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| Other names | 2-Carboxy-THC; THCA, 2-COOH-THC |
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| ECHA InfoCard | 100.216.805 |
| Chemical and physical data | |
| Formula | C22H30O4 |
| Molar mass | 358.478 g·mol−1 |
| 3D model (JSmol) | |
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Tetrahydrocannabinolic acid (THCA,2-COOH-THC;conjugate basetetrahydrocannabinolate) is a precursor oftetrahydrocannabinol (THC), an active component ofcannabis.[1]
THCA is found in variable quantities in fresh, undried cannabis, but is progressivelydecarboxylated to THC with drying, and especially under intense heating such as when cannabis is smoked or cooked intocannabis edibles.[1]
THCA is rarely directly used, but its presence is commonly analyzed when cannabis or hemp-based products are screened for THC; some countries require that it be measured in such screens.[2][3]: 32
THCA in its isolated form is available for purchase in select medical and recreational cannabis dispensaries in the form of a white crystalline powder. It can be smoked or vaporized in typical smoking devices, such as abong or dab rig (device used for vaporizinghash oil). These methods convert the THCA to THC and so are used for their psychoactive effects. THCA is also sometimes encapsulated and taken as a supplement for a variety of illnesses, although there are currently no established medical applications.[4]
Conversion of THCA toTHCin vivo appears to be very limited, giving it only very slight efficacy as aprodrug for THC.[1] In receptor binding assays it ispromiscuous;[5] there are papers showing it being an inhibitor ofPC-PLC,COX-1,COX-2,TRPM8,TRPV1,FAAH,NAAA,MGL, andDGLα, and an inhibitor ofanandamide transport, as well as an agonist ofTRPA1 andTRPV2.[1] Many THCAreagents used in biochemistry experiments are contaminated with THC due to THCA's instability.[5]
A study found THCA and unheatedCannabis sativaextracts exertimmuno-modulating effect, not mediated by thecannabinoidCB1 andCB2 receptor coupled pathways like THC. THCA was able to inhibit the tumor necrosis factor alpha (TNFα) levels inU937macrophages and peripheralblood macrophages, an inhibition that persisted over a longer period of time, whereas after prolonged exposure time THC and heated extract tend to induce the TNFα level. THCA and THC show distinct effects onphosphatidylcholine specificphospholipase C (PC-PLC) activity, as THCA and unheated extracts inhibit the PC-PLC activity in a dose-dependent manner, but THC only induced PC-PLC activity at high concentrations, suggest THCA and THC exert their immuno-modulating effects via differentmetabolic pathways.[6]
Theanti-inflammatory activity ofC. sativa extracts was studied on three lines ofepithelial cells and oncolontissue in a model ofinflammatory bowel diseases (IBDs), whereC. sativa flowers wereextracted withethanol, found the anti-inflammatory activity of Cannabis extracts derives from THCA present in fraction 7 (F7) of the extract. However, all fractions ofC. sativa at a certain combination of concentrations show a significant increasedcytotoxic activity and suppress COX-2 andMMP9gene expression in both cell culture and colon tissue, suggest the anti-inflammatory activity of Cannabis extracts on colon epithelial cells derives from a fraction of the extract that contains THCA, and is mediated, at least partially, viaGPR55 receptor. The cytotoxic activity of theC. sativa extract was increased by combining all fractions at a certain combination of concentrations and was partially affected byCB2 receptor antagonist that increasedcell proliferation. It is suggested that in a nonpsychoactive treatment for IBD, THCA should be used rather thanCBD.[7]
THCA binds to and activatesPPARγ with higher potency than itsdecarboxylated products.[8]
THCA shows a similarmetabolism to THC in humans, producing 11-OH-THCA and 11-nor-9-carboxy-THCA.[9] Although the decarboxylation of THCA to THC was assumed to be complete, which means that no THCA should be detectable inurine andblood serum of cannabis consumers, it is found in the urine and blood serum samples collected frompolice controls ofdrivers, suspected for driving under the influence of drugs (DUID). THCA was detected in the urine and blood serum samples of several cannabis consumers in concentrations of up to 10.8 ng/mL in urine and 14.8 ng/mL in serum. The concentration of THCA was below the THC concentration in most serum samples, resulting inmolar ratios of THCA/THC of approximately 5.0–18.6%. Where a short elapsed time between the last intake and blood sampling was assumed, the molar ratio was 18.6% in the serum.[10]
