## 2 Materials and Methods
### Preparative Extraction and Isolation  
A preparative sample (300 g) of the dried and grinded plant material was exhaustively extracted with acetone-water 70:30 (\(v/v\)) at room temperature (22-25 \({}^{\circ}\)C) by mechanical shaking (6 \(\times\) 3 L \(\times\) 8 h). The combined acetone-water extracts were concentrated _in vacuum_ until complete removal of acetone and then extracted with ethyl acetate (6 \(\times\) 100 mL) to remove less polar constituents. The water residue containing the compounds of interest was evaporated to dryness and resolved in boiling methanol (500 mL). After 24 h, the crystallised residue (12 g) containing compounds **1** and **2** was obtained. A portion of the precipitate (0.5 g) was subjected to open column gel permeation chromatography over Sephadex LH-20 and eluted with water. The eluates were monitored by TLC (ethyl acetate : methanol : formic acid, 18:1:1, \(v/v/v\)) on silica gel 60 G precoated plates. The fractions containing the separated analytes were combined and independently re-chromatographed over Sephadex LH-20 to obtain 35 mg of compound **1** and 40 mg of compound **2**, respectively. The replicate rounds of chromatography of two further portions (2 \(\times\) 0.5 g) of the precipitate confirmed the isolation yield of 2.80 mg/g and 3.20 mg/g dry weight (dw) of the plant material, respectively. The purity of the isolates assessed by HPLC-PDA was 97.3% and 98.1%, respectively.  
3\({}^{\prime}\)-dimethoxy-4-sulphoxyellagic acid potassium salt (**1**)--whitish amorphous powder; UV (H\({}_{2}\)O) \(\lambda_{\rm max}\): 245, 350 sh, 362; HR-ESI-TOF-MS: 408.9869 [M-K]\({}^{-}\) (caled. for C\({}_{16}\)H\({}_{9}\)O\({}_{11}\)S, 408.9877), 329.0244 [M-KSO\({}_{3}\)]\({}^{-}\); \({}^{1}\)H and \({}^{13}\)C NMR data (D\({}_{2}\)O): see Table 1.  
3\({}^{\prime}\),4\({}^{\prime}\)-trimethoxy-4-sulphoxyellagic acid potassium salt (**2**)--whitish amorphous powder; UV (H\({}_{2}\)O) \(\lambda_{\rm max}\): 246, 347 sh, 361; HR-ESI-TOF-MS: 423.0009 [M-K]\({}^{-}\) (caled. for C\({}_{17}\)H\({}_{11}\)O\({}_{11}\)S, 423.0022), 343.0397 [M-KSO\({}_{3}\)]\({}^{-}\); \({}^{1}\)H and \({}^{13}\)C NMR data (D\({}_{2}\)O): see Table 1.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Position b**} & \multicolumn{2}{c}{**1**} & \multicolumn{2}{c}{**2**} \\ \cline{2-5}  & \(\delta_{\rm H}\) & \(\delta_{\rm C}\) & \(\delta_{\rm H}\) & \(\delta_{\rm C}\) \\ \hline
**1** & & 116.1 & & 115.5 \\
**2** & & 139.5 \({}^{\rm e}\) & & 139.5 \({}^{\rm c}\) \\
**3** & & 144.8 & & 144.7 \\
**4** & & 144.4 & & 144.7 \\
**5** & 7.8 (1H, \(s\)) & 119.6 & 7.8 (1H, \(s\)) & 119.5 \\
**6** & & 110.0 \({}^{\rm f}\) & & 110.2 \({}^{\rm d}\) \\
**7** & & 159.3 & & 159.0 \\
**1\({}^{\prime}\)** & & 110.5 & & 111.6 \\
**2\({}^{\prime}\)** & & 140.0 \({}^{\rm e}\) & & 139.7 \({}^{\rm c}\) \\
**3\({}^{\prime}\)** & & 140.2 & & 140.8 \\
**4\({}^{\prime}\)** & & 152.2 & & 154.1 \\
**5\({}^{\prime}\)** & 7.0 (1H, \(s\)) & 111.9 & 7.1 (1H, \(s\)) & 107.7 \\
**6\({}^{\prime}\)** & & 111.6 \({}^{\rm f}\) & & 111.2 \({}^{\rm d}\) \\
**7\({}^{\prime}\)** & & 159.3 & & 159.0 \\
**Me-3** & 4.2 (3H, \(s\)) & 62.3 & 4.2 (3H, \(s\)) & 62.4 \\
**Me-3**\({}^{\prime}\)** & 4.1 (3H, \(s\)) & 61.6 & 4.1 (3H, \(s\)) & 61.8 \\
**Me-4** & & & 3.9 (3H, \(s\)) & 56.7 \\ \hline \hline \end{tabular} \({}^{\rm a}\) Data acquired with tetramethylsilane TMS as the internal standard, \(\delta\) in ppm. Multiplicities and coupling constants (in Hz) are given in parentheses. Assignments confirmed by HMQC and HMPC experiments;b For trivial atom numbering, see chemical formulas of **1** and **2**; \({}^{\rm c,d,e,f}\) signals marked with the same superscript letters may be interchanged.  
\end{table}
Table 1: NMR spectral data of compounds 3,3\({}^{\prime}\)-dimethoxy-4-sulphoxyellagic acid potassium salt (**1**) and 3,3\({}^{\prime}\),4\({}^{\prime}\)-trimethoxy-4-sulphoxyellagic acid potassium salt (**2**) in D\({}_{2}\)O (600 MHz for \({}^{1}\)H and 150.9 MHz for \({}^{13}\)C) a.