Neuroprotective potential of hydroalcoholic extracts of Juniperus species

The genus Juniperus (Cupressaceae), one of the most diverse of the conifers, comprises approximately 75 species of evergreen aromatic shrubs or trees native to northern hemisphere. Juniperus species have been widely used as herbal medicine from ancient time [1],[2]. The present study aimed to evaluate antioxidant and acetylcholinesterase (AChE) inhibitory activities as well as ex vivo neuroprotective effect of hydroalcoholic extracts of leaves and branches of three Juniperus species (J. communis L., J. oxycedrus L. and J. phoenicea L.) growing wild in Croatia. All tested Juniperus extracts were rich in polyphenols (3.0-3.9%). They possessed DPPH (IC50: 3-6 μg/mL) and nitric oxide (IC50: 115-186 μg/mL) free radical scavenging activities, ferric reducing properties (IC50: 14-22 μg/mL) and ability to inhibit lipid peroxidation (IC50: 51-60 μg/mL). The most potent inhibitory activity against AChE showed J. phoenicea and J. oxycedrus (IC50: 42 μg/mL and 72 μg/mL, respectively). Neuroprotection induced by extract treatment was evaluated in a model of cortical spreading depression described as a potential triggering mechanism in migraine. The extracts of J. communis and J. oxycedrus (800 µg/mL) significantly blunted K+ 60mM-induced decrease of serotonin turnover, evaluated as 5-HIAA/5-HT ratio in isolated rat cortex. The brine shrimp lethality assay showed that Juniperus extracts at the concentrations up to 800 μg/mL have no toxicity. Our results highlighted the potential for further in vivo research in order to confirm the protective effects of Juniperus species in neurological diseases characterized by increased burden of oxidative stress.