Phytochemical Study of Bergenia crassifolia
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PHYTOCHEMICAL STUDY OF Bergenia crassifolia
Zh. Akzhigitova,1 M. A. Dyusebaeva,1 T. Tokay,2 A. Ydyrys,1 Xuan Lijiang,3 and J. Jenis1*
Bergenia crassifolia (L.) Fritsch. (Saxifragaceae, Order Rosales) is commonly known as badan, Siberian tea, Mongolian tea, leather bergenia, or elephant’s ears [1]. The plant is broadly distributed in Siberia and Primorsky Krai and forms dense thickets, sometimes covering hundreds of hectares [2]. It is distributed in Mongolia in Khubsugul, Khentii, Khangai, and Mongolian Altai. It is widely employed as a decorative plant in the Northwest, central Russia, and Kazakhstan [3]. In continuation of our research [4–6], herein we communicate results from phytochemical studies of the BuOH fraction of roots of B. crassifolia (L.) collected in August 2018 in East Kazakhstan Region. Extraction and Isolation. Ground air-dried roots of B. crassifolia (900 g) were extracted (3×) with aqueous EtOH (70%) at room temperature for 3 d. The combined extract was concentrated and extracted sequentially with hexane, CHCl3, and n-BuOH. The BuOH fraction of B. crassifolia roots was separated over a column of HP-20 Sephadex with elution by MeOH–H2O (9:1) to produce fractions F1 (3.2 g) and F2 (2.3 g). Fraction F1 was flash chromatographed over an ODS column (MeOH–H2O), the subfractions of which were separated by preparative HPLC to produce six flavonoids: 1 (1.7 mg), 2 (3.2 mg), 3 (2.7 mg), 4 (1.7 mg), 5 (1.6 mg), and 6 (2.7 mg). Fraction F2 was flash chromatographed over an ODS column (MeOH–H2O). The subfractions were purified using a column of silica gel to produce two flavonoids 7 (2.8 mg) and 8 (3.3 mg). The structures of the isolated compounds were elucidated using NMR spectroscopy [7, 8]. The compounds were identified as follows based on the obtained spectra and comparisons with literature data. Kaempferol-3-O-glycoside (Astragalin) (1). C21H20O11, yellow powder. 1Í NMR spectrum (400 MHz, CD3OD, δ, ppm, J/Hz): 8.03 (2H, d, J = 8.3, H-2′, 6′), 6.87 (2H, d, J = 8.3, H-3′, 5′), 6.36 (1H, d, J = 1.8, H-8), 6.17 (1H, d, J = 1.8, H-6), 5.24 (1H, d, J = 7.6, Í-1′′), 3.68 (1H, dd, J = 12.1, 2.4, H-6a′′), 3.50 (1H, dd, J = 12.1, 5.5, H-6b′′), 3.22–3.48 (4H, m, Í-2′′–5′′). 13C NMR spectrum (100 MHz, CD3OD, δ, ppm): 179.1 (C-4), 165.2 (C-7), 162.7 (C-5), 161.0 (C-4′), 158.0 (C-9), 158.2 (C-2), 135.3 (C-3), 132.2 (C-2′, 6′), 122.6 (C-1′), 115.9 (C-3′, 5′), 105.6 (C-10′), 104.0 (C-1′′), 99.4 (C-6), 94.1 (C-8), 78.5 (C-3′′), 77.3 (C-5′′), 75.6 (C-2′′), 71.2 (C-4′′), 62.4 (C-6′′). ESI-MS, m/z 447.4 [M – H]– [9]. 7-Methoxykaempferol-3-O-glycoside (Rhamnocitrin-3-O-glycoside) (2). C22H22O11, yellow powder. 1Í NMR spectrum (400 MHz, CD3OD, δ, ppm, J/Hz): 8.03 (2H, d, J = 8.3, H-2′, 6′), 6.87 (2H, d, J = 8.3, H-3′, 5′), 6.56 (1H, d, J = 1.8, H-8), 6.37 (1H, d, J = 1.8, H-6), 5.24 (1H, d, J = 6.1, Í-1′′), 3.8 (3Í, s, H-7), 3.70 (1H, dd, J = 12.0, 2.3, H-6a′′), 3.54 (1H, dd, J = 12.0, 5.0, H-6b′′), 3.19–3.48 (4Í, m, Í-2′′–5′′). 13C NMR spectrum (100 MHz, CD3OD, δ, ppm): 178.2 (C-4), 165.5 (C-7), 161.5 (C-5), 160.3 (C-4′),
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