Chemical Interactions and Cytotoxicity of Terpene and Diluent Vaping Ingredients

Abstract

Vaping devices have risen in popularity since their inception in 2007. The practice involves using a variety of commercially available devices. Internal heating systems in devices aerosolize e-liquid formulations of complex mixtures including an active ingredient (e.g., THC, CBD, and nicotine), diluents (or cutting agents), solvents, and flavoring agents (e.g., terpenes and aldehydes). The vaping toxicology literature consists of cytotoxicity studies of individual chemicals and commercial formulas. Because of the variation of e-liquid composition, there is a limited understanding of the toxicity of ingredient combinations. This study analyzed the cytotoxic effects after exposure to individual and binary mixtures of a representative terpene (+-R-limonene) and diluent (triethyl citrate) on human lung cell models. Data were analyzed to determine the effects of 97:3 and 80:20% v/v (triethyl citrate/limonene) binary mixtures. BEAS-2B cells, a bronchial epithelial cell, and A549 cells, a type II alveolar epithelial cell, served as models for comparison. LC50 values were calculated and isobolograms were used to assess chemical interactions. Results show that limonene was more cytotoxic than triethyl citrate. Isobolographic analyses confirmed that the 97:3% v/v mixture resulted in an antagonistic chemical interaction. The 80:20% v/v mixture resulted in a similar result. Further testing of different ratios of binary mixtures is needed for chemical interaction screening to inform safety assessments.

Chemical and physiological interactions between e-liquid constituents: cause for concern?

“…23 A study by Baldovinos et al analysed the cytotoxic effects of individual compounds and binary mixtures of a representative terpene (R-limonene) and an additive (triethyl citrate) on human lung cell models. 25 Data were analysed to determine the effects of 97:3 and 80:20% v/v (triethyl citrate/limonene) binary mixtures on BEAS-2B and A549 cells. LC 50 values and isobolograms were used to assess toxicity and chemical interactions.…”

Evaluating Manganese, Zinc, and Copper Metal Toxicity on SH-SY5Y Cells in Establishing an Idiopathic Parkinson’s Disease Model

“…Viability was normalized to untreated cells and fitted to a 4-parameter logistic curve on Sigma Plot 14.0 (Systat Software, San Jose, CA, USA). The LC 10 and LC 50 for each metal were determined using linear extrapolation of the data points above and below 90% viability and 50% viability, respectively [65]. For visualization only, two "blank" points were added to 100% viability and 0% viability for each metal.…”

Sesquiterpene-evoked phytochemical toxicity in PC12 neuronal cells reveals a variable degree of oxidative stress and alpha-tocopherol and glutathione-dependent protection

“…While most C. sativa extracts are typically heated to decarboxylate the acidic cannabinoids to the more bioactive form, the effect of manufacturing, storage and decarboxylation can decrease sesquiterpene content and accelerate the development of their oxidized forms ( Milay et al, 2020 ). Furthermore, sesquiterpene oxide’s relative contribution to the bioactivity or cytotoxicity of complex botanical extracts more generally is unclear; considering the escalating use of cannabis products of varying formulations containing such sesquiterpenes and potentially their oxidized forms, it’s desirable that further neurological bioactivity and safety is explored for human health ( Baldovinos et al, 2023 , Guo et al, 2021 ).…”