Bioactive meroterpenoids and alkaloids from the fungus Eurotium chevalieri Kwanjai Kanokmedhakul a , Somdej Kanokmedhakul a, * , Ruchiruttikorn Suwannatrai a , Kasem Soytong b , Samran Prabpai c, d , Palangpon Kongsaeree c, d a Natural Products Research Unit, Department of Chemistry, and Center for Innovation in Chemistry, Faculty of Science, Khon Kaen University, Khon Kaen 40002, Thailand b Department of Plant Pest Management, Faculty of Agricultural Technology, King Mongkut’s Institute of Technology Ladkrabang, Ladkrabang, Bangkok 10520, Thailand c Department of Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand d Center for Excellence in Protein Structure and Function, Faculty of Science, Mahidol University, Bangkok 10400, Thailand article info Article history: Received 1 March 2011 Received in revised form 28 April 2011 Accepted 16 May 2011 Available online 25 May 2011 Keywords: Chevalones Aszonapyrone Eurochevalierine Meroterpenoids Antimalarial Antimycobacterial Anticancer Eurotium chevalieri abstract Five new meroterpenoids, chevalones AeD(1e4), aszonapyrone B (8), and a new sequiterpene alkaloid, eurochevalierine (5), together with four known compounds, sequiterpene (6), terpenoid pyrrolo- benzoxazine named CJ-12662 (7), meroterpenoid, aszonapyrone A (9), and ergosterol were isolated from the fungus Eurotium chevalieri. The structures were established on the basis of spectroscopic evidence. The configurations of 1 and 5 were determined by X-ray analysis. The biosynthetic pathway of 1e3, 8, and 9 were proposed. Chemical transformation of aszonapyrone A (9) was also studied. Compounds 4, 5, and 7 exhibited antimalarial activity against Plasmodium falciparum, while 3, 5, and 7 showed anti- mycobacterial activity against Mycobacterium tuberculosis. In addition, compounds 2e7 showed cyto- toxicity against cancer cell lines. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Eurotium chevalieri Mangin imperfect stage of Aspergillus che- valieri (Mangin) Thom and Church belongs to Phylum Ascomycota. 1 Colonies reach 7.00 cm diameter on potato dextrose agar in 10 days at a temperature of 30  C, with gray in the central areas and asco- mata abundant on medium in a continuous yellow layer. There are eight ascospores per ascus, ascospores lens-shaped, roughened, and with equatorial crests 0.8 mm apart, 4.5e4.83.2e3.4 mm. These characteristics are similar to those reported by Blaser (1976). 2 Previous investigation on secondary metabolites from the fungus genus Eurotium species 3e10 including E. chevalieri 1113 resulted in the isolation of numerous types of compounds, such as alkaloids, indole derivatives, phenolic compounds, anthraquinones, and diketopiperazines. In our continuing search for bioactive constitu- ents from fungi, we noted that hexane, EtOAc, and MeOH extracts of the fungus E. chevalieri showed antimycobacterial activity against Mycobacterium tuberculosis with MIC values of 12.5, 3.13, and 6.26 mg/mL, respectively. In addition, the EtOAc extract of the strain also exhibited cytotoxicity against cancer cell lines, NCI-H187 and KB. Investigation of the extracts of dried fungal biomass of E. che- valieri cultured in two different periods of time have led to the isolation of six new compounds (1e5, and 8) and four known compounds, 6, 7 , 9, and ergosterol (Fig. 1). We report herein the isolation, characterization, chemical transformation of 9 and pro- posed biosynthesis of 1e3, 8, and 9, as well as bioactivity of these compounds. 2. Results and discussion The fungus E. chevalieri was stationary cultured at 30  C for 40 days in potato dextrose broth (PDB). The hexane, EtOAc, and MeOH extracts from the air-dried fungal biomass was separated on silica gel column chromatography and preparative TLC to yield com- pounds 1e 7 . The PDB sample cultured for 30 days produced three compounds, 8, 9, and ergosterol. Structures of the known com- pounds were identified by physical and spectroscopic data mea- surements ( 1 H and 13 C NMR, 2D NMR, and MS) and by comparing the data obtained with published values, as diterpene (6), 14 ter- penoid pyrrolobenzoxazine (7), 14 and aszonapyrone A (9) [mp 240e242  C (lit., 15 242e244  C)]. Compound 1 was obtained as colorless crystals, and its molec- ular formula C 26 H 38 O 4, was deduced from HRMS m/z 437.2669 * Corresponding author. Tel.: þ66 43 202222x12243; fax: þ66 43 202373; e-mail address: somdej@kku.ac.th (S. Kanokmedhakul). Contents lists available at ScienceDirect Tetrahedron journal homepage: www.elsevier.com/locate/tet 0040-4020/$ e see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.tet.2011.05.066 Tetrahedron 67 (2011) 5461e5468