Quanolirones I and II, two new human cytomegalovirus protease inhibitors produced by Streptomyces sp. WC76535.

Two new naphthacenequinone glycosides, quanolirones I (1) and II (2) were isolated, together with the known compound galtamycin from the fermentation broth of Streptomyces sp. WC76535. The structures 1 and 2 were established by analysis of their spectroscopic data and by comparison of their data to those of galtamycin. Compounds 1, 2, and galtamycin showed inhibitory activity against HCMV protease with IC 50 values of 14, 35, and 52 μM, respectively.