Gallic acid (3,4,5-trihydroxybenzoic acid), found in many plants either in free-form or part of tannins, is known to possess anti-microbial, antioxidant and cytotoxic properties. NFkappaB regulates the expression of several genes involved in carcinogenesis. These include anti-apoptotic, cytokines and cell cycle-regulatory genes. It is well established that the transcriptional factor NFkappaB is deregulated in many forms of cancer. Thus, agents that can suppress NFkappaB activation have the potential of suppressing carcinogenesis. In the present investigation, gallic acid was isolated from Alchornea glandulosa (Euphorbiaceae) and eight esters were synthesised. These compounds were evaluated against TNF-alpha-induced NFkappaB activation with stably transfected 293/NFkappaB-Luc human embryonic kidney cells. Gallates with IC(50) values in a range of 10-56 microM mediated inhibitory activity higher than gallic acid (IC(50) 76.0 +/- 4.9 microM). In addition to inhibiting NFkappaB activation, gallic acid mediated a modest cytotoxic effect, and some of the gallates affected cell viability at the tested concentrations. Based on these results, suppression of NFkappaB activation by gallate esters could play a chemopreventive role in carcinogenesis.