Tetrahydrocannabinolic acid (THCA, Δ9-THCA, 2-COOH-THC), is a biosynthetic precursor of tetrahydrocannabinol (THC), the active component of Cannabis. When purified, it forms a powder which is unstable in the presense of acids, heat, oxygen, and/or light.
THCA is found in variable quantities in fresh, undried cannabis, but is progressively decarboxylated to THC with drying, and especially under intense heating such as when cannabis is smoked.
THCA does not have any known psychoactive effects on humans in its own right. It does have antiinflammatory, neuroprotective,antiemetic (anti-vomitting) and anti-prostate cancer effects. It inhibits COX-1 and COX-2 enzymes involved in inflammation in human colon cell cultures. It has also been shown to decrease the amount of oxidative stress caused by impairment of mitochondria which is a major mechanism in neural degeneration in mouse mesencephalic cell cultures .
Despite the ready decarboxylation by drying or heating ex vivo, conversion of THCA to THC in vivo appears to be very limited, giving it only very slight efficacy as a prodrug for THC. Consequently it is believed to be important in less-psychoactive preparations of cannabis used for medical use, such as cannabis tea.
THCA is commonly used as a biomarker in drug testing along with THCV, to distinguish between prescribed synthetic Delta-9-tetrahydrocannabinol, such as Marinol, and cannabis plant material which may also be used by patients.
THCA is not scheduled by the United Nations' Convention on Psychotropic Substances. United States
THCA is not scheduled at the federal level in the United States and is therefore legal to posses, buy, and sell. It is possible that THCA could legally be considered an analog (of THC) although that is somewhat unlikely since it does not provide a high and THC does. If it were legally considered an analog, sales or possession with intent for human consumption could be prosecuted under the Federal Analogue Act.