Abstract: The essential oils of Osmanthus fragrans var aurantiacus were obtained from different phases by steam distillation,which were analyzed by GC-MS,and the relative content of each component was determined by peak area normalization methods.The antioxidant activity of the essential oils was also investigated through the measurement of 1,1-Diphenyl-2-picrylhydrazyl radical 2,2-Diphenyl-1-(2,4,6-trinitrophenyl)hydrazyl (DPPH) scavenging activity.The results were as follows:there were 29,30,34 and 27 compounds,identified at start of flowering,start of peak season of flowering,peak season of flowering and end of flowering during different flower development stages in Osmanthus fragrans var aurantiacus,respectively.In total,61 components were identified from the volatile oils of four different development phases including terpenes (15),alcohols(15),aldehydes(6),ketones(9),esters(8),alkanes(6),alkyne(1) and oxides cervidaes(1).Only eight common components were detected in four flower phases of Osmanthus fragrans var aurantiacus,in addition,the numbers of special components among four phases were 14,5,5 and 4 components,respectively.Volatile oil from Osmanthus fragrans var aurantiacus showed antioxidant activity,and the capacity of scavenging DPPH radicals of the volatile oils lower than that of Vc at the same mass concentration.

Key words: Osmanthus fragrans var aurantiacus, volatile oil, chemical constituents, GC-MS, antioxidant capacity