Chemical and bioactive natural products from Microthyriaceae sp., an endophytic fungus from a tropical grass. (28th March 2014)

• Record Type: Journal Article
• Authors: Almeida, C.; Ortega, H.; Higginbotham, S.; Spadafora, C.; Arnold, A.E.; Coley, P.D.; Kursar, T.A.; Gerwick, W.H.; Cubilla‐Rios, L.
• Is Part Of: Letters in applied microbiology. Volume 59:Number 1(2014:Jul.)
• Page Start: 58
• Page End: 64
• Publication Date: 2014-03-28
• Subjects: Microbiology -- Periodicals; 660.62
• DOI: 10.1111/lam.12245
• Languages: English
• ISSNs: 0266-8254

Abstract

<abstract abstract-type="main" id="lam12245-abs-0001"> <title>Abstract</title> <sec id="lam12028-sec-1001" sec-type="section"> <p>In screening for natural products with antiparasitic activity, an endophytic fungus, strain F2611, isolated from above‐ground tissue of the tropical grass <italic>Paspalum conjugatum (Poaceae)</italic> in Panama, was chosen for bioactive principle elucidation. Cultivation on malt extract agar (MEA) followed by bioassay‐guided chromatographic fractionation of the extract led to the isolation of the new polyketide integrasone B (<bold>1</bold>) and two known mycotoxins, sterigmatocystin (<bold>2</bold>) and secosterigmatocystin (<bold>3</bold>). Sterigmatocystin (<bold>2</bold>) was found to be the main antiparasitic compound in the fermentation extract of this fungus, possessing potent and selective antiparasitic activity against <italic>Trypanosoma cruzi</italic>, the cause of Chagas disease, with an IC<sub>50</sub> value of 0·13 <italic>μ</italic>mol l<sup>−1</sup>. Compounds <bold>2</bold> and <bold>3</bold> showed high cytotoxicity against Vero cells (IC<sub>50</sub> of 0·06 and 0·97 <italic>μ</italic>mol l<sup>−1</sup>, respectively). The new natural product integrasone B (<bold>1</bold>), which was co‐purified from the active fractions, constitutes the second report of a natural product possessing an epoxyquinone with a lactone ring and exhibited no significant biological activity. Strain F2611 represents a previously undescribed taxon within the Microthyriaceae (Dothideomycetes, Ascomycota).</p> </sec> <sec id="lam12028-sec-0102" sec-type="section"> <title>Significance and Impact of the Study</title> <p>The present study attributes new antiparasitic and psychoactive biological activities to sterigmatocystin (<bold>2</bold>), and describes the structure elucidation of the new natural product integrasone B (<bold>1</bold>), which possesses a rare epoxyquinone with a lactone ring moiety. This is also the first report of sterigmatocystin (<bold>2</bold>) isolation in a fungal strain from this family, broadening the taxonomic range of sterigmatocystin‐producing fungi. The study also presents taxonomic analyses indicating that strain F2611 is strongly supported as a member of the Microthyriaceae (Ascomycota), but is not a member of any previously known or sequenced genus.</p> </sec> </abstract>