Combinations of polyphenols disaggregate Aβ1‑42 by passing through in vitro blood brain barrier developed by endothelium, astrocyte, and differentiated SH‑SY5Y cells.

Disaggregation of amyloid βeta (Aβ) is considered as one of the promising therapeutic strategies for Alzheimer's disease. Polyphenols are promising molecules for the disaggregation of Aβ. However, in order to find a potential therapeutic candidate, the in vitro analyses need to be performed on a model that mimics the blood‑brain barrier (BBB) as much as possible. Therefore, we aimed to establish an in vitro BBB representative transwell system by using differentiated human neuroblastoma (SH‑SY5Y), cerebral microvascular endothelial, and astrocyte cells to investigate transition and Aβ disaggregation capacity of punicalagin (PU), ellagic acid (EA), epigallocatechin gallate (EGCG), gastrodin, and their combinations on the established system. The efficiency of the established transwell systems was evaluated by measuring the transendothelial electrical resistance (TEER) and paracellular permeability coefficients (Pe) values. The transition and Aβ disaggregation capacities of the polyphenols were evaluated in the established tri‑culture transwell system based on obtained TEER (50,07 Ω.cm2) and Pe (65x10‑6 cm/s) values. Our results revealed that all polyphenols can successfully pass across the BBB system and disaggregate Aβ. While Aβ disaggregation capacities of the polyphenols were in the range of 30.52-45.01%, the percentages of their combinations were higher (75% for EGCG‑PU (Com 1) and 64% for EGCG‑EA (Com 2)). Consequently, this study provides the first evidence that Com 1 and Com 2 are promising polyphenol combinations in terms of Aβ disaggregation. Besides, the developed tri‑culture transwell system, containing differentiated SH‑SY5Y cells, may provide a new tool that closely mimics the BBB for basic research and testing of candidate agents.