Pyrrolomycin group antibiotics inhibit substance P-induced release of myeloperoxidase from human polymorphonuclear leukocytes.

In order to search for microbial modulators of the activity of neuropeptide, we established a screen based on substance P (SP)-induced myeloperoxidase (MPO) release from human polymorphonuclear leukocytes (PMN). SP induced MPO release in a dose-dependent manner at concentrations ranging from 1 approximately 10 x 10(-4) M. In comparison at 1 x 10(-4) M, induction was also observed with SP derivatives but not with other neuropeptides such as neurokinin and enkephalin. Based on this, we searched for microbial inhibitors against SP-induced MPO release. An actinomycete metabolite designated HS3, which turned out to be identical with dioxapyrrolomycin or A1-R2081, and structurally related pyrrolomycins were found to inhibit SP-induced MPO release. In addition, these compounds inhibited the f-Met-Leu-Phe (FMLP)-induced MPO release from PMN. Pyrrolomycin derivatives with an N-methylated pyrrole ring showed, however, a selective inhibition of the SP-induced MPO release. This was in contrast to results with aseanostatin P5 which selectively inhibited FMLP-induced MPO release.