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Two new coumarins from Talaromyces flavus.

ABSTRACT: Two new coumarins, talacoumarins A (1) and B (2), were isolated from the ethyl acetate extract of the wetland soil-derived fungus Talaromyces flavus BYD07-13. Their structures were elucidated by spectroscopic data (NMR, MS) analyses. The absolute configuration of C-12 in 1 was assigned using the modified Mosher's method, whereas that of C-12 in 2 was deduced via the circular dichroism data of its corresponding [Rh2(OCOCF3)4] complex. Compounds 1 and 2 were evaluated for their anti-A?42 aggregation, cytotoxic, and antimicrobial activities. The results showed that the two compounds had moderate anti-A?42 aggregation activity, and this is the first report on the A?42 inhibitory aggregation activity of coumarins.

SUBMITTER: He JW

PROVIDER: S-EPMC6271517 | biostudies-literature | 2014 Dec

REPOSITORIES: biostudies-literature

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Two new coumarins from Talaromyces flavus.

He Jun-Wei JW Qin Da-Peng DP Gao Hao H Kuang Run-Qiao RQ Yu Yang Y Liu Xing-Zhong XZ Yao Xin-Sheng XS

Molecules (Basel, Switzerland) 20141212 12

Two new coumarins, talacoumarins A (1) and B (2), were isolated from the ethyl acetate extract of the wetland soil-derived fungus Talaromyces flavus BYD07-13. Their structures were elucidated by spectroscopic data (NMR, MS) analyses. The absolute configuration of C-12 in 1 was assigned using the modified Mosher's method, whereas that of C-12 in 2 was deduced via the circular dichroism data of its corresponding [Rh2(OCOCF3)4] complex. Compounds 1 and 2 were evaluated for their anti-Aβ42 aggregati ...[more]

PMID: 25514227

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Project description:Fungal β-N-acetylhexosaminidases, though hydrolytic enzymes in vivo, are useful tools in the preparation of oligosaccharides of biological interest. The β-N-acetylhexosaminidase from Talaromyces flavus is remarkable in terms of its synthetic potential, broad substrate specificity, and tolerance to substrate modifications. It can be heterologously produced in Pichia pastoris in a high yield. The mutation of the Tyr470 residue to histidine greatly enhances its transglycosylation capability. The aim of this work was to identify the structural requirements of this model β-N-acetylhexosaminidase for its transglycosylation acceptors and formulate a structure-activity relationship study. Enzymatic reactions were performed using an activated glycosyl donor, 4-nitrophenyl N-acetyl-β-d-glucosaminide or 4-nitrophenyl N-acetyl-β-d-galactosaminide, and a panel of glycosyl acceptors of varying structural features (N-acetylglucosamine, glucose, N-acetylgalactosamine, galactose, N-acetylmuramic acid, and glucuronic acid). The transglycosylation products were isolated and structurally characterized. The C-2 N-acetamido group in the acceptor molecule was found to be essential for recognition by the enzyme. The presence of the C-2 hydroxyl moiety strongly hindered the normal course of transglycosylation, yielding unique non-reducing disaccharides in a low yield. Moreover, whereas the gluco-configuration at C-4 steered the glycosylation into the β(1-4) position, the galacto-acceptor afforded a β(1-6) glycosidic linkage. The Y470H mutant enzyme was tested with acceptors based on β-glycosides of uronic acid and N-acetylmuramic acid. With the latter acceptor, we were able to isolate and characterize one glycosylation product in a low yield. To our knowledge, this is the first example of enzymatic glycosylation of an N-acetylmuramic acid derivative. In order to explain these findings and predict enzyme behavior, a modeling study was accomplished that correlated with the acquired experimental data.

Dataset Information

Two new coumarins from Talaromyces flavus.

Publications

Two new coumarins from Talaromyces flavus.

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