New citrinin derivatives isolated from Penicillium citrinum

Three new coupling compounds derived from citrinin (9) and 2,3,4-trimethyl-5,7-dihydroxy-2,3-dihydrobenzofuran (8) – penicitrinone A (1), penicitrinol A (2) and penicitrinone B (3) – and a new citrinin derivative – decarboxydihydrocitrinin (4) – were isolated along with 3-methoxy-1-methyl-4(1H)-quinolone (5), quinolactacin A2 (6), dihydrocitrinone (7), 2,3,4-trimethyl-5,7-dihydroxy-2,3-dihydrobenzofuran (8), citrinin (9), quinocitrinin A or B (10), and decarboxydihydrocitrinone (11) from the extract of Penicillium citrinum IFM 53298. The relative structures of compounds 1–4 were confirmed on the basis of spectroscopic investigations and chemical correlations. Citrinin (9) and quinolactacin A2 (6) both showed antifungal activity.