Fig. 1

Postbiotics inhibited Cu²⁺ and Zn²⁺ induced aggregation of Aβ-40. The disaggregation assay began with incubation of Aβ-40 (40 µM) with metal ions ([Cu²⁺] = 25 µM; [Zn²⁺] = 25 µM) at 37 °C for 1 day with gentle shaking, then appropriate postbiotics were added at the above doses: ([FRAMELIM®] = 10 and 100 µg/ml; [Bifidobacterium longum lys.] = 10 µg/ml; [Lactobacillus acidophilus lys.] = 10 µg/ml). After 1 day of further agitation, both UV/Vis spectral analysis and ThT fluorescence assay was performed. A FRAMELIM® inhibited Zn²⁺-induced aggregation only at dose of 100 µg/ml, whereas B Cu²⁺ induced increase in ThT fluorescence was much smaller compared to the effects of Zn²⁺ ions indicating limited aggregation. Cu²⁺ enhanced β-sheet aggregation was only slightly altered by FRAMELIM®. C FRAMELIM® at both dosages basically modulated the absorption pattern of Zn²⁺-induced Aβ-40 aggregates. D For Cu²⁺-induced Aβ-40 aggregation a minor modulation in the absorbance in the range of 190–200 nm by FRAMELIM® is observed. E Bifidobacterium longum lys. and Lactobacillus acidophilus lys. strongly reduced aggregations at dose of 10 µg/ml in the presence of Zn²⁺ ions. F Similar results were observed in the case of Cu²⁺ ions: both postbiotics were very effective in inhibition. G Both postbiotics basically modulated absorbance pattern of Zn²⁺-induced Aβ-40 aggregates. H For Cu²⁺-induced Aβ-40 aggregation, a slight modulation of absorption in the 190–200 nm range by postbiotics is observed, similar to FRAMELIM®