Alzheimer's disease (AD), a form of neurodegenerative disorder characterized by the accumulation of amyloid-β (Aβ), hyperphosphorylated Tau, and neuroinflammation. The increasing population affected by AD urges for the development of effective treatments. The correlation between AD and gut microbiome remains underexplored, potentially providing a better understanding of the disease. Salvianolic acid A (Sal A) and salvianolic acid B (Sal B) are the active components extracted from Salvia miltiorrhiza (Danshen), and their antioxidant, anti-inflammation and Aβ inhibition activities were shown previously. In this study, these compounds were used to investigate their effects on Aβ toxicity, using Drosophila melanogaster expressing human Aβ42 as the model organism, by examining their lifespan and changes in gut bacterial communities. The study used two batches of flies, reared on food with or without methylparaben (MP) supplementation to evaluate the influence of MP on this animal model during pharmacological studies. MP is a common antimicrobial agent used in flies' food. The treatment of Sal A prolonged the lifespan of Aβ-expressing flies reared on MP-supplemented food significantly (P