Isolation and characterization of minor analogues of silvestrol and other constituents from a large-scale re-collection of Aglaia foveolata

Abstract

Two new minor silvestrol analogues [2'''-episilvestrol (1) and 2''',5'''-diepisilvestrol (2)], together with a new 21-norbaccharane-type triterpene (3), two new 3,4-secodammarane triterpenes (4 and 5), and a new eudesmane sesquiterpene (6), as well as nine known compounds, were isolated from a large-scale re-collection of the CHCl(3)-soluble extract of the stem bark of Aglaia foveolata obtained in Kalimantan, Indonesia. The structures of the new compounds were established by interpretation of their spectroscopic data. All of the isolates were tested for cytotoxicity against HT-29 cells. The new silvestrol analogues, 1 and 2, were considerably less active as cytotoxic agents than silvestrol (7) and episilvestrol (5'''-episilvestrol) (8) against this cell line, showing the importance of the configuration at C-2''' in mediating such activity within this compound class. Several of the compounds isolated were also evaluated in a NF-κB (p65) inhibition assay.

Figure 1

Selected NOESY () correlations observed for 1.

Figure 2

Selected HMBC () and NOESY () correlations observed for 3.

Figure 3

Selected HMBC () and NOESY () correlations observed for 4 and 5.

Figure 4

Selected HMBC () and NOESY () correlations observed for 6.