Synthesis and biological evaluation of new amino acids structurally related to the antitumor agent acivicin.

A set of racemic conformationally constrained analogues of the antitumor antibiotic acivicin (+)-1 has been prepared through a strategy based on 1,3-dipolar cycloaddition of bromonitrile oxide to suitable dipolarophiles. The bromo analogue (2) of acivicin was also synthesized and tested as a reference compound, together with its stereoisomer 3. The antitumor properties of novel amino acids 4-7 were evaluated in vitro against human tumor cell lines. Their efficacy to inhibit glutamate synthase (GltS) from Azospirillum brasilense was also assayed. None of the studied compounds, but 2, showed significant activity.