Citromycetins and Bilains A–C: New Aromatic Polyketides and Diketopiperazines from Australian Marine-Derived and Terrestrial Penicillium spp.

Robert J. Capon, Michael Stewart, Ranjala Ratnayake, Ernest Lacey, and Jennifer H. Gill

Journal of Natural Products, 2007, 70, 1746-1752.

Publication Date: October 25, 2007


Chemical analysis of an Australian marine-derived isolate of Penicillium bilaii, collected from the Huon estuary, Port Huon, Tasmania, yielded the known fungal aromatic polyketides citromycetin (1) and citromycin (2) together with two dihydro analogues, (–)-2,3-dihydrocitromycetin (3) and (–)-2,3-dihydrocitromycin (4). An Australian terrestrial isolate of Penicillium striatisporum collected near Shalvey, New South Wales, also yielded citromycetin (1), citromycin (2), and the new dihydro analogue (–)-2,3-dihydrocitromycetin (3), together with fulvic acid (5), anhydrofulvic acid (6), and a selection of new methoxylated analogues, 12-methoxycitromycetin (7), 12-methoxycitromycin (8), (–)-12-methoxy-2,3-dihydrocitromycetin (9), and 12-methoxyanhydrofulvic acid (10). P. bilaii also yielded the rare siderophore pistillarin (11), the known diketopiperazines cyclo-(lPhelPro) (12), cyclo-(l-Pro-l-Tyr) (13), cyclo-(l-Pro-l-Val) (14), and cis-bis(methylthio)silvatin (15), and three new diketopiperazines, bilains A–C (1618). The structures for the Penicillium metabolites 118 were assigned by a combination of detailed spectroscopic analysis, including correlation with relevant literature data, chemical derivatization, degradation, and biosynthetic considerations. The citromycin polyketides 2 and 4 and the diketopiperazine 15 were weakly cytotoxic.

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fulvic acid




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