Iizukines C-E from a saline soil fungus Aspergillus iizukae.

Three new alkaloids, iizukines C-E (1-3), including two aspochalasins (1 and 2), and one brasiliamide derivative (3), along with two known aspochalasins, rosellichalasin (4) and cytochalasin Z17 (5), were isolated from the culture of Aspergillus iizukae. Compound 1 was the first aspochalasin uniquely featuring a 1,2,4-triazole functionality, and 3 showed a pair of NMR signals in CDCl3 with a ratio of about 2:1 due to the existence of conformational isomers. Their structures were determined by extensive spectroscopic analyses and single-crystal X-ray diffractions. In particular, the 1,2,4-triazole moiety in 1 was assigned on the basis of extremely valuable 1H-15N HMBC spectrum. Compound 1 exhibited cytotoxic effect towards HL-60 and A549 cell lines with IC50 values of 3.8 and 7.2 µM, respectively.

New Butenolides and Cyclopentenones from Saline Soil-Derived Fungus Aspergillus Sclerotiorum.

Three new γ-hydroxyl butenolides (1-3), a pair of new enantiomeric spiro-butenolides (4a and 4b), a pair of enantiomeric cyclopentenones (5a new and 5b new natural), and six known compounds (6-11), were isolated from Aspergillus sclerotiorum. Their structures were established by spectroscopic data and electronic circular dichroism (ECD) spectra. Two pairs of enantiomers [(+)/(-)-6c and (+)/(-)-6d] obtained from the reaction of 6 with acetyl chloride (AcCl) confirmed that 6 was a mixture of two pairs of enantiomers. In addition, the X-ray data confirmed that 7 was also a racemate. The new metabolites (1-5) were evaluated for their inhibitory activity against cancer and non-cancer cell lines. As a result, compound 1 exhibited moderate cytotoxicity to HL60 and A549 with IC50 values of 6.5 and 8.9 µM, respectively, and weak potency to HL-7702 with IC50 values of 17.6 µM. Furthermore, compounds 1-9 were screened for their antimicrobial activity using the micro-broth dilution method. MIC values of 200 µg/mL were obtained for compounds 2 and 3 towards Staphylococcus aureus and Escherichia coli, while compound 8 exhibited a MIC of 50 µ/mL towards Candida albicans.

Potential Antiviral Xanthones from a Coastal Saline Soil Fungus Aspergillus iizukae.

Five new (1⁻5) and two known xanthones (6 and 7), one of the latter (6) obtained for the first time as a natural product, together with three known anthraquinones, questin, penipurdin A, and questinol, were isolated from the coastal saline soil-derived Aspergillus iizukae by application of an OSMAC (one strain many compounds) approach. Their structures were determined by interpretation of nuclear magnetic resonance (NMR) and high-resolution electrospray ionization mass spectroscopy (HRESIMS) data, as well as comparison of these data with those of related known compounds. Antiviral activity of xanthones 1-7 was evaluated through the cytopathic effect (CPE) inhibition assay, and compound 2 exhibited distinctly strong activity towards influenza virus (H1N1), herpes simplex virus types 1 (HSV-1) and 2 (HSV-2) with IC50 values of 44.6, 21.4, and 76.7 µM, respectively, which indicated that it was worth to further investigate it as a potential lead compound. The preliminary structure-activity relationship of the xanthones is discussed.