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Chemical and bioactive natural products from Microthyriaceae sp., an endophytic fungus from a tropical grass
Author(s) -
Almeida C.,
Ortega H.,
Higginbotham S.,
Spadafora C.,
Arnold A.E.,
Coley P.D.,
Kursar T.A.,
Gerwick W.H.,
CubillaRios L.
Publication year - 2014
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.12245
Subject(s) - sterigmatocystin , antiparasitic , biology , phthalide , natural product , fungus , botany , mycotoxin , biochemistry , medicine , pathology
In screening for natural products with antiparasitic activity, an endophytic fungus, strain F2611, isolated from above‐ground tissue of the tropical grass P aspalum conjugatum ( P oaceae) in P anama, 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 ( 1 ) and two known mycotoxins, sterigmatocystin ( 2 ) and secosterigmatocystin ( 3 ). Sterigmatocystin ( 2 ) was found to be the main antiparasitic compound in the fermentation extract of this fungus, possessing potent and selective antiparasitic activity against T rypanosoma cruzi , the cause of C hagas disease, with an IC 50 value of 0·13 μ mol l −1 . Compounds 2 and 3 showed high cytotoxicity against Vero cells ( IC 50 of 0·06 and 0·97 μ mol l −1 , respectively). The new natural product integrasone B ( 1 ), 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 M icrothyriaceae ( D othideomycetes, A scomycota). Significance and Impact of the Study The present study attributes new antiparasitic and psychoactive biological activities to sterigmatocystin ( 2 ), and describes the structure elucidation of the new natural product integrasone B ( 1 ), which possesses a rare epoxyquinone with a lactone ring moiety. This is also the first report of sterigmatocystin ( 2 ) 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 F 2611 is strongly supported as a member of the M icrothyriaceae ( A scomycota), but is not a member of any previously known or sequenced genus.