Anthocyanin as a therapeutic in Alzheimer’s disease: A systematic review of preclinical evidences

The aim of this systematic review is to ponder the possible mechanism of action of anthocyanin in Alzheimer's disease (AD), to prompt the development of anthocyanin-based dietary supplementation or therapeutic intervention for AD and to explore the natural sources of anthocyanins.Electronic bibliographic databases such as PubMed, ScienceDirect, Proquest, DOAJ, Scopus, and Google Scholar were searched for preclinical studies probing the efficacy of anthocyanin on AD. The search strategy included no time limit, but was restricted to English. The review protocol is registered on PROSPERO, registration no. CRD42021272972. The systematic review followed the PICO approach for inclusion of reports. All the reports were appraised for risk of bias using the SYRCLE's RoB tool.Bibliographic details of the article, animal strain/weight/age, induction model, anthocyanin source, type of anthocyanin, dose, route of administration, duration, and the outcome measures were extracted from 12 retrieved reports explicitly. The implication of food-based anthocyanin in acute and long-term cognition and Aβ mediated neurodegeneration appears alluring. Majority of the studies comprehended in this review had moderate methodological quality.Efficacy of anthocyanin in alleviating oxidative stress, reactive astrogliosis, cholinergic dysfunction, apoptosis, synaptotoxicity, neuroinflammation, tau hyperphosphorylation, dysregulated membrane potential, neuronal extracellular calcium, dysfunctional amyloidogenic pathway, and cognitive deficits in various rodent models of AD is manifested compositely in 12 studies.