Is Bottled Limonene the Same?

Is that limonene in the bottle the same as the limonene in the plant??

In recent years, many breeders have been focusing on creating limonene dominant plants. So, let’s take a look at the same analysis for limonene.?Limonene is also a monoterpene and it exists in Nature in two common forms, or enantiomers,?(-)-limonene, aka D-limonene,?and (+)-limonene, aka L-limonene. Confusingly, L’s and D’s are also interchangeable with R’s and S’s, but let’s just focus on (+) and (-) for sake of simplicity.?

The overlay of the chiral analysis of limonene found in cannabis and the limonene found in the most popular terpene providers online is shown above. Remarkably, the limonene in the bottles (red line) is NOT the same limonene produced in abundance in cannabis (green line). This is remarkable because limonene is one of the most popular terpenes added to manufactured products and sourced from online sources. As we learned above, different forms result in different aromas and bioactivities, and this is true for limonene enantiomers as well, with (+)-limonene having more citrusy notes and (-)-limonene exhibiting a more piney fuel-like profile.??

Limonene occurs in nature as a mixture of the (+) and (-) forms. In a recent study, test persons evaluated the smell associated with different enantiomers of limonene. (+)-limonene and the test persons largely associated the smell of this oil with the smell of citrus. On the other hand, far fewer test persons recognized the smell of (-)-limonene as citrusy. Instead, most didn’t recognize the smell as related to any citrus fruits tested (Kvittingen et. al., 2021).?

Simply, the genetics of a plant determine the terpene synthases that are present.?Cannabis sativa L.?has a different set of terpene synthases than those found in the plants most often used for industrially-sourced terpenes. Therefore, the underlying genetics explain the different compounds biosynthesized. For instance, the limonene synthase isolated from cannabis sativa produces (-)-limonene as the major product, while industrially sourced limonene is from citrus, which contains an enzyme that produces the other enantiomer (+)-limonene.??Similarly, the pinene synthase isolated from cannabis sativa produces (+)-pinene as the major product, but industrially sourced pinene comes from a byproduct of the wood pulp industry (turpentine) and the exact enantiomer composition depends on the type of tree it was sourced from.