Levopimaric acid is an

abietane Abietane is a diterpene that forms the structural basis for a variety of natural chemical compounds such as abietic acid, carnosic acid, and ferruginol which are collectively known as abietanes or abietane diterpenes. Abietanes are found in the ...

-type of

diterpene Diterpenes are a class of chemical compounds 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 ...

resin acid Resin acid refers to mixtures of several related carboxylic acids, primarily abietic acid, found in tree resins. Nearly all resin acids have the same basic skeleton: three fused rings having the empirical formula C19H29COOH. Resin acids are tack ...

. It is a major constituent of pine

oleoresin Oleoresins are semi-solid extracts composed of resin and essential or fatty oil, obtained by evaporation of the solvents used for their production. The oleoresin of conifers is known as crude turpentine or gum turpentine, which consists of oil of ...

with the chemical formula of C₂₀H₃₀O₂. In general, the abietene types of diterpene resin acid have various biological activities, such as antibacterial, cardiovascular and antioxidant. Levopimaric acid accounts for about 18 to 25% of pine oleoresin. The production of oleoresin by conifer species is an important component of the defense response against insect attack and fungal

pathogen In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ ...

infection.

Resin acids

Resin acid Resin acid refers to mixtures of several related carboxylic acids, primarily abietic acid, found in tree resins. Nearly all resin acids have the same basic skeleton: three fused rings having the empirical formula C19H29COOH. Resin acids are tack ...

is the general name for all kinds of acids that share the same basic skeleton, a three-fused ring and the empirical formula C₂₀H₃₀O₂. The resin acids may be classified into two types, abietic and pimaric. The abietic-type group include levopimaric, l-abietic and neoabietic. The structure of these compounds differ only in the position of the conjugated double bond system. This feature influences their chemical reactivity. The pimaric-type acids are dextropimaric and isodextropimaric.

Extraction from pine resin

Levopimaric acid can be extracted from

longleaf pine The longleaf pine (''Pinus palustris'') is a pine species native to the Southeastern United States, found along the coastal plain from East Texas to southern Virginia, extending into northern and central Florida. In this area it is also known as ...

oleoresin by first dissolving it in a solution of

acetone Acetone (2-propanone or dimethyl ketone), is an organic compound with the formula . It is the simplest and smallest ketone (). It is a colorless, highly volatile and flammable liquid with a characteristic pungent odour. Acetone is miscib ...

and

2-amino-2-methyl-1-propanol Aminomethyl propanol is an organic compound with the formula H2NC(CH3)2CH2OH. It is colorless liquid that is classified as an alkanolamine. It is a useful buffer and a precursor to numerous other organic compounds. Synthesis Aminomethyl propan ...

, then acidifying with phosphoric acid.

Biosynthesis

The

-like skeleton of levopimaric acid is formed by the cyclization of a

diterpenoid Diterpenes are a class of chemical compounds 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 ...

precursor, geranylgeranyl diphosphate, from which C₂₀ isoprenoids are typically derived. The intermediate which is formed, (+)-copalyl diphosphate, then goes through an oxidation and rearrangement to give levopimaradiene. Then, the levopimaradiene goes through several more steps of oxidation processes via the intermediates levopimaradienol and levepimaradienal to give levopimaric acid.

Role in biology

Oleoresin in pines is defined as pine gum, which is the nonaqueous secretion of resin acids dissolved in a terpene hydrocarbon oil, which is produced in or exuded from the intercellular resin ducts of a living tree. The viscous oleoresin secretion is composed of a complex mixture of terpenoids, consisting of roughly equal parts of volatile turpentine and rosin (also known as diterpene resin acids). Accumulated resin is released upon tissue injury and/or produced locally at the site of infestation, with the consequence that the beetle and associated fungal pathogens are killed, encased in resin, and expelled from the bore hole point of entry. This process is called pitching out, and it results in not only killing the attackers and flushing the wound site but also moving the oleoresin to the trunk surface where the turpentine evaporates to permit the resin acids to form a formidable physical barrier that seals the wound. Diterpene resin acids (DRA) play important roles in confer defense against insects and microbial pathogens. Levopimaric acid, an abietane-type DRA, is one of the principal resin acids.

References

{{Reflist Carboxylic acids Diterpenes