Isolation of a novel paxilline analog pyrapaxilline from fungus that inhibits LPS-induced NO production.

We have screened microbial culture filtrates for nitrogen monoxide (NO) production inhibitors using mouse macrophage cell line RAW264.7. As a result, paxilline, 21-isopentenylpaxilline and a novel analog of paxilline have been isolated from the culture filtrate of fungus Eupenicillium shearii. The novel analog possesses an additional dihydropyran ring, and was named as pyrapaxilline. This compound inhibited the NO production with lower toxicity than paxilline.