The synthesis and evaluation of a solution phase indexed combinatorial library of non-natural polyenes for reversal of p-glycoprotein mediated multidrug resistance

A combinatorial library of polyenes, based on (-)-stipiamide, has been cons tructed and evaluated for the discovery of new multidrug resistance reversa l agents. A palladium coupling was used to react each individual vinyl iodi de with a mixture of the seven acetylenes at near 1:1 stoichiometry. The co upling was also used to react each individual acetylene with the mixture of six vinyl iodides to create 13 pools indexed in two dimensions for a total of 42 compounds. Individual compounds were detected at equimolar concentra tion. The vinyl iodides, made initially using a crotylborane addition to ge nerate the anti1,2-hydroxylmethyl products, were now made using a more effi cient norephedrine propionate boron enolate aldol reaction. The indexed app roach, ideally suited for cellular assays that involve membrane-bound targe ts, allowed for the rapid identification of reversal agents using assays wi th drug-resistant human breast cancer MCF7-adrR cells. Intersections of pot ent pools identified new compounds with promising activity. Aryl dimension pools showed R = ph and naphthyl as the most potent. The acetylene dimensio n had R' = phenylalaninol and alaninol as the most potent. Isolated individ ual compounds, both active and nonpotent, were assayed to confirm the libra ry results. The most potent new compound was 4ek (R = naphthyl, R' = phenyl aninol) at 1.45 mu M. Other nonnatural individual naphthyl-amide compounds showed potent MDR reversal including the morpholino-amide 4ej (1.69 mu M). Synergistic activities attributed to the two ends of the molecule were also identified. Direct interaction with Pgp was established by ATPase and phot oaffinity displacement assays. The results indicate that both ends of the p olyene reversal agent are involved in Pgp interaction and can be further mo dified for increased potency.