Synthesis and evaluation of backbone/amide-modified analogs of leualacin

Leualacin (1), a cyclic depsi-pentapeptide, and its backbone/amide-modified analogs 2–4 were synthesized. Amide analogue 3 exhibited stronger vasodilatory effects. It also strongly inhibited collagen- and arachidonic acid (AA)-induced platelet aggregations with IC50s of 0.6 μM and 2.0 μM, respectively.