Desoxaphomin, das erste [13]Cytochalasan, ein möglicher biogenetischer Vorläufer der 24‐Oxa‐[14]cytochalasane

From cultures of a Phoma species (strain S 298) the hitherto unknown metabolite deoxaphomine has been isolated. On the basis of the spectral data, structure 1 of the (7 S , 16 R , 20 R )‐7,20‐dihydroxy‐16‐methyl‐10‐phenyl‐[13]cytochalasa‐6(12),13 t ,21 t ‐triene‐1,23‐dione is assigned to deoxaphomine. This structure is confirmed by the chemical degradation of 1 , yielding the products 4 and 6 which are identical with derivatives of phomine ( 2 )((7 S ,16 R ,20 R )‐7,20‐dihydroxy‐16‐methyl‐10‐phenyl‐24‐oxa‐[14]cytochalasa‐6(12), 13 t ,21 t ‐triene‐1,23‐dione) and cytohalasin D ( 8 ) ((7 S ,16 S ,18 R ,21 R )‐21‐acetoxy‐7,18‐dihydroxy‐16,18‐dimethyl‐10‐phenyl‐[11]sytochalasa‐6(12),13 t ,19 t ‐triene‐1,17‐dione). Deoxaphomine ( 1 ) is a potential biogenetic precursor of the 24‐oxa‐[14]cytochalasans. Preliminary results of the biological activity of deoxaphomine are reported.