Topostatin, a novel inhibitor of topoisomerases I and II produced by Thermomonospora alba strain No. 1520. II. Physico-chemical properties and structure elucidation

Topostatin is a new topoisomerase inhibitor isolated from the culture filtrate of Thermomonospora alba strain No. 1520. The inhibitor inhibits topoisomerases I and II, and it has neither ability to stabilize the cleavable complex nor ability to intercalate into DNA strands. The molecular formula of topostatin was determined as C 36 H 58 N 4 O 11 S based on the FAB-MS analyses, and the structure was elucidated to be a novel 14-membered ring containing peptide and terpenoid by various NMR spectroscopies.