Palustric acid is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the formula . It is classified as a

diterpenoid Diterpenes are a class of terpenes composed of four isoprene units, often with the molecular formula C20H32. They are biosynthesized by plants, animals and fungi via the HMG-CoA reductase pathway, with geranylgeranyl pyrophosphate being a primar ...

(a C20 hydrocarbon with oxygenated groups) and a

resin acid Resin acid refers to any of several related carboxylic acids found in tree resins. Nearly all resin acids have the same basic skeleton: three fused rings having the empirical formula C19H29COOH. Resin acids occur in nature as tacky, yellowish gum ...

. Palustric acid is an isomer of

abietic acid Abietic acid (also known as ''abietinic acid'' or ''sylvic acid'') is a diterpenoid found in coniferous trees. It is supposed to exist to defend the host plant from insect attack or various wounds. Chemically, it is a complicated molecule featurin ...

: 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 Plant defense against herbivory or host-plant resistance is a range of adaptations Evolution, evolved by plants which improve their fitness (biology), survival and reproduction by reducing the impact of herbivores. Many plants produce secondary ...

. It is biosynthesized from the C20 precursor

geranylgeranyl diphosphate Geranylgeranyl pyrophosphate is an intermediate in the biosynthesis of diterpenes and diterpenoids. It is also the precursor to carotenoids, gibberellins, tocopherols, and chlorophylls. It is also a precursor to geranylgeranylated proteins, whic ...

Safety

Palustric acid is very poorly soluble in water and has low acute toxicity.{{cite journal , doi=10.1016/s0043-1354(99)00406-6 , title=Solubility and Toxicity of Resin Acids , date=2000 , last1=Peng , first1=Guomei , last2=Roberts , first2=John C. , journal=Water Research , volume=34 , issue=10 , pages=2779–2785 , bibcode=2000WatRe..34.2779P

References

Carboxylic acids Diterpenes Phenanthrenes Wood extracts Cyclohexadienes Conjugated dienes