Coprisidins A and B (1 and 2) were isolated from a gut -associated Streptomyces sp. in the dung beetle Copris tripartitus. Using a combination of spectroscopic techniques, the structures of the compounds were determined to be the first examples of natural naphthoquinone oxindole alkaloids. Coprisidin A was found to inhibit the action of Na+/K+-ATPase, and coprisidin B showed activity for the induction of NAD(P)H:quinone oxidoreductase 1.