Genkwanin and iridoid glycosides from Leonurus turkestanicus

Abstract

Leonurus cardiaca L. (Labiatae) and L. quinquelobatus Gilib. are used in galenics as sedative and hypotensive agents [1]. Two species of Leonurus are indigenous to Uzbekistan, L. turkestanicus V. Krecz. et Kupr. and L. panceroides M. Pop. [2], and are used as medicinal plants instead of the official species. However, the chemical compositions of these plants have not been reported. This prompted us to study L. turkestanicus. The air-dried aerial part of L. turkestanicus (2 kg) that was collected in Kara-Tepe, Tashkent Oblast on June 30, 2007, during flowering was extracted with MeOH (4 14 L). The MeOH extract was evaporated to a thick condensate and dissolved in MeOH (70%, 1 L). The solution was filtered. The filtrate was evaporated to remove completely MeOH. The solution volume was adjusted to 0.5 L with H2O. The aqueous solution was extracted three times with n-BuOH. The n-BuOH extract was evaporated to dryness and dried. The yield of the n-BuOH extract was 63.42 g. The n-BuOH extract was chromatographed over a column of KSK silica gel with elution successively by CHCl3, CHCl3:MeOH (1, 100:1; 2, 50:1; 3, 10:1), and CHCl3:MeOH:H2O (4, 70:12:1). Fractions eluted by CHCl3 and system 1 contained sterols. System 2 eluted flavonoid 1 (40 mg).