Expression of the aranciamycin biosynthetic gene cluster in Streptomyces diastatochromogenes Tu6028 resulted in production of four novel compounds, aranciamycins E, F, G, and H with different decorations in the tetracyclic backbone. Two derivatives contain a D-amicetose moiety at C-7 (aranciamycins F and G), two are hydroxylated at position C-1 (aranciamycins E and G), and one is hydroxylated at C-13 (aranciamycin F). Analysis of the biological activities of the aranciamycins against two human tumor cell lines-MCF-7 and MATU-shows surprising impact of the hydroxyl group at position C-1 on activity. As aranciamycins E and G were the most active derivatives, hydroxylation of the C-1 appears to coincide with increased antitumor activity of aranciamycins.