Photodegradation of cannabidiol (CBD) and Δ⁹-THC in cannabis plant material

Δ⁹-THC, the psychotropic cannabinoid in Cannabis sativa L., for many years has been the focus of all the pharmacological attention as the main promising principle of the plant. Recently, however, cannabidiol (CBD) has brought a sudden change in the scenario, exponentially increasing the interest in pharmacology as the main non-psychotropic cannabinoid with potential therapeutic, cosmetical and clinical applications. Although the reactivity of CBD and Δ⁹-THC has been considered, little attention has been paid to the possible photodegradation of these cannabinoids in the vegetal matrix and the data available in the literature are, in some cases, contradictory. The aim of the present work is to provide a characterization of the photochemical behaviour of CBD and Δ⁹-THC in three cannabis chemotypes, namely I (Δ⁹-THC 2.50%_w/w), II (CBD:Δ⁹-THC 5.82%_w/w:3.19%_w/w) and III (CBD 3.02%_w/w).