Herquline B, a new platelet aggregation inhibitor produced by Penicillium herquei Fg-372.

A new herquline analog, herquline B was isolated from the culture broth of Penicillium herquei Fg-372. Herquline B contains one piperazine and two cyclohexenones. The pyrrolidine ring of herquline A was cleaved to yield herquline B. The IC50 value of herquline B against platelet aggregation induced by ADP and platelet-activating factor were 1.6 and 5.0 mu M, respectively.