In the present study, the chemical composition, antinociceptive effect and acute toxicity of essential oils（EOs） of Asarum heterotropoides Fr. Schmidt var. mandshuricum（Maxim.） Kitag.（AHM）, A. sieboldii Miq. var. seoulense Nakai（ASS） and A. himalaicum Hook. f. et Thoms. ex Klotzsch.（AH） were comparatively evaluated. A total of 55 compounds were identified in EOs of AHM, ASS and AH by GC-MS. Methyleugenol（20.16%–62.89%）, safrole（2.67%–32.42%）, 3,5-dimethoxytoluene（2.00%–18.59%） and eucarvone（1.52%–19.16%） were the major constituents of EO of AHM, and methyleugenol（48.35%–61.06%）, eucarvone（11.13%–13.93%） and elemicin（4.79%–11.14%） were the major constituents of EO of ASS. The EO of AH was different from that of AHM and ASS, in which patchouli alcohol（27.42%–51.95%） and elemicin（13.11%–42.23%） were found in a greater amount. Moreover, the antinociceptive effect of EOs of AHM（5.5, 11.0, 16.5 μL/kg） and AH（2.0, 4.0, 6.0 μL/kg） was comparatively assayed in acetic acid-induced writhing, hot plate and formalin tests. The results indicated a weak central, but potent peripheral antinociceptive effect of EO of AHM, and more potent central and peripheral antinociceptive effect of EO of AH. The LD50 of the EOs of AHM and AH were 1.7 and 7.7 mL/kg, respectively. These findings suggest that EOs of AHM and AH possess evident antinociceptive activity and are probably safe within the range of its clinical doses. However, their chemical compositions are quite different. Therefore, AH can be clinically used as an herbal medicinal product with broad analgesic effects, but should not be confused with AHM and ASS used in traditional Chinese medicine.
