Flavonoids from Salix caprea

Abstract

Salix caprea L. (Salicaceae) is widely used in folk medicine for rheumatoid arthritis, malaria, various hemorrhages, gout, neuralgia, and intestinal diseases as an antipyretic, analgesic, anti-inflammatory, antibacterial, hemostatic, sedative, and antihelminthic agent [1, 2].Carbohydrates [3], tanning agents [4], steroids [5], phenolglucosides [6], alkaloids, vitamins [7], phenolcarboxylic acids and their derivatives [8], flavonoids chultenin [3], kaempferol, luteolin, apigenin, naringenin, quercetin, isorhamnetin [9], luteolin 7-O-E-D-glucopyranoside, baccoside, salicaprin [10-12], diosmetin, caperoside, salicaperoside [13, 14], astragalin, quercemeritrin, and quercetin 3,7-di-O-glucoside [15] were isolated from S. caprea.Ground air-dried flowers of S. caprea (1000 g) that were collected in Hotan district of Xinjiang Autonomous Region, P. R. China, were extracted exhaustively with EtOH (70%) at room temperature. The combined extracts were evaporated in vacuo. The condensed residue was diluted with water and treated successively with petroleum ether, ether, EtOAc, and n-BuOH.The EtOAc fraction was separated by HPLC over a Phenomenex ODS-C 18 column (250 u 4.6 mm, 5 Pm) with a C 18 pre-column. Solvents were filtered through a 0.45 Pm filter before use. The mobile phase was MeOH:H 2 O (40:60, v/v) at flow rate 1 mL/min. UV detection was carried out at O 210, 260, 280, and 360 nm (at various recording scales I, II, III, IV). Four compounds (1-4) were eluted from the column with retention times of 15, 43, 64, and 70 min, respectively.Pure compounds were identified using UV, IR, PMR, and 13 C NMR spectra as astragalin (1) [15, 16], quercimeritrin (2) [15, 17], isorhamnetin-7-O-E-D-glucoside (3) [18], and isoquercitrin (4) [19]. Astragalin (1), C 21 H 20 O 11 , mp 177-179°C. UV spectrum (MeOH, O max , nm): 268, 301, 360; +AlCl 3 : 272, 304, 398; +AlCl 3 /HCl: 277, 302, 350, 398; +CH 3 COONa: 278, 370. Acid hydrolysis of astragalin produced kaempferol and D-glucose. Quercimeritrin (2), C 12 H 20 O 12 , mp 251-253°C. UV spectrum (MeOH, O max , nm): 260, 370; +CH 3 COONa: 260, 371. Acid hydrolysis of 2 produced quercetin and D-glucose. Isorhamnetin-7-O-E-D-glucoside (3), C 22 H 22 O 12 , mp 255-257°C. UV spectrum (MeOH, O max , nm): 257, 372; +CH 3 COONa: 257, 374. IR spectrum (KBr, Q, cm -1 ): 3308,

The effects of leaf extracts of crack willow (Salix fragilis) on the growth of Japanese knotweed (Fallopia japonica)

“…However, negative effects of willows on neighbouring plants (inhibited growth) were also reported due to shading, competition for mineral nutrients and allelopathy. At least 12 phenolic allelochemicals were detected in leaves of goat willow (Salix caprea) (Ikonen et al 2002, Hallgren et al 2003, Moohammadnor et al 2010. In some areas, crack willow (Salix fragilis) is even considered invasive (Cremer 2003).…”