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.