Palustric acid
Palustric acid is an organic compound with the formula. It is classified as a diterpenoid and a resin acid. Palustric acid is an isomer of abietic acid: the location of the two C=C bonds differ in these two compounds. It is a colorless solid that is soluble in polar organic solvents. In terms of biological function palustric acid protects its host trees, especially conifers, against insects, an example of plant defense against herbivory. It is biosynthesized from the C20 precursor geranylgeranyl diphosphate.