Four New Carvotanacetone Derivatives from Sphaeranthus ukambensis, Inhibitors of the Ubiquitin-Proteasome Pathway

Abstract

Six carvotanacetone derivatives (1–6), amongst which four new compounds (1–4), were isolated from the aerial parts of Sphaeranthus ukambensis Vatke & O. Hoffm. The structures of the molecules were elucidated by complementary spectroscopic methods, and their biological properties were investigated using human DLD-1 colon cancer cells engineered to stably express a 4 ubiquitin-luciferase (4 Ub-Luc) reporter protein. Five of the isolated carvotanacetone derivatives (2–6) were found to inhibit the proliferation of the colon cancer cells and interfere with the ubiquitin-proteasome pathway, with potencies in a micromolar range.

Supporting information available online at http://www.thieme-connect.de/ejournals/toc/plantamedica

Key words

carvotanacetone - Sphaeranthus ukambensis - Compositae - ubiquitin‐proteasome pathway - cancer

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