Acylglycosides and Acylquinic Acids from Roots of Panax ginseng
- PDF / 164,903 Bytes
- 4 Pages / 594 x 792 pts Page_size
- 85 Downloads / 172 Views
ACYLGLYCOSIDES AND ACYLQUINIC ACIDS FROM ROOTS OF Panax ginseng
D. N. Olennikov
Glucose esters of sinapic and ferulic acids including a novel O-acylglycoside (1) and coumaroyl- and feruloylquinic acids were found for the first time in roots of Panax ginseng C. A. Mey. (Araliaceae). Compound 1 was 4-O-sinapoyl-α/β-D-glucopyranose according to UV and NMR spectroscopic and mass spectrometric data. A comparison of the biological activities of the isolated compounds found high antiradical activity (IC50 36.79–37.75 μM) for the sinapic-acid derivatives. Keywords: Panax ginseng, Araliaceae, acylglycosides, acylquinic acids, antiradical activity. Panax ginseng C. A. Mey. is one of the most studied plant species in the family Araliaceae. Many investigations found that P. ginseng roots are a source of biologically active triterpenoids [1] and polysaccharides [2]. The chemical composition of phenolic compounds from this species is inadequately studied. Hydroxycinnamic [3] and benzoic acids [4] and flavonoid aglycons [3] and catechins [5] have been reported. In continuation of studies of phenolic compounds from Panax species [6], results from studies of phenolic constituents possessing antioxidant activity from the EtOAc fraction of cultivated P. ginseng are reported herein. The EtOAc fraction had the greatest antioxidant activity among fractions obtained from the EtOH extract of fresh P. ginseng roots. Its constituents were separated using column chromatography (CC) over polyamide, Sephadex LH-20, and silica gel and preparative HPLC. A total of 11 compounds were isolated including the new O-acylglycoside 1 and 10 known compounds that were identified using UV and NMR spectroscopy and mass spectrometry as 1-O-sinapoylglucose (2) [7], 2-O-sinapoylglucose (3) [8], 6-O-sinapoylglucose (4) [9], 1-O-feruloylglucose (5) [10], 2-O-feruloylglucose (6) [11], 4-O-feruloylglucose (7) [10], 6-O-feruloylglucose (8) [10], 5-O-cumaroylquinic acid (9) [12], 4-O-feruloylquinic acid (10) [13], and 5-O-feruloylquinic acid (11) [14]. Hydroxycinnamate 11 was found in P. vietnamensis Ha et. Grushv. [6]. However, compounds 2–11 were isolated from P. ginseng for the first time. Compound 1 had the formula C17H22O10 according to mass spectrometry (m/z 385.5211 [M – H]–, calcd 385.3170) 13 and C NMR spectroscopy. The mass spectrum (ESI-MS) contained peaks for the deprotonated molecule (m/z 385) and a fragment with m/z 223 that was indicative of the loss of hexose [(M – H) – C6H10O5]–. Acid hydrolysis in TFA (2 M) produced sinapic acid [7] and D-glucose, which was characteristic of O-sinapoyl glucosides. The PMR and 13C NMR spectra showed two similar sets of resonances of high and low intensity that were assigned to the β- and α-isomers of 1, respectively. The intensity ratio of resonances for anomeric protons of the β- (δH 4.51 ppm) and α-isomers (δH 5.21 ppm) in the PMR spectrum was 15.1:1, which was close to that (14.8:1) for resonances of the anomeric C atoms of the β- (δC 99.3 ppm) and α-isomers (δC 93.5 ppm) in the 13C NMR spectrum. Weak-field shi
Data Loading...
