Pinene is a terpene, and more specifically, a monoterpene. Terpenes have been shown to have important medicinal qualities in their own right, and researchers recently discovered that they exert synergistic biological effects in combination with THC and other cannabinoids.
What Is Pinene
Pinene is a naturally occurring plant compound belonging to a large and diverse class of organic hydrocarbons known as terpenes, which are made up of linked isoprene (C₅H₈) units. Within this class, pinene is a monoterpene, and thus each molecule consists of two linked isoprene units, giving the chemical formula C₁₀H₁₆.
The pinene molecule naturally occurs in two closely related forms known as structural isomers. For the sake of comparison, an isomer is a natural variant of a molecule; a structural isomer shares the same chemical formula, but the structure of the molecule or its chemical bonds differ; and a stereoisomer shares the same structure as the original molecule but is oriented differently in space.
The two subtypes of pinene are α-pinene and β-pinene. The two isomers each possess two stereoisomers (more specifically, enantiomers, which are perfect mirror images of the original molecule), either positive or negative. Thus, the four forms of pinene are (+)-α-pinene, (−)-α-pinene, (+)-β-pinene and (−)-β-pinene.
Bioactivity of Pinene
A recent study (The Journal of Essential Oil Research, 2006) investigated the antimalarial, antimicrobial and antioxidant effects of a range of common plant terpenoids including (+)-α-pinene. It was discovered that (+)-α-pinene, along with (-)-pulegone, (E- & Z-)-(±)-nerolidol and linalyl acetate, exhibited the most potent antimalarial activity.
Evidence suggests that the positive enantiomers of α-pinene and β-pinene have greater biological activity than the negative, such as a study (Molecules, 2012) that demonstrated that only the positive enantiomers of α- and β-pinene were active against bacterial and fungal cells. An earlier study (Journal of Essential Oil Research, 1999) also noted that the positive and negative forms of α-pinene had differing effects, with the negative enantiomer being more effective against certain bacteria, as well as being more likely to stimulate spasms in smooth muscle tissue.
Potential Health Risks of Pinene
Research has shown that both α-pinene and β-pinene may have an irritant effect on the skin and mucous membranes in humans and animals, and have been particularly associated with irritation to the upper airways. A Swedish study (Scandinavian Journal of Work, Environment & Health, 1997) found that workers exposed to 10-214mg/m³ of α-pinene, β-pinene and 3-carene exhibited chronically reduced lung function compared to local control groups.
Possible Synergistic Effects Between Terpenes
Several studies out there point to a possible synergistic effect between the various terpenes found in plants. For example, a study (Food Chemistry, 2008) compared essential oil extracted from Rosmarinus officinalis L. to its three main components (1,8-cineole, α-pinene, β-pinene) to investigate possible antioxidant effects, and found that the essential oil showed greater activity than its components.
As well as this, significant evidence is beginning to emerge on the nature of the interactions between terpenes and the endocannabinoid system. Although no research has been done on the specific interactions between pinene and the plant cannabinoids found in cannabis, Taming THC: Potential Cannabis Synergy and Phytocannabinoid-Terpenoid Entourage Effects by Dr. Ethan Russo is an important review. The former senior medical advisor to GW Pharmaceuticals suggested that pinene may interact with CBD, CBN and CBG to provide an enhanced antibacterial effect, specifically for the treatment of MRSA and other drug-resistant pathogens; with THC as a bronchodilator and with CBD as a means of reducing production of sebum and sebocytes.
Photo credit: Lachlan Gowen.