N-Hydroxyamino Acid Residues as Fragments of Natural Products

Free N-hydroxyamino acids (1) or (2) have never been isolated from living organisms, probably because of their instability. As already mentioned, N-hydroxyamino acid residues occur only as fragments of many natural products containing the N-hydroxyamide bond. The isolation of free N -hydroxy-L-arginine from the fermentation medium of Bacillus cereus (6, 7) may be considered as an exception however, this compound contains an N-hydroxyguanidine rather than an N-hydroxyamine group. 

However it is becoming increasingly difficult to assign naturally-occurring hydroxamic acids unequivocally to such classes as antibiotics, growth factors, tumor inhibitors, cell division factors, pigments and siderophores as the distinctions between there activity classes are becoming less clear. 

Synthetic methods and syntheses of individual compounds are described in parts VIII and IX. 

N-Hydroxy-amino acid Natural product Isolated from Ref. 

N -Hydroxy-2,3-diaminopropionic acid alanosine Streptomyces alanosinicum 73), 74) 

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II. N-Hydroxyamino Acid Residues as Fragments of Natural Products. 206... 

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