Identification of bioactive peptides from a Brazilian kefir sample, and their anti-Alzheimer potential in Drosophila melanogaster

Abstract

Alzheimer’s disease (AD) is the most common form of dementia in the elderly, affecting cognitive, intellectual, and motor functions. Different hypotheses explain AD’s mechanism, such as the amyloidogenic hypothesis. Moreover, this disease is multifactorial, and several studies have shown that gut dysbiosis and oxidative stress influence its pathogenesis. Knowing that kefir is a probiotic used in therapies to restore dysbiosis and that the bioactive peptides present in it have antioxidant properties, we explored its biotechnological potential as a source of molecules capable of modulating the amyloidogenic pathway and reducing oxidative stress, contributing to the treatment of AD. For that, we used Drosophila melanogaster model for AD (AD-like flies). Identification of bioactive peptides in the kefir sample was made by proteomic and peptidomic analyses, followed by in vitro evaluation of antioxidant and acetylcholinesterase inhibition potential. Flies were treated and their motor performance, brain morphology, and oxidative stress evaluated. Finally, we performed molecular docking between the peptides found and the main pathology-related proteins in the flies. The results showed that the fraction with the higher peptide concentration was positive for the parameters evaluated. In conclusion, these results revealed these kefir peptide-rich fractions have therapeutic potential for AD.

In vitro inhibition of acetylcholinesterase activity by yellow field pea (Pisum sativum) protein-derived peptides as revealed by kinetics and molecular docking

“…A previous work reported the FTIR spectra of AChE with similar result of 35% α-helical and 16% β-sheet fractions (38). AChE has high conformational flexibility due to its spatial arrangement of a pair of four helical structures placed in an antiparallel fashion leaving a large space at the center (15). As a result, the enzyme has increased solvation in aqueous environments, which could be the explanation for the slightly unfolded structure of AChE as observed with the fluorescence spectra (38).…”

“…However, the structure of the enzyme became more compact after interaction with LQHNA, and a higher intensity occurred with the Phe residue at 3.13 µg/ml peptide concentration. A study carried out by Fale et al (15) to determine the interaction between Plectranthus barbatus herbal tea components and AChE showed that only Trp residues contributed to the fluorescence emission of the enzyme. The study also showed that there was no shift in the position of the Trp residues, which means that although the inhibitor interacted very closely with AChE to quench fluorescence, the secondary and tertiary structures of the enzyme may not have been altered (15).…”

“…A study carried out by Fale et al (15) to determine the interaction between Plectranthus barbatus herbal tea components and AChE showed that only Trp residues contributed to the fluorescence emission of the enzyme. The study also showed that there was no shift in the position of the Trp residues, which means that although the inhibitor interacted very closely with AChE to quench fluorescence, the secondary and tertiary structures of the enzyme may not have been altered (15). Another study showed that increasing the concentration of polyphenols from Phyllanthus emblica Linn fruit in interaction with AChE reduced the FI and produced a blue (quercetin and fisetin) or red (gallic acid) shift, which was dependent on the substances involved (35).…”

“…In contrast to other natural products, information from the molecular docking studies of AChE -peptide complexes are scanty. Malta et al (15) reported molecular docking analysis of the interactions between Kefir's bioactive peptides and ADlike flies' model. The three-dimensional structure and molecular docking were predicted using nine peptides and result showed that peptide VYPFPGPIPN was the best ligand for human AChE binding at the PAS.…”

Consumption of the cell-free or heat-treated fractions of a pitched kefir confers some but not all positive impacts of the corresponding whole kefir

“…For instance, the exopolysaccharides produced by kefir specific microorganisms have been shown to have anti-obesity and immunomodulatory activity ( Vinderola et al, 2006a ; Lim et al, 2017 ), while cell-free fractions of kefir have also been shown to have immunomodulatory, lipid lowering, and anti-cancer effects ( Vinderola et al, 2006b ; Gao et al, 2013 ; Santanna et al, 2017 ). Additionally, kefir peptides and peptide fractions have been shown to have a wide range of health impacts including reductions in hyperlipidemia, atherosclerosis, improved neurological function, and reduced non-alcoholic fatty liver disease (NAFLD) risk ( Quiros et al, 2005 ; Chen et al, 2016 ; Tung et al, 2017 , 2020 ; Malta et al, 2022 ). There is also some evidence that kefir or kefir components may improve factors associated with atherosclerosis and cardiovascular disease (CVD) development, both of which are associated with obesity and hyperlipidemia ( Santanna et al, 2017 ; Tung et al, 2020 ; Ghizi et al, 2021 ).…”