Planta Med 2016; 82 - PA23
DOI: 10.1055/s-0036-1578638

An Investigation Of Decarboxylation Of Acidic Cannabinoids: THCA-A, CBDA And CBGA

M Wang 1, YH Wang 1, B Avula 1, MM Radwan 1, AS Wanas 1, J Van Antwerp 2, J Parcher 1, MA ElSohly 1, 3, IA Khan 1, 4
  • 1National Center for Natural Products Research, University of Mississippi, University, MS 38677, USA
  • 2Waters Corporation, Milford, MA 01757, USA
  • 3Department of Pharmaceutics and Drug Delivery, School of Pharmacy, University of Mississippi, University, MS 38677, USA
  • 4Division of Pharmacognosy, Department of Biomolecular Sciences, School of Pharmacy, University of Mississippi, University, MS 38677, USA

Supercritical fluid chromatography with both ESI (+) and ESI (-) MS along with photodiode array detection was used to separate and analyze cannabinoids and parent carboxy constituents in 30 cannabis samples. The analytical results were compared to those obtained using a validated UHPLC method, in which, there was an agreement between these two methods within ± 13% for Δ9-THC. The same SFC method was used to study the decarboxylation of Δ9-tetrahydrocannabinolic acid A (THCA-A), cannabidiolic acid (CBDA) and cannabigerolic acid (CBGA) over a range of time (0 – 60 min) and temperature (80, 95, 110, 130 and 145 °C). The reactions at 80 and 95 °C over the full time scale, and at 110 and 130 °C up to the time when decarboxylation was complete, displayed an exponential relation between concentration and time indicating a first-order or pseudo-first-order reaction [1]. The rate constants for THCA-A were twice those of the other two acids, viz., CBDA and CBGA. Moreover, the decarboxylation reaction for THCA-A was forthright, with no side reactions or byproducts. The decarboxylation reactions for CBDA and CBGA were not as distinctly clean purportedly due to evaporation or unexplained loss of reactants or products at high temperatures.

Acknowledgements: This research was partially supported by “The University of Mississippi NIDA Marijuana Project” as part of the “Cannabis Potency Monitoring Program” funded by the National Institute on Drug Abuse (N01DA-15 – 7793), and The United States Department of Agriculture, Agricultural Research Service, Specific Cooperative Agreement No. 58 – 6408 – 1-603 – 07. The authors would like to thank Annette Ford for the sample preparation.

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