LAUSR

Medicinal plants growing in the Russian Far East have been used since antiquity in folk medicine to treat gastrointestinal, cardiovascular, and other diseases [1, 2]. The potential for using such plants in official medicine [3] is limited because of incomplete knowledge of their chemical compositions. Synurus deltoides (Aiton) Nakai (Asteraceae) is one such poorly studied plant that possesses anti-inflammatory, antioxidant, diuretic, and analgesic properties [4–6] and is used in folk medicine as an antiscrofulous agent [1]. Roots of S. deltoides contained the triterpenoids lupeol, ursolic acid, α-amyrin, and β-amyrin with broad spectra of pharmacological activity [7–9]. Therefore, this plant can be considered a promising source of biologically active compounds (in particular, flavonoids) required for the pharmaceutical industry. Air-dried ground inflorescences (50 g) of S. deltoides that were collected in Primorsky Krai in the vicinity of Tavrichanka, Nadezhdinskii District, were extracted by refluxing EtOH (70%, 300 mL) on a boiling-water bath for 1.5 h. The resulting extract was evaporated to a watery residue that was worked up successively with CCl4, EtOAc, and n-BuOH. The BuOH fraction was evaporated to dryness and chromatographed over a column of silica gel using CCl4–EtOH with increasing EtOH content from 0 to 100%. Four yellow crystalline compounds were isolated from the extract of S. deltoides inflorescences. They were classified as flavonoids based on UV spectra because of absorption maxima characteristic of flavonols and flavones at 250–270 and 330–360 nm. Flavonoid 1. C22H22O12, ESI-MS, m/z 477.4032 [M – H] –. 1Í NMR spectrum (400 MHz, CD3OD, δ, ppm, J/Hz): 3.51–3.58 (4H, m, H-2′′, 3′′, 4′′, 5′′), 3.80 (3H, s, OCH3), 3.95 (1H, dd, J = 10.6, 1.8, H-6′′), 4.89 (1H, d, J = 7.3, H-1′′), 6.19 (1H, d, J = 2.1, H-6), 6.43 (1H, d, J = 2.1, H-8), 6.97 (1H, d, J = 8.6, H-5′), 7.75 (1H, dd, J = 8.6, 2.1, H-6′), 8.00 (1H, d, J = 2.1, Í-2′). 13C NMR spectrum (100 MHz, CD3OD, δ, ppm): 157.2 (C, C-2), 139.7 (C, C-3), 180.0 (C, C-4), 163.0 (C, C-5), 99.8 (CH, C-6), 166.0 (C, C-7), 94.9 (CH, C-8), 158.3 (C, C-9), 105.9 (C, C-10), 125.8 (C, C-1′), 117.4 (CH, C-2′), 146.7 (C, C-3′), 151.5 (C, C-4′), 118.7 (CH, C-5′), 123.1 (CH, C-6′), 104.3 (CH, C-1′′), 74.8 (CH, C-2′′), 77.5 (CH, C-3′′), 71.3 (CH, C-4′′), 78.4 (CH, C-5′′), 62.4 (CH2, C-6′′), 60.7 (OCH3). A comparison of the 13C NMR chemical shifts with the literature indicated that the aglycon in the flavonoid was quercetin [10, 11]. A methoxy resonance in the PMR spectrum of the flavonoid at 3.80 ppm (s) was located on C-3 according to a 1H–13C HMBC experiment so that the aglycon was 3-methylquercetin. The 13C NMR spectrum in the range 62–78 ppm showed characteristic resonances for the D-glucopyranose fragment (the absolute D-configuration of the carbohydrate was determined from its specific optical rotation) in the flavonoid [11, 12]. PMR data (for the anomeric proton, 4.89 ppm, 7.3 Hz) confirmed that the flavonoid contained a β-D-glucopyranoside. Correlations between the anomeric proton H-1′′ and C-3′ in the 1H–13C HMBC spectrum indicated that the flavonoid carbohydrate fragment was situated on C-3′ so that the isolated flavonoid was methyl quercetin-3′-O-β-D-glucopyranoside [13]. Flavonoid 2. C22H22O12. ESI-MS, m/z 477.4033 [M – H] –. 1Í NMR spectrum (400 MHz, CD3OD, δ, ppm, J/Hz): 3.51–3.58 (4H, m, H-2′′, 3′′, 4′′, 5′′), 3.79 (3H, s, OCH3), 3.95 (1H, dd, J = 10.6, 1.8, H-6′′), 4.87 (1H, d, J = 7.3, H-1′′), 6.17 (1H, d, J = 2.1, H-6), 6.38 (1H, d, J = 2.1, H-8), 7.29 (1H, d, J = 8.6, H-5′), 7.57 (1H, dd, J = 8.5, 2.1, H-6′), 7.62 (1H, d, J = 2.1, Í-2′). 13C NMR spectrum (100 MHz, CD3OD, δ, ppm): 157.0 (C, C-2), 140.1 (C, C-3), 179.9 (C, C-4), 162.9 (C, C-5), 99.9 (CH, C-6), 165.9 (C, C-7), 94.8 (CH, C-8), 158.3 (C, C-9), 105.9 (C, C-10), 126.3 (C, C-1′), 117.0 (CH, C-2′), 147.9