Bioassay-Guided Purification of Cytotoxic Isoflavonoids and Sesquiterpenoids of <i>Streptomyces coelicolor</i> Isolated from Marine Sponge <i>Axinella sinoxea</i>, and <i>In Silico</i> Target Prediction.

Among 13 different bacterial isolates, four <i>Streptomyces</i> strains were cytotoxic thus selected for further biological and chemical analyses. The WAK 9 strain was different from other strains based on its HPLC. Since WAK 9 was molecularly separated from the others and had the highest cytotoxic properties among tested strains and for the presence of the rare terpenoids (<b>4</b>-<b>8</b>), and the butenolide (<b>3</b>) this strain may be interesting for further investigations. <i>In silico</i> investigation revealed the possible target of <b>5</b> and <b>6</b> and their activities in the presence of Hsp90-beta, which is an essential target in the tumor cells.