Enzyme inhibitory constituents from Duranta repens

Isoprenylated flavonoids 5,7-dihydroxy-3'-(2-hydroxy-3-methyl-3-butenyl)-3,6,4'-trimethoxyflavone (1), 3,7-dihydroxy-3'-(2-hydroxy-3-methyl-3-butenyl)-5,6,4'-trimethoxyflavone (2) and an isoprenylated acetophenone derivative (3) have been isolated from Duranta repens along with known compounds, 5-hydroxy-3,6,7,4'-tetramethoxyflavone (4), rosenonolactone (5), 6,7-dimethoxycoumarin (6), 5alpha,8alpha-epidioxyergosta-6,22-dien-3beta-ol (7) and 5alpha,8alpha-epidioxyergosta-6,9(11),22-trien-3beta-ol (8), isolated for the first time from this species. Their structures and the relative configuration were determined by spectroscopic methods (1H- and 13C-NMR, IR, UV and MS) and two-dimensional (2D)-NMR experiments. The compounds 1-5 showed inhibitory activity against prolyl endopeptidase while 4 and 5 were also active against thrombin.