The aglycone of the ginseng triol-saponins is a PPT, which is a dammarane triterpenoid hydroxylated to C-3, C-12, and C-20 via β-linkage and to C-6 via α-linkage with a double bond between C-24 and C-25. In triol-saponins, sugars are attached to the hydroxyl groups at C-6 and C-20. The ginsenosides Re (1) and 20-gluco-ginsenoside Rf (4) are bisdesmosidic selleck and the ginsenosides Rf (2) and Rg2 (3) are monodesmosidic saponins. The ginsenoside Re (1) has an α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranose
moiety at 6-OH and a β-D-glucopyranose moiety at 20-OH. The 20-gluco-ginsenoside Rf (4) has a sophorose moiety (β-D-glucopyranosyl-(1→2)-β-D-glucopyranose) at 6-OH and a β-D-glucopyranose moiety at 20-OH. The monodesmoside ginsenosides
Rf (2) and Rg2 (3) have sophorose and α-L-rhamnopyranosyl-(1→2)-β-D-glucopyranose moieties, respectively, at selleck kinase inhibitor 6-OH (Fig. 1). The literature has varying assignments for the NMR signals for the hydroxyl group-linked atoms, the methyl carbon atoms, the olefinic carbon atoms, and for protons linked to individual carbon atoms [5], [6], [7], [8], [9], [10], [11], [12], [13], [14] and [15]. This study definitively identified individual proton and carbon signals using the two-dimensional NMR techniques of correlation spectroscopy, nuclear Overhauser effect spectroscopy, heteronuclear single quantum correlation (HSQC), and heteronuclear multiple bond Dapagliflozin connectivity (HMBC). Melting points, specific rotation, IR absorbance, and fast atom bombardment (FAB)/MS data were obtained using standard methods and data were compared to findings in the literature [5], [7], [10], [15], [16], [17], [18], [19], [20] and [21]. The retention factor (Rf) of each saponin in both normal and reverse-phase TLC experiments and the retention time of each ginsenoside by carbohydrate-based HPLC were also determined. Six-year-old fresh ginseng roots were purchased from the Geumsan Ginseng Market in Chungnam,
Korea in October 2007. Kieselgel 60 and LiChroprep RP-18 were used for column chromatography (Merck, Darmstadt, Germany). Kieselgel 60 F254 and RP-18 F254S were used as TLC solid phases (Merck). The former used a mobile phase of CHCl3–methanol (MeOH)–H2O (65:35:10) and the latter used MeOH–H2O (2:1). Detection of substances on TLC plates was by observation under a UV lamp (Spectroline, model ENF-240 C/F; Spectronics Corp., New York, NY, USA) or by spraying developed plates with 10% aqueous H2SO4 followed by heating and observing color development. HPLC was at 50°C and 30 psi using an LC-20A (Shimadzu, Kyoto, Japan) with an evaporative light scattering detector (ELSD; Shimadzu). HPLC analytical columns were Carbohydrate ES (5 μm, 250 × 46 mm; Grace, Deerfield, IL, USA) eluted with step-wise gradients at a flow rate of 0.8 mL/min using solvent A (acetonitrile–H2O–isopropanol = 80:5:15) and solvent B (acetonitrile–H2O–isopropanol = 60:25:15).