Chromones from the Endophytic Fungus Pestalotiopsis sp. Isolated from the Chinese Mangrove Plant Rhizophora mucronata Jing Xu, †,‡ Julia Kjer, † Jandirk Sendker, † Victor Wray, § Huashi Guan, ‡ RuAngelie Edrada, | Wenhan Lin, 3 Jun Wu,* ,⊥ and Peter Proksch* ,† Institut fu ¨r Pharmazeutische Biologie and Biotechnologie, Heinrich-Heine-UniVersita ¨t, Geb. 26.23, UniVersita ¨tsstrasse 1, D-40225 Du ¨sseldorf, Germany, Key Laboratory of Marine Drugs, Chinese Ministry of Education/Institute of Marine Drugs and Food, Ocean UniVersity of China, Qingdao 266003, People’s Republic of China, Department of Structural Biology, Helmholtz Centre for Infection Research, Inhoffenstrasse 7, D-38124 Braunschweig, Germany, Key Laboratory of Marine Bio-resources Sustainable Utilization, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, People’s Republic of China, Strathclyde Institute of Pharmacy and Biomedical Science, UniVersity of Strathclyde, The John Arbuthnott Building, 27 Taylor Street, Glasgow G4 0NR, U.K., and National Research Laboratories of Natural and Biomimetic Drugs, Peking UniVersity, Health Science Center, Beijing 100083, People’s Republic of China ReceiVed NoVember 25, 2008 Six new chromones, named pestalotiopsones A-F(1-6), and the known derivative 7-hydroxy-2-(2-hydroxypropyl)- 5-methylchromone (7) were obtained from the mycelia and culture filtrate of the mangrove endophytic fungus Pestalotiopsis sp., which was isolated from leaves of the Chinese Mangrove plant Rhizophora mucronata. Their structures were elucidated on the basis of spectroscopic data. Pestalotiopsones A-F are chromones having both an alkyl side chain substituted at C-2 and a free or substituted carboxyl group at C-5. Compound 6 exhibited moderate cytotoxicity against the murine cancer cell line L5178Y, whereas the other investigated compounds proved to be inactive. Fungi of the genus Pestalotiopsis are known as endophytes of tropical higher plants. 1-3 Previous chemical investigations of marine endophytes afforded a variety of bioactive natural products such as polyketides and terpenoids. 4-12 During our ongoing search for new bioactive metabolites from plant endophytes, 13,14 six new chromones, named pestalotiopsones A-F(1-6), in addition to 7-hydroxy-2-(2-hydroxypropyl)-5-methylchromone (7), a previously known metabolite from medicinal rhubarb Rhei Rhizoma (Rheum officinale), 15 were obtained from endophytic fungus Pestalotiopsis sp., which had been isolated from leaves of the Chinese Mangrove plant Rhizophora mucronata and cultured on solid rice medium. Their structures were elucidated on the basis of spectroscopic data. Pestalotiopsones A-F are chromones featuring both an alkyl side chain substituted at C-2 and a free or substituted carboxyl group at C-5. This is the first report of chromones from the genus Pestalotiopsis. Details of the isolation, structure elucidation, and biological activity of these chromones are reported herein. Results and Discussion The mycelia and culture medium of the fungus Pestalotiopsis sp. were extracted with ethyl acetate. The resulting ethyl acetate extract was dried and chromatographed on silica gel and Sephadex LH-20 followed by preparative HPLC to yield pestalotiopsones A-F(1-6) and 7-hydroxy-2-(2-hydroxypropyl)-5-methylchromone (7). 15 Pesta- lotiopsones A-F were identified as 5-carbomethoxymethyl-2-heptyl- 7-hydroxychromone (1), 5-carboethoxymethyl-2-heptyl-7-hydroxy- chromone (2), 5-carboxymethyl-2-heptyl-7-hydroxychromone (3), 5- carbomethoxymethyl-7-hydroxy-2-(6-hydroxyheptyl)chromone (4), 5-carboethoxymethyl-7-hydroxy-2-(6-hydroxyheptyl)chromone (5), and 5-carbomethoxymethyl-7-hydroxy-2-pentylchromone (6). Pestalotiopsone A (1), a colorless amorphous solid, has the molecular formula C 19 H 24 O 5 established by HR-ESIMS (m/z 333.1697). Consequently, 1 had eight degrees of unsaturation. The 1 H and 13 C NMR data of 1 (Tables 1 and 2) indicated that six of the eight units of unsaturation come from four carbon-carbon double bonds and two carbonyls. Therefore, the other two units of unsaturation come from two rings. The UV absorption maxima at 219, 243, and 250 nm indicated that 1 should be a chromone derivative. DEPT experiments showed that the compound had two methyl groups, including a methoxy and a terminal alkyl methyl, seven methylenes, three olefinic methines, and seven quaternary carbons, including two carbonyls. The 1 H and 13 C NMR data of 1 (Tables 1 and 2) and its 1 H- 1 H COSY and HSQC spectra showed the presence of a methoxy substituent (δ H 3.60, s, δ C 52.6, CH 3 ), an olefinic methine (δ H 5.92, s, δ C 111.9, CH-3), a methylene connecting a phenyl ring and a carboxyl group (δ H 4.12, s, δ C 41.9, CH 2 -1′′), two meta-coupled aromatic methines [δ H 6.75 (d, J ) 2.2 Hz), δ C 119.6, CH-6; δ H 6.81 (d, J ) 2.2 Hz), δ C 103.8, * To whom correspondence should be addressed. (J.W.) Tel: ++86-20- 8445-8442. Fax: ++86-20-8445-1672. E-mail: wwujun2003@yahoo.com. (P.P.) Tel: ++49-211-81-14163. Fax: ++49-211-81-11923. E-mail: proksch@ uni-duesseldorf.de. † Heinrich-Heine-Universita ¨t. ‡ Ocean University of China. § Helmholtz Centre for Infection Research. ⊥ Chinese Academy of Sciences. | University of Strathclyde. 3 Peking University. J. Nat. Prod. 2009, 72, 662–665 662 10.1021/np800748u CCC: $40.75  2009 American Chemical Society and American Society of Pharmacognosy Published on Web 03/09/2009