title: Chemical constituents of Papulaspora immersa, an endophyte from Smallanthus sonchifolius (Asteraceae), and their cytotoxic activity.
abstract: Papulaspora immersa H. H. Hotson was isolated from roots and leaves of Smallanthus sonchifolius (Poepp. and Endl.) H. Rob. (Asteraceae), traditionally known as Yacon. The fungus was cultured in rice, and, from the AcOEt fraction, 14 compounds were isolated. Among them, (22E,24R)-8,14-epoxyergosta-4,22-diene-3,6-dione (4), 2,3-epoxy-1,2,3,4-tetrahydronaphthalene-c-1,c-4,8-triol (10), and the chromone papulasporin (13) were new secondary metabolites. The spectral data of the known natural products were compared with the literature data, and their structures were established as the (24R)-stigmast-4-en-3-one (1), 24-methylenecycloartan-3β-ol (2), (22E,24R)-ergosta-4,6,8(14),22-tetraen-3-one (3), (-)-(3R,4R)-4-hydroxymellein (5), (-)-(3R)-5-hydroxymellein (6), 6,8-dihydroxy-3-methylisocoumarin (7), (-)-(4S)-4,8-dihydroxy-α-tetralone (8), naphthalene-1,8-diol (9), 6,7,8-trihydroxy-3-methylisocoumarin (11), 7-hydroxy-2,5-dimethylchromone (12), and tyrosol (14). Compound 4 showed the highest cytotoxic activity against the human tumor cell lines MDA-MB435 (melanoma), HCT-8 (colon), SF295 (glioblastoma), and HL-60 (promyelocytic leukemia), with IC₅₀ values of 3.3, 14.7, 5.0 and 1.6 μM, respectively. Strong synergistic effects were also observed with compound 5 and some of the isolated steroidal compounds.
authors.affiliation: Universidade de São Paulo, Ribeirão Preto, SP, Brazil.
authors.forename: Margareth Borges Coutinho
authors.initials: MB
authors.lastname: Gallo
authors.forename: Bruno Coêlho
authors.initials: BC
authors.lastname: Cavalcanti
authors.forename: Francisco Washington Araújo
authors.initials: FW
authors.lastname: Barros
authors.forename: Manoel
authors.initials: M
authors.lastname: Odorico de Moraes
authors.forename: Letícia Veras
authors.initials: LV
authors.lastname: Costa-Lotufo
authors.forename: Cláudia
authors.initials: C
authors.lastname: Pessoa
authors.forename: Jairo Kenupp
authors.initials: JK
authors.lastname: Bastos
authors.forename: Mônica Tallarico
authors.initials: MT
authors.lastname: Pupo
mesh_terms: D019659:Asteraceae / Q000737:chemistry*; D045744:Cell Line, Tumor; D002867:Chromones / Q000737:chemistry* / Q000302:isolation & purification / Q000633:toxicity; D004354:Drug Screening Assays, Antitumor; D004852:Epoxy Compounds / Q000737:chemistry* / Q000302:isolation & purification / Q000633:toxicity; D004875:Ergosterol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000302:isolation & purification / Q000633:toxicity; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008968:Molecular Conformation; D009284:Naphthols / Q000737:chemistry* / Q000302:isolation & purification / Q000633:toxicity; D018515:Plant Leaves / Q000737:chemistry; D018517:Plant Roots / Q000737:chemistry
chemical_list: C557097:8,14-epoxyergosta-4,22-diene-3,6-dione; D002867:Chromones; D004852:Epoxy Compounds; D009284:Naphthols; D004875:Ergosterol