Receptor Binding Affinities of Synthetic Cannabinoids Determined by Non-Isotopic Receptor Binding Assay

• Published in: Toxicological research (Seoul) Vol. 35; no. 1; pp. 37 - 44
• Main Authors: Cha, Hye Jin, Song, Yun Jeong, Lee, Da Eun, Kim, Young-Hoon, Shin, Jisoon, Jang, Choon-Gon, Suh, Soo Kyung, Kim, Sung Jin, Yun, Jaesuk
• Format: Journal Article
• Language: English
• Published: Singapore 한국독성학회 01.01.2019; Springer Singapore; Korean Society of Toxicology
• Subjects: Biomedicine; Original; Original Article; Pharmacology/Toxicology; 예방의학; SUP> Receptor binding assay; Synthetic cannabinoids; Surface plasmon resonance; Δ< Human cannabinoid type I receptor (CB1); THC; 9< Δ; ); Human cannabinoid type I receptor (CB; Δ9-THC
• ISSN: 1976-8257; 2234-2753
• DOI: 10.5487/TR.2019.35.1.037

A major predictor of the efficacy of natural or synthetic cannabinoids is their binding affinity to the cannabinoid type I receptor (CB 1 ) in the central nervous system, as the main psychological effects of cannabinoids are achieved via binding to this receptor. Conventionally, receptor binding assays have been performed using isotopes, which are inconvenient owing to the effects of radioactivity. In the present study, the binding affinities of five cannabinoids for purified CB 1 were measured using a surface plasmon resonance (SPR) technique as a putative non-isotopic receptor binding assay. Results were compared with those of a radio-isotope-labeled receptor binding assay. The representative natural cannabinoid Δ 9 -tetrahydrocannabinol and four synthetic cannabinoids, JWH-015, JWH-210, RCS-4, and JWH-250, were assessed using both the SPR biosensor assay and the conventional isotopic receptor binding assay. The binding affinities of the test substances to CB 1 were determined to be (from highest to lowest) 9.52 × 10 −13 M (JWH-210), 6.54 × 10 −12 M (JWH-250), 1.56 × 10 −11 M (Δ 9 -tetrahydrocannabinol), 2.75 × 10 −11 M (RCS-4), and 6.80 ×10 −11 M (JWH-015) using the non-isotopic method. Using the conventional isotopic receptor binding assay, the same order of affinities was observed. In conclusion, our results support the use of kinetic analysis via SPR in place of the isotopic receptor binding assay. To replace the receptor binding affinity assay with SPR techniques in routine assays, further studies for method validation will be needed in the future.