ABSTRACT
ObjectiveTo study the composition of volatile oil in Opisthopappus taihangensis （Taihangju）， and provide a reference for comprehensive development of this medicine. MethodTaking Chrysanthemum morifolium （Xiaobaiju）， C. morifolium （Xiaohuangju） and C. indicum （Yejuhua） as control， the qualitative and quantitative analysis of volatile oil in Taihangju and three control varieties were completed by gas chromatography-mass spectrometry （GC-MS） combined with retention index method. The GC conditions were as following：programmed temperature （initial temperature at 60 ℃， kept for 2 min； up to 120 ℃ with the heating rate of 5 ℃·min-1， still kept for 2 min； up to 180 ℃ with the heating rate of 2 ℃·min-1， kept for 3 min； and then up to 240 ℃ with the heating rate of 8 ℃·min-1， kept for 5 min； finally up to 280 ℃ with the heating rate of 10 ℃·min-1， kept it for 5 min and finished）， high-purity helium as the carrier gas， the split ratio of 50∶1. MS conditions were as follows：electron impact ion source （EI）， ion source temperature of 230 ℃， electron collision energy of 70 eV and scanning range of m/z 30-445. Principal component analysis （PCA） and orthogonal partial least squares-discriminant analysis （OPLS-DA） were used to obtain the characteristic components between Taihangju and the three control varieties. ResultA total of 86， 96， 112 and 109 compounds including 73 common components were identified in Taihangju， Xiaobaiju， Xiaohuangju and Yejuhua， respectively. The contents of volatile components in Taihangju were significantly different from that of the control varieties. In which， the relative contents of α-thujone， eucalyptol and terpinen-4-ol were high in Taihangju， and eucalyptol， camphor and α-terpinyl acetate were the main compositions in the control varieties. In addition， 11 compounds were screened as characteristic components to distinguish Taihangju and the three control varieties by PCA and OPLS-DA， including main differential components of chamazulene and δ-cadinene. ConclusionThe main components of volatile oil in Taihangju includes alcohols， terpenes， ketones and esters with high medicinal value. The accuracy of qualitative analysis of volatile oil is improved by GC-MS combined with retention index method， which provides scientific reference for development and utilization of Taihangju.