Antioxidant activity and essential oil composition of two Chinese medicines: Dahurian angelica and Alpinia japonica root

Essential oil was isolated from Dahurian angelica and Alpinia japonica root by simultaneous distillation extraction and analysed by gas chromatographymass spectrometry (GC-MS). The most abundant compounds in Dahurian angelica and Alpinia japonica root essential oil were ylangene (22.61%), 2-methyl-3-buten-2-ol (7.10%), (-)-1,7-dimethyl-7-(4-methyl-3-pentenyl)-tricyclo[2.2.1.0(2,6)]heptane (6.82%), (R)-2,4a,5,6,7,8-hexahydro-3,5,5,9tetramethyl-1H-benzocycloheptene (5.33%) and eucalyptol (50.69%), (S)-1-methyl-4-(5-methyl-1-methylene-4-hexenyl)-cyclohexene (4.16%), 2,6-dimethyl-6-(4-methyl-3-pentenyl)-bicyclo[3.1.1]hept-2-ene (3.92%) and caryophyllene (3.38%), respectively. Antioxidant potential of extracts was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2’-azinobis(3-ethylbenzothiozoline-6-sulfonic acid) diammonium salt (ABTS) radical scavenging, and ferric reducing antioxidant power (FRAP) assays. The contents of total phenolic compounds and total flavonoids were determined spectrophotometrically. The results indicated that Alpinia japonica root essential oil contained higher total phenolic and flavonoid contents with 100 ± 5.4 and 30.78 ± 1.86 µg/g, respectively, and Alpinia japonica root essential oil possessed higher antioxidant capacity. On the contrary, the essential oil from Dahurian angelica root had less total phenolic content, total flavonoid content and antioxidant capacity. Phenolic content of these essential oils was significantly correlated with antioxidant capacity.