Depsidones from the Endophytic Fungus BCC 8616 Pattama Pittayakhajonwut,* Aibrohim Dramae, Siribhorn Madla, Nattapat Lartpornmatulee, Nattawut Boonyuen, and Morakot Tanticharoen National Center for Genetic Engineering and Biotechnology (BIOTEC), Thailand Science Park, Paholyothin Road, Klong Luang, Pathumthani 12120, Thailand ReceiVed April 28, 2006 Three new depsidones (1-3) have been isolated from the endophytic fungus BCC 8616 and their structures analyzed on the basis of spectroscopic data interpretation. Compound 1 exhibited weak cytotoxic activity against breast and epidermoid carcinoma cell lines. In a continuing search for bioactive substances from microorgan- isms, 1-3 the crude extract of an endophyte deposited at the BIOTEC culture collection as BCC 8616 and classified as a member of the order Pleosporales (class Ascomycetes, subclass Dothideomycetidae; see the Fungus Identification section) exhibited cytotoxic activity against human epidermoid carcinoma (KB) and human breast cancer (BC) cell lines. We have therefore investigated this extract for its active constituents and have identified three new depsidones (1- 3), of which one exhibited weak cytotoxic activity. Depsidones have been isolated commonly from various lichens. 4-8 However, many depsidones are constituents of non-lichen sources, for example, auranticins from the mangrove fungus Preussia aurantica, 9 emegui- sins from the ascomycete Emericella unguis, 10 and garcidepsidones from the leaves of Garcinia spp. 11,12 The present finding represents the first example of depsidones being isolated from an endophytic fungus. Compound 1 revealed a molecular formula of C 23 H 22 O 6 by HRMS, showing a protonated molecular ion peak at m/z 395.1497 [M + H] + . Analysis of the 13 C NMR and DEPT spectra established 23 carbons in the molecule, consisting of five methyls, five methines, and 13 quaternary carbons. The proton at δ H 10.27 on the carbon at δ C 194.1 together with a strong absorption at ν max 1649 cm -1 indicated an aldehyde group. The aldehyde correlated in the HMBC spectrum to oxygen-bearing carbons at δ C 165.2 (C-3) and 110.5 (C-4), while a chelated hydroxyl proton at δ H 12.16 correlated to C-2, C-3, and C-4. The presence of a 1-methylprop-1-enyl moiety was revealed by the resonances of a methine at δ H 5.68, which exhibited coupling constants of 6.85 and 1.26 Hz, and of two methyls at δ H 1.80 (δ C 14.4) and 1.96 (δ C 18.0) ppm, respectively. This methine proton also correlated to C-1 and C-3′′ in the HMBC spectrum. The aromatic methine at δ H 6.70 (2-H) attached to the carbon at δ C 115.0 (C-2) correlated in the HMBC spectrum with C-1 and C-3. The above information suggested the partial structure A. Likewise, the methine at δ H 5.51, which coupled to two methyls at δ H 1.80 (δ C 13.8) and 2.04 (δ C 18.1), with coupling constants of 6.85 and 1.40 Hz, respectively, indicated the presence of another methylpropenyl unit in the molecule. The HMBC spectrum showed correlations from H-13 to C-9, C-9a, and C-8; from H-7 to C-8, C-6, and C-5a; from H-2′ to C-3′, C-4′, and C-6; from H-3′ to C-2′ and C-1′; and from H-4′ to C-6, C-1′, and C-2′. Three low-field resonances at δ C 142.3 (C-5a), 151.5 (C-8), and 143.4 (C-9a) suggested that these three carbons are attached to oxygen atoms, and hence, subunit B was inferred. The remaining carbon at δ C 166.0 (C-11) indicated a carbonyl ester due to the observation of a strong absorption at ν max 1721 cm -1 and could be adjacent to C-11a. * Corresponding author. Tel: +66-25646700, ext. 3559. Fax: +66- 25646632. E-mail: pattamap@biotec.or.th. 1361 J. Nat. Prod. 2006, 69, 1361-1363 10.1021/np060190c CCC: $33.50 © 2006 American Chemical Society and American Society of Pharmacognosy Published on Web 08/26/2006