Comparative analysis of chemical constituents and contents in volatile oil of Zhizhu pills extracted by different methods

Objective: To research the effects of different extraction methods on the chemical constituents and contents of volatile oil of Zhizhu pills,to provide a reference for studies of substance basis of Chinese compound prescription. Methods: The volatile oil of Zhizhu pills was extracted by steam distillation using two methods. In one method,the extractor was wrapped with black cloth to keep the oil out of the sun light( dark condition oil),while in the other method,the extractor was not wrapped so that the oil was exposed to the sun light( light condition oil). The volatile oil which obtained by the two methods were analyzed by GC-MS. GC conditions were as follows. A Rrestek-5MS capillary column( 30 m × 0. 25 mm × 0. 25 μm) was adopted with the inlet temperature of 250 ℃ under the following heating program. The initial temperature was 0 ℃,kept for 1 min,with 5 ℃ ·min-1heating to130 ℃,kept for 1 min,then 10 ℃ ·min-1heating to 240 ℃,kept for 1 min. The injection volume was 1 μL,the carrier gas was helium,and the split ratio was 1∶ 30. MS analysis conditions were as follows. Ionization mode was EI,the ion source temperature was 200 ℃,the interface temperature was 250 ℃,the electron energy was 70 e V,the ionization voltage was 1. 760 k V and the mass scan range( m / z) was 45-450 amu,the solvent cut time was3. 5 min. Then,the chemical constitutes of volatile oil were identified by data base retrieval and by comparing with mass spectrum data of the reference substance,and the relative amount of each constitute was calculated by area normalization method. Meanwhile,the fried Atractylodes macrocephala Koidz.( Chao Baizhu) and the fried Citrus aurantium L.( Chao Zhishi) volatile oils were adopted for comparison to determine the sources of chemical constitutes in Zhizhu volatile oil. Results: The yields of volatile oil extracted in dark and light conditions were 1. 05% and1. 03%,and fifty-four constitutes and sixty constitutes were identified in both conditions respectively. The main class of constituents were terpenes,as well as alcohols,acids,esters and so on,but the numbers of constitutes were different for each type. Among them,there were forty-six common constitutes in various types of volatile oils,but the relative amount of each constitute was different. There were 10 and 18 constitutes with contents higher than1. 0% under the two conditions which accounted for 82. 96% in dark volatile oil and 76. 17% in light volatile oil,respectively. The most abundant constitute was limonene,and the content of atractylone significantly varied among the samples. Compared with the volatile oil obtained in dark condition,eight constitutes disappeared and 13 constituents appeared in the volatile oil obtained in light condition. The changes of chemical constituents and contents in volatile oil of Zhizhu pills showed that constituent changes for the volatile oil of Zhizhu pills obtained in light condition were mainly attributed to the changes in the constituents of Chao Baizhu volatile oil. Conclusion: No significant differences of yields of volatile oil existed between the two extraction methods,but the chemical constituents and contents were markedly different,especially for the volatile oil of Chao Baizhu in which constituents were unstable in light condition. Thus,it is suggested that changes in the constituents caused by the experimental process should be concerned.