Subscribe to RSS
DOI: 10.1055/s-0028-1084482
Novel cytotoxic natural products from Papulaspora immersa, an endophyte in Smallanthus sonchifolius (Asteraceae)
The fungus Papulaspora immersa H. H. Hotson was isolated from roots and leaves of Smallanthus sonchifolius [Poepp. and Endl.] H. Robson (Asteraceae). Afterwards, it was cultured on parboiled rice for 20 days at 30o C. The culture was extracted with ethanol and partitioned with ethyl acetate. The obtained EtOAc fraction was submitted to chromatographic separation procedures and yielded 10 compounds. Among them, two were characterized by both 1D and 2D NMR (1H, 13C, HMBC, HMQC, and COSY), as well as positive ESI/HRMS spectra as new secondary metabolites and named 1,3-dihydro-1,3,8-trihydroxynaphtalene (1) and (22E,24R)-8,14-epoxiergosta-4,22-dien-3,6-dione (2). The spectral data of the other compounds were compared to literature data and they were identified as the known compounds (24R)-stigmast-4-en-3-one, (22E,24R)-ergost-4,6,8(14),22-tetraen-3-one, 24-methylenecycloarten-3β-ol, (3R,4R)-(-)-4-hydroxymellein, (3R)-(-)-5-hydroxymellein, 3-methyl-6,8-dihydroxyisocoumarin, 1,8-dihydroxynaphthalene and (4R)-4,8-dihydroxy-α-tetralone. All the compounds were submitted to MTT-dye reduction cytotoxic assay on human tumor cell lines MDA-MB435 (breast), HCT-8 (colon), SF295 (brain) and HL-60 (promyelocytic leukemia). Compound 2 showed promising results with IC50 of 1.44, 6.26, 2.15 and 0.7µg/mL, respectively.
Acknowledgements: financial support from FAPESP, CNPq and FINEP