ABSTRACT
Altersteroids A-D (1-4), four new 9,11-secosteroid-derived γ-lactones, were isolated from cultures of the ascomycete fungus Alternaria sp. Their structures were elucidated primarily by NMR experiments. The absolute configuration of 1 was established by X-ray crystallographic analysis of its di-p-nitrobenzenesulfonate 1a using Cu Kα radiation, whereas those for 2-4 were assigned by quantum-chemical calculations. Compounds 1-4 incorporate a γ-lactone moiety fused to the steroid D ring at C-13/C-14. Compound 3 showed moderate cytotoxicity toward four tumor cell lines and induced an apoptotic process in A549 cells. Notably, compound 3 showed equipotent activity against the cisplatin-sensitive MB49 and -resistant MB49 CisR cells, with an IC50 value of 12.7 µM.
Subject(s)
Ascomycota , Secosteroids , Alternaria/chemistry , Lactones/chemistry , Molecular Structure , Ascomycota/chemistry , Cell Line, TumorABSTRACT
Cladoxanthones A (1) and B (2), two xanthone-derived metabolites featuring a new spiro[cyclopentane-1,2'-[3,9a]ethanoxanthene]-2,4',9',11'(4a'H)-tetraone skeleton, were isolated from cultures of the ascomycete fungus Cladosporium sp., together with the known mangrovamide J (3). Their structures were elucidated primarily by NMR experiments. The absolute configurations of 1 and 2 were assigned by X-ray crystallography using Cu Kα radiation. Compound 1 could be generated from the hypothetical precursors related to α-methylene ketone and dihydro-xanthone via a Diels-Alder reaction, while 2 could be an oxidative coupling product resulting from 1 and 3. Compounds 1 and 2 showed weakly cytotoxic effects.
Subject(s)
Antineoplastic Agents , Cladosporium , Cyclopentanes , Xanthones , Humans , Antineoplastic Agents/chemistry , Antineoplastic Agents/isolation & purification , Antineoplastic Agents/pharmacology , Cell Line, Tumor , Cladosporium/chemistry , Crystallography, X-Ray , Cyclopentanes/chemistry , Cyclopentanes/isolation & purification , Cyclopentanes/pharmacology , Molecular Structure , Xanthones/chemistry , Xanthones/isolation & purification , Xanthones/pharmacologyABSTRACT
Four new diphenyl ether derivatives, neopestolides A-D (2-5), were isolated from cultures of the plant endophytic fungus Neopestalotiopsis sp., along with the known metabolite pestalotiollide A (1); their structures were elucidated primarily by NMR experiments. The absolute configurations of 2 and 3-5 were deduced by electronic circular dichroism calculations and via Snatzke's method, respectively. Compounds 2-4 incorporate tetrahydrofuran moieties attached to the dibenzo[b,g][1,5]dioxocin-5(7H)-one skeleton via C-C linkages. Compounds 1 and 2 showed modest cytotoxicity against HepG2 cells.
Subject(s)
Ascomycota , Xylariales , Ascomycota/chemistry , Molecular Structure , Phenyl Ethers/pharmacology , PlantsABSTRACT
Four new heptaketides, pseudonectrins A-D (1-4), and four known compounds (5-8) were isolated from cultures of an endophytic fungus Nectria pseudotrichia. Their structures were elucidated primarily by NMR experiments. The absolute configurations of 1-3 and 4 were assigned by electronic circular dichroism calculations and the modified Mosher method, respectively. Compound 1-3 showed moderate cytotoxicity, with IC50 values of 11.6-41.2 µM.
ABSTRACT
Sporulosol (1), a new ketal, together with four known compounds, has been isolated from the liquid fermentation cultures of a wetland-soil-derived fungus, Paraconiothyrium sporulosum. Its structure was elucidated primarily by NMR experiments, and was further confirmed by X-ray crystallography. Sporulosol was obtained as a racemic mixture and the resolved two enantiomers racemized immediately after chiral separation. Sporulosol appears to be the first ketal derived from a 6H-benzo[c]chromen-6-one and a benzofuranone unit. The compound showed modest cytotoxicity toward the human tumor cell line T24, with an IC50 value of 18.2 µM.