Limonoids from Aphanamixis polystachya Leaves and Their Interaction with Hsp90.

A phytochemical study of n-hexane, CHCl3, and CHCl3-MeOH extracts of Aphanamixis polystachya leaves led to the isolation of 10 compounds. Five of them turned out to be new natural compounds, including two mexicanolide-type (1, 2: ) and three polyoxyphragmalin-type (3: -5: ) limonoids, together with two known andirobin-type limonoids (6, 7: ) and three phenolic derivatives. The structures of the new compounds were established on the basis of spectroscopic methods to be 8-hydro-14,15-en-cabralin (1: ), 3-deacetyl-8-hydro-cabralin-14,15-en-3-one (2: ), 20,22-dihydroxy-21,23-dimethoxytetrahydrofuran khayanolide A (3: ), 1-deacetyl-3-dehydroxy-3-oxokhaysenelide E (4: ), and meliaphanamixin A (5: ). All compounds were isolated for the first time from this species. The ability of the isolated limonoids to interact with the molecular chaperone Hsp90 was tested. Compounds 6: and 7: were the most active.