The structurally diverse phytocannabinoids cannabichromene, cannabigerol and cannabinol significantly inhibit amyloid -evoked neurotoxicity and changes in cell morphology in PC12 cells

Background: Phytocannabinoids (pCBs) have been shown to inhibit the aggregation and neurotoxicity of the neurotoxic Alzheimer's disease protein beta amyloid (A beta). We characterized the capacity of six pCBscannabichromene (CBC), cannabigerol (CBG), cannabinol (CBN), cannabidivarin (CBDV), cannabidiol (CBD) and Delta(9)-tetrahydrocannabinol (Delta(9)-THC)-to disrupt A beta aggregation and protect against A beta-evoked neurotoxicity in PC12 cells. Methods: Neuroprotection against lipid peroxidation and A beta-induced cytotoxicity was assessed using the MTT assay. Transmission electron microscopy was used to visualize pCB effects on A beta aggregation and fluorescence microscopy, with morphometrics and principal component analysis to assess PC12 cell morphology. Results: CBD inhibited lipid peroxidation with no significant effect on A beta toxicity, whilst CBN, CBDV and CBG provided neuroprotection. CBC, CBG and CBN inhibited A beta 1-42-induced neurotoxicity in PC12 cells, as did Delta(9)-THC, CBD and CBDV. CBC, CBN and CBDV inhibited A beta aggregation, whilst Delta(9)-THC reduced aggregate density. A beta(1-42) induced morphological changes in PC12 cells, including a reduction in neuritic projections and rounded cell morphology. CBC and CBG inhibited this effect, whilst Delta(9)-THC, CBD and CBDV did not alter A beta(1- 42) effects on cell morphology. Conclusions: These findings highlight the neuroprotective activity of CBC, CBG and CBN as novel pCBs associated with variable effects on A beta-evoked neurite damage and inhibition of amyloid beta aggregation.