Isolation of propioxatin A from Actinosynnema sp. SI-23 during a screening for Serratia piscatorum metalloproteinase inhibitors.

An inhibitor of Serratia metalloproteinase was found in the cultured broth of strain SI-23, which was identified to be Actinosynnema sp. The inhibitor had a potent inhibitory effect on Serratia metalloproteinase and a weak effect on thermolysin, but no effect on other groups of proteinases. The structure of the inhibitor was deduced to be propioxatin A, reported as an enkephalinase B inhibitor.