# Olivetolic acid

> Olivetolic acid is the phenolic building block of cannabinoids; joined to geranyl pyrophosphate it forms CBGA, and its five-carbon chain becomes the pentyl tail of THC and CBD.

- Canonical: https://genetixbay.com/knowledge/glossary/olivetolic-acid.html
- Also written: OA, olivetolate, olivetolic
- Glossary category: Cannabinoids and terpenes · Evidence: Established
- Status: Draft: awaiting expert review · Updated: 2026-10-31
- Licence: CC BY-SA 4.0 (https://creativecommons.org/licenses/by-sa/4.0/), attribute "GenetixBay cannabis glossary"

Olivetolic acid is a polyketide made in [trichome](https://genetixbay.com/knowledge/glossary/trichome.md) secretory cells from hexanoyl-CoA and three malonyl-CoA units. Two enzymes do the work: a polyketide synthase (often called olivetol synthase or tetraketide synthase) and olivetolic acid cyclase. The product is the aromatic ring and five-carbon (pentyl) side chain that every "regular" [cannabinoid](https://genetixbay.com/knowledge/glossary/cannabinoid.md) carries.

## In practice

Growers never see olivetolic acid on a [COA](https://genetixbay.com/knowledge/glossary/coa.md); it is consumed as fast as it is made. Its relevance is conceptual. The side-chain length is set here: when the plant starts from a shorter precursor it makes divarinic acid instead, and the whole downstream chain shifts to the propyl "varin" cannabinoids (CBGVA, [THCVA](https://genetixbay.com/knowledge/glossary/thcva.md), CBDVA). That is why THCV-rich plants tend to be lower in [THC](https://genetixbay.com/knowledge/glossary/thc.md), not higher. Researchers producing cannabinoids in yeast also have to rebuild this step.

## Don't confuse with

- **Olivetol**: the [decarboxylated](https://genetixbay.com/knowledge/glossary/decarboxylation.md) form, used in chemical synthesis; not the natural plant substrate.
- **Geranyl pyrophosphate**: the terpene-derived partner that joins olivetolic acid to make [CBGA](https://genetixbay.com/knowledge/glossary/cbga.md).
- **CBGA**: the product, the first true cannabinoid in the pathway.

## Related terms

[Geranyl pyrophosphate](https://genetixbay.com/knowledge/glossary/geranyl-pyrophosphate.md), [CBGA](https://genetixbay.com/knowledge/glossary/cbga.md), [Phytocannabinoid](https://genetixbay.com/knowledge/glossary/phytocannabinoid.md), [THCVA](https://genetixbay.com/knowledge/glossary/thcva.md), [Cannabinoid](https://genetixbay.com/knowledge/glossary/cannabinoid.md)

## Sources

1. Gülck T, Møller BL. 2020. Phytocannabinoids: origins and biosynthesis. Trends in Plant Science 25(10):985-1004.