Derived from Tryptophan and Proline

The indoles 38 and 39 give a negative Ehrlich color reaction, indicating substitution at position 2 and 3 of the indole ring. The mass spectra of these compounds show a base peak at m/z 198, C,4H,6N, which originated via cleavage of the C-8-C-9 bond. On the basis of spectral data, 38 seemed to be identical to deoxybrevianamide E which had been obtained by Birch and Wright (72) upon treatment of brevianamide E (44) with Zn and AcOH. Later, 38 and 44 were 

Austamide (40), C21H21N3O3, [a] ° +152°, is an amorphous yellow compound with an intense green fluorescence and is toxic in 1-day-old ducklings. It shows UV absorptions at 234, 256, 268(sh), 282, and 392 nm, among which the absorptions at 234, 256, and 392 nm are typical of the f-indoxyl chromophore which occurs in brevianamide A (45) and other i[f-indoxyl alkaloids (76). The UV absorptions at 268 and 282 nm are absent in tetrahydroaustamide, so these are associated with the cyclic enamide chromophore. 

The structure of 12,13-dihydro-12-hydroxyaustamide (43), mp 164-165°C, was determined by comparison with the spectral data of austamide. The lack of a proton at C-12 ( 84.1) strongly supports the presence of an OH group at C-12. The mass spectrum of 43 shows a strong peak at m/z 363, C2 H2,N302, due to loss of H2O and subsequent fragmentation, virtually identical to that of austamide, with the base peak at m/z 218. 

Another group of tryptophan-proline-derived fungal metabolites having a 3,3-dimethylallyl (normal isopentenyl) unit at position 2 of the indole ring is the 

During investigation of toxigenic food-borne fungi, Yamazaki and co-workers 

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