title: Phylogenetic and chemical diversity of fungal endophytes isolated fromSilybum marianum(L) Gaertn. (milk thistle).
abstract: Use of the herb milk thistle (Silybum marianum) is widespread, and its chemistry has been studied for over 50 years. However, milk thistle endophytes have not been studied previously for their fungal and chemical diversity. We examined the fungal endophytes inhabiting this medicinal herb to determine: (1) species composition and phylogenetic diversity of fungal endophytes; (2) chemical diversity of secondary metabolites produced by these organisms; and (3) cytotoxicity of the pure compounds against the human prostate carcinoma (PC-3) cell line. Forty-one fungal isolates were identified from milk thistle comprising 25 operational taxonomic units based on BLAST search via GenBank using published authentic sequences from nuclear ribosomal internal transcribed spacer sequence data. Maximum likelihood analyses of partial 28S rRNA gene showed that these endophytes had phylogenetic affinities to four major classes of Ascomycota, the Dothideomycetes, Sordariomycetes, Eurotiomycetes, and Leotiomycetes. Chemical studies of solid-substrate fermentation cultures led to the isolation of four new natural products. In addition, 58 known secondary metabolites, representing diverse biosynthetic classes, were isolated and characterized using a suite of nuclear magnetic resonance and mass spectrometry techniques. Selected pure compounds were tested against the PC-3 cell line, where six compounds displayed cytotoxicity.
authors.affiliation: Department of Chemistry and Biochemistry, University of North Carolina at Greensboro , Greensboro , NC 27402 , USA.
authors.forename: Huzefa A
authors.initials: HA
authors.lastname: Raja
authors.affiliation: Department of Chemistry and Biochemistry, University of North Carolina at Greensboro , Greensboro , NC 27402 , USA.
authors.forename: Amninder
authors.initials: A
authors.lastname: Kaur
authors.affiliation: Department of Chemistry and Biochemistry, University of North Carolina at Greensboro , Greensboro , NC 27402 , USA.
authors.forename: Tamam
authors.initials: T
authors.lastname: El-Elimat
authors.affiliation: Facultad de Química, Universidad Nacional Autónoma de México , Mexico , DF 04510 , Mexico.
authors.forename: Mario
authors.initials: M
authors.lastname: Figueroa
authors.affiliation: Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Denver , Aurora , CO 80045 , USA.
authors.forename: Rahul
authors.initials: R
authors.lastname: Kumar
authors.affiliation: Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Denver , Aurora , CO 80045 , USA.
authors.forename: Gagan
authors.initials: G
authors.lastname: Deep
authors.affiliation: Department of Pharmaceutical Sciences, Skaggs School of Pharmacy and Pharmaceutical Sciences, University of Colorado Denver , Aurora , CO 80045 , USA.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Agarwal
authors.affiliation: Department of Biology, University of North Carolina at Greensboro , Greensboro , NC 27402 , USA.
authors.forename: Stanley H
authors.initials: SH
authors.lastname: Faeth
authors.affiliation: Department of Chemistry and Biochemistry, University of North Carolina at Greensboro , Greensboro , NC 27402 , USA.
authors.forename: Nadja B
authors.initials: NB
authors.lastname: Cech
authors.affiliation: Department of Chemistry and Biochemistry, University of North Carolina at Greensboro , Greensboro , NC 27402 , USA.
authors.forename: Nicholas H
authors.initials: NH
authors.lastname: Oberlies
keywords: Ascomycota; Silybum marianum; endophyte; milk thistle