Investigation on the Semi-synthetic Cannabinoids Distributed on the Internet in Japan: Reduced Forms or Acetyl Derivatives of Tetrahydrocannabinol (THC)

In recent years, products containing structurally similar substances to ∆9-tetrahydrocannbinol (∆9-THC), the main constituent for the hallucinogenic effects of cannabis, have been widely distributed through the internet. Hexahydrocannabinol (HHC), synthesized easily by the reduction of ∆8-THC and/or Δ9-THC, was listed as a Designated Substance under the Pharmaceutical and Medical Device Act in Japan in March 2022; however, other semi-synthetic cannabinoids such as acetyl derivatives of THC and HHC emerged soon. In this study, three products labelled as containing HHC, HHC-O-acetate or THC-O-acetate were analyzed by LC-QTOF MS and GC-QTOF MS, and substances detected in the products were investigated in detail. Three yellowish-brown oil-like products (A, B, and C) obtained via the internet between 2022 and 2023, were extracted under sonication with acetonitrile. Analytical references for diastereomers of HHC (11α- and 11β-HHC), and acetyl derivatives of HHC (11α- and 11β-HHC-O-acetate) and THC (∆8- and Δ9-THC-O-acetate) were synthetized in National Institute of Health Sciences in Japan. LC-QTOF MS measurements were performed under a gradient condition of 0.1% formic acid and 0.1% formic acid/acetonitrile using a Cortecs C18 column (2.1 mm i.d. x 150 mm, 2.7 µm, Waters). GC-QTOF MS measurements were carried out using a HP-5MS column (30 m x 0.25 mm i.d., 0.25 µm, Agilent). In GC-QTOF MS and LC-QTOF MS measurements, the diastereomers of HHC (11α- and 11β-HHC) and cannabinol (CBN) were detected as main peaks in Product A, and dihydro-iso-THC and Δ8-THC were also found in the product. The presence of HHC as the diastereomers together with Δ8-THC suggested that HHC was synthesized by the reduction of Δ8-THC. Furthermore, the detection of dihydro-iso-THC, the reduced form of Δ8-iso-THC and/or Δ4(6)-iso-THC which are by-products of the THC synthesis from cannabidiol (CBD), suggested that Δ8-THC may have been synthesized from CBD. In Product B, the diastereomers of HHC-O-acetate (11α- and 11β-HHC-O-acetate) and CBN-O-acetate were detected as main peaks, and small amounts of 11α- and 11β-HHC were detected only by LC-QTOF MS. The substances in Product B were almost the same as the acetyl derivatives of substances in Product A. In Product C, Δ8-THC-O-acetate was mainly detected, as well as other minor peaks of Δ9-THC-O-acetate, Δ8-THC and CBN-O-acetate. Several small peaks with the same protonated molecular ions as HHC, HHC-O-acetate and THC-O-acetate were also found in Product A, B and C, respectively. The semi-synthetic cannabinoids are detected not only in oil-like products but also in food products such as gummies, and there are concerns about health risks caused by accidental ingestion of these substances. The reduced forms and acetyl derivatives of cannabinoids with different lengths of alkyl side chains of THC have already emerged on the internet. Therefore, continuous surveys of distribution of the products containing these substances are needed. Δ8-THC-O-acetate, Δ9-THC-O-acetate and HHC-O-acetate were listed as Designated Substances in Japan in March this year after being reviewed for their pharmacological and metabolic properties.