## 4 Discussion  
For the worldwide steady-rate growing chestnut industry, the upgrade provided by this research at sustainably recovering bioactive phyto-complexes from waste/by-products of downstream applications is of great significance: green recovery of bioactive compounds from chestnut shells not only preserves their health properties for food, cosmetics, and pharmaceutical industries but also, importantly, reduces the environmental impact of organic solvents. According to this scientific report, chestnut waste is a valuable economic resource supporting the circular economy concept. This work aimed to investigate some health properties of polyphenolic waste extracts obtained through sustainable and eco-friendly methods for industrial applications. The research focused on water extracts of the outer shell of four chestnut accessions and one maron variety, with emphasis on their phenolic composition, antioxidant activity and antiproliferative effect on normal cells (fibroblasts), and on two colon (RKO and SW48), one breast (MCF7) and one melanoma (B16F10) cancer cell lines. The extraction of phenolic compounds from plant materials has been carried out with organic solvents (methanol, ethanol, acetone, etc.) for years, and it was the same for the chestnut [48; 49]. [PERSON] et al. [50] compared the yields resulting from different extraction methods, with organic solvents (96% n-hexane, acetone, ethyl acetate, ethanol and methanol), with water or with a 2.5% Na2 SO3 aqueous solution heated to 90 \({}^{\circ}\)C for one hour: the yield of extractable compounds increased with the polarity of the solvent and the highest yield corresponded to water. The same authors, studying the influence of extraction conditions (water and different alkaline solutions at 70 and 90 \({}^{\circ}\)C), observed an increase of total phenols and antioxidant activity when the temperature increased. The use of water, alone or combined in hydroalcoholic solutions, is more recent [18; 19; 21; 22], and there are green technologies, like subcritical water extraction, used to maximize the extraction yield and polyphenol content [51], which offer a more economically sustainable \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{4}{c}{**Cold Water Extracts**} \\ \cline{2-5}  & **MURG** & **LOCG** & **ILDP** & **COEV** & **MARRV** \\ \hline
**Fibroblasts** & 367.5 (\(-\)0.096-1.000) & 244.7 (0.598-10.067) & 177.3 (0.370-0.978) & 261.0 (0.049-0.971) & 493.3 (0.562-0.999) \\
**SW48** & 105.7 (\(-\)0.132-0.998) & 132.6 (\(-\)0.153-0.996) & 84.59 (0.100-0.985) & 117.8 (0.003-1.002) & 293.0 (0.535-0.997) \\
**RKO** & 274.7 (\(-\)0.385-1.019) & 82.59 (\(-\)0.024-1.002) & 99.9 (0.034–1.04) & 121.5 (\(-\)0.017-1.000) & 155.4 (0.624-1.005) \\
**MCF7** & 249.5 (0.523-1.073) & 244.7 (0.560–1.067) & 249.3 (0.523-1.166) & 252.8 (0.435-1.023) & 245.9 (0.401-0.990) \\
**B16F10** & 190.8 (\(-\)0.077-0.994) & 153.9 (0.065-1.062) & 124.4 (0.265-0.989) & 243.8 (\(-\)0.071-1.011) & 147.7 (\(-\)0.040-1.015) \\ \hline \hline \multicolumn{5}{c}{**Hot Water Extracts**} \\ \cline{2-5}  & **MURG** & **LOCG** & **ILDP** & **COEV** & **MARRV** \\ \hline
**Fibroblasts** & 118.1 (0.586-1.001) & \(>\)500 & \(>\)500 & \(>\)500 & \(>\)500 \\
**SW48** & 215.4 (0.014-1.000) & 249.3 (0.423-1.084) & 112.4 (0.119–1.015) & 129.1 (0.097-1.102) & 345.8 (0.296-0.995) \\
**RKO** & 151.3 (0.220–1.061) & 199.8 (0.256–1.200) & 264.4 (0.383-1.106) & 183.5 (0.071–1.019) & 253.1 (0.482-1.001) \\
**MCF7** & 259.6 (0.276–1.009) & -500 & -500 & 264.8 (0.424-1.055) & 243.7 (0.125–1.008) \\
**B16F10** & 268.4 (0.787–1.048) & 209.5 (0.458–0.983) & 249.1 (0.912–1.052) & 182.6 (0.256–1.046) & 231.4 (0.195-0.981) \\ \hline \hline \end{tabular}
\end{table} 
Table 6: GI50 values for ILDP, MURG, COEV, LOCG and MARRV cold and hot water extracts in fibroblasts, SW48, RKO, MCF7 and B16F10 cells. and environmentally friendly alternative for large-scale industrial applications.