Components of lemon essential oil attenuate dementia induced by scopolamine.

The anti-dementia effects of s-limonene and s-perillyl alcohol were observed using the passive avoidance test (PA) and the open field habituation test (OFH). These lemon essential oils showed strong ability to improve memory impaired by scopolamine; however, s-perillyl alcohol relieved the deficit of associative memory in PA only, and did not improve non-associative memory significantly in OFH. Analysis of neurotransmitter concentration in some brain regions on the test day showed that dopamine concentration of the vehicle/scopolamine group was significantly lower than that of the vehicle/vehicle group, but this phenomenon was reversed when s-limonene or s-perillyl alcohol were administered before the injection of scopolamine. Simultaneously, we found that these two lemon essential oil components could inhibit acetylcholinesterase activity in vitro using the Ellman method.