We previously reported that the biological acti-vity of analogues of desmosdumotin B (1) was dramatically changed depending on the B-ring system. A naphthalene B-ring analogue 3 exerted potent in vitro activity against a diverse panel of human tumor cell lines with GI50 values of 0.8− 2.1 μM. In contrast, 1 analogues with a phenyl B-ring showed unique selective activity against P-glycoprotein (P-gp) overexpressing multidrug resistant cell line. ...
