Isochromophilones I and II, novel inhibitors against gp120-CD4 binding produced by Penicillium multicolor FO-2338. I. Screening, taxonomy, fermentation, isolation and biological activity.

Isochromophilones I and II, the first novel gp120-CD4 binding inhibitors of microbial origin, were isolated from a cultured broth of a soil fungus designated as Penicillium multicolor FO-2338. These compounds were obtained as yellow powders from the cultured broth together with the known related compounds sclerotiorin, ochrephilone and rubrorotiorin. Isochromophilones I and II (C23H25O5Cl and C22H27O4Cl, respectively) have an azaphilone skeleton and a chlorine atom. Isochromophilones strongly inhibited gp120-CD4 binding (IC50: 6.6 and 3.9 microM, respectively), but the other related compounds did not. Isochromophilone II inhibited significantly HIV replication in peripheral human lymphocytes at 25 microM.