## 3 Results and Discussion
### Docking Studies
The highest interactions are evident from six hydrogen bonds from Tyr161, Lys190, Pro113 and Glu141 and other carbon-hydrogen and pi-donor hydrogen bond interactions from Arg186, Ser193 and Leu115. Besides, it forms pi-alkyl (Arg186 and Leu115) and pi-sigma interactions with HSA (Leu115). Protocatechuic acid (3, 4-dihydroxybenzoic acid) was identified only in 'Bidan' cultivar and has shown \(-\)90.03 as dock score and \(-\)69.0 kcal/mol as binding energy. It formed one conventional hydrogen bond interaction with Leu154, pi-donor hydrogen bond with Tyr161 and van der Waals interaction with Leu139. The other scaffold stabilizing interactions such as pi-pi stacked (Tyr138), amide-pi stacked (Tyr138) and pi-alkyl (Ala158) were also observed. From persimmon 'Fuyu' extract six compounds were identified such as gallic, vanillic and caffeic acids, epicatechin, kaempfer, and quercetin (Table 4). Among them, caffeic acid, kaempfer, and quercetin are reported for kiwifruit varieties. Quercetin and kaempfer have achieved high binding affinity with HSA with the dock score of \(-\)163 and \(-\)138.14, respectively [4; 5]. The ligand epicatechin has a dock score of \(-\)138.14, binding energy of \(-\)106.3 kcal/mol, van der Waals energy of \(-\)102.8 and the highest H-bond energy of \(-\)3.4, which might have favored the interaction with HSA (Table 4). Comparing the docking results, it was observed that the 'Bidan' cultivar among the kiwifruit has the maximum binding affinity with HSA and it is in good agreement with the fluorescence experiments where it showed the highest percentage of binding (51%) with HSA. All the kiwifruit cultivars (used in the current study) have hesperidin and quercetin ligands, which were predicted with high docking and binding energy values among all the ligands. Although, 'Bidan' shares similar ligands with 'Cheongsan', it possesses the distinct ligand named protocatechuic acid, which might have played a significant role in enhancing the binding affinity of the ligands to HSA receptor. Hence, 'Bidan' cultivar might have shown the highest binding in the fluorescence experiments. Interestingly, kaempfer and rutin are absent in 'Cheongsan'. However, 'Hayward' and 'Fuyu' have shown the least interaction with HSA in fluorescence results. HSA, a globular protein of 585 amino acids, comprises three homologous domains: I (5-197 residues), II (198-382 residues) and III (495-585 residues). Each domain has been further subdivided in to subdomain A and B (IA, IB, IIA, IIB, IIIA and IIIB). HSA has been reported to bind to a wide range of ligands at multiple sites with different binding affinities. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & & & & \multicolumn{3}{c}{**HSA + Persimmon’Fuyu’**} \\ \cline{4-7}
**S. No** & **PubChem ID** & **Compounds** & **BE** & **DS** & **VDW** & **HB** \\ \hline
1 & 370 & Gallic acid & \(-\)72 & \(-\)95.4 & \(-\)68.7 & \(-\)3.2 \\
2 & 72276 & Epicatechin & \(-\)103.2 & \(-\)137.4 & \(-\)92.6 & \(-\)10.4 \\
3 & 5280863 & Kaempfer & \(-\)106.3 & \(-\)138.14 & \(-\)102.8 & \(-\)3.4 \\
4 & 8468 & Vanillic acid & \(-\)71.6 & \(-\)95.25 & \(-\)68.1 & \(-\)3.4 \\
5 & 689043 & Caffeic acid & \(-\)75.0 & \(-\)99.36 & \(-\)71.5 & \(-\)3.5 \\
6 & 5280343 & Quercetin & \(-\)116.8 & \(-\)163 & \(-\)106.2 & \(-\)10.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The ligands from persimmon ’Fuyu’ showing interaction with HSA represented with binding energy (BE), dock score (DS), van der Waals (VDW) and H-bond (HB) energy. From our docking analysis, it is apparent that all the ligands identified from kiwifruit and persimmon extracts have binding pockets in domain I of HSA. These results were in accordance with other investigations. Molecular docking showed that (-)-epigallocatechin-3-gallate (EGCG) mainly bound to subdomain IIA and IIIA Results of competitive binding experiments confirmed that the location of EGCG binding in BSA was site I [40,49]. Molecular docking analysis highlighted that GA binds at Sudlow site I of BSA and binding of GA at site I of BSA is stable [48].