Antinociceptive effect of citronellal in mice.

Citronellal is a monoterpene reported to be a major component of the essential oils in various aromatic species of plants. The present study evaluated the central nervous system depressant and antinociceptive properties of citronellal through behavioral experimental models. Following intraperitoneal injection, citronellal induced the reduction of spontaneous activity, ataxia, analgesia, and sedation. In pentobarbital-induced hypnosis, CTL (citronellal) at 50, 100, and 200 mg/kg (i.p.) significantly increased sleeping time (88.0 +/- 11.4, 100.2 +/- 16.4, and 119.5 +/- 20.9 min) when compared to vehicle solution injections (43.0 +/- 6.1). Citronellal (100 and 200 mg/kg, i.p.) significantly reduced the number of writhes (66.4 and 81.9%) in a writhing test and the number of paw licks during phase 1 (47.0 and 66.8%) and phase 2 (71.1 and 79.2%) of a formalin test when compared to control group animals. In addition, the results of a hot plate test showed central analgesic properties for citronellal (p < 0.05). These results indicate depressant, hypnotic, and antinociceptive properties of this monoterpene.