A Convergent, Enantioselective Total Synthesis of Hapalosin: A Drug with Multidrug-Resistance Reversing Activity

摘要

Hapalosin (1), a novel cyclodepsipeptide isolated recently from the blue-green alga Hapalosiphon welwitschii, has shown important multidrug-resistance reversing activity. The term multidrug-resistance (MDR), is defined us ihe ability of tumor cells exposed to one drug to develop eross resistance to seemingly unrelated drugs. This phenomenon is apparently caused by an overexpression of P-glycoprotein, a 170-200 kDa transmembrane, protein that acts as an ATP-dependent drug efflux pump. As a consequence, chemotherap) very often becomes ineffective.