Synthesis, Antiproliferative Activity, and Effect on Carcinoma A549 Cell Microtubules of New Tubuloclustin Analogs

Abstract

Combretastatin analogs of the antitumor agent tubuloclustin {N-[7-(adamant-2-yloxy)-7-oxoheptanoyl]-Ndeacetylcolchicine} were prepared via esterification of combretastatin by monoesters of pimelic or adipic acid with adamantan-2-ol or (adamantan-1-yl)methanol. These conjugates were stable and cytotoxic to human lung carcinoma A549 cells (EC₅₀ ≈ 50 – 70 nM) and caused depolymerization of microtubules and slight clustering of tubulin. Tubuloclustin analogs with shortened linkers were prepared via amidation by N-deacetylcolchicine of monoesters of adipic or succinic acids with adamantan-1-ol or (adamantan-1-yl)methanol. The conjugate N-[6-(adamantyl)-6-oxohexanoyl]-N-deacetylcolchicine was more active (EC₅₀ ≈ 4 nM) than tubuloclustin and promoted strong tubulin clusterization. All compounds induced apoptosis of A549 cells. Tests in vivo of N-[6-(adamantyl)-6-oxoheaxnoyl]-N-deacetylcolchicine on carcinoma A549 experimental models were concluded to be promising.