Shikonin derivatives from the roots of Onosma nigricaule (Boraginaceae)

The genus Onosma (Boraginaceae) is represented by 87 species in Turkey [1]. The roots of some Onosma species are used for wound healing and burns [2,3] in Turkey. Onosma nigricaule is an endemic species for Turkey [1] and its roots are used for wound healing and burns in Erzurum Province. In this sudy, the roots of O. nigricaule (500g) were extracted with n-hexane:dichloromethane (1:1) (2L x 3) and then filtered. The filtrate was evaporated at 40°C. Three shikonin derivatives (deoxyshikonin (1), β,β-dimethylacryl shikonin (2), and acetyl shikonin (3)) were isolated from this extract by using several chromatographic methods. The structures of the pure compounds were elucidated by using ¹H-NMR and ¹³C-NMR Spectroscopy, and ESI-MS.

Acknowledgements: The authors would like to thank Prof. Dr. Mehmet Koyuncu (Ankara University, Faculty of Pharmacy, Department of Pharmaceutical Botany, Ankara) for identification of the plant material.

References: 1. Riedl H. (1978) Onosma L. Flora of Turkey and the East Aegean Islands. Vol. 6, pp. 326–376. Edinburgh University Press, UK.

2. Ozgen U., Ikbal M., Hacimuftuoglu A., Houghton P.J., Gocer F., Dogan H., Coskun M. (2006)J. Ethnopharmacol. 104:100–103.

3. Cadirci E., Suleyman H., Aksoy H., Halici Z., Ozgen U., Koc A., Ozturk N. (2007) Chem. Biol. Interact. 170(1):40–48.