Interaction of α-synuclein with Rhus typhina tannin - Implication for Parkinson's disease

The etiology of Parkinson's disease (PD) relates to alpha-synuclein, a small protein with the ability to aggregate and form Lewy bodies. One of its prevention strategies is inhibition of alpha-synuclein oligomerization. We have investigated the interaction of alpha-synuclein and human serum albumin with 3,6-bis-O-di-O-galloyl-1,2,4-tri-O-galloyl-beta-D-glucose (a tannin isolated from the plant Rhus typhina). Using fluorescence spectroscopy method we found that this tannin interacts strongly with alpha-synuclein forming complexes. Circular dichroism analysis showed a time-dependent inhibition of alpha-synuclein aggregation in the presence of the tannin. On the other hand, 3,6-bis-O-di-O-galloyl-1,2,4-tri-O-galloyl-beta,D-glucose had a much stronger interaction with human serum albumin than alpha-synuclein. The calculated binding constant for tannin-protein interaction was considerably higher for albumin than alpha-synuclein. This tannin interacted with albumin through a "sphere of action" mechanism. The results lead to the conclusion that 3,6-bis-O-di-O-galloyl-1,2,4-tri-O-galloyl-S-D-glucose is a potent preventive compound against Parkinson's disease. However, this tannin interacts very strongly with human serum albumin, significantly reducing the bioavailability of this compound. (C) 2017 Elsevier B.V. All rights reserved.