Characterizing cannabis-prevalent terpenes for neuroprotection reveal a role for α and ß-pinenes in mitigating amyloid ß-evoked neurotoxicity and aggregation in vitro.

BACKGROUND: Cannabis sativa L. (C. sativa) can efficiently synthesize of over 200 terpenes, including monoterpenes, sesquiterpenes and triterpenes that may contribute to the known biological activities of phytocannabinoids of relevance for the burgeoning access to medicinal cannabis formulations globally; however, to date have been uncharacterized. We assessed twelve predominant terpenes in C. sativa for neuroprotective and anti-aggregative properties in semi-differentiated PC12 neuronal cell line that is robust and validated as a cell model responsive to amyloid ß (Aß1-42) protein exposure and oxidative stress. METHODS: Cell viability was assessed biochemically using the MTT assay in the presence of myrcene, ß-caryophyllene, terpinolene, limonene, linalool, humulene, α-pinene, nerolidol, ß-pinene, terpineol, citronellol and friedelin (1-200 µM) for 24 hr. Sub-toxic threshold test concentrations of each terpene were then applied to cells, alone or with concomitant incubation with the lipid peroxidant tert-butyl hyrdroperoxide (t-BHP; 0-250 µM) or amyloid ß (Aß1-42; 0-1 µM) to assess neuroprotective effects. Direct effects of each terpene on Aß fibril formation and aggregation were also evaluated using the Thioflavin T (ThT) fluorometric kinetic assay and transmission electron microscopy (TEM) to visualize fibril and aggregate morphology. RESULTS: Terpenes were intrinsically benign to PC12 cells up to 50 µM, with higher concentrations of ß-caryophyllene, humulene and nerolidol inducing some loss of PC12 cell viability. No significant protective effects of terpenes were observed following t-BHP (0-200 µM) administration, with some enhanced toxicity instead demonstrated from both ß-caryophyllene and humulene treatment (each at 50 µM). α-pinene and ß-pinene demonstrated a significant neuroprotective effect against amyloid ß exposure. α-pinene, ß-pinene, terpineol, terpinolene and friedelin were associated with a variable inhibition of Aß1-42 fibril and aggregate density. CONCLUSIONS: The outcomes of this study underline a neuroprotective role of α-pinene and ß-pinene against Aß-mediated neurotoxicity associated with an inhibition of Aß1-42 fibrilization and density. This demonstrates the bioactive potential of selected terpenes for consideration in the development of medicinal cannabis formulations targeting neurodegenerative diseases.

Evaluating Cannabis sativa L.'s neuroprotection potential: From bench to bedside.

BACKGROUND: Neurodegenerative diseases and dementia pose a global health challenge in an aging population, exemplified by the increasing incidence and prevalence of its most common form, Alzheimer's disease. Although several approved treatments exist for Alzheimer's disease, they only afford transient symptomatic improvements and are not considered disease-modifying. The psychoactive properties of Cannabis sativa L. have been recognized for thousands of years and now with burgeoning access to medicinal formulations globally, research has turned to re-evaluate cannabis and its myriad phytochemicals as a potential treatment and adjunctive agent for neurodegenerative diseases. PURPOSE: This review evaluated the neuroprotective potential of C. sativa's active constituents for potential therapeutic use in dementia and Alzheimer's disease, based on published studies demonstrating efficacy in experimental preclinical settings associated with neurodegeneration. STUDY DESIGN: Relevant information on the neuroprotective potential of the C. sativa's phytoconstituents in preclinical studies (in vitro, in vivo) were included. The collated information on C. sativa's component bioactivity was organized for therapeutic applications against neurodegenerative diseases. METHODS: The therapeutic use of C. sativa related to Alzheimer's disease relative to known phytocannabinoids and other phytochemical constituents were derived from online databases, including PubMed, Elsevier, The Plant List (TPL, www.theplantlist.org), Science Direct, as well as relevant information on the known pharmacological actions of the listed phytochemicals. RESULTS: Numerous C. sativa -prevalent phytochemicals were evidenced in the body of literature as having efficacy in the treatment of neurodegenerative conditions exemplified by Alzheimer's disease. Several phytocannabinoids, terpenes and select flavonoids demonstrated neuroprotection through a myriad of cellular and molecular pathways, including cannabinoid receptor-mediated, antioxidant and direct anti-aggregatory actions against the pathological toxic hallmark protein in Alzheimer's disease, amyloid ß. CONCLUSIONS: These findings provide strong evidence for a role of cannabis constituents, individually or in combination, as potential neuroprotectants timely to the emergent use of medicinal cannabis as a novel treatment for neurodegenerative diseases. Future randomized and controlled clinical studies are required to substantiate the bioactivities of phytocannabinoids and terpenes and their likely synergies.