부산대학교 도서관

In the course of our search for new antitumor agents from microorganisms, the fungus Acremonium sp. KY4917 was found to produce novel compounds. Two novel compounds, UCS1025A (1) and B (2), were isolated from the culture broth by chromatographic methods. Molecular formulae of 1 and 2 were determined to be C_<20>H_<25>NO_5 and C_<20>H_<25>NO_6 from HRFAB-MS data, respectively. Structures of 1 and 2 were elucidated on the basis of spectroscopic methods, mainly by detailed analyses of their NMR spectra. Absolute stereochemistry of 1 was established by an X-ray crystallographic analysis of the 3'-bromo derivative 3'. As a result of spectroscopic analyses and chemical transformations of 1, the unique chemical equilibrium of 1 was found out. Three tautomeric isomers of 1 have been identified to be ketone 1a in CDCl_3 by NMR analyses, enol 1b by an X-ray crystallographic analysis, and enedione 1c in an aqueous buffered solution, respectively. UCS1025A (1) exhibited antimicrobial activity against Gram-positive bacteria, Staphylococcus anreus, Bacillus subtilis and Enterococcus hirae, and Gram-negative bacterium, Proteus vulgaris with the MIC values ranged from 1.3μg/mL to 5.2 μg/mL, and antiproliferative activity against human tumor cell lines (A431 and MCF-7) with the IC_<50> values 55 μM and 21 μM, respectively. In contrast, UCS1025B (2) showed weak antimicrobial and no antiproliferative activity.