THC

THC is the common abbreviation for tetrahydrocannabinol, typically referring to the Δ⁹ isomer unless otherwise specified. The IUPAC name of (−)-trans-Δ⁹-THC is (6aR,10aR)-6,6,9-trimethyl-3-pentyl-6a,7,8,10a-tetrahydro-6H-benzo[c]chromen-1-ol. Molecular formula C₂₁H₃₀O₂, molecular weight 314.46 g/mol. THC was first isolated and structurally characterized by Gaoni and Mechoulam (1964, Journal of the American Chemical Society 86:1646) and fully synthesized by Mechoulam et al. in 1967. It is a partial agonist at CB1 (Ki ≈ 10–80 nM across studies) and a weaker partial agonist at CB2. Effects are dose-dependent and biphasic — low doses can be anxiolytic while higher doses may be anxiogenic, a pattern documented in controlled human studies (Childs et al., 2017, Drug and Alcohol Dependence 177:136). → See also: Delta-9 THC, CB1 receptor, Decarboxylation.