Jacaric acid is a conjugated polyunsaturated fatty acid first isolated from seeds of Jacaranda plants. Structurally, it is an 18-carbon ω-6 triene isomer of γ-linolenic acid . Jacaric acid induces cell cycle arrest and apoptosis in a variety of cancer cell lines (GI50 = 1-5 μM). It increases the production of reactive oxygen species, and cytotoxicity is abolished by the antioxidant α-tocopherol, suggesting that apoptosis results from oxidative stress. Jacaric acid is metabolized in vivo to conjugated linoleic acid , which is also cytotoxic to cancer cells. Jacaric acid inhibits cyclooxygenase-1 in vitro (Ki = 1.7 μM) and, with long term feeding, decreases stearoyl-CoA desaturase expression and activity in mice.