Abstract
Chemical investigation of the Antarctic lichen-derived fungal strain Acremonium sp. SF-7394 yielded a new amphilectane-type diterpene, acrepseudoterin (1), and a new acorane-type sesquiterpene glycoside, isocordycepoloside A (2). In addition, three known fungal metabolites, (−)-ternatin (3), [D-Leu]-ternatin (4), and pseurotin A (5), were isolated from the EtOAc extract of the fungal strain. Their structures were mainly elucidated by analyzing their NMR and MS data. The absolute configuration of 1 was proposed by electronic circular dichroism calculations, and the absolute configuration of the sugar unit in 2 was determined by a chemical method. The inhibitory effects of the isolated compounds on protein tyrosine phosphatase 1B (PTP1B) were evaluated by enzymatic assays; results indicated that acrepseudoterin (1) and [D-Leu]-ternatin (4) dose-dependently inhibited the enzyme activity with IC50 values of 22.8 ± 1.1 μM and 14.8 ± 0.3 μM, respectively. Moreover, compound 1 was identified as a competitive inhibitor of PTP1B.
Highlights
The fungal genus Acremonium has been identified in various sources such as soil, plants, and marine organisms [1]
Secondary metabolites derived from Acremonium species have been reported to contain steroids, terpenoids, meroterpenoids, polyketides, alkaloids, and peptides, which show a variety of biological activities, especially anti-bacterial, antifungal, and cytotoxic effects [1]
In the course of our ongoing search for bioactive secondary metabolites from Antarctic-derived fungal strains [6,7], the EtOAc extract obtained from cultures of Acremonium sp
Summary
The fungal genus Acremonium has been identified in various sources such as soil, plants, and marine organisms [1]. Secondary metabolites derived from Acremonium species have been reported to contain steroids, terpenoids, meroterpenoids, polyketides, alkaloids, and peptides, which show a variety of biological activities, especially anti-bacterial, antifungal, and cytotoxic effects [1]. Some examples of these biologically active metabolites include cephalosporin antibiotics [2], cytotoxic heptelidic acid chlorohydrin [3], anti-fungal acremoxanthone A [4], and antibiotic cephaibol B [5]. Two novel fungal metabolites including an amphilectane-type diterpene, acrepseudoterin (1), and an acorane-type sesquiterpene glycoside, isocordycepoloside A (2), were isolated
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