of C. sativa extracts was studied on three lines of epithelial cells and on colon tissue in a model of inflammatory bowel diseases (IBDs), where C. sativa flowers were extracted with ethanol, found the anti-inflammatory activity of Cannabis extracts derives from THCA present in fraction 7 (F7) of the extract. However, all fractions of C. sativa at a certain combination of concentrations show a significant increased cytotoxic activity and suppress COX-2 and MMP9 gene 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, via GPR55 receptor. The cytotoxic activity of the C. sativa extract was increased by combining all fractions at a certain combination of concentrations and was partially affected by CB2 receptor antagonist that increased cell proliferation. It is suggested that in a nonpsychoactive treatment for IBD, THCA should be used rather than CBD. THCA binds to and activates PPARγ with higher potency than its decarboxylated products. THCA show a similar metabolism as THC in humans, producing 11-OH-THCA and 11-nor-9-carboxy-THCA. Although the decarboxylation of THCA to THC was assumed to be complete, which means that no THCA should be detectable in urine and blood serum of cannabis consumers, it is found in the urine and blood serum samples collected from police controls of drivers, 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 in molar 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. Chemistry 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. The crystal structures of both THCA-A (colourless prisms, orthorhombic P212121) and THCA-B (also colourless prisms, orthorhombic P212121) have been reported. In the past THCA was thought to be formed in plants by cyclization of cannabidiolic acid but due to studies in the late 1990s it became