# Deposition Efficacy of Natural and Synthetic Antioxidants on Fabrics
## 3 Results and Discussion
### Structural Aspects of Pine Tannin  
The structural characterisation of the tannins consisted of the determination of the distribution of molecular weights by means of gel permeation chromatography (GPC), the total phenol content by spectrophotometry using the Folin-Ciocalteau test [41], \({}^{31}\)P NMR analysis of the different phenolic groups and the proanthocyanidin content of pine tannins using the Scalbert method [42]. In view of the fact that selected properties, i.e., antioxidant activities, of natural resources that render them potential natural active ingredients to be used in the target products are significantly correlated with their prevailing structural features [46; 47; 48; 49; 50; 51; 52; 53; 54], polyphenic and proanthocyanidin's features of pine tannins are crucial aspects to know for an overall data interpretation. Selected structural data related to the characterisation of different pine bark extracts are summarised in Tables 1 and 2. Tannins arising from extraction using both aqueous acetone and sulphite-containing water exhibit mean average molecular weights (Mn) of around 500 Da. The results indicated that both extraction methods are suitable for extracting tannins with comparable molecular weight from the bark matrix but with different content of phenols and condensed tannins, higher in the case of **PTT-AW1** (Table 1, entry 2). \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Entry** & **Pine Tannin** & **Extraction** & \begin{tabular}{c} **Mn** \\ **[Da]\({}^{\text{[a]}}\)** \\ \end{tabular} & \
\begin{tabular}{c} **Total Phenolic Content** \\ **[mg GAE/mg PT]\({}^{\text{[b]}}\)** \\ \end{tabular} &
\begin{tabular}{c} **Proanthocyanidin** \\ **Content [mg CyE/g]\({}^{\text{[c]}}\)** \\ \end{tabular} \\ \hline
1 & **PST-sW1** & water/2\%NaHSO3 & 500 & 0.15 & 22 \\
2 & **PTT-AW1** & acetone/water & 530 & 0.23 & 43 \\ \hline \({}^{\text{[a]}}\) Determined by GPC in THF after acetobromination of the sample; results reflect the soluble part. Numbers in square brackets represent exact molecular weight; \({}^{\text{[b]}}\) Determined by Folin–Ciocalteau test; \({}^{\text{[c]}}\) Determined by Scalbert test. & & \\ \end{tabular}
\end{table} 
Table 1: Structural characteristics obtained for pine tannins (**PT**). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**OH-Group/Motif** & **Integration Range [ppm]** & \multicolumn{2}{c}{**Av. Abundance [mmol g\({}^{-1}\)]**} \\ \cline{3-4}  & & & **PTT-sW1\({}^{\text{[a]}}\)** & **PTT-AW1** \\ \hline
**aliphatic** & 145.94–145.25 & 3.11 \(\pm\) 0.5 & 2.22 \(\pm\) 0.2 \\ _ortho_-disubstututed OH & 142.46–141.06 & 0.56 \(\pm\) 0.5 & 0.77 \(\pm\) 0.2 \\ gallo/epigallocatechin & 142.46–141.87 & 1.22 \(\pm\) 0.5 & 0.39 \(\pm\) 0.2 \\ gallate & 141.47–141.05 & 0.01 \(\pm\) 0.5 & 0.12 \(\pm\) 0.2 \\ _ortho_-substituted OH & 140.60–137.60 & 1.00 \(\pm\) 0.5 & 1.66 \(\pm\) 0.2 \\ catechol & 140.20–138.30 & 0.89 \(\pm\) 0.5 & 0.72 \(\pm\) 0.2 \\ non-catechols & 138.80–137.60 & 0.44 \(\pm\) 0.5 & 0.91 \(\pm\) 0.2 \\ _ortho_-unsubstituted OH & 137.60–137.40 & 0.11 \(\pm\) 0.5 & 0.79 \(\pm\) 0.2 \\ acidic & 135.50–134.00 & 0.44 \(\pm\) 0.5 & 0.82 \(\pm\) 0.2 \\ \hline \hline \end{tabular} \({}^{\text{[a]}}\) Sample only scarcely soluble under standardised analysis conditions, approx. 10–15% of the sample was adequately solubilised.  
\end{table} 
Table 2: Averaged quantitative structural characteristics obtained for pine bark extracts of by quantitative \({}^{31}\)P NMR. The \({}^{31}\)P NMR spectra (Figure 1A and data (Table 2)) reveal that pine tannins are essentially comprised of catechin/epicatechin units, with some gallocatechin/epigallocatechin moieties as well as gallates incorporated. Figure 1B shows a representative structure of the main composition, in which the GPC-derived data regarding the number average molecular weight (Mn) were used for estimating an average degree of polymerisation (DP) equal to three.