Chemical composition of Artemisia hippolyti

Abstract

Artemisia hippolyti A. But. sp. n. is an endemic species that grows on stony peaks in the Betpak-Dala desert and the southern part of Karaganda Province, Republic of Kazakhstan. The species A. hippolyti is similar to A. glabella Kar. et Kir. but differs sharply from the latter by the tomentose downiness of the leaves, the external spathe leaflets, and the thalamus shape. These species under natural conditions grow together but develop asynchronously because A. glabella flowers and fruits somewhat earlier than A. hippolyti [1]. We studied the constituent composition of the essential oil, determined the qualitative and quantitative contents of sesquiterpene lactones of A. hippolyti, and compared these results with those obtained earlier by us for A. glabella because these species were similar botanically. Raw material (flower heads, leaves, buds) of A. hippolyti was collected during flowering in the vicinity of Pystan mountain, Zhana-arkin Region, Karaganda Province. Essential oil was obtained by steam distillation of air-dried aerial part of the raw material in a Clevenger apparatus for 3 h. The qualitative composition and quantitative content of the constituents in essential oil were analyzed by GC-MS on an Agilent 7890/5975C GC with a mass-selective detector using an HP-5MS 5% Phenyl Methyl Silox column (30 m 0.25 mm) with He carrier gas flow rate 1 mL/min and vaporizer temperature 230°C. The GC column was held at 40°C for 5 min with the temperature programmed to 240°C at 5°C/min and then held isothermally for 10 min. Samples were introduced by flow division with sample volume 0.2 L. The mass spectra recording conditions were 70 eV and mass range m/z 10–350. The percent contents of constituents were calculated automatically from the peak areas of the total-ion chromatogram. Constituents were identified by mass spectra and RT using the Wiley GC/MS library. Essential oil of A. hippolyti had a pleasant aroma and was a blue liquid (yield 0.15%) (Table 1). According to previous results [2], essential oil of A. glabella contained quantitatively 1,8-cineol ~12%; linalool, up to 8%; terpineol-4, 6.5; and -terpineol, 5. Therefore, the constituent compositions of essential oils of both species were similar but differed in the quantitative contents of the main constituents with the minor constituents differing both qualitatively and quantitatively. Finely ground aerial part of A. hippolyti was extracted with CHCl 3 (3) for the study of extracted compounds. The obtained extract was evaporated in vacuo in a rotary evaporator. HPLC of the CHCl 3 extract detected the sesquiterpene lactones arglabin, ludartin, isoepoxyestafiatin, hanphyllin, and artefin, the quantitative contents of which were 0.103%, 0.012, 0.13, 0.705, and 0.333, respectively, calculated as air-dried raw material. These sesquiterpene lactones were identified for the first time from this species. Qualitative and quantitative analyses of the extract of A. hippolyti were performed by reversed-phase HPLC on a Hewlett–Packard Agilent 1100 Series instrument in isocratic mode with an analytical column packed with Zorbax CB-C 18 sorbent (9.4 250 mm, 5 m), mobile phase MeCN:H 2 O (50:50), detection at 204 nm, column at room temperature, mobile phase flow rate 1.5 mL/min, and injected sample volume 20 L. The quantitative contents of the samples (%) were determined by comparison with an internal standard. The data were processed using ChemStation software. The sesquiterpene lactones arglabin, ludartin, isoepoxyestafiatin, hanphyllin, and artefin were isolated as a result of the study. According to data previously obtained by us [3], A. glabella contained 0.34, 0.008, and 0.0007% of arglabin, argolide, and ketopelenolide B, respectively. A comparison of A. hippolyti and A. glabella found a difference in the qualitative composition of sesquiterpene lactones. However, arglabin was present in both species although its content in A. hippolyti was significantly less than in A. glabella.