Eurothiocin A and B, Sulfur-Containing Benzofurans from a Soft Coral-Derived Fungus Eurotium rubrum SH-823

• Main Authors: Zhaoming Liu, Guoping Xia, Senhua Chen, Yayue Liu, Hanxiang Li, Zhigang She
• Format: Article
• Language: English
• Published: MDPI AG 2014-06-01
• Series: Marine Drugs
• Subjects: marine fungi; secondary metabolites; α-glucosidase inhibitor; theoretical calculations; ECD; TDDFT
• Online Access: http://www.mdpi.com/1660-3397/12/6/3669

Two new sulfur-containing benzofuran derivatives, eurothiocin A and B (1 and 2), along with five known compounds, zinniol (3), butyrolactone I (4), aspernolide D (5), vermistatin (6), and methoxyvermistatin (7), were isolated from the cultures of Eurotium rubrum SH-823, a fungus obtained from a Sarcophyton sp. soft coral collected from the South China Sea. The new compounds (1 and 2) share a methyl thiolester moiety, which is quite rare among natural secondary metabolites. The structures of these metabolites were assigned on the basis of detailed spectroscopic analysis. The absolute configurations of 1 and 2 were determined by comparison of the experimental and calculated electronic circular dichroism (ECD) data. Compounds 1 and 2 exhibited more potent inhibitory effects against α-glucosidase activity than the clinical α-glucosidase inhibitor acarbose. Further mechanistic analysis showed that both of them exhibited competitive inhibition characteristics.