Retymicin, Galtamycin B, Saquayamycin Z and Ribofuranosyllumichrome, Novel Secondary Metabolites from Micromonospora sp. Tü 6368: I. Taxonomy, Fermentation, Isolation and Biological Activities

A new xanthone compound named retymicin ( 1 ) was isolated together with galtamycin B ( 2 ) and saquayamycin Z ( 3 ), new members of the galtamycin and saquayamycin families, respectively, and the new lumichrome derivative 1-(α-ribofuranosyl)-lumichrome ( 4 ) from Micromonospora strain Tü 6368, isolated from a soil sample collected in Romania. Retymicin, galtamycin B and saquayamycin Z show cytostatic effects to various human tumor cell lines whereas saquayamycin Z is also active against Gram-positive bacteria.