Secondary metabolites characteristic of Penicillium citrinum, Penicillium steckii and related species

Two new carboxylic acids, tanzawaic acid E (1) and F (2) in addition to the unknown benzopyran 3,7-dimethyl-1,8-dihydroxy6-methoxy-isochroman (3), and the known mycotoxin 3,7-dimethyl-8-hydroxy-6-methoxyisochroman (4) were pr oduced by a marine-derived strain of Penicillium steckii isolated from an u nidentified tunicate. The carboxylic acids and the benzopyran were identifi ed on the basis of mass spectrometry, and one and two dimensional NMR spect roscopic techniques. The structures 1 and 2 resemble tanzawaic acid A-D, pr eviously isolated from Penicillium citrinum. Screening of isolates of speci es related to P. citrinum and P. steckii showed that P. citrinum (25 isolat es) consistently produced citrinin and tanzawaic acid A. P. steckii (18 iso lates) produced isochroman toxins (except 2) and tanzawaic acid E. P. sizov ae consistently produced tanzawaic acid A. P. corylophilum (10 isolates) pr oduced citreoisocoumarinol and P. sumatrense (15 isolates) always produced curvularin. (C) 2000 Elsevier Science Ltd. All rights reserved.