Metabolites of the fungus Arthropsistruncata

Abstract

. 70, 1338 (1992). The structures of 12 new polyketide metabolites produced in liquid cultures of the fungus Arthropsis truncata have been determined by a combination of chemical and spectroscopic methods. Four of these metabolites possess an unusual 2-oxaspiro[4.5]decane skeleton, and the structure assigned to one of these metabolites 20 has been confirmed by an X-ray crystallographic study of the dibenzoyl derivative 21. The absolute stereochemistry of these compounds has been predicted by application of the Harada-Nakanishi dibenzoate rule to arthropsolide D tribenzoate (32). [Traduit par la rCdaction]

Biosynthesis and biogenetic interrelationships of metabolites of the fungus Arthropsistruncata

“…Fractions of 7 mL were eluted from the column using dichloromethane-methanol (10: I) to give fractions containing ar- water (50:50), 2 mL min-I) to give arthropsadiol A (19 mg), which crystallized on standing; 'H nmr identical with that reported previously (1). Acetylation gave arthropsadiol A diacetate (6); 'H nmr identical with that reported previously ( 1 ).…”

“…Arthropsis tr-utzcnta was grown as before (1) in liquid shake culture on a modified malt extract medium and was periodically supplemented with injections of a sterile solution of sodium [lL1'~]acetate. Chromatography of the ethyl acetate extract of the culture broth gave mainly arthropsadiol A (1) and lesser amounts of cycloarthropsone (2), and arthropsatriols C (3) and D (4).…”

“…The two spectra were recorded successively using identical nmr instrument parameters and similar concentrations of arthropsadiol A diacetate (6). Enhancements of the signals due to C2, C4, C6, C 8 , and C10 were observed ( merization of the a-hydroxy ketone moiety in 1 0 to the conjugated a'-hydroxy enone would give intermediate 11, which possesses the cyclohexenone unit of arthropsadiol A (1). Methylation of the terminal acetate unit at C11 by methionine, followed by oxidative decarboxylation of the enzymebound carboxyl group (C 12'), would form the three-carbon chain (C 10-C 12), and account for the lack of enhancement of the signal for C12 in the "C nmr spectrum of arthropsadiol A diacetate (6).…”

“…In the 2D-INADEQUATE spectra of 6 the signal of C4 is correlated not only to the signal of C3 but also to C5 and C9. This suggests that a significant number of molecules of arthropsadiol A (1) have multiple incorporation of sodium [1,[2][3][4][5][6][7][8][9][10][11][12][13] Cz]acetate at C3-C4, C5-C6, and C9-C10. Assuming that Jcc between C4 and C9 is approximately 35-40 Hz, then incorporation of sodium [I ,2-13~,]acetate at C3-C4, C5-C6, and C9-C10 would result in a ddd of satellite peaks due to coupling of C4 to C3, C5, and C9.…”

“…In the preceding paper we described the isolation and structure determination of 12 new polyketide metabolites produced in liquid cultures of the fungus Arthropsis trurzcnta (1). As a continuation of our investigations of the chemistry of this fungus we have examined the incorporation of sodium [ l -I3c]acetate and sodium [ 1 , 2 -"~~] a c e t a t e by the fungus with the aim of elucidating the biosynthesis and biogenetic interrelationship of these interesting polyketide metabolites.…”