The novel hybrid antitumor compound premithramycinone H provides indirect evidence for a tricyclic intermediate of the biosynthesis of the aureolic acid antibiotic mithramycin - Lombó, F; Künzel, E; Prado, L; Braña, A F; Bindseil, K U; Frevert, J; Bearden, D; Méndez, C; Salas, J A; Rohr, J (Angew Chem Int Ed Engl, 2000)