Heating of consumer cannabis oils can lead to free radical initiated degradation, causing CBD and THC depletion.

Commercial cannabis oil products are widely available in Canada even though there is a significant gap in scientific information regarding them. Oils, such as vegetable oils, are known to undergo oxidative changes through free radical mechanisms when they are heated or aged, but the cannabis oils used in this study did not have expiry dates or best-before usage dates. This led to the question of how these products would be affected with time. We hypothesized that cannabis oils would produce increased concentrations of free radicals in aging-simulated conditions, which would be related to a decrease in cannabidiol (CBD) or Δ9-tetrahydrocannabinol (THC) content. Cannabis oils and their respective vehicles (oils) were heated using two protocols: One (moderate aging method) used a 2-day heating protocol at 50 °C, and the other (enhanced aging method) used a 14-day heating protocol at 70 °C. We used electron paramagnetic resonance (EPR) spectroscopy for free radical analysis using the spin trapping technique using 200 mM PBN and 0.02 mM CuCl2 (for peroxide breakdown to free radicals). For active ingredient analysis (CBD, THC), we used LC/MS. Cannabis oils that contained unsaturated oils as their vehicles, such as olive or sunflower oil, all showed varying degrees of free radical formation. In both aged and unaged oils containing CBD or THC, less free radical formation was detected compared to the vehicle controls. Cannabis oils using medium-chain triglycerides (MCT) showed little or no free radical formation. The most significant decrease in CBD or THC was observed in the products using sunflower oil, to a lesser extent in MCT oil, and THC also decreased in olive oil. These findings are important for consumers and policymakers considering using such products in hot beverages or cooking and highlighting the importance of appropriate storage conditions.

Induction of quinone oxidoreductase 1 enzyme by Rhazya stricta through Nrf2-dependent mechanism.

ETHNOPHARMACOLOGICAL RELEVANCE: Rhazya stricta Decne. (Apocynaceae) is a common medicinal plant in the Arabian Peninsula, Pakistan and India. Rhazya stricta has been used traditionally to treat several diseases including tumors; however, the underlying mechanism is still not fully elucidated. AIM OF THE STUDY: The aim of this study is to examine the ability of Rhazya stricta to induce a key enzyme involved in cancer chemoprevention, NAD(P)H:quinone oxidoreductase 1 (Nqo1) in murine and human hepatoma cells. Nqo1 is regulated by the nuclear factor erythroid 2-related factor 2 (Nrf2) and the aryl hydrocarbon receptor (AhR) transcription factors. MATERIALS AND METHODS: Rhazya stricta leaves were extracted using ethanol, the strong basic alkaloid fraction (AF) was isolated according to a bioassay-guided fractionation and its mass spectrum was used as a fingerprint for its identity. The effect of increasing concentrations of AF on Nqo1 was tested in murine hepatoma Hepa 1c1c7 and human HepG2 cells. The role of Nrf2-dependent mechanism was tested by using Nrf2-dependent luciferase assay and by determining the Nrf2 nuclear accumulation in Hepa 1c1c7 cells. The role of AhR-dependent mechanism was assessed by using an AhR-deficient version of murine hepatoma c12 cells. RESULTS: AF significantly induced the Nqo1 at mRNA, protein and catalytic activity levels in murine hepatoma Hepa 1c1c7 cells. Moreover, the induction of Nqo1 by AF was completely abolished by using the transcriptional inhibitor, actinomycin D, implying a role of transcriptional regulation. In addition, the role of Nrf2 signaling pathway was confirmed by the induction of Nrf2-dependent luciferase activity and the induced Nrf2 nuclear accumulation in Hepa 1c1c7 cells. Interestingly, AF induced Nqo1 at mRNA and catalytic activity in c12 and HepG2 cells. Finally, the AF induced the Nrf2-dependent luciferase activity in HepG2 cells, confirming the role of Nrf2 in its regulation. CONCLUSIONS: The present study presents the first evidence that Rhazya stricta and its active strongly basic alkaloid fraction induce the chemopreventative enzyme, Nqo1 through Nrf2-dependent mechanism.