Chemical Composition and In Vitro Neuroprotective Activity of Fibre-Type Cannabis sativa L. (Hemp)

Background: Fibre-type Cannabis sativa L. (hemp) usually contains cannabidiolic acid and cannabidiol as the main non-psychoactive cannabinoids. Even though there is evidence of the neuroprotective activity of pure cannabidiol, no in vitro studies have reported so far the role of hemp extracts on neuroprotection. The objective of this study was to evaluate the neuroprotective effect of hemp extracts in in vitro cellular models of neurotoxicity. Methods: One extract was obtained from raw hemp inflorescences, while the other was prepared from the same plant material submitted to a decarboxylation process. The composition of both these extracts was evaluated by HPLC-UV/DAD. Human neuroblastoma SH-SY5Y and microglial BV-2 cell lines treated with rotenone were selected as the model of neurodegeneration. The neuroprotection of hemp extracts was assessed also in serum-free conditions both in the presence and in the absence of rotenone as the toxic agent by using the same cell lines. The neuroprotective potential of cannabidiol was tested in parallel. Results: The decarboxylated hemp extract possesses a mild neuroprotective activity on BV-2 cells treated with rotenone, higher than that of pure cannabidiol. As regards serum-free experiments, the nondecarboxylated hemp extract was the most effective neuroprotective agent toward SH-SY5Y cells, while BV-2 cells were better protected from the toxic insult by the decarboxylated extract and cannabidiol. Conclusion: Both hemp extracts and pure cannabidiol displayed a moderate neuroprotective activity in the neurotoxicity models considered in this study; in addition, they showed a trophic effect on SHSY5Y cells.