It has two isomers, THCA-A, in which the carboxylic acid group is in the 1 position, between the hydroxy group and the carbon chain, and THCA-B, in which the carboxylic acid group is in the 3 position, following the carbon chain.[11]: 20 The crystal structures of both THCA-A (colourless prisms,orthorhombic P212121) and THCA-B (also colourless prisms, orthorhombic P212121) have been reported.[12][13]
In the past THCA was thought to be formed in plants bycyclization ofcannabidiolic acid but due to studies in the late 1990s it became apparent that its precursor iscannabigerolic acid, which goes through oxidocyclization through the actions of the enzymeTHCA-synthase.[3]: 14
It is unstable, and slowlydecarboxylates into THC during storage, and the THC itself slowly degrades to CBN, which has potentialimmunosuppressive andanti-inflammatory activities.[1] When heated or burned, as when cannabis is smoked or included in baked goods, the decarboxylation is rapid but not complete; THCA is detectable in people who smoke or otherwise consume cannabis.[1]
THCA is not scheduled by theUnited Nations'Convention on Psychotropic Substances.[14]
Hemp-derived THCA is prevalent and explicitly unscheduled under the Controlled Substances Act's definition that legalizes all cannabis with less than 0.3% delta-9 tetrahydrocannabinol concentration.[15] THCA is notscheduled at thefederal level in theUnited States,[16] but it is possible that THCA could legally be considered ananalog of THC and sales orpossession could potentially be prosecuted under theFederal Analogue Act.[17] In practice, because THCA spontaneously decarboxylates to form THC, no real sample of purified THCA will be completely free of THC. Thus, any laboratory analysis of THCA using any technique involving significant heat will generate THC in the handling and analytical process. Further, both the Farm Bill and the USDA specify that analytical testing of samples for total THC must use "post-decarboxylation or other similarly reliable methods".[15][18]
Despite the marketing of THCa flower and products as being lawful hemp under the 2018 farm bill, many arrests and raids have happened as a result of the retail sale of these products in locales with strict anti-marijuana laws.[19][20][21][22][23] The Colorado Attorney General's Office has sued at least two businesses for the sale of THCa products with more than .3% delta-9 THC, as well as mislabeling, and toxic compounds found in some products by one company.[24][25][26] One notable arrest in Charlotte, NC, resulted in a woman being beaten and arrested for smoking a pre-roll sold as lawful THCa hemp at a local retailer. Charges for marijuana possession were later dropped and the officer involved was suspended for excessive force.[27] Several of these raids have resulted in lawsuits against law enforcement agencies and their agents, many of which are currently pending.[28][29] Tennessee is unique in that THCa is explicitly listed as an allowed hemp-derived cannabinoid,[30] and defense attorneys have successfully had prosecutions overturned due to post-decarboxylation testing of post-harvest plant material.[31] There is not a clear current consensus, as far as case law goes, on a state or national level.
As of June 25, 2025, theU.S. 8th Circuit Court of Appeals overturned a lower court's injunction, allowingArkansas to enforce its ban on hemp-derived THC products, including THCA (listed in some interpretations). This ruling means that Act 629, which classifies Delta-8, Delta-9 (above 0.3%), and Delta-10 THC ("Psychoactive hemp-derived cannabinoids" as stated in Act 629, although THCa is not active on its own and is only transformed into Delta-9-THC when heated) as Schedule VI controlled substances in the state, is now enforceable. Previously, sales of these products had been temporarily permitted due to the injunction.[32][33]