Naphthoquinone–Oxindole Alkaloids, Coprisidins A and B, from a Gut-Associated Bacterium in the Dung Beetle, Copris tripartitus

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.