Four new carvotanacetone derivatives from Sphaeranthus ukambensis, inhibitors of the ubiquitin-proteasome pathway.

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.

Meroterpenes from Dichrostachys cinerea inhibit protein farnesyl transferase activity.

Eighteen new meroterpene derivatives, dichrostachines A-R (1-18), have been isolated from the root and stem barks of Dichrostachys cinerea, and their structures determined by spectroscopic means and molecular modeling. From a biosynthetic standpoint these compounds arise from a Diels-Alder reaction between a labdane diene of the raimonol type and a flavonoid B-ring-derived quinone. The hypothesis was tested by the partial synthesis of similar compounds by simply mixing methyl communate and a synthetic flavonoid quinone.

Alisiaquinones and alisiaquinol, dual inhibitors of Plasmodium falciparum enzyme targets from a New Caledonian deep water sponge.

Four new meroterpenes, alisiaquinones A-C (1-3) and alisiaquinol (4), were isolated from a New Caledonian deep water sponge. Their structures and relative stereochemistry were elucidated by spectroscopic data analysis. They are related to xestoquinone, but showed unusual substitution on a tetrahydrofuran junction.