Oxidative byproducts of cannabidiol (CBD) are known to be cytotoxic. However, CBD susceptibility to oxidation and resulting toxicity dissolved in two common solvents, ethanol (EtOH) and dimethyl sulfoxide (DMSO), is seldom discussed. Furthermore, CBD products contain a wide range of concentrations, making it challenging to link general health risks associated with CBD cytotoxicity. Here, we report on the effect of CBD and CBD analogues dissolved in EtOH or DMSO at various concentrations. The cells used in these studies were human umbilical vascular endothelial cells (HUVECs). Our findings show significant CBD oxidation to cannabidiol-quinone (CBD-Q) and subsequent cytotoxicity, occurring at 10 μM concentration, regardless of the solution delivery vehicle. Moreover, a new analogue of CBD, cannabidiol-diacetate (CBD-DA), exhibits significantly more stability and reduced toxicity compared with CBD or CBD-Q, respectively. This knowledge is important for determining concentration-dependent health risks of complex cannabinoid mixtures and establishing legal limits.

Chemical modifications such as intercalation can be used to modify surface properties or to further functionalize the surface states of topological insulators (TIs). Using ambient pressure x-ray photoelectron spectroscopy, we report copper migration in C u x B i 2 S e 3 , which occurs on a timescale of hours to days after initial surface cleaving. The increase in near-surface copper proceeds along with the oxidation of the sample surface and large changes in the selenium content. These complex changes are further modeled with core-level spectroscopy simulations, which suggest a composition gradient near the surface which develops with oxygen exposure. Our results shed light on a new phenomenon that must be considered for intercalated TIs—and intercalated materials in general—that surface chemical composition can change when specimens are exposed to ambient conditions.