Two New Austocystin Analogs from the Marine‐Derived Fungus Aspergillus sp. WHUF05236

Abstract

Two new austocystin analogs, austocystin P (1) and austocystin Q (2), along with fourteen known compounds (3–16) were isolated from the fermentation extract of Aspergillus sp. WHUF05236. The planar structures of 1 and 2 were elucidated through 1D, 2D NMR and MS analyses. Their absolute configurations were determined by the time‐dependent density functional (TDDFT)‐ECD calculation. Compounds 3, 11, and 12 exhibited antimicrobial activities against Helicobacter pylori with MIC values ranging from 20.00 to 43.47 μM. Compounds 3, 6, and 7 showed cytotoxicities against the human colon cancer cell lines Hct‐116 with IC50 values of 101.79, 65.46, and 36.72 μM, respectively.

Asperustins A–J: Austocystins with Immunosuppressive and Cytotoxic Activities from Aspergillus ustus NRRL 5856

“…The 1 H and 13 C NMR data (Tables and ), together with the HSQC spectrum, displayed signals for one methylene (δ H 2.37/δ C 38.4), three methines (δ H 4.08/δ C 42.9; δ H 5.21/δ C 106.7; and δ H 6.47/δ C 113.2), one 1,2,3,4-tetrasubstituted benzene (δ H 7.12/δ C 114.1; δ H 7.59/δ C 134.3; and δ C 118.4, 124.0, 155.2, 155.9), one pentasubstituted benzene (δ H 6.54/δ C 93.7; and δ C 111.2, 119.7, 156.7, 158.9, 163.8), one carbonyl group (δ C 174.3), and three methoxy groups (δ H 3.19/δ C 55.0; δ H 4.01/δ C 61.8; and δ H 4.01/δ C 62.0). A literature search of the NMR data indicated that 1 was an austocystin analogue . The HMBC correlations (Figure ) of H-5/C-8a, C-9, C-10a and H-4/C-2, C-3, C-9, C-9a confirmed the presence of a xanthone unit.…”

“…Aspergillus ustus , belonging to the section Usti , is capable of producing multiple metabolites, including austocystins, , sterigmatocystins, , isochromanes, drimane sesquiterpenes, , ophiobolins, , and austalides . Austocystins are a group of mycotoxins consisting of a xanthone unit fused with a bisdihydrofuran and have attracted attention due to their diverse biological activities, including cytotoxic, , antioxidant, enzyme inhibitory, and brine shrimp toxic effects. , …”

Marine natural products

“…167) aromatic bisabolene sesquiterpenoids 428 – 431 and benzaldehyde derivative 432 (the last a known synthetic compound but new NP) 168 and cyclohexapeptides 433 – 436 . 169 Other Aspergillus strains derived from sediment yielded nucleoside derivatives 437 , 438 , 170 austocystin analogues 439 , 440 , 171 diketopiperazines 441 – 444 (ref. 172) and indole diketopiperazine alkaloids 445 – 448 , 173 and gorgonian-derived strains were the source of indole diketopiperazine hybrids 449 – 452 , 174 benzodipyrans comprising eurotiumide G enantiomers 453 , 454 (configurations revised to 1 S ,3 R ,4 R and 1 R ,3 S ,4 S respectively), 455 – 462 (all isolated as racemates but separated by chiral HPLC), 175 asperbenzophenone A 463 and versicolamide C 464 .…”

Marine Aspergillus: A Treasure Trove of Antimicrobial Compounds

“…Six known compounds, including cyclopiamide (79), speradine H (80), speradine G (81), speradine B (82), speradine C (83) and cyclopiazonic acid (CPA) (84), were isolated from A. flavus SCSIO F025 from deep-sea sediments in the South China Sea (Figure 8). Compounds 79-84 showed weak antibacterial activity against E. coli, and CPA also exhibited strong antibacterial activity against MRSA, B. subtilis, S. aureus, M. luteus and Bacillus thuringiensis [75].…”

“…They included 6,8-di-O-methylversicolorin A (96), 6,8,1 -tri-O-methylaverantin (97) and 6,8-di-O-methylaverantin (98). They exhibited antibacterial activity against H. pylori, with MIC values ranging from 20.00 to 43.47 µM [79].…”