Cis-THC
cis-Delta-9-Tetrahydrocannabinol is an isomer of tetrahydrocannabinol found in the Cannabis plant but in lower quantities than the more well-known trans isomer. Formation of cis-THC could take place in process of epimerization associated with acid-catalyzed cyclization of CBD to THC. It has similar psychoactive effects to trans-Δ9-THC in tests on mice, but with only around 1/5th the potency. The equivalent Δ8 isomer is also known as a synthetic compound, but has not been isolated from Cannabis plant material. All four cis/trans isomers are known, though only the and enantiomers are psychoactive, while the others retain activity at targets such as GPR18 and GPR55.