscopic analysis and the absolute configuration of 1 was unambiguously determined by ECD calculation. Compounds 1-5 showed no significant inhibitory effect against Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB).

Porous diatomite-mixed 1,4,5,8-NTCDA nanowires as high-performance electrode materials for lithium-ion batteries.

A porous composite electrode composed of diatomite-mixed 1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA) is prepared by electrostatic spinning technology. Compared with traditional coated electrodes without diatomite mixing, the obtained composite electrode materials have higher porosity, larger specific surface area and faster lithium ion transport channels, which makes them exhibit better electrochemical performance, such as smaller impedance, higher capacity, and better cycling stability and rate performance. The electrospun diatomite-mixed 1,4,5,8-NTCDA composite (ED-1,4,5,8-NTCDA) electrode shows an initial coulombic efficiency of 77.2%, which is much higher than that of the electrospun 1,4,5,8-NTCA (E-1,4,5,8-NTCDA) electrode without diatomite mixing (63.8%) and the coated 1,4,5,8-NTCA (C-1,4,5,8-NTCDA) electrode (48.3%). Moreover, the ED-1,4,5,8-NTCDA electrode displays an initial discharge capacity of 1106.5 mA h g-1, which is much higher than that of the E-1,4,5,8-NTCDA electrode (546.0 mA h g-1) and the C-1,4,5,8-NTCDA electrode (185.4 mA h g-1). After 200 cycles, the capacity of the ED-1,4,5,8-NTCDA electrode remains at 1008.5 mA h g-1 with a retention ratio of 91.2%, which is also much higher than that of 753.2 mA h g-1 for the E-1,4,5,8-NTCDA electrode and 288.1 mA h g-1 for the C-1,4,5,8-NTCDA electrode. Even at a higher current density of 1500 mA g-1, its capacity remains above 508.9 mA h g-1. The ED-1,4,5,8-NTCDA electrode presents superior performance, which opens up a promising new approach for further utilization of organic materials as electrode materials in rechargeable lithium-ion batteries.

Acetylcholinesterase Inhibitory Meroterpenoid from a Mangrove Endophytic Fungus Aspergillus sp. 16-5c.

One new meroterpenoid, named 2-hydroacetoxydehydroaustin (1), together with nine known meroterpenoids, 11-acetoxyisoaustinone (2), isoaustinol (3), austin (4), austinol (5), acetoxydehydroaustin (6), dehydroaustin (7), dehydroaustinol (8), preaustinoid A2 (9), and 1,2-dihydro-acetoxydehydroaustin B (10), were isolated from the mangrove endophytic fungus, Aspergillus sp. 16-5c. These structures were characterized by spectroscopic analysis, further the absolute configurations of stereogenic carbons for Compounds 1, 3, 4, 6, 7, 8, 9, and 10 were determined by single crystal X-ray diffraction analysis using Cu Kα radiation. Moreover, the absolute configurations of stereogenic carbons for Known Compounds 3, 7, 8, and 9 are identified here for the first time. Compounds 3, 7, and 8 showed acetylcholinesterase (AchE) inhibitory activity with IC50 values of 2.50, 0.40, and 3.00 µM, respectively.

New furoisocoumarins and isocoumarins from the mangrove endophytic fungus Aspergillus sp. 085242.

The chemical investigation of the mangrove endophytic fungus Aspergillus sp. 085242 afforded eight isocoumarin derivatives 1-8 and one isoquinoline 9. Asperisocoumarins A and B (1 and 2) were new furoisocoumarins, and asperisocoumarins E and F (5 and 6) were new isocoumarins. Their structures were established by analysis of their spectroscopic data and the absolute configuration of compound 2 was unambiguously determined by X-ray structure analysis and ECD calculation. Moreover, the absolute configurations of compounds 3-5 were assigned by comparison of their ECD spectra with isocoumarins described in the literature. Asperisocoumarins C and D (3 and 4) were fully characterized spectroscopically and isolated from a natural source for the first time. Asperisocoumarins A-D (1-4) related to the class of furo[3,2-h]isocoumarins are rarely occurring in natural sources. Compounds 2, 5, and 6 showed moderate α-glucosidase inhibitory activity with IC50 of 87.8, 52.3, and 95.6 µM, respectively. In addition, compounds 1 and 3 exhibited weak radical scavenging activity with EC50 values of 125 and 138 µM, respectively.

Asperlones A and B, dinaphthalenone derivatives from a mangrove endophytic fungus Aspergillus sp. 16-5C.

Racemic dinaphthalenone derivatives, (±)-asperlone A (1) and (±)-asperlone B (2), and two new azaphilones, 6'-hydroxy-(R)-mitorubrinic acid (3) and purpurquinone D (4), along with four known compounds, (-)-mitorubrinic acid (5), (-)-mitorubrin (6), purpurquinone A (7) and orsellinic acid (8), were isolated from the cultures of Aspergillus sp. 16-5C. The structures were elucidated using comprehensive spectroscopic methods, including 1D and 2D NMR spectra and the structures of 1 further confirmed by single-crystal X-ray diffraction analysis, while the absolute configuration of 3 and 4 were determined by comparing their optical rotation and CD with those of the literature, respectively. Compounds 1, 2 and 6 exhibited potent inhibitory effects against Mycobacterium tuberculosis protein tyrosine phosphatase B (MptpB) with IC50 values of 4.24 ± 0.41, 4.32 ± 0.60 and 3.99 ± 0.34 µM, respectively.

Xylanthraquinone, a new anthraquinone from the fungus Xylaria sp. 2508 from the South China Sea.

Xylanthraquinone (1), a new anthraquinone, along with three known compounds, altersolanol A (2), deoxybostrycin (3) and bostrycin (4) was isolated from the fungus Xylaria sp. 2508 from the South China Sea. The structures of these compounds were identified by NMR experiments, and the absolute configuration of compound 1 was further confirmed by single-crystal X-ray diffraction with Cu Kα radiation. Compounds 1-4 did not show inhibitory activities against Mycobacterium tuberculosis protein tyrosine phosphatase B (IC50 values more than 100 µM).

Asperterpenols A and B, new sesterterpenoids isolated from a mangrove endophytic fungus Aspergillus sp. 085242.

Asperterpenol A (1) and asperterpenol B (2), two novel sesterterpenoids with an unusual 5/8/6/6 tetracyclic ring skeleton, were isolated from a mangrove endophytic fungus Aspergillus sp. 085242. The structures were elucidated on the basis of spectroscopic methods and the absolute configurations determined by single-crystal X-ray diffraction analysis. Compounds 1 and 2 inhibit acetylcholinesterase with IC50 values of 2.3 and 3.0 µM, respectively.

Azaphilones and p-terphenyls from the mangrove endophytic fungus Penicillium chermesinum (ZH4-E2) isolated from the South China Sea.

Eight secondary metabolites, including three new azaphilones (chermesinones A-C, 1-3), three new p-terphenyls (6'-O-desmethylterphenyllin, 4; 3-hydroxy-6'-O-desmethylterphenyllin, 5; 3''-deoxy-6'-O-desmethylcandidusin B, 7), and two known p-terphenyls (6, 8), were isolated from the culture of the mangrove endophytic fungus Penicillium chermesinum (ZH4-E2). Their structures were established by spectroscopic analysis. The absolute configuration of 1 was determined by X-ray crystallography. Terphenyls 4, 5, and 6 exhibited strong inhibitory effects against α-glucosidase with IC50 values of 0.9, 4.9, and 2.5 µM, respectively. Terphenyls 7 and 8 showed inhibitory activity toward acetylcholinesterase with IC50 values of 7.8 and 5.2 µM.