Search

Six new α-pyrone meroterpenoid chevalones H-M ( 1 - 6 ), together with six known compounds ( 7 - 12 ), were isolated from the gorgonian coral-derived fungus Aspergillus hiratsukae SCSIO 7S2001 collected from Mischief Reef in the South China Sea. Their structures, including absolute configurations, were elucidated on the basis of spectroscopic analysis and X-ray diffraction data. Compounds 1 - 5 and 7 showed different degrees of antibacterial activity with MIC values of 6.25-100 μg/mL. Compound 8 exhibited potent cytotoxicity against SF-268, MCF-7, and A549 cell lines with IC 50 values of 12.75, 9.29, and 20.11 μM, respectively.

To enlarge the chemical diversity of Eurotium sp. SCSIO F452, a talented marine-derived fungus, we further investigated its chemical constituents from a large-scale fermentation with modified culture. Four pairs of new salicylaldehyde derivative enantiomers, euroticins F-I ( 1 - 4 ), as well as a known one eurotirumin ( 5 ) were isolated and characterized. Compound 1 features an unprecedented constructed 6/6/6/5 tetracyclic structures, while 2 and 3 represent two new types of 6/6/5 scaffolds. Their structures were established by comprehensive spectroscopic analyses, X-ray diffraction, 13 C NMR, and electronic circular dichroism calculations. Selected compounds showed significant inhibitory activity against α-glucosidase and moderate cytotoxic activities against SF-268, MCF-7, HepG2, and A549 cell lines.

Four phenylfuropyridone racemates, (±)-tersones A-C and E ( 1 - 3 , 5 ), one phenylpyridone racemate, (±)-tersone D ( 4 ), one new pyridine alkaloid, tersone F ( 6 ), single new phenylfuropyridone, tersone G ( 7 ) and two known analogs 8 and 9 were isolated from the deep-sea fungus Phomopsis tersa . Their structures and absolute configurations were characterized on the basis of comprehensive spectroscopic analyses, single-crystal X-ray diffraction experiments, and electronic circular dichroism (ECD) calculations. Moreover, compounds 1 - 9 were evaluated for in vitro antimicrobial and cytotoxic activity. Compounds 5b and 8b exhibited antibacterial activity against S. aureus with the MIC value of 31.5 μg/mL, while compound 5b showed cytoxic activities against SF-268, MCF-7, HepG-2 and A549 cell lines with IC 50 values of 32.0, 29.5, 39.5 and 33.2 μM, respectively.

Five new chromone-derived polyketides phaseolorins A-F ( 1 ⁻ 5 ), together with nine known compounds, were isolated from the deep-sea derived fungus Diaporthe phaseolorum FS431. The structures of new compounds were determined by analysis of their NMR and high-resolution electrospray ionization mass spectroscopy (HRESIMS) spectroscopic data. The absolute configurations were confirmed by chemical transformations, extensively experimental electron capture detection (ECD) calculations, or X-ray crystallography. Among them, compound 2 represented the first example for a new family of chromone derivative possessing an unprecedented recombined five-member γ -lactone ring. Moreover, the new compounds ( 1 ⁻ 5 ) were evaluated for in vitro cytotoxic activities against a panel of human cancer cell lines.

Three new thiodiketopiperazines, geospallins A⁻C ( 1 ⁻ 3 ), together with nine known analogues ( 4 ⁻ 12 ), were isolated from the culture of the deep-sea sediment-derived fungus Geosmithia pallida FS140. Among them, geospallins A and B ( 1 and 2 ) represent rare examples of thiodiketopiperazines featuring an S-methyl group at C-10 and a tertiary hydroxyl group at C-11. Their structures were determined by high-resolution electrospray mass spectrometry (HRESIMS), spectroscopic analyses, and electronic circular dichroism (ECD) calculations. Their angiotensin-converting enzyme (ACE) inhibitory activity was reported, and geospallins A⁻C ( 1 ⁻ 3 ) showed inhibitory activity with IC 50 values of 29⁻35 µM.

Five new benzophenone derivatives named tenellones D⁻H ( 1 ⁻ 5 ), sharing a rare naturally occurring aldehyde functionality in this family, and a new eremophilane derivative named lithocarin A ( 7 ), together with two known compounds ( 6 and 8 ), were isolated from the deep marine sediment-derived fungus Phomopsis lithocarpus FS508. All of the structures for these new compounds were fully characterized and established on the basis of extensive spectroscopic interpretation and X-ray crystallographic analysis. Compound 5 exhibited cytotoxic activity against HepG-2 and A549 cell lines with IC 50 values of 16.0 and 17.6 μM, respectively.

Three new prenylated indole 2,5-diketopiperazine alkaloids ( 1 ⁻ 3 ) with nine known ones ( 5 ⁻ 13 ), one new indole alkaloid ( 4 ), and one new bis-benzyl pyrimidine derivative ( 14 ) were isolated and characterized from the marine-derived fungus Eurotium sp. SCSIO F452. 1 and 2 , occurring as a pair of diastereomers, both presented a hexahydropyrrolo[2,3- b ]indole skeleton. Their chemical structures, including absolute configurations, were elucidated by 1D and 2D NMR, HRESIMS, quantum chemical calculations of electronic circular dichroism, and single crystal X-ray diffraction experiments. Most isolated compounds were screened for antioxidative potency. Compounds 3 , 5 , 6 , 7 , 9 , 10 , and 12 showed significant radical scavenging activities against DPPH with IC 50 values of 13, 19, 4, 3, 24, 13, and 18 µM, respectively. Five new compounds were evaluated for cytotoxic activities.

Three new diketopiperazines, dichotocejpins A-C (1-3), together with eight known analogues (4-11), were isolated from the culture of the deep-sea sediment derived fungus Dichotomomyces cejpii FS110. Their structures, including absolute configurations, were elucidated by a combination of HRESIMS, NMR, X-ray crystallography, and ECD calculations. Compounds 4-6, 10-11 showed significant cytotoxic activities against MCF-7, NCI-H460, HepG-2, and SF-268 tumor cell lines. Compound 1 exhibited excellent inhibitory activity against α-glucosidase with an IC50 of 138 μM., Competing Interests: The authors declare no conflict of interest.