Trijugin- and mexicanolide-type limonoids from the fruits of Heynea trijuga that reverse multidrug resistance in MCF-7/DOX cells

Eleven previously undescribed limonoids, trichisins A-K, including eight structural analogues A-H of trijugin and three H-J mexicanolide derivatives, together with two known mexicanolide derivatives were isolated from the fruits of Heynea trijuga Roxb. ex Sims. The structure determination was based on extensive physical data analyses (NMR, MS), and their basic skeletons and the absolute configurations of trichisins A, B, E, K and trichiconnarone A were assigned via X-ray crystallographic analysis (Cu K alpha radiation). The hemiketal motifs in trijugins A, B, and E-G are rare in limonoids. Bioactivity screenings suggested that the trijugin H and mexicanolide-type trichiconnarones A and B limonoids were effective in reversing resistance in MCF-7/DOX cells at a nontoxic concentration of 50 mu M with IC50 values of 12.45, 10.86, and 14.96 mu M, respectively. (C) 2018 Elsevier Ltd. All rights reserved.