TNF and colitis: Based on a synthetic method previously described by us [25], the goals of the present study were to (a) prepare the novel fused-cyclopentenone phosphonate, diethyl 3-nonyl-5-oxo-3,5,6,6a-tetrahydro-1H-cyclopenta[c]furan-4-ylphosphonate (denoted by P-5), (b) test whether P-5 can inhibit local secretion of TNFα, (c) examine, in vitro and in vivo, whether P-5 can ameliorate chronic inflammation, such as experimental colitis, and (d) explore mechanistically the possible anti-inflammatory effect of P-5.