Bioprospection of Cytotoxic Compounds in Fungal Strains Recovered from Sediments of the Brazilian Coast by Bµrbara S. F. Rodrigues a ), Bianca D. B. Sahm b ), Paula C. Jimenez b ), Francisco C. L. Pinto a ), Jair Mafezoli a ), Marcos C. Mattos a ), Edson Rodrigues-Filho c ), Ludwig H. Pfenning d ), Lucas M. Abreu d ), Letícia V. Costa-Lotufo* b ), and Maria C. F. Oliveira* a ) a ) Departamento de Química Orgânica e Inorgânica, Universidade Federal do Cearµ, Campus do Pici, P.O. Box 6044, 60.455-970, Fortaleza-CE, Brazil (phone: þ 55-85-33669144; e-mail: mcfo@ufc.br) b )Instituto de CiÞncias do Mar, LABOMAR, Universidade Federal do Cearµ, Av. Aboliżo, 3207, 60185-061, Fortaleza-CE, Brazil; Departamento de Fisiologia e Farmacologia, Universidade Federal do Cearµ, Fortaleza-CE, Brazil (phone: þ 55-85-33667029; e-mail: lvcosta@ufc.br) c )Departamento de Química, Universidade Federal de S¼o Carlos, S¼o Carlos-SP, Brazil d ) Departamento de Fitopatologia, Universidade Federal de Lavras, Lavras-MG, Brazil The cytotoxic activities of extracts (50 mg/ml) from 48 fungal strains, recovered from sediments of PecØms offshore port terminal (Northeast coast of Brazil) , against HCT-116 colon cancer cell lines were investigated. The most promising extract was obtained from strain BRF082, identified as Dichotomo- myces cejpii by phylogenetic analyses of partial RPB2 gene sequence. Thus, it was selected for bioassay- guided isolation of the cytotoxic compounds. Large-scale fermentation of BRF082 in potato dextrose broth, followed by chromatographic purification of the bioactive fractions from the liquid medium, yielded gliotoxin (4) and its derivatives acetylgliotoxin G ( 3), bis(dethio)bis(methylsulfanyl)gliotoxin (1), acetylgliotoxin (5), 6-acetylbis(dethio)bis(methylsulfanyl)gliotoxin (2), besides the quinazolinone alkaloid fiscalin B. All isolated compounds were tested for their cytotoxicities against the tumor cell lines HCT-116, revealing 4 and 3 as the most cytotoxic ones ( IC 50 0.41 and 1.06 mg/ml, resp.). Introduction. – A complex microbiota lives in the oceans, and is considered an important source of bioactive compounds [1] [2] . Since the isolation of cephalosporin C from Acremonium chrysogenum (as Cephalosporium acremonium) in 1949, marine fungi have already provided more than 1,000 new secondary metabolites [ 3] [4] . About two-thirds of these compounds were produced by fungal strains associated with living organisms, such as algae, plants, sponges, and ascidians, while the others were isolated from fungi recovered from non-living material, especially sediments [2]. Cytotoxicity is the most expressive biological activity of the extracts from marine sources, and the number of compounds under clinical investigation confirms the potential of the marine natural products for anticancer chemotherapy [5]. In the last years, we have focused on the identification of antitumor compounds from the Brazilian marine biodiversity [6]. Here, we report the bioprospection of cytotoxic compounds in marine-derived fungal strains recovered from sediments from the Northeastern coast of Brazil, and the isolation of epipolithiodioxopiperazine compounds, bis(dethio)bis(methylsulfanyl)gliotoxin (1), 6-acetylbis(dethio)bis(meth- ylsulfanyl)gliotoxin (2), acetylgliotoxin G ( 3), gliotoxin (4), and acetylgliotoxin (5), besides fiscalin B (6)( Fig. 1), from Dichotomomyces cejpii (BRF082). CHEMISTRY & BIODIVERSITY – Vol. 12 (2015) 432  2015 Verlag Helvetica Chimica Acta AG, Zürich