Xanthoquinodin B3, a New Anticoccidial Agent Produced by Humicola sp. FO-888.

Xanthoquinodin B3, a new component of anticoccidial xanthoquinodins, which was detected in the culture broth of Humicola sp. FO-888, was isolated by heat treatment of the xanthoquinodins complex. Structural elucidation indicated that Xanthoquinodin B3 has the same heterodimer of xanthone- and anthraquinone-derived monomers as other xanthoquinodins. Schizont formation of monensin-resistant Eimeria tenella in BHK-21 cells was inhibited by Xanthoquinodin B3 at concentrations greater than 0.035μM.