Comparative analysis of two species of Asari Radix et Rhizoma by electronic nose, headspace GC-MS and chemometrics.

Traditional Chinese medicines (TCM) can be identified by experts according to their odors. However, the identification of these medicines is subjective and requires long-term experience. In this paper, electronic nose, headspace gas chromatography-mass spectrometry (GC-MS) and chemometrics methods were applied to differentiate two species of Asari Radix et Rhizoma by their odors. The samples used were the dried roots and rhizomes of Asarum heterotropoides var. mandshuricum (AH) and Asarum sieboldii (AS). The electronic nose was used to determine the odors of the samples and enabled rapid differentiation of AH and AS when coupled with principal component analysis. Headspace GC-MS was utilized to reveal the differences between the volatile constituents of AH and AS. In all, 54 volatile constituents were identified, and 9 major constituents (eucalyptol, eucarvone, 3,5-dimethoxytoluene, 3,4,5-trimethoxytoluene, methyleugenol, 2,3,5-trimethoxytoluene, croweacin, pentadecane and asaricin) could be used as chemical markers to distinguish these two species. AH contained higher relative contents of eucarvone (1.79-16.76%), 3,5-dimethoxytoluene (6.64-26.52%), 3,4,5-trimethoxytoluene/methyleugenol (6.43-31.67%) and 2,3,5-trimethoxytoluene (1.64-6.66%), whereas AS had higher relative contents of eucalyptol (14.06-24.95%), croweacin (5.64-13.55%), pentadecane (8.44-20.82%) and asaricin (7.03-13.45%). Moreover, AH and AS could be distinguished according to the contents of either all 54 identified volatile constituents or only the 9 major constituents by employing cluster analysis. The proposed method is rapid, simple, eco-friendly and can successfully differentiate these two species of Asari Radix et Rhizoma by their odors.