Cancer chemopreventive effects of constituents of Caesalpinia ferrea and related compounds.

The anti-tumor promoting effects of fruits of Caesalpinia ferrea MART. (Leguminosae) were tested by the in vitro Epstein-Barr virus early antigen (EBV-EA) activation assay, and its active constituents were identified as gallic acid (1) and methyl gallate (2). A total of 49 related compounds of 1 and 2 were analysed for the effects by this assay, and the structure activity relationships have been proposed. Three acetophenone derivatives, 2,6-dihydroxyacetophenone (48), 2,3,4-trihydroxyacetophenone (50) and 2,4,6-trihydroxy- acetophenone (51) were found to show potent inhibitory activity.