抄録
Glutathione S-transferase inhibition assay-guided fractionations on the ethanolic extract of the bark of Caesalpinia bonduc resulted in the isolation of a new sterol, 17-hydroxy-campesta-4,6-dien-3-one (1) along with four known compounds, 13,14-seco-stigmasta-5,14-dien-3α-ol (2), 13,14-seco-stigmasta-9(11),14-dien-3α-ol (3), caesaldekarin J (4) and pipataline (5) as active constituents. Structures of compounds 1—5 were established on the basis of extensive NMR spectroscopic studies. The compounds (1—5) were isolated on the basis of their inhibitory activity against glutathione S-transferase, an enzyme that has been implicated in resistances during treatment of cancer and parasitic infections. Efforts to study structure–activity relationships of compounds 2 and 3 were also made by modifying their structures. The IC50 values of these compounds and their derivatives ranged from 57—380 μM and were compared to the inhibitory effects due to sodium taurocholate, an isoprene-derived GST inhibitor (IC50=398 μM). A plausible biosynthesis of 13,14-seco-steroids has also been proposed.
