In this work, RLWPF (Arg-Leu-
Trp-Pro-Phe) and VLRLF (
Val-Leu-Arg-
Leu-Phe) were investigated for the effects against
D-galactose (D-gal) induced
cognitive impairment by modulating the gut microbiota composition. The effects on serum metabolite production were further investigated. The two novel
peptides derived from walnut
protein alkaline protease hydrolysates were predicted by docking to
acetylcholinesterase (AChE) with the highest binding affinities, -10.3 and -9.9 kcal mol-1, considered as the potential neuroprotective
peptides. In behavioral experiments, RLWPF and VLRLF treatment significantly restored spatial learning and memory impairment induced by D-gal. The results showed that RLWPF and VLRLF could alleviate
cholinergic dysfunction, oxidative stress, and
inflammation to varying degrees caused by D-gal-induced aging. Furthermore,
16S rRNA analysis revealed that RLWPF and VLRLF treatment improved
cognitive impairment by regulating the composition of the gut microbiota and the abundance of harmful bacteria, including the ratio of Firmicutes to Bacteroidetes, Helicobacter, Allobaculum, Alistipes, Mucispirillum, and Odoribacter. In addition to the same regulation, RLWPF and VLRLF had their marker and regulatory flora. Studies based on the gut microbiota would allow a better understanding of the
neuroprotective effects of walnut-derived
peptides, supporting that walnut-derived
peptides could be potential functional ingredients in foods and nutraceuticals or
drug candidates in the treatment of
cognitive dysfunction.