Occurrence in Microorganisms and Plants

Mycobacterium johnei12. Hadacidin (8) is produced by several Penicillia its antitumor activity has been related to its antagonism to aspartic acid in adenylate synthesis73. 

N-Oxygenated C=N functionalities also occur in plants. Thus, harman N-oxide (har-manine, 9) is the main alkaloid in all parts of Calligonium minimum14. The trunk bark of Aspidosperma nigricans contains the unstable olivacine N-oxide (10)74. Orellanine (11) has been isolated from the toadstool Cortinarius orellanus15. The substance is heat-stable and exerts considerable nephrotoxicity. 

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