New antitumor substances, BE-12406A and BE-12406B, produced by a streptomycete. II. Structure determination.

The structure of BE-12406A and BE-12406B, which were isolated from the culture broth of a streptomycete as antitumor substances, were determined by means of spectral analyses and chemical studies. The structure of BE-12406A is 1-hydroxy-10-methoxy-8-methyl-12-alpha- L-rhamnopyranosyloxy-6H-benzo[d]naphtho[1,2-b]pyran-6-one, and that of BE-12406B is 1,10-dihydroxy-8-methyl-12-alpha-L-rhamnopyranosyloxy-6H- benzo[d]naphtho[1,2-b]pyran-6-one.